tyco transformer. Alternative to #42TM022??

[m_charles]

Hi,

I've been chasing the sound of a friend's early Fulltone Octa-fuzz (#112 I think?). I hit it with a multimeter and confirmed that it had all emitters facing "down" on the schem. PNP, NPN emitting the same way to ground through their biasing resistors. I know transistor orientation on tyco's is a whole other debate, but the f-tone's trannies were this way (all down) and the thing sounds great.
I gain checked the trannies in the circuit, found a bag of the exact same part #'s and sorted for gains. And EVERY time...my circuit would sound good with the PNP's flipped with emitter UP. Bad with them down, but neither as good as the f-tone.

Only differences I found: It's got a physically bigger transformer, with no part number. Any Ideas for alternatives I could try? Mouser? The Ge diodes are these fat barrel looking things, probably not 1n34's, with black coloring on the cathode side. I didn't think these two parts could make that big a difference but....

At this point, it's not even that I think this pedal will sound that much better, I'm just determined to make an octavia that sounds good with all the trannies oriented the same. And it's making me crazy!!!

thanks in advance.

Chuck

[m_charles]

no ideas guys?

[R.G.]

1. Have you done any measurements on the "PNPs" to find out if they are, in fact, PNPs?
2. Have you done any measurements on the transformer to find out its turns ratio and frequency response?

[m_charles]

Hi RG.

1. Have you done any measurements on the "PNPs" to find out if they are, in fact, PNPs?

Yep, MPS6519's, measured the gains (in the PCB), and matched them as close as I could. Same with the MPSA18. My method for measuring in the circuit was to take the smallest clips I could find, clip them to the legs of the trannies, and run them to the gain checker on my DMM. Took a few tries, but I got the readings. Would the trannies being in the circuit (power off) screw up my gain readings?

2. Have you done any measurements on the transformer to find out its turns ratio and frequency response?

I didn't know this could be done on a regular DMM. Anything on your site that describes this?

I seem to remember a post about a year ago where you and G. Tripps respectfully disagreed about the MPS6519's orientation in the Tyco. Am I remembering correctly?

thanks in advance for the help.

chuck

[brett]

Would the trannies being in the circuit (power off) screw up my gain readings?

Yes.  Possibly by a lot.

It's got a physically bigger transformer

Improves bass response.  Might also reduce distortion.  Many really small, cheap transformers are very poor quality.

frequency response

You might assume that everything else in the circuit is capable of a flat frequency response from 50 Hz to 20kHz.  Therefore, if you run test signals into it at different frequencies, the -3dB points for the transformer are roughly where the output is "down" to half the amplitude (ie half the RMS Volts) that it was when the input was at about 1 kHz.