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Old 14th October 2012, 06:43 PM   #1
felipemuniz is offline felipemuniz  Brazil
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Default Vibrato/Tremolo

I'm finishing this amp here and works pretty well the power amp and the 2 channels (normal and bright) but the other channel, vibrato/tremolo is getting a overdrive on instead a vib/trem effect..

I'm trying to test it with a 12ax7 instead a 12au7 (I dont have a 12au7 here, i bought 2 of them, but left 2 weeks to be delivered)... BUT just for test, I changed the cathode resistor from V3 to 47K instead a 1.5K, and the effect dont worked.. Nothing at all of vibrato or tremelo, nothing..

I wanna be sure that's because I changed the tube... Anyone can help? Perhaps explain to me how this effect channel works..

There's the schematic on attachment.
Thank you for read ^^

Copyrighted material removed by moderation. This schematic was clearly marked as restricted use copyrighted material and may not be posted here. You may post a complete hand drawn version of the schematic or excerpts as preferred. Please read the forum rules!
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Old 14th October 2012, 10:33 PM   #2
jazbo8 is offline jazbo8
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The Valve Wizard- Tremolo Oscillator

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Old 14th October 2012, 10:43 PM   #3
trobbins is offline trobbins  Australia
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Do you have LFO output signal from V1a, and at anode/cathode of V1b ?

Why did you choose 47k ?

Do you get acceptable amplified input signal at anode of V1a and V1b ?
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Old 15th October 2012, 04:21 PM   #4
kevinkr is offline kevinkr  United States
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This clearly belongs in the Instruments & Amplifier forum. To wit:

Tubes / Valves All about our sweet vacuum tubes Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Instruments and Amps Everything that makes music, Especially including instrument amps.
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