Have anyone built this 6V6 amp?

[Cassiel]

Originally Posted by lawbadman

so I will be fine with this DIY Push-Pull (PP) 6V6 / 6V6GT Tube Amplifier Schematic version right??? It seems to have all the modifications you guys mentioned.

I would use a 470 Ohm resistor to bias the 6SL7 and then apply best feedback ratio for your taste, OT's, speakers, etc. If that's too complicated for you use 1K. Not the 10K in the schematic you posted. Is that clear now?

EDIT: Miles your theory is correct however the amp sounds great. I did try an LTP first. Talking about the phase splitter, not about the PS.

The Leben CS300 uses same splitter, maybe you have the chance to hear that amp one day.

[kevinkr]

Originally Posted by stalker

Well, could be. Maybe a bad layout or bad power supply design. Anyway 10K to bias the 6SL7 is ridiculous.
I didn't have oscillation using 1K feedback resistor with Hammond OT's.

BTW, the 6V6's sounded better in triode mode.

Not surprised to hear the 6V6s sounded better in triode mode.. As a general comment you clearly know exactly what you are doing and why - such may not be the case with a relative newbie, and as described that particular project amp is broken.

[Cassiel]

Right.

Lawbadman build it like it is, just beef up the power supply caps, 100uF instead of 47uF, and remember 1K not 10K for that resistor

That's it.

[Mosquito]

I'm wondering how serious could be the fact (pointed by Crowhurst, that hates this type of paraphase) that , from the point of view of the NFB signal, it passes two stages on the (-) phase, and three stages on the (+) phase (V1a + op tube vs V1a+V1b+op lower tube)
I'm wrong?

[Miles Prower]

Originally Posted by Mosquito

I'm wondering how serious could be the fact (pointed by Crowhurst, that hate this type of paraphase) that , from the point of view of the NFB signal, it passes two stages on the (-) phase, and three stages on the (+) phase (V1a + op tube vs V1a+V1b+op lower tube)
I'm wrong?

The NFB doesn't go through three stages, since there's that 100uF bypass capacitor to help prevent this. Still, the whole arrangement smells of "quick 'n' dirty", and I would expect that, at low frequencies where the 100uF bypass begins to lose effectiveness, you would have low frequency stability issues (and high frequency issues where the internal inductive reactance becomes significant).

[Cassiel]

(pointed by Crowhurst, that hates this type of paraphase)

Where did you read it? I have serious doubts about that.
World's full of skeptics; I say build it, listen and then comment. In that order.

[Mosquito]

Originally Posted by Miles Prower

since there's that 100uF bypass capacitor to help prevent this. ", and

Completely missed this one. Isn't exactly as the Magnavox though..

[lawbadman]

ok hmmm im not getting a good vibe about this design from you guys. I did actually try the original version of the amp but with 12ax7 and 6v6 and a 6.6k hammond trafo. I did not like the sound at all so I dismantled it. I was going to give it another shot but.....
Soooo can someone point me to a well designed 6v6 amp???

I did find these though:
http://www.joeltunnah.com/images/jt_6SN7_6V6_v2.jpg
Frankenhouse


Any thoughts? ideas? suggestion?

[Miles Prower]

Originally Posted by lawbadman

Soooo can someone point me to a well designed 6v6 amp???

Poindexter's Musical Machine. (He's on here, so you might want to look him up, and there are just esssssss-loads of threads dedicated to this particular project.) The one and only "drawback" to this design is that the 6V6s are being used as pseudotriodes. That does compromise on the output power, but 6V6s do make excellent pseudotriodes. (They're also excellent as pentode finals as well.)

This also uncomplicates the design since you won't need screen voltage regulators if you're not running the finals as pents.

[lawbadman]

Originally Posted by Miles Prower

Poindexter's Musical Machine. (He's on here, so you might want to look him up, and there are just esssssss-loads of threads dedicated to this particular project.) The one and only "drawback" to this design is that the 6V6s are being used as pseudotriodes. That does compromise on the output power, but 6V6s do make excellent pseudotriodes. (They're also excellent as pentode finals as well.)

This also uncomplicates the design since you won't need screen voltage regulators if you're not running the finals as pents.

I did actually consider that amp but I got scared when I saw it needs a -160Vdc. That means I would need an extra high voltage trafo, and im trying to keep costs down.