RE: [Harp-L] low impedance

["John Balding" <John.Balding@xxxxxxxxx>]

The tone will not change. What will change is the output level. I will
not go into electronic theory, but suffice to say that you will have to
turn the amp volume up to attain the same volume and "grit" that your
mic produced when wired high impedance. The only advantage to rewiring a
mic for low impedance (my opinion) would be to make the mic more
"versatile", in that you can plug it into anything at any time (kind of
like the 70s).

Using a low-imp mic in a guitar amp will not harm the mic or the amp. In
fact, many players use low-imp SM57 and SM58 mics in guitar amps all the
time.

Sometimes mic companies will produce harp mics as low-imp, and then
speak of how feedback-resistant they are. These are also referred to as
"dual-impedance" mics, except that there is no way to "switch"
impedances. If there is no way to physically switch the impedance level,
(as with the GB, 545, etc.) then most likely the mic is hard-wired
low-imp. (Low-imp mics are safe to use in high-imp amps, but high-imp
mics are NOT safe to use in low-imp connections such as PA boards, some
mic pre-amps, etc.) User accolades for these "wonder mics" will include
statements such as: "I used to play my amp on 2 with my old mic, but now
I can crank it all the way to 7 with NO feedback!" Well...duh! If the
low-imp mic is getting less of the signal strength to the amp, then you
would have to crank the amp higher to achieve the same volume, tone,
texture, etc. The "lack" of feedback is misleading. Once the same actual
VOLUME level (not amp volume setting) is attained, the amp and mic will
still cheerfully screech and howl as easily as it did with a high-imp
mic at the lower amp setting.

Some players will say that using a low-imp mic into an amp will produce
a sound that is too "clean" for them. Again, this comes back to the
signal level. I have used an SM57 straight into a Fender Blues DeVille
4X10 and produced every bit of the growl and grit of my high-imp 545.
The only difference was the volume settings on the amp.

One last thing - If you use low-gain preamp tubes in your amp (12AU7,
12AY7), the amp may "max-out" on the volume control before you get the
volume and grit of a low-imp mic. If you do use a low-imp mic, it is
usually beneficial to step up the preamp tubes to the next gain level to
compensate.

12AX7 - Gain Level - 100
12AT7 - Gain Level - 70
12AY7 - Gain Level - 40
12AU7 - Gain Level - 17

John Balding
Tallahassee, FL



-----Original Message-----
From: harp-l-bounces@xxxxxxxxxx [mailto:harp-l-bounces@xxxxxxxxxx] On
Behalf Of Jim Alciere
Sent: Thursday, December 06, 2007 10:47 AM
To: harp-l@xxxxxxxxxx
Subject: [Harp-L] low impedance

If I rewire my old green bullet to low impedance xlr will the tone
change?
Will the mic lose volume?

-- 
Rainbow Jimmy
http://www.spaceanimals.com
http://www.myspace.com/theelectricstarlightspaceanimals
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