GREENBULLETMICS.COM

Everything you could ever want to know about the Shure Green Bullet mic and more!

                                            Welcome to GREENBULLETMICS.COM!      

         I have put this site together at the request of friends, and many people who have contacted me for information, advice, or just to get an opinion about harp mics in general over the past few years. It's here to share the information that I have gathered over many years of collecting and researching harmonica mics, and looking for ways to get the tone that we're all looking for by using different mic's, amp's, and other gadgets. I have been collecting and researching harp mics for the past 15 years, getting as much information as I could from various sources, but mostly through collecting, and closely inspecting mics from various periods in time from the early 1940's to present day mics. Much of the information also came from a couple of long time employees of Shure Brothers Inc., whom I would like to thank for their time spent with me on the phone, the info they gave me as they remembered it, and the info they sent to me from the very limited records that Shure kept on most of their early day microphones. I would also like to thank Rick Beall from bluesharp.org for helping me to share info and providing a link to me for anyone wishing to contact me for whatever reason. After all, what good is information if you keep it to yourself and don't share it?
            As many of you may have already figured out through the name of this website, the info on this site will pertain mostly to vintage Shure microphones, mainly, the Shure 520, otherwise known as the “Green Bullet”. I will also give some info on the early Shure crystal mics, and touch briefly on a couple of the Aststic Corp. mics, and, a few mics from other companies as well.
           Before we get into it, a bit of info about myself. My name is David K. I was born and raised in Upstate, NY where I still reside. I consider myself lucky to reside in a city that has such a great number of blues fans, and a wealth of local blues bands that consist of musicians whom are without a doubt, talented enough to be on the national blues scene on their own. A few local musicians have made it to be part of nationally known blues artist’s bands such as Carey Bell, Savoy Brown, The Nighthawks, William Clarke, and others. Others have toured Europe and other countries on their own. To get a taste of the talented central NY blues scene, pick up a few CD's from local CNY blues artists such as, The Kingsnakes, Built for Comfort, Roosevelt Dean and the Spellbinders, Kim Lembo & Blue Heat, Tom Townsley & the Backsliders, Phil Petroff & the Natural Fact, The Dirty Pool Band, Ron Spencer & Jumpstart, and other CNY bands. Email me for info on how to get them. Many of these great bands were recorded at a local recording studio, "Blue Wave Records" of Baldwinsville, NY. With all the search engines available today, I'm sure you can find these artists CD's without much trouble. 
These bands ALL consist of professional talent, and are well worth seeking out to add to your blues collection.
          I started playing harp when I was about 15, listening to stuff by J.Geils, The Allman Bros.Band, which is one of my all time favorite bands, Southside Johnny, and a lot of southern rock before I really got into the heavy blues bands. I didn't start playing amplified harp until I was in my early 20's when I could afford to buy the stuff needed to do so. I was intrigued by the gritty Chicago blues harp tone heard in many old and new blues recordings, and thus started my investigation I guess you could say, into finding out how they were getting these incredible sounds out of a simple 10 hole diatonic harp.
         My first mic was a Mexican made Shure 520D, and my first amp was a Fender Champ. Like many beginners, I thought that the right mic and a tube amp was going to give me this great tone that I was hoping for. Well, it helped, but I quickly found out that playing ability and technique are just as, if not more important to getting good tone. So like many others, I started to try different mics and amps hoping to get good tone. This is about when I started researching and collecting mics. I quickly became infatuated with my new hobby of vintage mic collecting, and since I liked the Shure mics the best after trying many of the more traditional and funkified harp mics, I decided to do most of my research on the Shure 520, "Green Bullet" mic.
        OK, let's get to the good stuff, but first let me say this. Most of this info was obtained from documents, and or information given to me years ago by a couple of very helpful Shure Brothers employees whom have been with Shure for 35+ years, and have since retired from the company. All the info given is correct to the best of my knowledge, but I can't say that all the information is 100% fact because there is no written info, or records kept by Shure to back it up. So, given that, take this info for what it's worth, with a grain of salt, but it is the result of many years of collecting information and the microphones themselves from various periods in time.                                                         
                                      THE HISTORY of the "GREEN BULLET"
 
                                                                        
            The Different Models
          The Green Bullet mic, also known as the model 520, was introduced in mid 1949 by Shure Brothers Inc. of Chicago, ILL. It was intended for use as a high quality, moderately priced microphone to be used mainly as a communications, recording, and public address microphone. It became popular with ham radio operators as well as commercial use as a dispatch mic for police, fire, and other commercial dispatch uses, as well as military use. The mic was tailored for good speech response, and was made to withstand temperature extremes, and to be practically moisture proof. It is unaffected by weather extremes and salt spray making an ideal choice for coastal areas. The mic was offered in 1950 with a stand and a handle with a built in "squeeze to talk" handle, which was known as the model 520SL. It was the exact same 520 mic with a built in desk stand and a squeeze to transmit switch. Shure also introduced a medium impedance mic, model 520SLB in 1961, which was meant for use where a long cable was needed between the transmitter and the microphone. The 520 mic without the stand was also available as a medium impedance mic called the 520B in 1952.
            IMPEDANCE is a measurement of a microphone's resistance when certain voltages are applied to it and is measured at certain frequencies. It's a rather complicated formula and is difficult for the average person to completely understand. In just about all instances when it comes to people asking someone with a mic for sale what the impedance of the microphone is in ohm's, what they are really asking for is the DC resistance of the microphone's coil, or in the case of the Shure 520 Green Bullet, the DC resistance of the built in transformer winding. Impedance is often refered to as "Z", such as High Z or Low Z. So just to make things clear, throughout this website, when I refer to "impedance", I will be refering to the microphone's element DC resistance as measured in ohm's. For example, when I say an element has an impedance of 1,100 ohm's, I am refering to the DC resistance with no load or voltage applied to it. This is not the real definition of impedance, but it is what just about everyone is asking about when they ask for an impedance reading of a mic or element.
            The high impedance model's had an impedance (DC resistance) of about 1200 to 1350 ohms in the first few years of production. The medium impedance models were 150 to 320 ohms, but later on in 1961 became available in a 15 ohm model in which the element model was labeled 99C86. The medium impedance models had an element model # 99E86. Over the first 10 years, the high impedance elements had model #'s that were 99A86, 99B86, 99G86, and 99H86, although the first green bullet mic's were made using the model 99A86, and later on in the early 50's changed to 99B86, and then 99G86 in the late 50's. 
           These models were all basically built the same way, with the same materials, although they were used in many different types of mics including mics made for other companies such as RCA, Wilcox Gay, Bell & Howell, General Electric, Revere, and Telectro, to name some of the more popular companies of the day. Shure also made mics for many other lesser known companies, as well as the military. The majority of the mics made for other companies were made for reel to reel tape recorders, console units that had recording capabilities, and mobile or base station radio applications. Not all of these mics incorporated high impedance CR or CM elements. In fact, many had crystal and ceramic elements. The mics carried many different model #'s, way too many to list. The Shure models that came with a desk stand and PTT switch were known as "The "Dispatcher" (models 520SL & 520SLB).


                                                                   
The Controlled Reluctance Elements
          From 1949 to sometime around June of 1958, the microphone elements were called "Controlled Reluctance Transducers". They were described as being a magnetic unit, with its stability assured by unique control of the reluctance of the magnetic system, with good response, high output, and high impedance without the need for an external transformer (1949). It claimed to have a frequency response of 100 to 7,000 cycles per second, or Hz. The list price for a 520 in 1949 was $16.50. In 1959, the price went up to $22.50, and the 520SL had a list price of $45.00.
         Over the first few years of production of the controlled reluctance transducers (which I will refer to as "CR's" from now on), Shure experimented with different materials, but only minor changes were made. The construction of the element remained the same, but they used different glues to secure the metal foil diaphram to the center pin of the magnetic armature assembly, and also experimented with different sized windings on the built in transformer. In the very first few years of production of the CR element's, Shure used a plain black piece of cloth tape with the model # and date code stamped on the tape with silver ink as the elements label. Sometime around early 1954, Shure started to use a white label with the patent #'s and other information on the labels with the model # and date code stamped in red ink on the label.
          It appears that Shure started making the windings smaller over the first several years, thus reducing the impedance readings slightly. An improvement was also made to the magnet holder assembly making it much easier to assemble by switching from a 4 piece magnet holder, to a 2 piece magnet holder. I've seen 1949 elements with impedance readings close to 1,400 ohms, and it seemed that over the first 6 or 7 years, the readings consistently went down and settled at about 1100 to 1150 ohms in the late 50's. Most of the white labeled CR's will have an impedance reading in this range. From 1960 on, the readings for the high impedance models dropped even further then remained pretty consistent at roughly 1050 ohms. Contrary to some peoples belief's, the impedance reading (DC resistance!) has nothing to do with how "hot", or how much gain the element has, at least not at differences this small as used on this type of magnetic element. There are many other factors that affect the gain and tone of these elements which I will explain in the "ELEMENTS" section of this website.
          The green bullet mic shells were made of die cast zinc, and had a green painted body and a brushed, or "satin finish" nickel plated grille. The very first shells did not have an ID tag on them, but very few without a tag were produced. These were the very first 520's made in mid 1949. The element was mounted in a rubber gasket that had a metal "shield" ring glued into it. The rubber gasket provided an airtight seal around the shell, and around the element itself. Being pressure actuated elements, this helped with the response of the element especially in the lower frequencies.
         Shure also made a few different types of handheld mics using these same element's, but used a different way of mounting it. They put a small plastic cup on the back of these elements and sealed them with tape to provide an airtight chamber on the back of the element to help increase low frequency response. Although some people do use them in the green bullet shells, they did not come that way from the factory and are not needed since the shell itself makes for the airtight chamber behind the element provided the mic has the proper gasket in it.
  
        I'm not exactly sure when they were added, but I do know that the 1950 models did come with a 39K carbon composition resistor across the leads of the elements. The 1949 models did not, at least the very first ones didn't. I was told by the guys at Shure that this resistor was put on to roll off some of the high frequencies. From what I've seen, most harp players like them better with the resistor removed. Also, sometime in I believe late 1949, Shure began to put a metal tag on the shell with 2 small pins to secure it to the shell. The very first tags had the lettering embossed in silver, and the background of the tag was painted the same shade of green that the shells were painted. I have only seen this type of tag on models that were dated 1950. I have only seen one 1949 model in green, and it had no tag, or holes to mount the tag. The only other 1949 model I've seen is one that I own, which I believe is a rare introductory model made for Shure management or employees upon the introduction of the model 520, or something of that nature because I have never seen another like it. Its shell is all brushed nickel, and is the old 40's style smaller version of the 707A style shell, which as far as I know, was never used to make any production models of the 520. The smaller version shells were used only for older Shure crystal mics such as the early 707A's, and 7A's as well as the all brown bullet mics with the "Specially Designed for Recording" tags on them.
           The crystal mic shells had no small vent holes in them as do all the 520 mics. I'll have pictures of all the different mic's and element styles later on including the rare 1949 model I own. The CR elements first used in the 520's had a black tape label over them with the elements model # and date code stamped in silver ink on them. There are a bunch of different model #'s on these elements which we'll get into later, but the very first model # used in the 1949 model 520 had 99A86 stamped on it with an obvious date code that looked like this for example: "10-49", stamped right beneath the 99A86. All of the 1950 models that I've seen are also very obviously dated in the same fashion. I believe it was in 1951 that Shure went to a date code system using a 3 digit date code beneath the model # on the element. In 1961, Shure went to a two letter date code system. (More on element dating later).
                                             
                                                                    
          There seems to be some big hype about the black label CR's these days that really, I think, is just that, hype. Granted, they do sound great, but so do the white label CR's and CM's (controlled magnetic transducers). I really wouldn't go so far as to say that they are superior tonally than the white labeled CR's, or even the CM's. Generally, CR's tend to be slightly grittier sounding than CM's, due I believe to the metal disc that is glued to the foil diaphram. Other than that, there is no difference in construction of the CR's as compared to the CM's. The black labeled CR's are more resistant to the heat of a soldering iron since they have a phenolic bobbin for the built in winding (transformer) which also supports the main leads of the element which do get hot enough to melt the plastic bobbin's used on the white labeled CR's and CM's. If this happens, the main leads can become loose or may melt right through the plastic bobbin and become detatched from the bobbin if you're trying to pull a wire off the element lead that is wrapped around the loop at the end of it. Many mics were made with the wires connected to the element wrapped around the loop. If you happen to have an element like this and you're trying to remove those wires, it's best to clip the wires as close as you can to the loop with wire clippers without cutting into the looped end of the main leads of the element. Then heat them again and remove the remaining wire as quickly as possible. It's a good idea to have a small wet sponge available to quickly cool the element leads once the loop has been cleaned, or when attatching the leads to a mic shell.       
          The black CR's are tonally about the same as the white ones. As I mention many times throughout this site, this type of element, because of the way they are constructed and the way they work, will sound different tonally from one to another even if they are of the same model # and even the same date code. However, sometimes you'll come across one or two elements that stand out from all the rest. This goes for all types of this element from the black CR's to the Mexican made CM's. When you happen to find a really good black CR element, they do have a fantastic tone and really strong output. They may be slightly stronger in gain and may have a very strong mid presence which is a bit stronger than a good strong white CR or CM, which I think is why some people rave about them. However, finding one like this is not so easy. A very small percentage of them stand out from the rest and they are not easy to find these days. In my opinion, an average black labeled CR is about as good tonally as an average white labeled CR. Keep in mind that they all will differ in some way from one to another, so if you find one of a certain model that sounds outstanding, don't expect all others with the same model # to sound just as good. Their model #'s really have nothing to do with how they sound as long as they are of the same impedance. There are many different factors that determine how these elements will perform which I do mention later on.

          The black labeled CR's were made from mid 1949, up until some time in late February, or early March of 1954, when Shure started using a white label with the Shure name, model # and patent #'s as well on them. The black labeled elements had a small white sticker on the side of the elements with that same info on them. These elements were all made with a transformer bobbin made of a phenolic material that could withstand a lot of heat. This was a great design that kept the main element leads in place because the phenolic bobbin also supported them.
          At about the time the company changed to the white element labels, they also switched from using the phenolic bobbin to a plastic bobbin. The plastic material cannot handle much heat before it starts to melt, which did nothing to improve the quality of the elements, but were likely much cheaper to produce. There is really no other logical reason to switch to the plastic bobbins other than to cut the cost of production because the phenolic bobbins would not melt and cause the lead wires of the element to become loose, or possibly detached from the bobbin itself. The elements were still being called controlled reluctance transducers when the label change was made in early 1954. Although almost all the white labeled CR's you'll see have a plastic bobbin, some white labeled CR's with a phenolic bobbin were produced, although they are not common. White labeled CR's with the phenolic bobbins were only made for a couple months.
          The white labeled CR's were used in the green bullet mics up until roughly March of 1958, usually with a model # of 99G86 before Shure started calling the elements "Controlled Magnetic Transducers". The difference between the early black labeled elements and the white labeled elements is minimal as far as tone goes. There were physical differences such as the phenolic bobbins, and the magnet holder assembly which was refined over the years. Electronically, the early black labeled elements had slightly larger transformer windings, which is why the elements in the fist few years of production had slightly higher impedance readings. This didn't make them tonally any better than the later white labeled elements or any higher in gain. As I mention throughout the text on this site, all these elements will differ tonally from one to another based on many different factors. However, if you happen to come across a black labeled CR that really stands out from the masses of all the others, it's likely to be one of the hottest, best sounding elements of this type that you'll ever use, but coming across one like this is not a common occurrence. Why this is I really can't say for sure. It may be something to do with the magnet assy, the armature gap or something of this nature. You could go through 100 of these elements before you find one that really stands out, so don't set out to find one without expecting to spend a small fortune. If you do happen to come across one of these elements, you'll know it right away. If I could compare one to another element, I would say that a really good CR would sound similar to a new 707A crystal, better known as an R7, but the CR's are grittier sounding and don't have quite as good high end sparkle as the R7's, and not quite as good bass response but the mid presence and overall tone, and gain are about the same
.

                              
   
            So you don't get confused with the statement under the black label picture, the 99A86 model # was used in the Green Bullet mics in 1949 only. The 520 was introduced in mid 1949, and the very first 520's had this model in them. They did not have the resistor on them as seen in all the models built from 1950 up until they stopped producing Controlled Magnetic Transducers in 1996. Sometime in late 1949 or early 1950, Shure began putting a 39K resistor across the element leads to roll off some of the high end response. Most harp players like the tone better with the resistor removed. At about that same time, the 520 element model was changed to 99B68. The model 99A86 elements were made well into the 1980's and were used in many different types of microphones. The 99B86 elements were used in the Green Bullets up to the time that they changed to the white label in 1954. The element model was then changed to 99G86 and was used up until sometime in late 1958 or early 1959. Most of the white labeled CR elements used in the 520 were labeled 99G86. When they started labeling them as Controlled Magnetic Transducers in 1960, the model number was changed back to 99B86. Physically, there is no difference between the 99B86 and 99G86 models. The 99A86 models are identical physically as well, but the negative lead on the element is not grounded to the body as it is on the 99B86 and 99G86 models. Why this was done I don't know. They all sound about the same tonally, and there are no ground hum problems with any of the models that are not grounded.

                                        
                                            
Typical white labeled Controlled Reluctance Transducer


                                     

                                         
1958 and 1960 Controlled Magnetic Transducers

 
                                                                     CR-CM, What’s the Difference?
           In mid 1958, Shure changed the description of the elements and started calling them "Controlled Magnetic Transducers", which I'll refer to as CM's. The model # was also changed to 99B86, from 99G86. The two models were identical in construction for the most part, but the metal disc in the middle of the diaphram was no longer being used. They were described as being, "pressure operated units using the balanced armature, controlled magnetic principle". They were also described as having a high output level, smooth response, and a semi-directional pickup. Frequency response remained the same as the early CR's at 100 to 7,000Hz.
           The only physical difference between a CR and a CM is that the CR's used a small, cymbal shaped metal disc to glue the foil diaphram to the center pin of the magnetic armature assembly, whereas the CM's simply used a small blob of white glue that hardened like modern day epoxy. I would imagine that it was some type of epoxy glue that they used in place of the small disc being glued to the diaphram, that wasn't available previously. The glue used on most of the early black labeled CR's, these days tends to become brittle and will often come loose from the foil diaphram making the element sound weak. This is something that I see often and it can be repaired if done carefully without damaging the diaphram. The only other thing that I know of that is different from the CM's is the location of the transformer wires where they come off the transformer and head over to the copper lead wires. I doubt this has any affect on the tonal qualities of the elements. The metal disc found on the CR's on the other hand I would think would have some affect on the tone, being that it's right on the center of the diaphram. What affect it has if any I really can't say for sure, but it seems to be that the CR elements have a slightly raspier tone to them than the CM's. The CM's have a blob of glue in that exact spot and probably has the some affect as well, whatever it may, or, may not be. I can say this with confidence, I've had many CM's that sounded as good as any CR, but a bit less raspy.
           The tonal qualities of both CR's and CM's will vary from one to another in one way or another. Most of the time, the tonal difference will be very minor, but other times it can be drastic. It's due to the nature of the beast. In other words, it's due to the materials used, and the way they are made and work, (more on the way they're made later) but they generally all have the same flavor if you will, just that some will sound a bit different than others, even those that have the same model # and date code. This is more often seen in the oldest elements these days because of age deterioration, and corrosion that can form under the magnet assembly which knocks the armature out of alignment. The magnets themselves can also loose strength if exposed to strong magnetic fields too, (from being stored inside amp's with big ceramic magnets) or many drops to the floor, which will also make a magnet go weak and will affect the performance of the element.

  
                                                        THE LATER YEARS 
                                                                       
The Different Shell Tag's
           In 1961, Shure had pretty much settled on the winding size, keeping the impedance at somewhere near 1050 ohms. Over the past 5 or 6 years, Shure changed the appearance of the tags that were used on the shells. After the first tags that were the same green color as the shells, they changed the tags to a deeper sort of "Hunter Green". The lettering was still embossed on the tag. Shure made a move from Chicago to Evanston, ILL sometime in 1956. It was during this period in time that the deep green colored tags were used. You will find them with both Chicago, and Evanston,ILL on them, which can help clue you in onto when a mic was made. I suspect that Shure started using the deeper green embossed tags shortly after 1950. A large majority of the CR tags are the deep green color rather than the same shade of green that the mic shell was painted. When Shure made the change of names from CR to CM, the tags changed again as well. The tag no longer had embossed lettering. They were a deep, sort of emerald green color with the same information on them as the old tags, with the model # and impedance stamped in the blank boxes .
         In 1970, Shure began production of the 520D, which is a dual impedance microphone. The very first 520D's were made in Evanston, ILL. The green tags were still used for these mics but Shure now was putting a serial # in the box on the tag where the impedance used to be. When Shure move production of the 520D to Mexico, the appearance of the mic tags was changed to the silver tags with black lettering that are still being used on the newest version of the green bullet mic, the 520DX, which
is still being used today                                             
  
                                                                 The 520D 
                                                                             
The Dual Impedance Model
           In 1970, Shure designed a dual impedance controlled magnetic transducer, and began to use them in the green bullet mics which were now being called the 520D. The element was labeled as model 99S556. The first 520D's were made in Evanston, and for the first time, the tags now incorporated a serial # where the impedance used to be stamped. The tags were still the dark emerald green, smooth surfaced, and basically the same as the previous tags, except for the serial #. The grille's on the US made 520D's have a brushed nickel finish just like the older 520's, and the shell's were exactly the same color as the 520's as well. The Mexican made 520D's were painted a slightly darker green and didn't have a glossy finish like the US made models, and the grille's were no longer brushed nickel, rather they were painted silver giving the 520D a whole new look. I don't know exactly how long the 520D's were made in the US, but judging from the very few that you see around these days I would think that not very many were made in Evanston before Shure decided to retool the factory and get rid of the 1940's machinery still being used to make the elements, then contracted the work out to a Mexican plant. So my guess is that shortly after 1970 when the 520D was introduced, the dual impedance CM elements being used in the green bullet mics were now being assembled in Mexico with US made parts. If you have an American made 520D with a readable serial number on it, I would like to know what that number is and the date code on the element. Please send me an email along with a picture of it if you can. I can't post information that I can't confirm. I'd like to see how high the number's will go.
             I have seen quite a few elements with labels that said "Made in the USA", with the "Made in the USA" blackened out with marker and a stamp on the side that says "Assembled in Mexico". I guess they wanted to use up what labels they had left before changing them to a new, totally different looking label. The tag on the shell was also changed dramatically. They were no longer green at all. They changed it to a silver aluminum tag with black lettering, the same as the present day 520DX tags but of course without the X. 
          I have heard many people say that the CM elements made in Mexico are inferior to the US made counterparts, but I have played many of them and can tell you that this simply is not true. In fact, my first 520D had a Mexican made element and it is just as strong, and has just as good tone as the vintage elements I'm used to hearing. I've had many, and played quite a few of other peoples Mexican made CM's and I can't say that they're inferior at all. To me, I would say that they may be a bit brighter sounding, but not so much that they sound like a whole different element. Take into consideration that they all will differ tonally in one way or another too, no matter where or when they were made. I have heard some fantastic sounding Mexican made CM's that could pass for a good CR even to someone familiar with these elements. So do not judge your mics by where they were made. Use your ears, not your eyes!

           I'm not sure if it was in 1980 or later that Shure stopped production of the 520D in the US. There is a Shure web page that indicated the 520D being made from 1985 to 1996, but I know that the first 520D's were made in Evanston, ILL. I would have to believe that this would indicate the 520D production in Mexico, because the 520D's made in the US were being made in 1980. The one that I have is dated August 1980 and was made in Evanston. Its serial # is 511. I do not know how many 520D's were made in the US, but it appears that production of the 520D did stop for a period of time until production was
resumed in 1985 in Mexico until 1996.


                        
                                         AMERICAN AND MEXICAN MADE 520D's
                                                            
                                                             
The 520DX
           In 1996, Shure began production of the newest version of the green bullet which is now the model 520DX. This microphone, according to Shure, is based on the old 520 we all know and love. The mic now came with a built in volume control in the stand hole, and a whole new element. Unfortunately, the 520DX does not quite stand up to the older green bullets tone. The new mic is a whole different animal. The 520DX has a dynamic element made with a plastic diaphram with a large plastic housing mounted behind it, and a transformer mounted to it with high and low impedance hookup leads. It claims to have a frequency response of 100 to 5,000Hz. Its tone is much cleaner than the metal foil diaphramed CR and CM elements, and just doesn't have the bite and grit of a vintage green bullet element.
          I wouldn't toss it in the trash though, it's better than many of the so called harp mics out there today. It does have a tone that is usable for blues players who don't want that much grit, or for certain styles of music other than blues. Many guys do like the mic and having the volume control, but as you probably already know, a volume pot can be put onto just about any type of harp mic. The pot that comes with the 520DX is not exactly what I would call a high quality pot. It's very small, sealed, and does get dirty even though it is a sealed unit and can't be properly cleaned. I've replaced quite a few of them because of scratchy noises heard when turning the control. .Other than this, I can't say much about them because I don't use one at all. I believe they are still being produced today. In case you're wondering, they can easily be converted to accept a vintage CR or CM element to turn it into the real deal.
 
                                                                      
The Popular Shells & Crystals
          There are very many different mic shells out there today that make for great harp mics. The most popular are the Shure green bullet, the Astatic JT30, and the Astatic model 30 better known as "The Biscuit". These three mic shells will accept just about any element you want in them including the vintage Shure CM and CR's. The Astatic mic's were mostly crystal mic's, but some used ceramic elements, of which both have more of what I consider to be a "tinny" tone to them, and lack bottom end. They have an extended high end which really doesn't help much if you have no bottom end, and this will increase amplifier feedback at higher volumes.
         There are however some very good sounding crystal mic's out there that do have a big fat bottom end. Most are older crystal's, MC151's from the 70's and 80's, and the best crystal's ever made in my opinion, the Shure 99A94,99B94, and 99A47 which are the later versions of the 99-131 crystals used in the 707A mics made from 1940 to 1970. These crystals are better known by their Shure replacement model #, R7. Unfortunately, these crystals were not made well enough to last, and finding one today that’s still delivering it's full potential is near impossible. There are still some good MC151's around that seemed to hold up over time better than the R7's but as far as I'm concerned, the R7 was the best crystal ever made. It had a big fat bold tone with plenty of grit and punch, with excellent low end as well. They sounded very similar to a very strong, fat sounding CR element, with a more refined high end that is slightly crispier.  
           The drawback to crystal mics is that they are fragile, and cannot withstand moisture and temperature extremes. Leaving a crystal mic locked up in a car on a hot sunny day can kill it dead. Being fragile, I don't think you'd want to leave one out in the cold either. A Shure 520 will be unaffected by any of this. You can pull one out of the freezer and start playing. Heat is no problem for them either, and they will survive numerous drops. Don't expect this from a crystal mic. Don't get me wrong, I'm not downing crystal mic's. The good ones have great tone, you just need to be very careful with them. I own about 6 crystal mics in my collection that all sound very good. It is a good idea for any gigging harp player to have at least 2 different mics to work with, to get different tones, and to have a backup should one fail. A green bullet and a good crystal mic is a great combination.
           As I said, there are thousands of good mics out there that will sound great for harp so look around. You can get a good idea of what’s out there by visiting the vintage mic and amp museum at the
Harmonica Masterclass Company website. You'll see my rare 1949 520 there too! Read more about crystal elements on the "ELEMENTS" page.

                                
OTHER BULLET SHAPED MICS FROM SHURE
                                                                                  
The Early Shure Bullets
          The very first bullet shaped mic from Shure was the model 705A, otherwise known as "The Rocket", because of its streamlined shape and the fins at the rear of the shell. This was a crystal model, and was made in 1938 only. It had a swivel base attached to it like many of the later larger mics.
          In 1939, Shure introduced the model 50, which was identical to the 705A but was a dynamic version of "The Rocket". There were 3 versions of this mic, the 50A, which was a low impedance model (35 to 50 ohms), the model 50B, which was a medium impedance model (200 to 250 ohms), and the model 50C which was a high impedance model of the dynamic version of "The Rocket". This dynamic version of the rocket was made only in 1939 and was an all brushed nickel plated shell like the 705A.
           Some of the other bullet shaped mic's that Shure made starting in 1939 were the Series 5 mic's. These mic's were made only in 1939, and all except the model 5G were made in all brushed chrome. The model 5 mics were all dynamic mics. The 5E being a low Z model (35 to 50 ohms), the 5F was a medium Z model (200 to 250 ohms), and the 5F being a high Z model. The 5G was also a high Z model, but it came in iridescent grey paint.
           The model 7 mics were also made only in 1939. The model 7 mics were crystal mics also known as the "Streamliner". The model 7A was an all satin chrome model. The model 7S came in iridescent grey paint. Both were high Z crystal microphones.
          The model 500 microphones were made in 1940 only, except for the model 500C, which was the high Z model also made in 1941. The model 500 was a dynamic microphone, with the model 500A being a low Z model, the 500B a medium Z model, and the 500C which was the high Z model. All were available in iridescent grey only.
          The model 52, also called the "Econodyne", was also a high Z dynamic model which was made in 1947 only. It came with an all brushed chrome body and grille, and had a very high output. 
          The Shure model 707A was a high output crystal microphone made from 1940 to 1970. There were a few different versions of this mic. The earliest models having the slightly smaller shells. The later versions had the full sized shell. Most were available in either a light or dark grey color with a brushed satin chrome grille. Another of the smaller versioned shelled mics was the model 9822A, and the 9922B. Both of these models were all brown including the grille although some were available with a chrome grille. These were also crystal mics that had a tag on them that said "Shure Crystal Microphone, Specially Designed for Recording". These mics along with the 707A's and other early crystal mics had a very high output crystal element with a huge bottom end. Unfortunately, it's very rare to find any of these in good working condition these days.
          In 1940, Shure introduced the 708A, a crystal mic also known as the "Stratoliner". This mic was not really bullet shaped. It looks more like a miniature "bomb" that you might have seen falling from a plane in WWII. It was made from 1940 to 1958. It came on a stand and really didn't make for a very popular harp mic because of it's size and shape.
         Some of the other bullet shaped mics made by Shure are the model CR41, the CR20, and the 440, which I may have mentioned before. These were just variations of the 520 and all had the full sized shells. The CR41 came in a robin’s egg blue color with a brushed satin grille and were made in the late 50's. The CR20's that I have seen were mostly low Z mic's although I believe there were high Z models. These mics had CR elements in them. The 440's were made from 1960 to 1970, and like the 520 were available as a 440SL and 440SLB meaning that they came with a desk stand with the squeeze to talk handle for dispatch and PA use. The 440's came with the same 99B86 controlled magnetic transducer that was used in the later 520's. They were grey, with the brushed satin grille and had a single larger vent hole in the bottom as opposed to the two small vent holes as on the 520's. Shure also produced various bullet shaped mic's for other companies to use with home console units that had recording capabilities. Two that I know of were RCA and Bell & Howell. These were usually the older, smaller shelled crystal mics.
          Shure also made a full sized high Z bullet mic identical to the 520 for the Stromberg Carlson Co. of Rochester, NY. It had a model number MR-34C on the tag which was silver with a black background. These were made in the early 50's and had the black labeled CR elements in them. You can see some of these other mic's made for other companies in the pictures section
.

 
                                             MICS FROM OTHER COMPANIES
                                                                                                      Turner
          Another company that has produced a few mics very popular with harp players is the Turner Co. Turner produced a few mic's that had fantastic tone for harp, and produced one of the better crystals for harp mics as well. The most popular of the Turners are the CD and CX mic's, which were dynamic (CD) and crystal (CX). The CD has a strong output and very good tone. They had a very good low end, strong mid's and decent high end, although not as gritty as the Shures. The CX has a very strong output with a good bottom end as well as a responsive high end. The mics were available in an all brown, or brushed nickel finish. The all brown mics had different model #'s which were BD, and BX. The CX and CD had the brushed chrome finish. The CX and CD both had a frequency response of 50 to 7,000 Hz, whereas the BX and BD had a response of 50 to 5,500Hz. Why the difference in Frequency response, I don't know. As far as I know they used the same dynamic elements and crystals. Both the CD and the BD were available in low and high impedance versions. They have a rounded grille (high dome), and a fin on the top of the shell that make them hard for some people with small hands to get a good seal on. The fin seemed to be the Turner signature, as many of the older Turner mics also had the fin as well. The CD and CX are also about the same diameter as a green bullet, so they would be best suited for players with hands large enough to handle one of the larger mics, given the high domed grille and the fin.
 
                                                                                    
    Electro-Voice
           Another popular company who made a few mics popular with harp players is the Electro-Voice Co., better known as just EV. The most popular models for harp were the model 605, and 606, which were much smaller than most of the other more popular harp mics in the 50's and 60's. They are both dynamic microphones having a plastic diaphram and a built in transformer. They have high output, a good bottom and mid presence with less high end response and grit than the Shure and Astatic mics. I believe both were available in high and low impedance versions. The 605 seems to be the most sought after of the EV's, likely because of its small, streamlined shape and high output. The 605 and 606 are similar looking except that the 606 has openings on the sides of the mic near the top, probably making it less directional than the 605 which has a small grille opening. These shells seem to be popular with players with small hands as they are much smaller than most of the more popular shells and very easy to hold. Many players will use these shells with their favorite element as they will accept just about any of the more popular elements with a little custom work.
          EV also produced a couple other mics popular with some players but they were too large and hard to handle for most players. They had a large, cumbersome and heavy piece of metal attached to them that housed an on-off switch, and a stand mounting piece that turned a lot of players off. Some guy's had the stand mounts cut off to be able to use them easier and bypassed the switch, but the EV's other than the 605 never really made it big into the harp scene of today, although they were quite popular years ago as vocal mics. There were as I mentioned earlier, so many different companies who made mics that made for great harp mic's. Unfortunately, it's impossible for me to mention all of them out there, (mainly because I don't know about many of them), but you can get an idea of how many different shapes and sizes they came in by visiting the harmonica masterclass website and checking out the vintage mic and amp museum
.


                                                                                   
BUYING CUSTOM MICS
         There seems to be a big influx of so called "harp mic builders" popping up in the past couple of years. I think eBay is partially to blame for this, and all the guy's who are trying their hand at mic building many of who don't even play since it doesn't seem to be so very difficult to the average DIY'er to slap a bullet shaped mic together. Beware of these guy's when looking to buy a quality harp mic. You won't get one from them! If you've been watching, you've seen the prices of these mics with Shure CR and CM elements in them skyrocket these past few years. Some people are buying them and putting together very poorly made mic's with a coat of shiny paint and selling them for $250 to $300 each. Why? Because unknowing beginners are paying big bucks for mics with flashy paint jobs that have Shure elements in them. Many of these uneducated beginners end up with medium or low impedance elements in them that are not properly mounted, as well as mic connectors that aren't properly installed either. Do some homework before setting out to purchase a harp mic and you'll get a good quality mic at a fair price. 
           My strong advice to you is; know exactly who you’re buying your mic from, ask around and get some references. There is a lot more than meets the eye required to build a high quality harp mic. Those of you who have been ripped off know exactly what I mean. There are a few guys out there who are building quality mics, and selling them at fair prices, but there are more guys out there selling junk for big bucks! If you're in the market for a serious harp mic, ask around! Get the names of people who have proven track records. Don't do a Google search on "harp mic's". This is where you'll find most of the junk builders. The good guy's may be there too, but you'll need to find out who they are. Do a search on the HARP-L forum, and ask around for references.
           Most good mic builders will have very few if any mics on hand ready to go. That’s because the guys who know what they're doing make mic's to order, and will guarantee them. If you find a site that has all kinds of mics available, all with flashy paint jobs and high prices, keep looking. Chances are the sellers are painters, not mic builders. Most of these guys wouldn't know a hot CR from a half dead one! You're better off taking a chance buying an element on eBay.
           I have noticed recently that there are guy's out there now who are adding transformers to low impedance elements and putting them into shells and selling them as high Z mic's. These mics are being sold on eBay as "high impedance" mics and some are not being described as mics with low Z elements with a transformer installed. Some are actually straight up low Z mic's that aren't described as such etc. They use all kinds of tricky language trying to make you think that you're buying the real deal. Phrases like "the most widely sought after harp mic's", and "the original" or " the granddaddy of harp mic's" and all kinds of other garbage can be found in their auctions. Be EXTREMELY careful if buying a mic on eBay! Find out exactly what is inside the mic and get element model numbers if possible and compare them to the ones on this website to see exactly what they are if you're not sure. Unfortunately, there seems to be some people who have nothing better to do but to spend all day every day on eBay looking for the vintage Shure CR and CM elements. They bid on every one they see trying to win them only to put them back on eBay for a higher price, or they're building crappy mic's and selling them at high prices. This can make it hard to get one at a decent price, but there are still some being sold at bargain prices. You'll have to look hard for them but they are there.
          There are all kinds of sellers getting in on the action on eBay these day's. They will tell you that their mics with the transformers on low Z elements will sound as good as any high Z mic when they have no idea what a good harp mic even sounds like!  My advice is, "STAY AWAY" from these mic's. They WILL NOT sound as good the real deal and I don't care what they tell you! There are also guy's tearing the elements apart now and rebuilding them with rewound windings. As this will boost the impedance, once they have been taken apart, they usually never sound as good as they did before. For one, there is a pin that was either welded or press fit extremely tightly into another part that once removed can never be put back as good as it was, once it has been removed. The elements were also fine tuned for gain and response with special equipment at the factory before being put into microphones. I highly doubt that anyone has the equipment or capability to do this as accurately. There are also other parameters that just cannot be put back to the exact same specs, mainly, because nobody knows what they are. 
         I have rebuilt many of these elements, and have experimented with capacitors, magnets and many other ideas trying to make these things better. The fact is, they are as good as they're going to get if they're in good working order, and once they are taken apart, they'll likely never sound as good as they did before. If that were the case, I'd be doing the same rebuilding and rewinding the elements. The low Z elements that are rewound to be high Z elements will sound better than they did when they were low Z, but they will not sound as good as a good strong high Z element that has never been taken apart. Thats just the way it is and don't believe anything else. If money is tight and you can have a low Z element rewound for $20, then it may be a good option, but personally I would never pay for a rewound element if I could buy a (never rebuilt) high Z element for the same or less money, and this is likely the case.
          I'm not writing this because I want your business, I'm telling you this to save you some money, and probably a big headache and disappointment. I've seen many of the mics that these weekend mic builders are selling because people end up sending them to me, or other reputable mic builders to be fixed. All I'm saying is that if you're looking to buy a quality harp mic, look around, and ask friends and other harp players who might be able to help you find a good mic builder. Go on Harp-L and ask for opinions. You'll be able find the guys who build quality mics very easily with a little effort! Building your own mic can be fun and can save you some money, but if you've never done it, do some research because there are certain things that need to be done right or your mic may not sound as good as it could. Do it right and you'll have a great mic and save a lot of money too. If you need some advice on how to build your own mic you can contact me via email and I'll be happy to help you with any question's you may have about building your mic or any other question's you may have. Just click on the email link at the bottom of any page.o adjusted for optimum performance at the factory with special equipment before being put into mics. I highly doubt that anyone has the capability to do this. These elements will work, but will never have the capability to sound as good as the really good high Z CR and CM elements that are out there waiting to be found. 
   
       
                                           
                                                                                                       
Building Your Own Mic 
          Building your own harp mic can be a fun and rewarding project, whether you build it from vintage parts, or new parts, but it must be done right if you want the mic to work properly. Whatever type of connector you use, it will need to be grounded to the mic shell to keep hum and noise to a minimum. Your choice of element will need to be properly mounted as well, and should be held securely in place with the proper rubber gasket. This is VERY IMPORTANT as it will provide a good airtight seal around the element and the mic shell to prevent air leakage around the element. Most harp mic elements are pressure actuated, which means that the element needs to be sealed properly for the mic to perform as it was designed. If you don't use the proper gasket, you will loose response and the mic will not provide the sound that it's capable of providing.
         Factory mic gaskets for the old Shure CR and CM elements are not available from the company anymore, but you can still get quality custom made gaskets from,
HarpMicGaskets.com. The original owner and I teamed up awhile back and we designed some custom gaskets to be able to use vintage Shure elements in a variety of vintage shells. They also designed gaskets for some of the older crystal elements, and other mics that are impossible to find gaskets for these days. Contact Harpmicgaskets and let them know what you need. If they don't already have it, they'll probably be able to make it. Many thanks Tim and Jeff for all your hard work, and for providing a crucial part for us mic builders to use that wouldn't be available otherwise! NOTE: Harpmicgaskets is now owned by Jeff Spoor, who has taken over the gasket making, and who is also offering his customers custom mic painting services. Jeff is now using a powder coat process which offers a more durable finish in just about any color. Jeff can be contacted at the same harpmicgasket link above if you need a gasket or a new custom powder coat paint job for your mic. Tell Jeff I sent you! 
          Using the right gasket also helps to keep mic handling noise to a minimum, so don't try to make a gasket from a roll of electrical tape, or secure the element with a piece of foam or whatever it is you have in the house. The proper gasket is an important part of a good harp mic that does a lot more than just hold the element in place. A professional harp mic needs a professionally made gasket!
          I also recommend using a high quality mic cable too, whether you hardwire it permanently into the mic shell, or use it with whichever type of connector you choose to use. You may not think it will make much of a difference, but it does. Use the best quality cable that you can afford. Cheap cables made with copper alloys I have seen oxidize, which will make your mic sound as if it's getting weak, when it's actually the cable causing the problem. High quality cables are made of pure oxygen free copper which won't oxidize like the cheaper ones will. High impedance mics require unbalanced, single conductor shielded mic cables (sometimes referred to as coax). Regular guitar or other instrument cables are unbalanced cables, but are available in lots of different forms and qualities. One of the better cables that isn't outrageously priced that I like to use is made by Planet Waves. They are very good quality cables with molded jacks. If you're hardwiring a mic, you'll need to cut one of the jack's off. You will notice that these cables have one end that is shielded and one that is not. If cutting one end off, cut the jack that is not shielded off and make sure that you ground the mic shell properly. There are a few other high quality cables available such as Mogami and Klotz, but they can be very pricey and for the money you won't notice any difference from the Planet Waves cables.
         Low impedance mic’s use balanced cables, which usually have more than a single center wire plus the shield. Unbalanced cables usually have a braided shield, which you use as the ground wire, and a single wire in the center of the cable which is used for the positive connection to the element. There are a number of adaptors, and ways to connect to a cable, some which have drawbacks that go along with the advantages like the adaptors that allow you to use a regular guitar cable that just plugs into the mic. While this is a convenient method, the cables have been known to pull out of these adaptors if you happen to step on the cable, or if a band mate stumbles across your cable and out it comes cutting you off in the middle of a solo!
          Personally, I prefer the screw on type connectors using the correct type of screw on cable connector, or the XLR connectors that clip onto the mic's so they won't pull out. Whatever you choose to use, build your mic using the correct parts and build it the right way or you may end up with a mic that doesn't sound half as good as it could.
          When building a harp mic, it is imparative that you use a rubber gasket that fits whatever element you choose to use in your mic to get the best response from it! Most elements are pressure actuated and need to be sealed both around the element and the shell. If air is able to pass by the element into the shell, the element will not give you all the tone that it's capable of giving. Most of the popular elements can be fit into almost any shell using stock gaskets, or, stock gaskets that may need to be customized a bit. If you don't think you can get the proper gasket for your project, contact Jeff at the link above for a custom made gasket. The rubber gasket also helps to reduce handling noise picked up by the element, so don't skimp on the gasket. It's one of the most important parts of your mic. Using a rubber gasket is the only way to go. Using tape, or other ways of holding the element in place just won't work as well. Yes, the mic will work, but it won't sound anywhere near as good as it could, and hand techniques will not produce the effects that they otherwise would. Rubber gasket, thats it, or loose out! I can't emphasize this enough. As I mentioned earlier, you may be able to get a custom made gasket at the above link or they may have something that you might be able to use with a little customization. The material they use is very easy to mold and work with, and grinds nicely if you have a grinding wheel to use. Just be
extremely carefull if you try this because they doesn't make any rubber fingers as far as I know!

                                                        Examples of Custom Made Gaskets

                                          
                                                                                           FIG 1a                                       FIG 1b
        Figure 1a and 1b show an Electro-Voice model 605 shell fitted with a Shure Controlled Magnetic element. The gasket was made using a 1/4 in. thick rubber O ring that was flattened out on the outside and on the inside. It was then glued to the element. It was fitted to seal around the shell front and it is held in place by the casting in the front part of the shell that held the screws for the bracket of the original dynamic element, and the diameter of the back part of the shell. This provided for a good seal around the element and the shell for best response, and I didn't have to damage the shell should the owner decide to replace the element with an original EV dynamic element in the future.

                                                
                                                             FIG 2a                                                 FIG 2b
        Figure 2a and 2b show an American Microphone Co. shell fitted with a Shure CM element. The gasket I molded from a copy of a stock Green Bullet gasket made for me by Tim Dougherty. I had to cut a notch in the bottom side of the gasket as shown in Fig. 2a so the gasket would go deep enough into the shell to allow the grill to fit. Again, the gasket seals both the element and the shell as shown in Fig. 2b. The grille seats on the front perimeter of the gasket and the gasket was molded at an angle around the diameter to fit the angled shell. It's very important that any harp mic using pressure actuated elements be sealed around the element and the shell to get the best tone and performance from the mic.

  
         Your mic shell, if made of metal, should be grounded with the braid, or shield of the mic cable if the cable is permanently attached to the mic. This can be done in a number of ways. I like to drill a hole and tap it for a #6-32TPI screw and use some type of a lug that you will screw onto the shell. Most shells have a nub or two inside the shell that you can drill and tap to do this. Grounding the shell will eliminate problems with hum which you may end up with if you don't properly ground the shell.
          If you plan on installing a screw on button type connector like the older JT30's used, it should have a solid metal to metal contact with the shell. I've seen many of these connectors glued into the shell. This won't allow for a good electrical contact, and they usually end up falling out eventually or become loose. Avoid glueing if at all possible. If you must glue it into the shell, first solder a ground wire to the body of the connector, on the inside of the collar that goes up into the mic shell. Then run that wire to a ground lug inside the shell to properly ground the shell. Then run a wire from the ground lug to the element's negative side.
         When I install this type of connector, I drill the hole in the mic large enough to tap with the proper size tap so I can screw the connectors into the mic shell tightly making for a good contact between the shell and the connector. Some connectors have a band at the bottom of the threads that you may need to grind off to screw the connector all the way in. If you attempt to install a connector this way, you must be carefull not to grind too much metal from the side of the hole in the mic shell where a set screw is located if it has one. If you do, you may not be able to use the set screw which you should use. I try not to remove any metal from that part of the hole, and just make the hole larger by grinding the metal from the opposite side of the hole to enlarge it enough to tap. If you install the connector this way, it's not necessary to solder a ground wire to the connector. You can just run the wire from a ground lug inside the shell directly to the element.
          If you plan on using a volume control in your mic, it too must be grounded to the shell. That is, the negative tab of the volume pot that should be grounded to the shell. When using a volume pot, make sure that you have the proper value for the type of element that you're using. For Shure CR and CM's, I like to use 250K pot's, or 100K pot's if no 250K's are available. You can use up to a 500K pot with these elements if you must, but the 250K's work best. I prefer to use linear taper pot's for even and steady control of the volume
.
          If you're using a crystal element, I would suggest that you use a volume pot with as high a value as you can find. I prefer to use 5 Meg Ohm's or higher if possible, but use at least a 2.5 Meg pot for a crystal element. You may have a real hard time finding a pot higher than 5 meg ohm's in value, but the 5 meg pot's can usually be found at electronic's outlets such as Mouser or Allied Electronic's. These work very well for crystal elements. If you use a low value pot with a crystal, you will loose response, especially in the low end, which is something you don't want to loose with a crystal since good ones seem to be getting very hard to find these days.
          No matter what element you use, if you're using a volume pot, use a pot that is made with a conductive plastic element. You don't want to use carbon or graphite pot's with volume controls. They will work, but will eventually cause problems. The conductive plastic pots are smooth and noise free when operating and won't oxidize. When connecting a volume pot, the center or + positive lead from either your mic cable or the connector will be soldered to the center tab of the pot. You will use the two side tabs as the + to the element, and the - negative side to the element. Just make sure that the side you use for the negative is grounded to the shell and the shield or negative lead of the mic cable. You can use either side tab of the pot for the positive and negative element leads, but, if you want the pot to operate increasing the volume if you turn the pot shaft in a certain direction, then you must wire the side tabs with the positive and negative leads in a certain way. If you wire the pot in a way that the volume control operates backwards, simply reverse the two side tabs and swap the negative and positive leads at the pot (not the element), and the pot will operate the way you want it to.


                                                        Wiring Your Microphone
       Wiring your mic properly is crucial to get the best performance from it. It is possible to wire a mic improperly and still have it work. It is very important to ground your mic properly to prevent hum. The shell of your mic, if it's made of metal must be grounded as well. As they come from the factory, the Shure green bullet mic's have the shell grounded via the tension spring where the cable enters the shell. The shielding from the mic cable (the bare outer wire that wraps around the inner wire(s) of the cable is soldered to the upper part of the tension spring that enters the mic. The spring has a wire (usually gray) that is soldered to the top of the spring as well and it is used as the ground wire to the mic element. This way of grounding is a poor design which usually ends up with frayed ground wires inside the spring which causes the mic to crackle, or stop working completely after a while. If you have a mic that sometimes cut's out or is noisy when you move the cable around at the mic, this is usually the problem and the mic will need to be rewired.
      When wiring a mic, I prefer to strip about 5 inches of the cable end then twist the bare wires together. Then run the wires from the cable up through the spring as far as it will go and then insert it all into the mic shell. I drill a small hole with a 7/64" drill about 1/4" deep into one of the 2 nub's cast into the shell on the inside. I then tap it with a #6 X 32 tpi tap and install a ground lug using a quarter inch #6 x 32 screw. A short sheet metal screw can also be used if you don't have the tool's to tap the hole. I then solder the braid from the cable to the ground lug along with a short wire to use to ground the element (and pot) as well. If the mic has a volume pot, I'll run the wire from the ground lug to the negative side of the volume pot. Grounding the mic in this manner will prevent the shield from fraying inside the spring and provide a much better ground for the mic and shell.
              Holding an element with the terminal's up, and closest to your body, the terminal on the right will always be the negative, or ground terminal. The terminal on the left side will always be the positive terminal. With the 520D elements, you can actually use either one of the two terminals that are on the same side as the positive terminal, but as they come from the factory, the lower terminal is the one used for the positive terminal. If it hasn't already been removed, there will be a 39K resistor soldered to the positive and the negative terminals of the green bullet mic's. It is there to roll off some of the high frequencies to make for better speech reproduction. Most harp players prefer to remove the resistor to allow for the higher frequencies. There really is not a big difference with the resistor removed and some people can't tell much of a difference at all.
       Soldering wires to the elements that have plastic bobbin's must be done very quickly or the bobbin will begin to melt where the terminal enters it. Unless you have a black label CR, or one of the few white label CR's that has a phenolic bobbin, your's is plastic. It's a good idea to use soldering flux on the wire's and the terminals before making the solder joint. Tinning the end of the wires is a good idea too. This will help to make the solder flow onto the terminal fast and to make a better joint. Do not keep the iron on the terminal's for more than 2 seconds or the bobbin will begin to melt. If the solder doesn't take quickly, let it cool off before attempting to solder it again and add some more flux to the parts.
       When using a volume pot, you'll see that it has three terminals. The center terminal will be used for the positive wire coming from the mic cable. The remaining two terminals are used for the positive and negative wires going to the element. Either terminal can be used for the + or the negative side. How you wire it will determine which way the volume control will work. One way will make the volume increase if you turn the shaft in a clockwise direction. Reverse the wires and the pot will work increase volume if you turn it in a counterclockwise direction. Whichever way you wire it, the terminal that you use for the negative side must be grounded to the shell's ground lug as well as the negative side of the element.
         The diagrams below show how the Shure 520D is wired using a standard 1/4" mono phone jack and an XLR connector as shown on the sheet that comes with the microphone's. Actually, on the sheet that comes with the mic, the lower terminal is shown as being the positive terminal, but either one of the two that are on the same side can be used as the + terminal. As you can see, the element has two terminals on one side and only one on the other. The 520D is a dual impedance mic, thus the extra terminal on the positive side. The straight up high and low impedance elements have only one terminal on each side. 
        To wire the mic for low impedance, you will use only the two terminals that are on the left side of the element as shown in the top figure. With an XLR connector, pin 1 is the ground (shield from mic cable), pin 2 is the positive (red wire), and pin 3 would get the black wire from the cable that comes on the Shure 520D. NOTE: Pin 1 and pin 3 should have a metal clip on the pin side that shorts pin's 1 and 3. If it doesn't, solder a piece of wire to connect pin's 1 and 3 to achieve the proper ground. When using an XLR connector wired for high Z with a mic such as a Hohner Blues Blaster or a CAD HM50, pin 1 is used for ground, and pin 3 is used for the positive connection. In this case, do not short pin's 1 and 3, and make sure that there is no clip shorting these pin's on the pin side of the connector. Pin # 2 will not be used when wiring for high Z. For high impedance using a standard 1/4" phone jack, either one of the two terminals on the left side is used as the positive, and the terminal on the right for the negative.
       When using a regular high Z guitar cable to wire a mic, you will use the outer braid or cable shielding (bare wires) for the ground, and the single center conductor as the positive conductor. Some cables such as the Planet Waves guitar cables have a cable shield and two center conductors. One is red and one is black. The red wire would be used as the positive conductor. The black wire is connected to the cable shielding, but only at one end. These cables have one end labeled as being shielded. This is the end that you will leave on and cut the other end off to wire into your mic shell. With a cable like this, you can simply solder the shielding to your ground lug inside the shell, and then run the black wire right to the element. Since the shield and the black wire are connected at the other end of the cable, there is no need to use a seperate wire from the ground lug to the element.
       The Planet Waves cables are very good cables and are usually priced right around $30 for a 20 foot cable. I have used many of them and would recommend that you get one if you plan on wiring up a mic with a permanent cable. Just be careful to cut off the UNSHIELDED end if you're going to hard wire your mic. It's a good idea to use a high quality cable to use for your mic. I have seen some of the cheap cables oxidize on the shielding causing the mic to loose strength. Using a high quality mic cable will help you get all the tone that your mic can deliver and help prevent oxidation problems.
                       

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