The Amp Garage

Ciao Martin,
I've built something similar for a friend of mine. That "pony" screams like a damned! The first stage was a plexi like 100k 820R//680n, then like a trainwreck.
Great job!

Hi Gordon,
Great work! Do you have any sample or layout?

Thanks!

Robi

Ciao Martin, thanks for the answer. In this post I've attached some frequency simulations of the modified "tonestack". Name of file is related to knob position (12 o'clock is half way vertical knob). These simulations fits quite well a regular stack. Please note the mid-band raise as you add a resis...

Well, 160 views of the thread in 24h, alot of downloadas and no idea..
Quite strange!

Hi all, I'm working on my 2+2 channel amp, but meanwhile I keep on projecting the next amp: a Trainwreck based minimalist two knobs head. The idea is born while I was figuring out the scoop mod for the clean channel of the current head: adjust the scoop with a single pot (clean versatility gains but...

Structo is right. Supply Caps (and supply structure in general) can change the way an amp sounds. In bass amps, using "switching" capacitors can change a dull amp in a war hammer. But this concept fits also guitar amps. Guitar punch is basically in the low-mid of the spectrum, so good caps (and a in...

Thanks Greg! I like inductances too, in supply, for everithing above 40w. More punch, more airy, less low-mid colour. I think supply is one of the main thing on an amp with master above 4. I've got an OT idea reading your post. Have you ever used tv shielded cables? They are solid-core, low capacita...

Hi Massy!
A good 100u cap can work better than cheapy 220u, but with the same brand, half the capacitance means less punch and less bite. This is more evident as you raise the volume (because the amp needs more current and capacitors could not have enought to punch in the right way).

Greg, now it works, great sound! what mods have you done? El_Martin, please stop repeating "all work and no play make Martin a dull boy" :wink: jerrydyer, as the input impedance raises, high-mid rolls of, and the whole eq works totally different. A post CF eq stack has a 1k input impedance, a trainw...

Hi Lefty,
just a typo: reducing the 150k resistor will allow less bass through the amp.

jerrydyer,
does this mod is on pre-gain-eq amps? Or you do it in marshall-like amps?

rhinson,
I think you talk about valve-state's contour. Isn't it?

gcenker,
I can't play that file. Renamed with mp3 extension, doesn't work.

I buy them at Tube Town. They are German. Search them as Fischer & Tausche.

Ears, we are both quite wrong. The shortest way to ground depends on tube, plate resistance, capacitance and load. I said the shortest way to ground for the second cap is the load because reactance is 1/(2 pi f C). Usually you have 1n to 22n caps. A 22n at 5kHz has a reactance of 1450ohm at 1kHz 725...

Well, no. In a cathode bypass cap, the outer foil is to ground, the inner to cathode. Otherwise no shield effect will appen.
But in this thread we are not talking about general cap orientation, but the orientation of a series of two cap.

My thought is: outer foil has to shield the signal from external noises, so you have to "ground" it in the shortest way you can.
But a cap is not conductive, so if you want to "ground" the outer foil, you have to solder the two in opposite direction. Isn't it?