HI Guy's,
Again a question about one of my amps.
I've build a tube amp with ecc83's in the pre amp, ECC83 PI and 2x 6V6 fixed biase end stage.
I've leaned not to put big electrolytic caps in the preamp stage.
Made the power string with:
5AR4, 50uF, choke, 50uF, R, 10uF, R, 10uF, R, 10uF.
So PI and pre amp tubes are feeded by 10uF electrolytic caps.
When turning the amp flat open I had bad 'cracks' in the distorded sound.
I switched the 10uF by a 22 uF cap at the PI and the problem was solved.
Question:
is 10uF to small for a PI? or is it a bad electrolytic cap?
grtz
Guss.
Electrolytic cap to small?
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Stevem
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Re: Electrolytic cap to small?
You will find that most amps use 22 to 50 uf filters for and after the PI section.
That being said I also think you should have at least 70 to 100 uf for the first main filter section and then you can knock it down to 50uf after the choke.
That being said I also think you should have at least 70 to 100 uf for the first main filter section and then you can knock it down to 50uf after the choke.
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Not screaming like the passengers in his car!
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Not screaming like the passengers in his car!
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David Root
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Re: Electrolytic cap to small?
60uF for a 5AR4. According to the datasheet, but I would think that is on the conservative side in practice. I don't think I'd push it to 100uF though.
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Stevem
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Re: Electrolytic cap to small?
I have found that most 5AR4s take 100 uf just fine due to it being none directly heated and as long as the amp does not use 4 big output tubes.
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!
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David Root
- Posts: 3540
- Joined: Fri Aug 04, 2006 3:00 pm
- Location: Chilliwack BC
Re: Electrolytic cap to small?
Thanx for the tip, Stevem. I can see why an indirectly heated cathode would help, but why the caveat about 4 big-ass output tubes? Large current draw?