access to high powered single-ended transformers - thoughts?

[spiralstairs]

Hi all,

Long time reader, first time poster

I have access to some oldstock hifi single ended transformers.
One 15w, One 45w, one 50w

Ignoring the specifics of the transformers for now, what are peoples' thoughts on project ideas for high powered single-ended guitar amp?
What sort of pluses/minuses would be seen with this?

I thought it'd be interesting to try a 50w single bigbottle amp (gu 50 anyone?). Perhaps kt88 could be used.
Or perhaps running multiple el84's into a single-ended 15w, if all the numbers match up.

But ignoring the science for now, what would you do with a high powered single ended amp? Anyone experimented with this? Not sure how much of a plus it would be over typical classA vox/rocket/etc setup

The obvious choice for the project would be a rocket or a liverpool, but any other thoughts?
Because of the hifi characteristics of the trannies and perhaps even the tubes, I was thinking something hiwatt -ish.

Anyone with experience using gu50 or 6h13c/6c33c tubes in a guitar amp? Or should I try and force a el84/kt88 more standard tube

[M Fowler]

I kinda like Ted's recent entry with 806 tube.

[tubeswell]

hey that looks interesting Mr Fowler. You got any other SE schemes like that?

[tubeswell]

Hi all,

Long time reader, first time poster

I have access to some oldstock hifi single ended transformers.
One 15w, One 45w, one 50w

Ignoring the specifics of the transformers for now, what are peoples' thoughts on project ideas for high powered single-ended guitar amp?

How about a parallel SE amp with 2 x KT66s or KT88s?, and a 3 or 4 stage pre-amp with something like a cascode driver to drive the output tube grids really hard?

http://www.freewebs.com/valvewizard/cascode.html

[M Fowler]

I had saved some that thought were interesting when I looking at the Allen class act and DLM kind of amps.

[spiralstairs]

Thanks for those - ever helpful as usual. Being a HIWATT fan, I've obviously browsed your pages quite a bit

These are all definitely along the lines of my original thoughts.

2-KT66 JTM-45 inspired amp, with cathode bias, something which seems a lot like the KT66 rocket builds that have been going on, which I found when searching this idea. I'd want to do a test build with a PP transformer to see what differences there might be between the 2 - this is what I'm really curious on and whether anyone has experience with this. Of course, sound quality is largely subjective

The octal fatness seems interesting, I'm always interested in trying out new tube types. Thanks to your suggestion, I think I'll try giving that a test just for fun.

Where did you get the 8W schematic, if you remember?

I'm still curious why I don't see much in the way of single-ended 20-35w amps, I'm thinking 4-el84 ac30 style, it seems like something which might be popular to try. Even ac15 style?
Is the reason simply a lack of transformers to use?
Or massive heat issues?

Either way, more schematics are always a plus More to learn from

Edit - I've now found 2 amps doing the single-ended thing:
http://www.fargenamps.com/ampminiplex.html
http://www.savageamps.com/index.cfm?id=7&s=1
But both are 12w, which isn't too uncommon to find 8-10w SE. And I guess I was stuck searching 15-20w and so didn't see ones which are officially called 12w yet use 2xel84. So perhaps this validates me trying out these ideas, but I'm still curious why its not more common

[joebob]

Here are a few I have saved. I think there were some ax84 amps that used parallel output tubes. There are a few on the hoffman amp site too. Let me know if you need a board built, I build boards on the side.

Dave

[dartanion]

There are lots of cool options with the OTs that you have. I love SE amps but wanted more power, so I decided to try a wreck style amp but SE and that turned into my production amp the Absinthe. It can use multiple octal output tubes, but I favor EL34s in it. I haven't tried mixing pairs yet, but it has parallel octal sockets in the output.

Here's a you video demo. The first section is with the VVR turned down to about 1/3 output, then you see a little edit, then the VVR is turned up to 100% power:

http://www.youtube.com/watch?v=7T3itawwRe0

It's not the greatest video, but it gives you an idea of the amp. It is pretty freaking loud and has enough clean headroom to play live with a drummer.

[tubeswell]

Since everyone is posting schematics, here is the Angela Dual SE, which has disappeared off their site - don't know why - Many thanks to Angela - hope I'm not infringing anything

If it is let me know and I'll take it off

[Structo]

I think I remember seeing that on Steve's site before.

I take it that the two preamp stages are halves of one tube, and not the first half of two tubes?
Just the way it's drawn looks like two tubes.

And what benefit are the two rectifier tubes vs one?

[mcrracer]

Since everyone is posting schematics, here is the Angela Dual SE, which has disappeared off their site - don't know why - Many thanks to Angela - hope I'm not infringing anything

If it is let me know and I'll take it off

It is still there...under The How To Section

[David Root]

I built a single tube SE 14W amp a few years ago that nailed the plexi tone. Used a JJ E34L and Sozo coupling caps. My dentist loved it. 1 x 10 Weber Silver Bell was perfect in a Princeton reverb cab with a Mojotone BFPR chassis.

I'll see if I can dig up the schematic, I used Dave Allen's iron, his iron is very good.

I just roughed out a a schematic for a dual 6550 SE amp with a 5F6A preamp/tonestack, cannot decide between fixed and cathode bias yet or whether to do a head or combo, still working on the details but looking at 400V plate/225V screen per the 6550 GE data sheet and a Hammond 1640SE 1k25 primary, as Parts Connexion has cut the price to $70.00 which is a real good price for an 11 lb OT. Or maybe the Edcor equivalent at $83.50. I have a 2x12 cab and a pair of G12s that I think would fit the bill in a combo.

Any comments on fixed/cathode bias?

[UR12]

Hi all,

But ignoring the science for now, what would you do with a high powered single ended amp? Anyone experimented with this? Not sure how much of a plus it would be over typical classA vox/rocket/etc setup

I have a 35w dual single ended amp that I built a couple years back, Dual channel, blendable channels, one octal preamp ( 6sj7 pentode and 6sl7 with baxandall tone stack) and a 12ax7 Wreck side. The Output tranny is a custom wound air gapped 35W made by Heyboer. Both channels are summed/mixed in a 12ax7 2 channel mixer stage that was used to substitute for the gain of a PI. This was a group project designed by a bunch of guys. As far as I know it was the only one built.

Here is a clip of both channels being combined (Blended) using a Tele. The guitar is straight into the amp. Not much Class A in the clip

http://users.zoominternet.net/~jdhall/a ... mbined.mp3

[mcrracer]

Dana, that sounds like an interesting combination. I was / am doing some work with a DLM type of amp. Wreck front end into a KT88 and a Rocket front end into an EL34. The KT88 was awesome, the Rocket I have to get back to. Got busy doing other builds. Do you have a schematic on this amp? I would like to look it over and possibly build one when I get some time. Thanks

[UR12]

I'll see if I can dig it up. It's been a while.