Adding Direct Outs to Tube Mixer

[drummerman1515]

Hello all!

I have a 3 channel tube mixer (2 mic in - 1 line in) that sum down to one mono output.  I would like to take the 2 mic pres and give them direct outs with separate transformers.  The current output transformer shows 16k primary/250ohm secondary. 

1. Is this even possible?

2. If so, at what point in the circuit would would the transformer be inserted.  I am guessing the outputs of the 2 mic pres are combined before feeding the current output transformer and that may be the spot split and send to the new transformers.

3. What transformers would work as decent outputs?

Sorry, no schematic so I will have to trace the signal.

Thanks in advance.

 

[drummerman1515]

Another photo

 

[ruffrecords]

Hard to tell without a schematic but it looks like the mic pres each use a single 12AX7 (7025) double triode. It is unlikely that this will be able to drive a direct out  even with a transformer. I would guess the output stage uses another 12AX7 (7025) and the first 12AU7 to drive the output transformer. It is not clear what the second 12AU7 is used for but perhaps this could be repurposed to buffer the mic pre and provide an unbalanced direct out.

Cheers

Ian

 

[emrr]

I generally think these ideas involve such a big redesign and hacking, it's better to leave as-is and just build something else from scratch.    You hack it, it's de-valued from the collector standpoint and harder to resell. 

 

[drummerman1515]

Excellent and sage advice! Thank you!

I had hoped it would be as easy as "buy transformer X, plug it in here...play" - never seems to work out that way.  Better off trying to procure a second one of these if I want stereo.