Hi y’all! A buddy of mine is interested in sending me his VHT special 6 ultra to improve. He’s running it with a 6L6 at the moment and seems open to all kinds of ideas. He wants more clean headroom out of the amp. I’ve been checking out some single ended KT88 designs that interest me. I don’t have the amp to measure the clearance for replacement transformers, if anyone has any idea of what is possible let me know!
I’d even be into rebuilding the amp essentially, it seems like a great chassis and cabinet to build into, he also would like the amp to be the simplest design possible. Anyway, I’d love to hear some suggestions, there’s a whole lot of info on Rob’s site and tdpri but they seem to be suggestions that go in the opposite direction of the proposed goal! Thanks y’all
VHT Special 6 Ultra project
Moderators: pompeiisneaks, Colossal
Re: VHT Special 6 Ultra project
Check out my recent SE build. Very simple, good sounding. I'm getting about 9 watts clean into an 8-ohm load.
https://ampgarage.com/forum/viewtopic.php?f=6&t=33171
https://ampgarage.com/forum/viewtopic.php?f=6&t=33171
I build and repair tube amps. http://amps.monkeymatic.com
Re: VHT Special 6 Ultra project
The transformers in the Special 6 (and Ultra) are the only components that aren't bottom of the barrel. The layout is terrible, and the only "redeeming" part of the chassis is that the circuit board is easy to get to by just removing the chassis from the cabinet.
Despite their attempt to be the most affordable tube amp available they're not the worst amps ever made. I actually like them if you can get them dirt cheap, and/or if you want something easy to learn how to solder on.
Despite their attempt to be the most affordable tube amp available they're not the worst amps ever made. I actually like them if you can get them dirt cheap, and/or if you want something easy to learn how to solder on.
Re: VHT Special 6 Ultra project
I've found the chassis awkward to work on. Being a deep U shape, the components at the bottom of the U (jack sockets, fx loop , speaker etc - back of the amp) dificult to get to with a soldering iron, necessitating quite a bit of dismantling to get to them, or trying to work through a forest of flying wires from the board to the controls (on the sides of the U). Lots of cursing usually ensues.
I've moved the loop and line out components off the jack sockets and onto tag board close to V2. Easier to get to to modify or repair.
The good thing is that there is plenty of space in there.
I was going to convert the amp to push-pull 6v6 only, no tube swapping afterwards. But to ease the layout I think I will move most of the signal components off the main board and onto tag strip and directly to the tube bases. hopefully that will cut down on the number of flying wires. The main board will just be power supply components (mostly). Plan to put the new OT closer to the output tubes, and that should tidy up some more of the wiring.
I beginning to wonder whether I should just build a new amp, and leave the SP6U as it is.
I've moved the loop and line out components off the jack sockets and onto tag board close to V2. Easier to get to to modify or repair.
The good thing is that there is plenty of space in there.
I was going to convert the amp to push-pull 6v6 only, no tube swapping afterwards. But to ease the layout I think I will move most of the signal components off the main board and onto tag strip and directly to the tube bases. hopefully that will cut down on the number of flying wires. The main board will just be power supply components (mostly). Plan to put the new OT closer to the output tubes, and that should tidy up some more of the wiring.
I beginning to wonder whether I should just build a new amp, and leave the SP6U as it is.
Re: VHT Special 6 Ultra project
Everything that jml77 said in the first paragraph, I personally summarized that into "The layout is terrible". I personally have both a S6 and a S6U and the significantly smaller and more crowded non-Ultra makes it even more difficult to work on anything that isn't on the circuit board.
I acually built an entirely new audio signal path circuit board to go into the base model, leaving the power supply on the original board. If I hated myself a little bit more I could have squeezed that into place and forced the project to completion, but I decided that I don't deserve that kind of punishmment. Like I said, I actually like the transformers and want to use them. Instead my current intention is to take the transformers from the pair of VHTs and build a dual mono amp in a single chassis that isn't an awkward gimmicky shape. (And yes this *is* one of a million projects that I've started and not finished.)
I acually built an entirely new audio signal path circuit board to go into the base model, leaving the power supply on the original board. If I hated myself a little bit more I could have squeezed that into place and forced the project to completion, but I decided that I don't deserve that kind of punishmment. Like I said, I actually like the transformers and want to use them. Instead my current intention is to take the transformers from the pair of VHTs and build a dual mono amp in a single chassis that isn't an awkward gimmicky shape. (And yes this *is* one of a million projects that I've started and not finished.)