Re: [Harp-L] Impedance Advice

[Greg Heumann <greg@xxxxxxxxxxx>]

"Because when you take a Hi Z  microphone and run it into a Low Z   
XFMR, you
destroy the tone and the Hi Z's power output.  It's better to run a Hi  
Z mic
into a pedal or DI Box and whatever power and  tone is robbed that way
won't be near as much as coverting the mic to Low Z."

I will respectfully disagree. The statement above is incorrect, and  
makes no sense.  A DI box and an impedance matching transformer are  
the same thing save for the sex of the connectors. What we usually  
CALL an Impedance matching transformer is a device with an XLR female  
jack at one end (to plug into the amp end of an XLR cable connected at  
its other end to a low-Z mic) and 1/4" male (to plug into an amp.) A  
DI box is usually 1/4" female (to plug in your 1/4" mic or guitar  
cable) and has XLR male out, so you can connect an XLR cable between  
it and a low-Z input like a PA. But there are exceptions, like the  
ATC6824 under discussion, which is called an impedance matching  
transformer but has the connector sex of the DI box I just described.  
ALL of these are technically impedance matching transformers, and in  
fact the physical transformer inside both is the same.

There is virtually no perceptible change in tone with use of an IMT.  
Yeah, I'd rather not go through an extra transformer, but we're  
talking barely noticeable here.  Output level will come up or down a  
few dB. Impedance matching transformers aren't inherently "low-Z" or  
"high-Z" - they simply exchange voltage for current according to the  
laws of physics, based on the ratio of turns from one of the  
transformer's coils to the other. An impedance matching transformer of  
say, 50:1, will take a 600 ohm ("Low") impedance signal and convert it  
to a 300K ohm  one. You can run it in either direction, the  
transformer doesn't care.


/Greg

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