How the “Green Bullet” Became the Definitive Blues Harp Mic


Written by  on  under Education

Contributors: Dennis Gruenling, Michael Pettersen

Since the 1950s, blues harmonica players have amplified their instruments with bullet-shaped microphones and tube amplifiers. But how it all started remains a mystery.

According to one legend, the mac daddy of all Chicago blues harp players, Marion “Little Walter” Jacobs, innovated the technique by playing his harmonica near a bullet microphone. The result was a punchy mid-range sound that could be heard even over an electric guitar. Overdriven tube amplifiers produced distortion at higher volumes, adding an essential ingredient to Little Walter’s sound.

Dennis Gruenling and one his many vintage Shure ‘Bullets’

Dennis Gruenling and one his many vintage Shure ‘Bullets’

Other blues harp enthusiasts, like David Kott who has devoted an entire website to Shure’s Green Bullet mics, believe that the early greats (Little Walter is still considered the king of all post-war blues harpists) used whatever mics were available to them, especially in the studio.  We’ll never know for sure, because Little Walter died in 1968. Still, credit goes to Little Walter for taking, according to music journalist Bill Dahl “the humble mouth organ in dazzling amplified directions that were unimaginable prior to his ascendancy.” One way or another, the Shure 520 was there just about from the beginning and became one of two blues harp must-haves (the other is the Astatic JT-30) for the next 60+ years.

Shure’s Michael Pettersen, resident historian (along with managing the company’s Product Support Group) offers this 1949 catalog description introducing the Shure 520:

The Green Bullet

The “Green Bullet” is a new Shure Controlled Reluctance Microphone.  It is a magnetic unit, especially designed to provide quality music and speech reproduction at moderate cost.  The “Green Bullet” is practically immune to the effects of high temperatures and humidity.  It is a rugged streamlined unit that lends itself to fine quality low-cost installations where durability is an important factor.

Courtesy: Dennis Gruenling

Courtesy: Dennis Gruenling

The “Green Bullet” has a stability assured by unique control of the reluctance of the magnetic system.  It features: high output, good response, high impedance without the need of a transformer.  The “Green Bullet” has a beautiful modern metallic green finish with a plated grille.  Frequency response is 100 to 87000 c.p.s. (Editor’s note: The use of c.p.s. (cycles per second) as the technical nomenclature of Hz (Hertz) was not introduced until the 1960s.) Furnished with 15’ single-conductor shielded cable.”

Streamliner in Catalog 152, 1939

Streamliner in Catalog 152, 1939

Additional text stated:  “The Controlled Reluctance element of the 520 was originally developed during the war [World War II].  A testimony to the ruggedness of the Controlled Reluctance principle is the fact that the military models successfully passed all destructive shock, tumble, heat, cold, blast, and other tests which determined the fitness of a microphone for battle operation.  The 520 provides the ruggedness, clear reproduction, high output, and low price needed for outdoor public address, mobile communications, ham radio, audience participation shows, outdoor paging (carnivals, circuses, parking lots, athletic fields), dictation machines, portable recording machines, intercom, and high humidity-tropical installations.”

The retail price of the 520 was $16.50 ($156.00 in 2013 dollars).  The bullet-shaped housing of the 520 first appeared in 1939, Catalog 152. It was the housing design for the “Streamliner” 5G dynamic microphone and 7A crystal microphone.

Michael reminds us that there is no mention of the Green Bullet being a mic for harmonica/blues harp.  “The first Shure catalog that advertised the 520 as a harmonica microphone was published in 1986 – 36 years after the introduction of the Green Bullet.”

Evolution of the Shure Green Bullet

1949–Model 520 introduced. High impedance (>10,000 ohms). Employed R5 element.
1953–Model 520B introduced. Low impedance (150 to 250 ohms).
1974–Model 520B discontinued.
1980–Model 520 discontinued.
1980–Model 520D introduced. High/low impedance. Employed R44 element.
1997–Model 520D discontinued.
1997–Model 520DX introduced. High/low impedance. New dynamic element designed to sound like the original R5 element. 5/8″-27 internal threaded hole replaced by volume control.

How did the 520 become a favorite of harmonica players?

Unfortunately, these details are lost in history, but Pettersen offers these observations:

• The 520 housing fits nicely into cupped hands and allow the harmonica to be comfortably placed on top of the grille.
• The original 520 was high impedance. With the addition of a 1/4” male phone plug, it worked well with guitar tube amplifiers available since the 1940s.
• The $16.50 price in 1949 was affordable for most musicians. In comparison, the model 55 Unidyne was $67.50 – four times as expensive.
• The combination of the harmonica being so close to the mic element, and the mic output level being great enough to overload the guitar amp, led to a distorted, funky timbre.  It is unknown if this was the desired timbre or if this timbre simply became associated with blues harp.

Eric Oblander on The HarpCarp blog site adds a few more:

• Velvety tone that is thick as molasses
• Fantastic, bassy low-end tone
• Distinctive tone, one of a kind classic sound
• Makes even the crappiest amplifiers sound great
• Volume knob

How to Get the Blues Harp Sound

We called award-winning East Coast blues harp player, Living Blues top ten CD artist, radio host of “Blues & the Beat” and collector of vintage harp mics Dennis Gruenling and asked him to provide a few tips for blues harp newbies.  What he told us is what he tells his students:

1.  Choose the right key harmonica. For most blues, rock & roll, and country harmonica you hear (even in those TV commercials and movies) harmonica players choose the “2nd” position key harmonica to play, with the same key as the song. For instance, if the song is in the Key of E, 2nd position (a fourth up) is a harmonica in the key of A.

2.  Learn basic harmonica techniques. The harmonica was actually made to be tongue-blocked, which is why it is tuned the way it is. You can accompany any melody you play in 1st or 2nd position with chords all by yourself! Tongue-blocking also enables you tone to be richer, and makes it easier to do other effects like shuffle rhythms, tongue-trills, octaves, etc…

3.  Use a bullet microphone. For that classic “blues harmonica” sound, you will definitely want a classic bullet microphone, which fits in the hand when you play harmonica. Also keep in mind, the more you control the cupping of the microphone, the more you can manipulate the sound of your amplified harmonica.

4. Listen to the greats. Players such as Little Walter, Big Walter (un-related, but equally as good), Sonny Boy Williamson I & II (also un-related but both pioneers), James Cotton, Junior Wells, George Smith, and others.

Shure Green Bullet Model 520DX

Shure Green Bullet Model 520DX

Where to Find The Green Bullet

The current model of the Green Bullet is the Shure 520DX, widely available for about $120, depending on where you shop.  There are also sellers of early vintage bullet-style mics and mic parts on the Internet with 1950s-era selling for much more.   As always, use caution when purchasing from auction sites.  Reputable collectors, who restore and rebuild vintage mics, can be found with some careful research.

Now, all you need is a blues name …

If you don’t want to rely on one of the many web-based blues names generators to give you an authentic-sounding names, here’s another way to do it:

• First, think of an ailment of affliction.  Yuppie-type ailments like tennis elbow or shin splints are not suitable for a blues name.  This is your first name.

• Add the name of a piece of fruit and you have your second name.

• End it with the name of a former U.S. president.  Put them together and you have a proper blues name.

The goal here is a name like Blind Melon Jefferson, but you can also end up with something like Stuttering Peach Harding.

…and the legendary mic.

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