The Amp Garage

This is the current status. On the preamp side, most of the wiring except for channel 3 has been removed, and all pots for other channels have also been removed. The wiring is a bit messy as I tried to temporarily change the earth point. vhgut.jpg Even when the jack is not plugged in and all knobs a...

I tried removing the wire connected from the master volume to the power amplifier (Phase Inverter input), and this thin tone bleeding appears the same as when the wire was connected and the master volume was set to 0. In addition to the sound leakage problem, low frequency noise is also present. Is ...

Thank you for your reply. Parasitic capacitance is a concept I have never heard of before. Because I like making small-sized amplifiers with large output, I have always produced a high-density board layout, and there have been no major problems so far. This build's symptoms are particularly severe, ...

martin manning wrote: ↑Sun Oct 08, 2023 11:41 am The signal may be leaking between board mounted components, bypassing the MV.

bepone wrote: ↑Sun Oct 08, 2023 11:43 am Parasitic capacitance on any point

Could it be caused by overly dense components or wiring placement? What are the cases that mainly cause this phenomenon?

Could it be caused by incorrect ground placement?

I'm making a Diezel VH4 clone, and quite a bit of sound leaks out at master volume 0. If I set the gain knob to 0, no sound comes out. However, when I raise the gain knob, the increase or decrease in the gain amount is reflected. This leaking sound is thin and tearing compared to the normal sound of...

Since I have never experienced a positive feedback phenomenon in a situation where there is no preamplifier amplification signal, I was ruling out the possibility that positive feedback was the cause. However, when I looked at the symptoms, I came to the conclusion that it was likely positive feedba...

SteveM highlights a concern: if pins 1 and 8 are actually measuring 30v to ground with a 1 ohm resistor there is something wrong. Unless you are using pin 1 as a grid resistor mount, or tying it to the 1 ohm at pin 8 , there shouldn’t be anything there . Millivolts only with 1 ohm I'm really sorry....

Why are you reporting voltages on the pin 1 and 8 of your output tubes? For example there is no physical pin 1 on a 6L6 and pin 8 should be at ground with fixed bias unless you have a1 ohm resistor in series to ground to read current. To measure bias, a 1 ohm resistor is connected between pin 8 and...

What’s your rationale for thinking that, what do you mean by ‘stable’ here? The rectifier for the 12V supply is weird, looks like a voltage doubler; why do it like that if you’re using a custom transformer? As a few general points, I think it’s a good idea to - power up via a light bulb limiter unt...

I did a little more testing. Thinking that the 50VAC tap of the power transformer itself might be defective, I checked the AC voltage of the tap in standby mode. The voltage was measured to be within the normal range of 52VAC. Next, I measured the voltage of the bias voltage output unit. When I plac...

I suggest using the high voltage (345VAC) to supply your bias circuit. Change R1 to about 220K. Like this... http://sluckeyamps.com/phoenix/phoenix.pdf I've often made like this. I thought that using a separate 50V tap would be more stable, so recently I have been manufacturing power transformers w...

I am building an amplifier with 6L6 pair Fixed Bias power. It is a Diezel VH4 based amplifier, and the power amplifier is being produced with the same specifications as other amplifiers I have previously produced. Power transformer with the same specifications, output transformer, same output tube (...

The cap across the resistor is more like a high boost, it lets high frequencies pass unaffected by the voltage divider, just like the cap across the gain pot. The treble peak may be less prominent with less attenuation from the voltage divider no matter which of the two resistors you change. I woul...

Doing it exactly like the Marshall would get you the closest of course, but here are 3 other alternatives. They should all give you more gain (less attenuation). They all assume the "unboost" 100K resistor is out of the circuit. Your references are very helpful. thank you Looking at the images you ...

Your references are very helpful. thank you Looking at the images you suggested, I was curious. I understand that the 500K resistor in parallel with the 470pF in the voltage divider works as a voltage divider but also as a high cut. Are the facts I know correct? If so, does lowering the resistance r...