The Amp Garage

Stevem wrote: ↑Sat Aug 26, 2023 1:39 pm At the speaker.
Amp chassis ground to + on speaker(s)

I don't get it. That makes it out of phase with what? I don't see how it would make a difference unless the speaker is out of phase with the microphone?
I'm curious about this as a bandmate has started to play harp.

Stevem wrote: ↑Wed Apr 26, 2023 11:40 am One of the main things I have heard about Harp amps and having them not be as prone to feedback is to wire the speaker out of phase.

Out of phase with the first gain stage?

As you said, this 500K+470pF/500K chain after the gain pot is the same result as the 1M pot with the 470pF bright cap attached, so remove them altogether and attach the 1M pot + 470pF cap to the corresponding location to find the sweet spot before applying It seems like a way to try it. I don't thi...

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 ...

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.

In the case of most amplifiers, additional Grid Leak is rarely installed with the gain pot installed. In the case of the ecstasy circuit, assuming that the gain pot is set to the maximum, it seems to be the same form as applying a grid leak of about 330K in parallel with a 500K pot +500K gird stopp...

Are you sure the solid state diodes are soldered to the right lugs on the rectifier socket? It's hard to tell from the pics, but it looks to me like one of them is going to pin 7 instead of pin 6.

This "Unboost" function is working normally, but I wonder why the 500K Grid Leak at the same location did not change the signal even after changing or removing the value. I checked the switch but it was normal. Why was there no change at all when the Grid Leak value was changed? Anyway, let's get b...

You still need to change the 500K gain pot to 1M (with the grid leak at 1M) if you want it to have about the same amount of available gain as the Marshall.

Are you familiar with the concept of voltage dividers?

Sorry. "pot" is just a typo. So, how can improving this part help get closer to the JCM800? Of course, it would be impossible to make it the same as the JCM800, but since I got satisfactory voicing through the current 22n coupling cap mode, it would be nice to add a little gain and high frequency c...

Can you elaborate on the 500K/500K pot you are talking about? Is this about where it is mounted? Or is it about value? It's not a pot, it is in your Bogner schematic right after the gain pot. You have a 500K resistor in series with the signal, followed by a 500K resistor to ground. The two resistor...

The additional 500K/500K voltage divider right after the 500K gain pot is probably the main reason your amp has less gain than a Marshall.

Tobyk wrote: ↑Tue Aug 15, 2023 7:25 pm Can the gain stage part of the cathode follower circuit be a cold clipper? Why is this stage often set to 820R?

The tonestack still needs a fair bit of signal before it. A tradtitional cold clipper isn't the best option right before a tonestack because it can sound a little muffled and "lame".

I'm not sure why you need to have separate jacks for slave in/out? If you want effects on the sound going to an external power amp, the signal from the effects return needs to go via the slave out jack.

If you use a passive loop you may need to place it after the master volume. If you put it where the active loop is in a SLO100, the signal will be way too hot.