SE 6v6?
- Thread starter golana
- Start date
MickeySmile
Well-Known Member
I will follow as well
cubby01
aka Buck
Golana, color me ignorant. You mention RH84 but then talk about pre tubes of 6SL7/6SN7/6AU6. Why swap out the 12AT7 that's indicated in that schematic. They aren't exaclty direct replacements. I see guitarist swaping these tube types all the time with guitar amps but they are decidedly looking for coloration to their sound. Just asking to learn.
To me, what makes a first generation RH amp distinctive is that it's run in pentode mode with the feedback being of the plate-to-grid short loop variety. The original designer says that the 12AT7 is his personal favorite because it's synergy with that style of topology beat other driver choices. I tried a different driver before exactly following his schematic, and indeed, it did not sound as good as the solution he derived.
That being said, I've built and heard amps similar to the RH84 that did not use the 12AT7 and sounded wonderful. They deviated from the original RH topology in that they had output transformers with a UL tap, and were run in UL and triode mode. In those cases, the plate-to-grid feedback was still there, but much reduced. Pentode mode needs more feedback to be stable, UL and triode strapped do not. A very good example of an amp of this nature would be Kegger's KT-88 schematic, or the Compactron amp.
I find the RH schematic to be a good way to recycle output iron that lacks UL taps, especially smaller iron and smaller tubes. You get to run them in pentode mode for most power, and at single digit WPC sometimes you need all the help you can get. It's a stable and good sounding schematic. I tend to not screw around with it too much, because I've not found a change under those circumstances that made it any better.
If I have output iron that has UL taps, I would not build a RH amp as it would be a waste of those taps. If my output iron lacked taps but I still specifically wanted to run it in triode mode only, I'd also not use the RH schematic. (Note that triode and pentode modes are usually incompatible enough to provide easy switching, unlike triode and UL.)
That being said, I've built and heard amps similar to the RH84 that did not use the 12AT7 and sounded wonderful. They deviated from the original RH topology in that they had output transformers with a UL tap, and were run in UL and triode mode. In those cases, the plate-to-grid feedback was still there, but much reduced. Pentode mode needs more feedback to be stable, UL and triode strapped do not. A very good example of an amp of this nature would be Kegger's KT-88 schematic, or the Compactron amp.
I find the RH schematic to be a good way to recycle output iron that lacks UL taps, especially smaller iron and smaller tubes. You get to run them in pentode mode for most power, and at single digit WPC sometimes you need all the help you can get. It's a stable and good sounding schematic. I tend to not screw around with it too much, because I've not found a change under those circumstances that made it any better.
If I have output iron that has UL taps, I would not build a RH amp as it would be a waste of those taps. If my output iron lacked taps but I still specifically wanted to run it in triode mode only, I'd also not use the RH schematic. (Note that triode and pentode modes are usually incompatible enough to provide easy switching, unlike triode and UL.)
Which is where I am also, recycling iron. If I chose to build ala RH.
But i have other outputs available if I wanted and well, you never know.
Having built several RH84, Redboy then built one of Keggers(I never saw a schem.) and seems to like it.
Although it is probaly UL, but these are why I ask.
Cubby, before I build if someone had some'n they thought was a better idea than the other, I felt I'd like to look at it.
Also I have other tubes and no AT7's.
But i have other outputs available if I wanted and well, you never know.
Having built several RH84, Redboy then built one of Keggers(I never saw a schem.) and seems to like it.
Although it is probaly UL, but these are why I ask.
Cubby, before I build if someone had some'n they thought was a better idea than the other, I felt I'd like to look at it.
Also I have other tubes and no AT7's.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
(as far as I'm concerned Squid hit the nail on the head), but. 
Yes Redboy's SE amplifier is running UL and that different circuit.
If your running Pentode (because you want to or have outputs with no UL taps) the RH
setup is a good way to go, off the top of my head probably the way I would go as well.
(given some time I may think of another option)
Anywho do your outputs have UL taps?
Yes Redboy's SE amplifier is running UL and that different circuit.
If your running Pentode (because you want to or have outputs with no UL taps) the RH
setup is a good way to go, off the top of my head probably the way I would go as well.
(given some time I may think of another option)
Anywho do your outputs have UL taps?
Not the ones I have now, IIRC they're Zenith 5K that ran 84's.
I'm going to build the RH version to have something to do here.
I've been watching and bidding on SE/5K, I will in the future play with these several more times.
6V6's are so good, I could stick my foot in them.
I'm going to build the RH version to have something to do here.
I've been watching and bidding on SE/5K, I will in the future play with these several more times.
6V6's are so good, I could stick my foot in them.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
If you want to run your 6SL7, I could mod the RH setup to where I think it should be
very comparable to the 12AT7, I think it would work rather well and you can use the
tubes you already have instead of finding 12AT7's, although I do like 12AT7's as well.
Just let me know if I need to do some "designing"
very comparable to the 12AT7, I think it would work rather well and you can use the
tubes you already have instead of finding 12AT7's, although I do like 12AT7's as well.
Just let me know if I need to do some "designing"
Those cheap Edcor output transformers are... well, cheap and great quality for the price. Might want to order up a pair of those for grins n' giggles.
Certainly not the Tango, that went for 270.
Keg, thanks I might use that at some point. Could have sworn I saw everything except the FB, in a thread, hmm. Maybe it was for a SN7.
I have a couple AT7's, and my brother has a hoard(McIntosh) I think I'll waddle thru this low rent version first.
Appreciate it.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
Well I forgot I had a similar setup going, so I tweaked it a bit..
This should be a good working version using the 6SL7 if you decide to do it..
(about 1v to drive it full pwr, an same amount of feedback as the 12at7 circuit)
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Higher B+ raise the 6V6 cathode resistor,
This should be a good working version using the 6SL7 if you decide to do it..
(about 1v to drive it full pwr, an same amount of feedback as the 12at7 circuit)
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Higher B+ raise the 6V6 cathode resistor,
Attachments
PabloL
Active Member
Thanks
I too am trying out the 6v6's in both PP and SE arrangments, thanks for posting this schematic. I just need to order up some russian SL7's for experimentation.
Pablo
Well I forgot I had a similar setup going, so I tweaked it a bit..
This should be a good working version using the 6SL7 if you decide to do it..
.
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I too am trying out the 6v6's in both PP and SE arrangments, thanks for posting this schematic. I just need to order up some russian SL7's for experimentation.
Pablo
Kegger
R.I.P. 1/12/1966 - 6/1/2017
I'm sure we could figure something out, let me look at the pdf's and I'll post something.
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EDIT: Posted is schem for 6BM8 that should work well I think for that tube in this setup.
(an isolation power tranny with a voltage doubler should give you decent B+ as well)
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Recent tweak, to "optimize" the driver section a bit. (second schematic)
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EDIT: Posted is schem for 6BM8 that should work well I think for that tube in this setup.
(an isolation power tranny with a voltage doubler should give you decent B+ as well)
.
.
Recent tweak, to "optimize" the driver section a bit. (second schematic)
