Tape Head Output Levels

  I'm working to make a stereo 3M tube machine into a mic pre/compressor limiter. I've been searching for the best way to take audio out of the machine and have determined that the signal being used to send audio to the tape head is the most isolated, and has the least amount of crosstalk between the two channels. The level coming from that output is too hot. Any audio signal, unless heavily padded, registers as a peak on my mic pres. I don't have variable control over the signal either. What standard signal level is used to send audio to a tape head, and what can I do, aside from padding the signal, to get the signal into something that I can use?

  -P

The level of the voltage delivered by the record amp is very likely to be about 1-10 volts. Record heads are current-driven; there are several ways to achieve that, and that will affect the voltage level, which will also depend on the record head impedance. In addition, the signal is heavily EQ'd in accordance with the NAB (US-Japan) or IEC curve (Europe). You need to modify the record amp and make it a standard linear voltage amp; since the level will likely be too high, you will need to attenuate it, either via a step-down xfmr (which would also provide better impedance bridging) or a resistive pad (could be a simple pot).

Any good resources for transformers?

The usual suspects: Jensen, Cinemag, Sowter, Lundahl, OEP

I found some Line Level General Purpose 1:1 Bifilar Output Transformers  on Jensen's website. http://www.jensen-transformers.com/ln_out.html What do I have to know to find out if a certain transformer will work with my setup?

You should look at step-down transformers (5:1 to 10:1)

Is there any reason (other than crosstalk) not to take the signal after the recovery stage after the tape heads? That stage ought to perform the de-emphasis that abbey referred to, returning to whatever passed for "flat" frequency response in this unit. That would effectively give you a tape emulator. I've done this before with tape machines and, provided the tape heads are of worthwhile quality and the pre-emphasis/de-emphasis networks well implemented, it can be very cool sounding.

Ah, that's not an option anymore. I disassembled the machine, which mainly consisted of removing all of the tape motors and heads.