• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Finally building my MkIIIs, a pictorial thread

Well, happy to make a small report back here. Life gets busy and I fall out of this hobby, then find myself always sucked back in🙏🏼 Amp 1 is up and running. Someone had commented about paralleling up the feedback R's, so @6.8k that was 3.4k. I knew it needed at least as much, and had some carbon comps I wanted to use, so I'm testing out 3.3k. I can see I'll be going up to 3.6-4, it's a little too much but, right now it sounds about 3db louder than my el-84 push pull, which is running channel 2 (yes only one side driven). What really suprises me is just HOW much this thing sounds better with the feedback change. A/B with a balance slider shows the 6550's putting out a sound with comparable low end, comparable maybe better mids, and comparable highs. Which is saying something, the soundstage on the el-84 amp is amazing🙏🏼
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Hmm..well, seems I remember drawing that up as well, oh yeah, I ended up running last years KT-88 PP stereo amp that way, L7>N7. I might try it out. These Heresey 1s are pretty good at filling my living room anyhow, them and a 10" powered sub. This is good field proven info, thanks for anyone who checks this out. I'll probably go near 3.8k. I always prefer some constraint 🙏🏼