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TS9: Ge diodes = low output

10/20/2004 8:43 PM
Gord TS9: Ge diodes = low output
I have tried building TS9 type clones with Ge clipping diodes, but no matter how many times I've tried, the sound is great, but with very low output. I have even tried with two or three diodes in series in each direction. Is there a way to increase the output sufficiently to compensate this problem?  
10/21/2004 4:44 PM

The distortion output is limited by the clipping diodes, however, the "recovery gain" is in the tone circuit. Do you have the right values? 25k pot, 1k fb resistor?
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10/21/2004 8:35 PM
Yeah, all the values are correct. Would increasing that resistor increase the output volume? If so, would it alter the sound?  
10/21/2004 9:08 PM
You want to make it smaller. Try 500 ohms.
10/21/2004 9:11 PM
"You want to make it smaller. "
strike that... -Rf/Ri...make it bigger.
10/22/2004 8:06 AM
The problem is that Ge-diodes limit the output of the first stage to much. For nearly equal volume to Si-diodes wire 3 in series ( maybe that you don't like the sound afterwards, 'cos difference is only subtle).  
Other solution:  
Junk the TS-output recovery stage, it's to weak.  
Junk the TS-tone circuit.  
Junk the output buffer.  
Replace it with a Voodoo LAB OD type gain recovery stage (OD not Sparkle drive!) which can deliver a lot more output. Replace the 100k VOL pot with a 100k to 470k resister to taste.  
Replace the TS tone circuit with a RAT or BF style tone control and VOL pot. A tweed princeton type vol-tone circuit will even work fine.  
For even more output replace the 4558 with a TLO72CN/P.  
10/22/2004 1:00 PM
How 'bout replace each Ge diode with two Ge diodes in series? The amplitude of the signal that gets passed would be roughly back to where it was with Si diodes (ddGe ~ 1/2 ddSi?), but I believe you'll still have the softer knee of the Ge diodes.
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