How do the various single-ended amp projects compare?

[PB Wilson]

I'm about to digest the monstrous Eagle Supre thread but was wondering what folks thought of other single-ended amp projects out there.

AX84 amps?
Hunter Two-Stroke/Weber Maggie?
Trinity Tramp?
The ubiquitous Fender Champ?

It's not gonna be for playing out, nor for bedroom use, just maybe some recording and playing in small settings with friends.

[rp]

I built the basic AX84, came out dead on perfect and I thought it sucked big time. I built it for a buddy and it embarrassed me as he thinks it sucks too. I was trying do a tube SE into a Marshall Lead 12 chassis with 5 pot holes to fill and this was pretty much it for circuits. Maybe High Octane better?

Don't know about others but a 5F1 will give you joy and no regrets.

[LeftyStrat]

Honestly, I've never found a single-ended amp that I was pleased with. Now it could just be me, or it could be I just never tried the right one, but they all seem to come out stiff and less organic than a PP amp.

I build the P1 Extreme, and tweaked it every which way, but I ended up using the parts for other amps.

It might be that a lot of single-ended designs tend to be simple, with limited tone controls and number of preamp tubes.

But the clips I have heard of a Wreck pre-amp into an SE power amp, were, meh.

I did play an old Vibrochamp that was nice, but it was the tremolo effect that made me like it. (Damn it Leo, my Strat has a tremolo bar that does vibrato, and the Vibrochamp only does tremolo, what gives?).

[RJ Guitars]

PB,

The Eagle series of amps/threads are all about the DIY experience with the potential to add a useful amp to your arsenal. They are all based on the Fender 5E1 Champ schematic. The Eagle Supre allows you to maximize the wattage you can get in the Single Ended format and has a lot of room for experimenting.

I would tend to agree that in general the talk about awesome amps seldom focuses in on the single ended variety. There are a few things they do well. They are certainly a great place to learn a few things about the DIY tube amp craft... plus they are very affordable and easy to carry.

I haven't built the others you've mentioned so I couldn't comment on how they compare. In all cases you'll have a great tech support network available here at TAG.

As far as the previously mentioned experimental options, the Eagle Supre amp is built in a large chassis and adding a tube or two and growing the amp into something more complex is a possibility once you've learned everything you want to from the original circuit.

rj

[tubeswell]

Make up your own SE amp. Its more fun. Attached is my 'this years' SE amp schematic, a parallel SE with EF86 front end and trem

and soundbytes

Tremolo

http://www.nzguitars.com/forum/download ... hp?id=8232


Blues track

http://www.nzguitars.com/forum/download ... hp?id=8258

[rp]

they all seem to come out stiff and less organic than a PP amp.

stiff and less organic does not = a 5F1. 5F1 = wild, loose, rambunctious.

It might be that a lot of single-ended designs tend to be simple, with limited tone controls and number of preamp tubes.

that's actually the secret to success IME. On the 5C1 you can pretty much get rid of the vol knob too

I haven't built a lot but I've played quite a few little SEs and the 5F1(with V1 bypass cap and a bigger and bright speaker) is as good as it gets. If you no like then 5W SEs might not be for you.

If you want functionality cheap little commercial SS amps can sound better and louder and be more versatile than most tube SE amps to me, like an old Marshall Lead 12 or those Roland Cubes. Good stuff.

[LeftyStrat]

Just to clarify, I'm not knocking SE amps. Just the ones I've built. And it may be the lack of bottom end, or the looseness of the bottom end, or the typically small cabinets/speakers used.

Maybe I should try a design with more power for the low end.

[Zippy]

Just to clarify, I'm not knocking SE amps. Just the ones I've built. And it may be the lack of bottom end, or the looseness of the bottom end, or the typically small cabinets/speakers used.

Bingo!

Try using your lil' combo as a head for your 2-10, 2-12, or 4-12 cabinets and watch out for the smile on your face. A lot of SE amps sound constipated because they are - free up that bottom end with a more efficient output!

[OneWithNot]

I'll vote for the humble 5F1 Champ.

This was the first amp I built, and I was not happy with it UNTIL I took out the recommended cathode bypass cap, used a NOS 5Y3, and 6V6 and traded the C8R jensen reissue I put in for an old Jensen alnico speaker from an organ pull (a '57 P8PS smooth cone I got for the heck of it).

It sounds great now, and I am really happy with it. It is nothing more or less than what it is.

I have loaned it to a number of people with no complaints.

One word of caution, however, just about any of the recommended PTs for that amp put out way over 400 vdc (even with a NOS recto) and you will have to change the cathode bias resistor for something larger (like 1000 ohms). The tube still idles at 11.7Wm (better than the 17W I had with the old resistor!).

If you want a tone control, build a Princeton 5F2-A. Same circuit, plus bigger speaker, bigger cab. But by all means, use NOS tubes and an old alnico, low wattage speaker.

[Phil_S]

I have two SE amps I think are really good. Both use non-standard iron, and both are heads. I have a thing about buying used/vintage transformers on eBay and keep them until a project materializes for them. I run them through good speaker cabs, either a Celestion G10L-35, a 2x10 Jensen C10R, or a Weber 12" ceramic blue dog.

One amp is a 5F2-A Princeton circuit, all octal, using a 6AQ7 and a 6SL7. I don't recall where the iron came from. I want to say it was an Eicor Model 15 tape recorder. It has a comparatively large OT for a single 6V6.

The other is a VibroChamp (tremolo to die for!) using a 6AQ5 power tube, a toroid PT from Antek, and a Stancor A-3823 rated for 8W.

Both of these are distinctly low volume affairs -- no window shakers here. I keep thinking I should make one with a 6L6, 5881, or EL34. That's probably about 20W and could push out some mean tone that you can "feel." I have a theory that your ears and body can sense music as much as it can hear music. The low volume amps don't push enough air for you to feel much.

Of course, I'm not discussing the type of low power amp that offers very little clean headroom. That is a whole other discussion and a matter of personal taste, as well.

[LeftyStrat]

Just to clarify, I'm not knocking SE amps. Just the ones I've built. And it may be the lack of bottom end, or the looseness of the bottom end, or the typically small cabinets/speakers used.

Bingo!

Try using your lil' combo as a head for your 2-10, 2-12, or 4-12 cabinets and watch out for the smile on your face. A lot of SE amps sound constipated because they are - free up that bottom end with a more efficient output!

LOL. "Constipated" was the word I was looking for. I may have another go at it. I'm thinking Vibrochamp with an EL34 in just a head cab.

[wicker]

This thread made me think of a new design, for home playing, but a bit different though, think - 6L6 or KT88 SE, clean preamp + fender style reverb, remaining triode of recovery tube used as power tube driver, and we could get a damn good amp for home recording.

[dcribbs1412]

Not sure if this is relevant.
but maybe take a look at the info in this thread
https://tubeamparchive.com/viewtopic.php?t=16324

Darin

[rp]

I'm thinking Vibrochamp with an EL34 in just a head cab.

IMHO it's lack of tone stack that's the winning ticket in small SEs but my experience is limited. And I do dig BF Champs.

Question for the savants: is it possible Fender took the BF Champ voltages to over 400V to compensate for the addition of the tonestack and vibrato? I know that in 1970 you could run 6V6GTs at 430V but I never understood why you'd want to. Never good to be at the limit of something, at least for a large company with warranty issues and such.

The Mojo Champ/Princeton PT 330-0-330 gave me 380 on my 5F1, bit too high IMO but it Raaawks so it'll do. My next one will have a Hammond HX372X at 310-0-310 that's in the mail. I'll report back on that one.

[Zippy]

I keep thinking I should make one with a 6L6, 5881, or EL34.

I'm thinking Vibrochamp with an EL34 in just a head cab.

RJ Guitars' "Eagle Supre" is just the SE platform for that - big Edcor iron fit for your favorite big bottle tube. I've got a couple "in progress" - one with a BF tone stack (and tone stack lift), the other is 5F2-based with a boost.

https://tubeamparchive.com/viewtopic.php?t=14349