Huge transformers.
Looking at the Univox U-1061 schematic it has 650v B+ at 117vac!
Dorrisant B+ droppers to trim off 40-50 volts? Will that do anything meaningful with B+ this high?
I received the amp "HEAVILY" modified and it did not sound too good.
So I gutted it and am going to build something here.
Thinking mostly just a clean amp with character.
I have owned 3 Redplates amps(Rock Machine, Astrodust Duo, Magic Dust) mostly liked the cleans on them vs regular fender stuff, a bit too much bass though - like to trim that up(sold all of them).
The "haunting mids" keep me awake at night.
So thinking great clean with mids and a loop.
I'll test actual PT voltage tomorrow.
Univox donor amp, U-1061
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sonofmickel
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Univox donor amp, U-1061
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sonofmickel
- Posts: 162
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Re: Univox donor amp, U-1061
All filament secondaries look good on no load test.
B+ is 270/270 = 540v ac, no load.
B+ is 270/270 = 540v ac, no load.
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Stevem
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Re: Univox donor amp, U-1061
They only thing allowing 6l6s to be run with that high a plate voltage due to the voltage doubling power supply is that low 320 volts on there screen.
That 100 ohm 2watt on plates of only the second set of outputs is strange to me, if anything I would expect four resistors.
Maybe someone here on the site can explain this to me?
That 100 ohm 2watt on plates of only the second set of outputs is strange to me, if anything I would expect four resistors.
Maybe someone here on the site can explain this to me?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Univox donor amp, U-1061
My guess is to combat internal oscillation - like the 807 (6L6 derivative) which has 47R 1W directly in the top cap plate connector.
100R per pair would be within a few percent of 47R per tube.
But what about the same with the 1K5s on the grids?
cheers,
Jack Briggs
Briggs Guitars
Briggs Guitars
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sonofmickel
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Re: Univox donor amp, U-1061
How about not using the doubling rectifier.
Low voltage 6l6 build?
Low voltage 6l6 build?
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tubetek
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2 others liked this
Re: Univox donor amp, U-1061
I wound up gutting the power supply section and re-wiring conventional full-wave bridge for 350ish DCV. 4x6V6 worked out pretty good. I thought about a doubler with 2x6550/KT88 but never got around to it.
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sonofmickel
- Posts: 162
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Re: Univox donor amp, U-1061
350vdc would be pretty nice and clean for a quad of anything.
I have a quad of 6550's, I don't know if they like that low plate voltage though.
I have a quad of 6550's, I don't know if they like that low plate voltage though.