The Amp Garage

I just installed a slightly less comical looking 20k 5 watt dropping resister instead of these 2 in series. I'm looking forward to running this all through its paces in a variety of settings to see if it's hype-worthy yet.

In the diagram the switch is set to fast ( higher gain) mode. https://ampgarage.com/forum/files/Express_pre_amp_variation.jpg OK, thanks. So I guess since I'm wired to the plate load being split, I'm in the lower gain mode as far as the plate is concerned. But mine's not that circuit otherwise, bec...

The resistor values are 82K and 22K. Yes, that's the values I currently have in there.. with no switch.. just hardwired in with a 0.005uF cap and a 150K resister to ground. The 82k is not visible in the picture because it is wired over the edge of the board right to the tube socket. 20240424_221042...

Well, I did a bit more tweaking and I think I should button this up and play it for a little while in some different settings. Where it's at compared to the original MHartman layout (aside from the physical chassis layout being different and having the separate CF Driver and Bias power supply): 2024...

martin manning wrote: ↑Wed Apr 17, 2024 1:00 pm To be strictly correct in eliminating position 1 you would do this:

OK, great, that's what I was thinking I would do.

I realized that I had tweaked the wrong cathode resister when I thought I was doing the stage after the filters. Wires to V4 cathode components were hidden under the board, so I was actually lowering the headroom for the reverb I think. I had just put its value back to 1.5k when my soldering iron ti...

Good to hear you are happy with the result! Yes I have made some small adjustments re the schematic at the top of this thread. What you posted just above is the latest. There are a couple of ways you could do six positions, one would be to recalculate all of the resistor values to keep the "taper,"...

Thanks for this Martin! I'm really impressed with this iteration of your updated filters. This looks to be the same as the schematic that I implemented yesterday to my SSS (The conversion from a YGL-3a). I had to search around to find your newest version. I can't right now find the original schemati...

I got the Martin Manning Step Filters in, and I have to say how much I love them! Such even useful steps; each giving the appropriate perceivable increase in their respect highs or lows. Such a beautiful implementation. Definitely worth making the update for anyone considering this and wondering if ...

I'm still working on this amp continually. I took a week off work to painting our main level of our house, and tweaking this amp in the late evenings after our kids are in bed. I went back to the GNFB on the Hartman layout with no presence this time (for now). I may play with more GNFB arrangements ...

Here's a better layout. It is only missing a 1meg resistor at the input jack AFAIK. Feedback network consists of a 220k series resistor and a 4k7 resistor at the tail of the PI. The only thing the presence pot does, is gradually paralleling a 100n cap to that 4l7 resistor. You can vary the 220k ser...

I've just taken a big detour revisiting the global Negative Feedback and presence circuit... because they seem to have a big impact on potentially creating some harsh frequencies in the 5kHz ish? region... especially on the pick attack. I've changed the circuit before in this area when I first wante...

I was just checking out your schematic and layout today for inspiration on altering my presence and GNFB values on my MHartman layout #004? inspired build. Anyways, I tried wiring mine like your schematic, but it seems like something is a little wrong. When I use the presence circuit in your schemat...

I also see that it should not accompany a bypass cap. It might be true when the idle point is shifted so far towards cutoff but you can try a mildly asymmetric bias and see how that works, even small changes in value have an effect on the headroom. In my case I used a 2k7 resistor with an unremarka...

I believe the Mhartman version of the SSS has the mixer tube that mixes the clean and reverb signals like the JM Signature clone. I wonder if changing this can get you what you want. The #005 SSS does not use that method of mixing the clean with the reverb and it has lots of gain on tap. You can li...