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previous: John Stokes OK, I'll go out on the limb for ya.... -- 10/25/1999 6:55 PM

Re: Tremelo question

10/25/1999 8:32 PM
moocow	Re: Tremelo question My least favorite tremolo circuit modulates the bias of a preamp tube. This introduces a subsonic waveform into the signal path that gets to the speakers and cause them to move alarmingly in their frames. It can be removed by limiting the low-frequency response, but then the guitar signal lows may be affected. This method does work well in small amps like the Champ, but I would not use it in big amps. The photoresistor in the AB763 tremolo circuit can degrade with time and the tremolo won't sound right. Replacing it brings the tremolo back to life. It also varies with the amp. Some amps just seem to have better tremolo than others. I've built the Magnatone circuit, but the varistors are impossible to find. I had to use the varistors out of my Magnatone to make the circuit work, which sort of defeated the purpose of building it in the first place ! Ampeg built a vibrato circuit similar to the Magnatone M9 that used neon bulb/photoresistor LDRs instead of varistors, but I haven't tried them in my circuit. I did try CLM6000 LDR with a solid-state oscillator driving the LED, and it worked in the M9 circuit. Based on performance and parts availability, my vote for best-sounding DIY tremolo also goes to the brown Harmonic Vibrato circuit, while second place goes to the power tube bias modulation circuit.

10/25/1999 8:32 PM

moocow

Re: Tremelo question

My least favorite tremolo circuit modulates the bias of a preamp tube. This introduces a subsonic waveform into the signal path that gets to the speakers and cause them to move alarmingly in their frames. It can be removed by limiting the low-frequency response, but then the guitar signal lows may be affected. This method does work well in small amps like the Champ, but I would not use it in big amps.

The photoresistor in the AB763 tremolo circuit can degrade with time and the tremolo won't sound right. Replacing it brings the tremolo back to life. It also varies with the amp. Some amps just seem to have better tremolo than others.

I've built the Magnatone circuit, but the varistors are impossible to find. I had to use the varistors out of my Magnatone to make the circuit work, which sort of defeated the purpose of building it in the first place ! Ampeg built a vibrato circuit similar to the Magnatone M9 that used neon bulb/photoresistor LDRs instead of varistors, but I haven't tried them in my circuit. I did try CLM6000 LDR with a solid-state oscillator driving the LED, and it worked in the M9 circuit.

Based on performance and parts availability, my vote for best-sounding DIY tremolo also goes to the brown Harmonic Vibrato circuit, while second place goes to the power tube bias modulation circuit.

Replies:

dave You guys sure know yer stuff! Is th... -- 10/27/1999 12:51 AM