The Amp Garage

Just looking at the actual power section of this YGL:

I want to forget about adding reverb for now... but am still obsessing about trying to build in a Dumbleator. I am maybe redoing someone's work, but I haven't found it exactly... so I messed around with Paint to theorize how one would add a dumbleator to a 102 circuit: 102 with Dumbleator Theorized....

Since KT8K8 are beam tubes like 6L6, and the power amp is a clean Hi-Fi type, I don't think it would matter. That's what I figured. Mostly it's something like the 183 or HRM that get a little different. I'm getting a little mixed up keeping track of all the different models and trying to hear the d...

I'm becoming quite happy with my other YGL-3a that was completely gutted and converted to an SSS... I'm feeling like this YGL-3a finally deserves a proper conversion to an ODS circuit. I'm thinking I'd like to keep it running these 2 KT-88s. It seems to be working well, with this VVR for the screen ...

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...