Dave Kott on Green Bullets - Rick Beall 4/12/03









The Early Shure Crystal Elements

Back and front of the earliest crystal, 99-131
Back and front of the R7 crystal that was used after the 99-131.



Awia back and front. Dave says the Awia crystal element is the closest sounding crystal to the R7 that he's ever heard. Very strong output with great bottom end and rich mids and highs.

The Shure Controlled Reluctance Elements


Back and front of a 99H86 Black Label CR.
Here is a white label CR,the 99G86,that has the same construction as the black labeled CR's.It has the phenolic material winding bobbin with the spacers. These elements are rare. Dave believes these are the last of the old style construction seen on the black CR's.

99H86 White Label CR


Back and front of a typical White Label CM element. The 99B86 White Label CM is the model number used in the later GB mics.

Bluesharp.org:
Dave Kott is known online by his descriptive moniker,
GRBullets2 . Dave has been selling harmonica microphones on Ebay since before there was an Ebay. Well, that's not exactly what I meant to say, he has been selling them since before there was an Ebay. I mention Ebay because that's where I first met GRBullet2. He was buying and selling some really choice mics! Dave has also been known to give generously of his knowledge on the various online harmonica lists.

Bluesharp.org:
What part of the country do you hail from?

Dave:
I'm from Syracuse, New York. Lived here all my life. Real kickin blues scene here. We've got some serious talent here and of course, the world famous Dinosaur Bar-B-Que. I've met some of the most famous blues artists there.Mostly harp players like Carey Bell, Charlie Musselwhite, Rod Piazza (even sold him an element!), Mark Wenner (sold him one too), James Cotton and a bunch of others.

Bluesharp:
How long have you been playing harp?

Dave:
I have been playing harp since I was about 14 or 15 years old, roughly about 24 years. I started listening to stuff like J. Geils and Paul Butterfield. One of my favorites also was James Montgomery who I've had the pleasure of meeting and talking to a few times when he came through town. I didn't start playing amplified until i was about 28 or 29, when I could afford to start buying the stuff I needed. I was intrigued by the Chicago blues sound and set out to find the right equipment. My first amp was an old Fender Champ. That sounded great but wasn't loud enough for me. I then bought a Fender Tweed Blues Deluxe. Great amp. Kept it for quite awhile before I sold it and bought a Fender Bassman RI which I still have. I also own a tweed Blues Jr.

Bluesharp:
What got you into modifying mics?

Dave:
I was very curious about why in the proper hands these mic and tube amps gave such a cool sound --almost as if it were a different instrument! So ... I began digging into the various types of mics and what the bluesmen used to create this sound. This is when I first began researching the Shure green bullet. Shortly after that, I began building my own mics using whatever shells I could find. I tried all of the usual more widely known harp mics and a few of the oddballs.

Bluesharp:
And now, the burning question of the hour: What is your favorite harp mic?

Dave:
Green Bullets! I use the black labled CR's controlled reluctance element) in my personal mics. There's no disputing that they are the best elements to own if you're a bullet player. The white CR's and the CM's (controlled magnetic) are very good elements as well. I have probably 10 or 12 mics in my bag, all with black CR elements. Strangely, my top 4 mics are all elements made in 1949, the first year they were made. A few are JT-30's
and I also have 2 Astatic biscuit mics that I had chromed.

Dave:
I've been collecting and researching the GB mic for about 10 or 12 years now getting my info from long time Shure employees and collecting the various versions of the GB as well as any literature I could find on them. There's not much documented info on these mics and many of the oldest Shure mics as well, so I had to get my info from asking questions of the older Shure tech's and through collecting and noting the different changes made to the mic and materials used over the years.

Bluesharp:
You like the Controlled Reluctance elements?

Dave:
I prefer the sound of the black labeled controlled reluctance elements (CRs). These are the very first version of the element we know as the controlled magnetic transducer (CM). They were made only from sometime in 1949 to mid 1951 before they started to use the white labels and started using different materials in the making of them. These oldest versions have slightly larger windings, are slightly higher in impedance, and used different materials in parts of the element than they used on the later white labled CR's and CM's. These black labled CR's generally have a little more gain than the later elements and have the grittiest tone of all the Shure elements. Although really no two are exactly the same, they are all very close in tone if they are in good electrical condition. These elements can be weakened by various conditions, mainly magnet strength, corrosion, or other foreign materials making their way into the elements. Although they are very rugged and dependable elements, they can go weak on you.

Bluesharp:
What makes them the best for harp?

Dave:
I would have to say their tone and grittiness. Now this is the sound that I prefer, though it may not necessarily be the best for everyone else. We all have our own preferences, and these elements may not appeal to those who prefer a less gritty or a cleaner tone. But for players who are hooked on the green bullet sound, they generally like the black CR's the best. I get a lot of players emailing me back and some even calling me on the phone to tell me how much they like the tone of the black CR's as opposed to the CM's and the newest version of the green bullet which is called the 520DX.

Bluesharp:
You mentioned different versions of the Green Bullet, can you give us some history?

Dave:
In 1949, Shure introduced the first Green Bullet (GB) mic or 520. Its main purpose was for use in paging systems --ham radio, PA's, and dispatch systems. It was called a "Controlled Reluctance Microphone" and was made to withstand just about any situation or climate it could be put into: extremes of heat and cold, moisture and dryness. It is described by Shure as being a pressure operated unit using the balanced armature, controlled magnetic principle. The earliest versions were said to have a frequency response from 100 to 7000 Hz. It was designed for speech intelligibility.

In 1952,Shure introduced the 520B,which was a low impedance version of the 520 to be used where long cables were needed. The list price for a 520 in 1949 was $16.50. Sometime around mid to late 1951, Shure began to use different materials on the CR elements and reduced the windings on them. About this time is when they switched from the black to the white labels, although there were some CR's (controlled reluctance) made with the older materials and larger windings
that have a white label. The windings on the earliest CR's were wound onto a bobbin made of phenolic material, similar to old circuit board material. This material can withstand a lot of heat as where the later elements were wound on a plastic bobbin that could be easily damaged if overheated. The CR elements also were constructed with a small metal disc that was used to glue the metal foil diaphram to the center pin that transmitted the vibrations from the diaphram to the magnetic armature. Around 1959, they stopped using the disc and started using a drop of very hard glue that appears to be some kind of epoxy to secure the diaphram to the center pin. Now whether this disc plays any role in the CR's being a little more gritty sounding, I am not sure about, but it makes sense that anything on the diaphram would affect the way it sounds. The 520SL and 520SLB were called "The Dispatcher" because they were geared toward dispatching. They came on a stand with a push to transmit switch. The 520SL was the high impedance version, the 520SLB was the low impedance version. The low impedance version was designed for cases where a longer cord was needed.

Sometime around 1960, Shure decided to call the elements controlled magnetic transducers, instead of controlled reluctance transducers. There are slight differences in the way the elements were wired,and this is about the time that they stopped using the discs on the diaphram and switched to just a blob of glue. Shure manufactured many different models of the CM (controlled magnetic) element for use in different types of mics, although most of them looked identical. Shure made the 520 and 520B up until about 1970, when they started making the 520D, which is a dual impedance microphone. They made them up until 1977 when they stopped making them in the US, and decided it would upgrade its machinery to more modern machinery. The machinery used to make the CM elements was not replaced and they decided to have them made in Mexico to their specifications.

In 1978, Shure began the production of the 520D in Mexico. Some say these mics were inferior to the US made mics but I have heard some real good sounding Mexican versions of the 520D.

In 1996 I believe, Shure stopped producing the controlled magnetic transducers and replaced them with a dynamic element with a plastic diaphram. They also started putting a volume control in the mics and renamed this version the 520DX. It claims to have a frequency response of 100 to 5000 Hz and is geared toward harmonica players and not for use as a dispatch mic. The 520DX mic sounds a little different than its earlier brothers being a little cleaner in tone and not as raspy sounding as the vintage elements. For players used to the vintage sound, this mic really didn't appeal to them although it does have its place in the harmonica community. Shure still makes this version of the green bullet today.

Bluesharp:
A lot of these mics are very similiar, and even have the same model number, how can you tell them apart?

Dave:
The elements are stamped with a model number and a date code on the label. The elements used in the GB mics and the model 440, which is a silver colored mic (mfg.from 1960 to 1977)identical to the GB except for a larger hole in the underside of the shell where the GB's have 2 small vent holes, were usually stamped 99B86. The very earliest version of the GB used a black 99G86 CR element. Both elements are constructed the same way.


The early white label CR's also used a 99G86 element. dating the elements is kind of tricky before 1961. Shure used a 3 number code stamped on the element after the model number which I still don't know how to read. Nobody at Shure could tell me how the early date code numbers work. From 1961 on, Shure used a 2 letter date code system that I will explain later. It is possible to figure out approximately within a year or two,the mfg. date of the early 3 digit date coded elements by knowing what type of materials were used not only on the elements, but on the mics themselves as well, and where they were made. Shure was based in Chicago up untill 1955, when they moved to Evanston,ILL. So if you have a mic made in Chicago, its safe to say its at least 1955 or older. Shure also used different versions of the tags that are riveted to the shells during certain times. These also give clues as to the age of a mic.The material used on the white labels also can give clues to their age.


Shure Labels

The earliest CR had no label.
 

This tag is from the earliest 520's, which dated from 1950. The color of the tag matches the color of the mic. Dave believes they used these tags for only a couple years before they switched to the darker green tags.
 

The dark green tags started about 1952 or 1953 and were used up to the time that they switched to the non-embossed tags. There were a couple versions of this tag, some having chrome like lettering which I think were the earliest type of this tag. The lettering on these tags were also embossed as were the letters on the earlier "same color" tags.
 

This is the next type of tag. Dave believes these began in the early or mid 60's. He's not real sure about the exact time they switched. These tags were smooth and letters not embossed, and had a bright green color. They used these tags up to the time that they stopped making the GB mic's in 1977. Some of the earliest 520D's had this type of tag.
 

Then they switched to the silver & black tags which are still being used on the 520DX mic's.

 

Bluesharp:
Now, It's time to ask the burning question, "How do you date a Green Bullet?"

Dave:
The picture of the brown bullet(9922A) is actually an early 40's crystal mic.They were the predicessor to the 707A crystal mic.They had the same crystal element (99-131) in them as the early 707A's.The 99-131's were made up till sometime around 1946 or 47.The early bullets(the brown bullets and the dark grey early 707A's ) actually have a smaller shell than the 520 green bullets.The later (1950's)707A's (light grey,made in Chicago)were made with the larger size shell,and came with the crystals commonly known as the R7,which was actually the replacement #.The model # of the R7 crystals was 99A47 in 1947,and switched to 99A94 sometime after then,until they were discontinued in 1970.It's quite hard to find a good strong R7 crystal these days let alone a 99-131,although there are a few out there that have been well kept over the years.I just got my hands on a brown bullet 9922A,that is in near mint condition (dated 5/40) and is the strongest Shure crystal I've ever had. Found it on Ebay. The guy selling it lived about 25 minutes from me so I went to check it out and could not believe how strong it was. Needless to say,the auction ended early!
The elements used in the GB mics were 99B86, and the 99G86. The pic you have of the CM is not a good example. Actually,it's an odd-ball. Not many 99J86 elements around. I have no idea what it came out of. The very first green bullet mics made actually had NO tag. Then in 1950, they used tags that were the exact same color as the mic itself. Those were used for a year or two before they went to the darker green embossed tags. Those were used right up to about 1958 or 59,when they changed the tags from controlled reluctance to controlled magnetic. Then they started to use the smooth bright green tags. These tags were used on the very first 520D's, before they switched to the silver and black tags on the 520D and then the 520DX.I'm not exactually sure how long they used the green tags on the 520D's,but I don't think it was more than a year or two.

Bluesharp:
I'm almost afraid to ask you any more questions about the Green Bullet. I'm afraid my head might explode! What do you think of the JT-30?

Dave:
To my ear the Astatic crystal mics are kind of tinny sounding, or have a very strong high end with much to be desired when it comes to bottom end. In my experience, I have yet to hear a JT-30 that has anywhere near the bottom that a GB has. Astatic claims on their spec sheet, that the MC151 crystals have a frequency response of 30 to 10,000 Hz. Now I don't doubt the 10,000 HZ, but 30Hz is below what the human ear can hear. Maybe thats why they have no bottom, you can't hear it! Seriously, though, the human ear picks up low frequency's at about 50Hz. If the Astatics do indeed have such a response, I don't know why they are so thin sounding. They seem to be very strong starting in the mids, and can get way up into the highs as well.


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"Specially made for recording".
But as for lows, the only crystals I've heard that have good bottom end are the Shure R7 crystals,and the early 99-131 crystals that were used in the early 707A's and the Shure Brown bullets that say "specially made for recording" on the tags, and a crystal made by Awia that I think was called a C-3. All 3 of these elements have more bottom end than any Astatic MC151 that I have ever heard. I have heard that some of the very old Astatic crystals like the ones that were put into the model 30 brown biscuit, and the old brown model 200's were pretty good, but I never heard a very strong one. I don't think that this is just my opinion because many players have said the same thing to me when looking for more bottom end. I ask what they're playing and 99% of the time the answer is a JT-30. So as for as the JT-30 having more tonal range, it may say so on the spec sheet, but in the real world, I don't think this is true at all. I never really did like the Astatic crystals, including the 101's, 111's, and the ceramic MC127's. I have an early 40's Astatic JT-31 that has a crystal element stamped 707 that seems to be an odd ball. I've never seen another like it but its one of the best sounding Astatic crystals I've ever heard. It has a tag on the back with the Brush Co. licensing numbers on it. I believe they called it a "Spokesman" model from the Youngstown era.

Bluesharp:
What do you think of the old version versus the newer versions of the Astatic?

Dave:
There's no doubt that the older Astatic JT-30's have a better sound than the mass produced ones of today. Quality control was much higher back in the 60's and 70's, and I was told by an Astatic employee that the crystals were individually tested and had to pass strict quality control testing before being put into production. When Astatic started mass producing the JT-30's, the quality of the crystals went down the tubes. That's not to say they were all inferrior to the older ones, but it seems that a lot were.

I never did research the Astatics like I did the Shure elements because they really didn't appeal to me although there's no doubt that they are well liked by many players, amateur and professional. They have a very different sound than the GB's and its nice to have the option to switch from one mic to another if you're
a harp player. Every harp player should have a few different mics to use in different situations. Its nice to have that option of versatility.

It seems to me that when it comes to harp players, they either favor a GB or a JT-30 although most usually have one or two of each. There are also a lot of players who favor other mics like the Shure SM57 which makes a great harp mic as well. There are a lot of mics out there that make great harp mics, but I think it's safe to say that the GB and the JT-30 are the top two choices.

Bluesharp:
Between the GB and JT-30, which do you think has more variety of tone, or is more "flexible"?

Dave:
The Astatic mics are cleaner to start with, so when you play them without cupping them, they give a cleaner tone than the GB. The GB mics are grittier sounding mics by nature, and the tighter cup will make them sound grittier than the JT-30. As to which one is more flexible tonewise, I guess it depends where you want to start and end up. For my tastes, the GB is more flexible.

Bluesharp:
Some people say the CM's are less smooth than the CR's?


Dave:
Maybe I'm not quite sure what you mean by smooth. It has my general finding that the CR elements are grittier sounding than the CM's. So I guess I would say that the CM's are smoother than the CR's. But as I mentioned before, really no two elements are going to sound exactly the same. You could play 4 different elements all with the same model number, and have 4 different sounding elements, though the differences might not be real noticeable.




Pictures of some of Dave Kott's custom jobs. If you buy a Green Bullet from him, you will be getting the best, and know exactly what you are getting. It looks like Charlie thought they were cool.


I tell my customers that if you find an element that you're happy with, don't keep on trying to find a better one because you may drive yourself nuts and spend a lot of money only to end up with the element you started with. When you find the right one for your amp, you'll usually know it with the first few notes that you blow. Unless you need to drastically change your tone, I tell players not to switch mics, but to consider working on technique, or maybe a tube or speaker swap.

In general, if you like the gritty Chicago blues sound, I'd say try a GB mic. If you like the cleaner, crispy tone thats not real gritty, try a JT-30. But I usually tell players to get one of each if they can, and either choose the one they like best, or keep one of each to really have the versatility of switching from one sound to another with a simple mic switch.

Bluesharp:
Do you have any advice concerning other gear to compliment that mic?

Dave:
I'd rather not talk too much about other gear like effects, because there are so many to choose from these days. Personally, I sometimes use a Boss AD-3 which has a digital reverb, a 2X2 chorus, a 2 band EQ and an anti feedback circuit. It is a great little known box that works great for harp because it is an acoustic instrument processor made for acoustic guitar. It has a great reverb that sounds just like a spring. Everything is quickly adjustable from a touch to a lot.


Tubes are another thing that can affect the tone of your amp so experiment with tubes first and find the best for your particular amp.

So what it really comes down to, is what sound you're
looking for. I'm not going to tell everyone that JT-30's aren't any good, they are good mics and absolutely have their place in the harp world. I'm not going to tell you to run out and buy a GB either. What I will tell you is to try as many mics as you can get your hands on and keep all the ones you like. I happen to be a GB man and thats what I know about.

Bluesharp:
Thank you for talking to us today! What if people have questions?

Dave:
If you have a question concerning a GB mic, I will be happy to help you if I can. I don't claim to know everything about them, but I have gathered quite

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a bit of information on them over the years of collecting and research. Feel free to email me anytime with a question or if you're looking for a mic.
I'd be happy to build one for you, or answer your question to the best of my ability.



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