Re: [Harp-L] On wiring mics

["G." <gigs@xxxxxxxxxxxxxxx>]

<quote>
Date: Thu, 26 Aug 2004 09:59:11 -0700
From: Greg Heumann <greg@xxxxxxxxxxx>
Subject: [Harp-L] On wiring mics
8<
I can tell you that the Shure 520D is an exception to the rule above.
At least the one I got - the element (made in Mex. controlled magnetic)
has 3 wires - blue, red, black. They were wired to the built in cable,
red to red, black to shield, and blue to black. The guy I bought it
from had someone put a connector on the cable so I don't know how the
mic came wired from the factory. But mine came with the black wire
soldered together with the shield at the connector ground (as suggested
above) - output was almost non-existant. In this case, the black wire
should be left DISCONNECTED - it is there to allow external re-wiring
of the mic to low impedance.
GH
</quote>

Yep, I've got three different CM elements that came in Green Bullets that I
bought.
  Two of them were simple enough, both elements US made, although different
model cartridges they're the same size and shape, Model 99G86AL is my
favourite runs slightly hotter than the other model 99A86114, but otherwise
tonally the same.

The third element I got is a Mexican made Shure CM element, Model 995556GD
and like you describe, it has three connections, two of them are simple
enough: red & black, the third thin blue wire is connected to another tab on
the cartridge.
  It was sold to me (a fellow harp-ler :) with a fixed cable fitted with a 3
pin XLR connector, and a handy little impedance convertor.  I tried rewiring
the element in different configurations to see if I could get a hot signal
out of it, but I couldn't, although there are a few ways you can wire this
into a 1/4" plug and get a low signal from it.  Some may remember me asking
about this here.
  What I did find out is that this is a low impedance balanced mic element,
in the same way that the mics like the Shure SM58 is - if you wire it to a 3
pin XLR jack thus:
  Blue is shield/earth - wire this to pin 1 and the plug's ground - good
idea to make sure this is wired to the mic's shell as well to ground it
properly.
  Red is positive signal which you wire to pin 2.
  Black is negative signal which you wire to pin 3.

Like this, you can use it with an XLR to XLR cable, and plug it into any
balanced XLR equipment, and benefit the advantages of balanced signal (low
noise with long balanced chords).   If you wish to plug it into an amp, then
its best to use it with an impedance convertor to boost the signal,  if you
choose to do this make sure that any cable you use is shielded properly.
Plugged in to an amp this way the result is similar to my other CM element
Green Bullets, though weaker - crank up the gain a bit and you can't tell
the difference.

  I've been informed by a reliable source the original US made CM elements
were reasonably consistant in tone and strength, then Shure had their
elements made in Mexico,  the quality of which varied somewhat.  Finally
Shure changed to the current Mexican 520DX with dynamic element which has
half the frequency response (100 to 5000Hz) range and a weak signal giving
the muffled tone.   And I suspect there are both high impedance elements as
well as low impedance balanced elements like the ones you and I have.
Perhaps someone who knows more about this can fill us in.

-- G.
http://www.angelfire.com/music/harmonica/ampdmics.html