Transformer in microphone

R

Robert Moehle

New member
Does it make a difference if a microphone has an internal transformer? I have used condenser mics, both large and small, for many years. Mostly they have been MXL, Studio Projects, and Audio Technica, and none of them had internal transformers. I just bought a Sterling Audio ST51 which does have a transformer, and I was surprised by how much richer and detailed the midrange seemed to be.

In the Studio Projects and Audio Technica mics, there seems to be a deliberate emphasis on midrange in imitation of the transformer mics. It can make the mics sound hard, and it can build up so much when using the same mic on multiple tracks that it was almost painful.

Many years ago I rented a pair of Neumann U-67 mics for a major project and they seemed to have a midrange similar to this Sterling Audio mic - both mics seem to have a fuller sound that really made recordings pop out.

Is it me or is it actually true of mics that use transformers?
 
Interesting that you thought of that. I've always liked the sound of "fuller" or warmer mics with transformers. But the transformer in the u-67 and the ST51 are completely different. If I remember right (without going into the studio and opening it) the ST51 has a much smaller transformer. I've always found those smaller transformers choke frequencies. I do like a lot of those Sterling mics for what they are, and I've got about 6 of them now (though I've modded most of them now, mostly replacing the transformers with Lundahls or head basket mods, but some of them had decent sized transformers).

The transformerless circuitry of those Chinese Schoeps rip offs isn't something I'm fond of usually. Sometimes they get it right and make a nice inexpensive mic. My feelings is that the transformers in cheaper mics choke the high frequencies making it sound "warmer," and the transformerless circuits allow too much high frequency to cut through making them very bright for some sources.

This is what I have found with the little experience I know of mic building and modding. For those electrical guys who know, "the C4 should be 40uf to drop the 4k down 2dB" or whatever, they might be able to state exactly what is happening.
 
A transformer adds distortion to a mic.

But it is a distortion that a lot of people like, especially in a vocal mic.

This is why Gefell offer a choice in their M930 mic. The M930 is electronically balanced, the M930Ts is transformer balanced, otherwise they are the same - you you have a choice.

Personally I prefer lower distortion and prefer a mic. without a transformer.
 
John Willett said:
A transformer adds distortion to a mic.

But it is a distortion that a lot of people like, especially in a vocal mic.
Click to expand...

Is this like the distortion like the 2nd or 3rd order harmonic distortion in tubes? Or is it because tube amps use transformers that causes this distortion?
 
I just found an article about high quality transformers and it stated this:

"Of course, nothing absolutely eliminates RFI. However, the right transformer can be a simple and elegant way to purify the desired signal. They do a terrific job of isolating the sound from the hostile world outside so that the active circuitry can work its best.

It is important to look beyond the lack of distortion and the great specifications of these transformers. They are also so subjectively transparent that the underlying characteristics of the electronics behind them are more readily apparent in critical listening. The quiet around the elements of the soundstage (both in time and space – dimensionality) is so dramatic that it reveals by exposing, rather than by exacerbating. The tiniest contributions of other components in the signal chain are unmasked."
Jeff Rowland Design Group - Line-level Transformers in High-End Audio

I recorded a choir in a church right by a radio tower - which had the unfortunate affect of RFI being caught by my transistor based mics and pres. In a last resort, I used transformer based mics and my John Hardy's with Jensens and it worked great. I do think my Jensens do add a good "color" to the sound and someone said that the Hardy's had a "euphoric" quality (my favorite color is blue, so I'll go with they have a euphoric blue), but they are not transparent like my Millennias. That being said, there is no audible "distortion" (just in case someone thinks of a distortion from a pedal or amp). From what I understand, the distortion comes from the odd or even order harmonics - but correct me if I don't understand this correctly.
 
citizen77 said:
My feelings is that the transformers in cheaper mics choke the high frequencies making it sound "warmer," and the transformerless circuits allow too much high frequency to cut through making them very bright for some sources.
Click to expand...

This was a little inaccurate by that article. The cheaper transformers lose low end - but this might only be in regard to changing impedance though.

Too many variables to contend with right now. Brain shutting down.
 
Thanks! That was a good read. Maybe I shouldn't bash Peavey anymore! I wonder how much of tube design in amps correlates to mics? If it does, than that really explains what's happening with the transformers (along with his comparison of hi-fi vs. guitar).
 
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