Hi all
I´ve got the old DIY build nerv itch again and this time I´m looking for a schematic for an PP integrated stereo with 6V6 for output. I´ve seen a couple of schematics floating around but can´t make up which one to choose.
Anyone have any sugestions or recommendation?
Cheers
I´ve got the old DIY build nerv itch again and this time I´m looking for a schematic for an PP integrated stereo with 6V6 for output. I´ve seen a couple of schematics floating around but can´t make up which one to choose.
Anyone have any sugestions or recommendation?
Cheers
Don´t over do it! Keep it simple please, Im no technician.
What would you suggest?
How about this one? Would you say that it could be something worth building?
Cheers
I don't think so, with a paraphase, AKA seesaw, phase splitter and a "funky" bias supply.
What's the budget? Poindexter's "Musical Machine" and the "El Cheapo" project I've been involved with both employ differential splitters and solid PSUs. If you plan to use O/P "iron" that's not particularly costly, "El Cheapo", with its NFB loop will (IMO) serve you better.
Oh yeah, the 'AQ5 shown in the "El Cheapo" schematic is, for all practical purposes, a 6V6 in a 7 pin mini bottle. 😉
Attachments
Sorry, I was fooled by the 270 KOhm part.
It is differential, if slightly "weird". A voltage divider is setting grid bias for both 'T7 sections. Still the tail is way too short for identical 100 KOhm load resistors to be used.My highly negative opinion remains intact, as that circuit uses full pentode mode "finals" and no NFB. The damping factor will be VERY poor. 🙁
Agreed. But easily fixed. I do like the idea of raising the cathodes quite a bit, now you can use a CCS without a negative supply. Hook up some NFB to the idle grid and bingo. You're in biz.
First, as above pointed out, it's not paraphase. Second, so what if it's paraphase? Don't knock it before you hear it. Sonically, I'd take paraphase over differential any day. Aside from transformer being the best sound, paraphase and split-load are my favorites.
The old Magnavox 6V6 amps I think used paraphrase splitters and are really nice sounding amps. You could do a rebuild of one of those unless you want a new build
How about this one? Would you say that it could be something worth building?
Cheers
Well, I'd say build and listen. Any mods could be easily applied.
The whole point is - Keep It Simple, St*p*d. 😀
Personally, I like the negative bias on the O/P valves. It allows for a bit more power output.
What about something like this?
This originally came out of an old Sears Silvertone console set.
(Original schematic)
This is the schematic after I did some of the first mods. (added cathode bypass cap on the outputs,and used some larger coupling caps,etc.)
One of my most recent mods was swapping the first 60uf/40uf sections around in the PSU,to be a bit kinder to the rectifier. (Yes,it had 60uf on the rect. cathode,stock.)
For a small amp,with small 'run-of-the-mill' output transformers,it sounds great and has good (mid)bass response. Some nicer (Edcor?) iron might put this into the 'major leagues',IMO.
I get about 8Wpc before any visible distortion on the 'scope.
I use JAN (Phillips) 6V6's and Sovtek 12AX7LPS tubes.
I used a (RCA,or GE) 5U4GB for the rectifier for a long time,and just recently tried a Svetlana 5UC3/5S3P (?) and like it even better than the 5U4GB!
This originally came out of an old Sears Silvertone console set.
(Original schematic)
An externally hosted image should be here but it was not working when we last tested it.
This is the schematic after I did some of the first mods. (added cathode bypass cap on the outputs,and used some larger coupling caps,etc.)
One of my most recent mods was swapping the first 60uf/40uf sections around in the PSU,to be a bit kinder to the rectifier. (Yes,it had 60uf on the rect. cathode,stock.)
An externally hosted image should be here but it was not working when we last tested it.
For a small amp,with small 'run-of-the-mill' output transformers,it sounds great and has good (mid)bass response. Some nicer (Edcor?) iron might put this into the 'major leagues',IMO.
I get about 8Wpc before any visible distortion on the 'scope.
I use JAN (Phillips) 6V6's and Sovtek 12AX7LPS tubes.
I used a (RCA,or GE) 5U4GB for the rectifier for a long time,and just recently tried a Svetlana 5UC3/5S3P (?) and like it even better than the 5U4GB!
My favorite PP small power amp is the Pilot SA-232. It uses EL84/6BQ5 but can be easily adapted to use 6V6. I have used its circuit to apply to other amps, mods, and rebuilds, etc... The circuit might look old fashion to some but the sweet sound never fails impress.
Full schematic with both channels and power supply:
Only one channel shown:
Full schematic with both channels and power supply:
An externally hosted image should be here but it was not working when we last tested it.
Only one channel shown:
An externally hosted image should be here but it was not working when we last tested it.
The voltage amplifier/DC coupled "concertina" splitter small signal topology is a good choice. The modifications to the OEM setup make sense. The Sovtek 12AX7LPS happens to be a genuine 7025 equivalent. 😉 Poindexter likes "reissue" TungSol 6V6s made at Saratov, Russia. He prefers them to NOS.
The inexpensive, but very effective, Greinacher doubler B+ PSU from "El Cheapo" would work WELL with this setup.
Lower CMiller at the amp's I/P, along with higher small signal gm, would be (IMO) an improvement. Reducing CMiller reduces the risk of HF info. loss. High gm in circuits with GNFB loops provides resistance to HF error correction signal induced slew limiting. A 6GK5 as the voltage amplifier and an ECC99 section as the "concertina" splitter would achieve those goals.
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