The Amp Garage

Disconnect the mains earth ground wire from the chassis. If the hum disappears you have a ground loop. There is a simple ground isolator circuit that works well and allows the earth ground to be connected to chassis. Thanks! As in unsoldering the arrowed ground wire from the AC socket shown in the ...

martin manning wrote: ↑Tue Nov 21, 2023 10:16 pm Sorry, I don't follow. Here is the schematic based on 124. How do you short the regulator input (pin 1) by shorting the output (pin 3)?

Touche!I stand corrected, Martin -- shouldn't have typed without having a look at the schematic!
G.

Yes, with one jack pin per relay coil and one pin per LED (Dumble configuration), the limit resistors can be placed inside the amp, with equal brightness on the LEDs. All good, that is what is shown on the 124 schematic. But suppose you want three functions on a 5-pin jack? A common 12V feed to the...

...if anything were to get short-circuited from that point on out -- i.e., towards the footswitch... I don't think this is a problem. LM78XX regulators have internal current and thermal protection which will cause them to shut down in the event of a short at the output. The down side of a placing a...

The panel LED needs a current limiting resistor, where the full 12V can be sent to the relay coils and to the footswitch jack. The current limiting resistors for the footswitch LEDs are in the footswitch. Which, if I might add, is not the best of ideas as it would mean that the + and - connections ...

It was discussed in this topic. Some educated guesses came up but no conclusive information: https://ampgarage.com/forum/viewtopic.php?f=4&t=36247 Looking at the gut shot in the above thread, as well as hearing the effect of the rotary switch, I suspect the additional gain -- it's not just more 'fe...

Adding to my previous post: Thank you to the admin who run this site and all of the contributors that have made it what it is. This is something I can't say often enough and should have included in the opening post of this thread. I particularly want to give a shout-out to ic-racer for the work he ...

Does anyone know or did I miss that if Gil ever got to update his #124 with the resistors that he talked about that he got from Jelle for the #102 build, that was an incredible story! Just curious if it was updated and what the outcome was, I'm sure it was good if he got the chance to update. I had...

This finished the amp Heyboer Marshall (Fender) style 50w OT. 3k9. Amp isn't a (bad) toy. The clean hangs out after bouncing like a ball. The volume difference was going from injured Deluxe Reverb to 70w Park. The headroom went up 5 floors. I clipped the LNFB and reality lives in the World. The cho...

instead to removing all the coax cables to be replaced , it is easy to put 50pF-75pF to the ground on al the nodes where is suspected the cable has too low capacitance (increasing shield capacitance) . :wink: At least in theory, yes. In practice, it doesn't necessarily always seem to be that simple...

is that installed like a cut control (Vox style)? Connected to the input of the OD ratio control. That's the way I had tried it as well. I think it'd preferable to use a slightly larger resistor at the V2B output, like 180K instead of 150K - in case you haven't done it that way. The HF trim inevita...

Thanks. Sorry, no clips yet. The small board above the PI is a high-frequency taper. HAD used it in 094 and at some point in 102 (I believe). It's just a 500K trimmer with a 0.001 to ground. You can shave some of the top-end off as these amps can be on the bright side. Mine wasn't overly bright but...

Purists, I accept your scorn without judgment. :mrgreen: In your opinion, what does the Dumble overdrive circuit do for your Dumble sound that an overdrive pedal in the loop can’t/won’t? Interested in your thoughts. The only ODS style amp I own is a Fuchs ODS II, and I don’t find myself needing the...

I am kicking myself today :cry: Robben Ford played a concert last night at our lake community which is free to residents. We were at the lake during the day and saw/heard the soundcheck but didn't realize he was playing (we also had guests over). I have never seen RF live and thought even if he cam...