The Amp Garage

M Fowler wrote:A guy posted this schematic a few years back.

Not 100 or 150 watter but good platform.

Thanks a lot for the schematics! Are the High/Low filters as simple as that? Just switching between tonestack values for MIDDLE and TREBLE?

Thanks a lot

Hi all, below is a very well known mod to disconnect the tremolo circuit on a Fender BF amp Here's how it's done: 1. Disconnect the wires from the 50k RA Intensity pot. 2. Remove the pot. 3. Install new 50k RA Intensity pot with SPST switch attached. 4. Solder Brown wire to center lug as before. 5. ...

See http://www.aikenamps.com/index.php/designing-phase-shift-oscillators-for-tremolo-circuits Thanks for the reply! This was indeed my source for the calculations. What is not clear to me is soundwise the difference between 100K with 820 vs 220K with 2.7K, and the consequence of using smaller resis...

double post

The only picture I have seen of the contour circuit looked like a full on wired presence cuitar (1uf cap across the 390 resistor) and a VOX cut circuit that was copied from an AC30. I think the AC30 (or maybe AC15) were the first amplifiers to make use of the PI cut ccircuit. A .001uf in series wit...

The problem is the range is too limited by this design. for a wider range, a pedal, or a transistor oscillator is required. Thanks for the reply! I did all the calculations with 200k resistors instead of 1M and this would give a much better range to fine tune. What I don't know is the consequence o...

3Hz to 10Hz is typical for the AB763 circuit. I've never seen a trem circuit that goes down to 0.8Hz. I was doing some calculations and found the following: The cathode bypass capacitor of 22uF 25v should give the slowest speed of 2.55 Hz. Does it make any difference in using a 25uF here? The Phase...

sluckey wrote:3Hz to 10Hz is typical for the AB763 circuit. I've never seen a trem circuit that goes down to 0.8Hz.

Thanks a lot for clarifying!

Thanks for the reply Stevem! I guess the stock original amp come with .08 to 10, right

Hi all I am just wondering if anyone knows the phase shift oscillator frequency range of a stock ab763 blackface optocoupler circuit (like a deluxe reverb)? I found different values in different sources so just wondering what is the actual correct one What I've seen: (I) 0.08 to 10 hz (II) 2 to 20 h...

Hi all,

I've searched in many older posts but could not find the info i am after

I am wondering if anyone has further info (ie schematics) about the tremolo circuit used by dumble on the Overdrive Deluxe, Showman, Twin, etc

This is what i am referring to: https://youtu.be/9U1mrbqyEyw


Thanks a lot

Thanks for the reply and sorry for my mistake

I thought the amp had the same circuit as this one https://youtu.be/9U1mrbqyEyw

But now I realise they only share the same name

Well, i am referring to the tremolo/Vibrato (effect and level knobs on the faceplate of the amp) which are equivalent to the fender speed and intensity

Amazing amp! I am wondering if anyone has the schematic for the tremolo?

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