Incorporating an output transformer into a TS-type OD

[mordechai]

Since we've all got more home-based time on our hands now  I thought a new project might be a productive way to stave-off cabin fever...

I gave a listen to the Greer Soma 63 and the Hudson Electronics Broadcast circuits, and really liked what the output transformers were doing in those -- more beef, without the mud, in the bottom end.  How would I incorporate a transformer like that into a TS-type (Son of Screamer, actually!) circuit?  I have a circuitboard from a kit I can hack this into, but I'm not sure where to make the connections and would appreciate some tips or suggestions...including which transformers might be best for the job.

[willienillie]

How does an OT give more beef to the bottom end?  My first thought for a TS would be to replace the output buffer with a stepdown OT, for similar impedance ratio, though maybe more loss (I don't know).  But the SoS has no output buffer.  You could stick a 1:1 anywhere I suppose.

[merlinb]

[teemuk]

I would be very cautious of giving credit to transformers when particular characteristics in tone might as well be explained by other circuit details. In my experience signal coupling transformers contribute almost nothing in low voltage, narrow bandwidth circuits. Saturation doesn't happen and bandwidth should be more than sufficient unless impedance is deliberately mismatched. In such case the transformer is just a cumbersome substitute for plain RC filter.   

[highwater]

A couple years ago I stuck one of those tiny radio shack transformers in a breadboard with a basic opamp boost in front. It definitely distorted, but I don't remember how much gain I was pushing it with. Sounded pretty terrible, but since it was just a proof-of-concept I wasn't doing any frequency shaping whatsoever, so that's to be expected.

[mordechai]

Thanks for the graphic...I had thought maybe that was the way to do it, but when I looked at the schematic for a pedal that does a nice job of using a transformer at the output -- the Hudson Broadcast -- there is a resistor network before the signal hits the transformer:




Is this specific to the needs of the rest of the circuit or would this sort of resistor network be of benefit in a SOS-type output scenario?