Hello dears
I have recently aquired tube preamplifier from one of my friends, he claims that he got it from Singapore, i saw same design on ali excpress though. Anyway, pre is very nice, in very good shape, sounds amazing, however, i noticed small shhhhh sound when i put my ears next to speakers, this shhhh were audible on my solid state preamp before also, but was twice lower,
This preamp is pushing allot of power to my power amp were i need to raise volume only on 1 ( 8 o'clock ) , i will try attaching some videos and photos for the pre and willing to get your kind openions.
Tube pre (unnamed)
Power amp (krell kst 100)
Speakers ls50
https://photos.app.goo.gl/RxKK8sPHEoCdSdrY9
Thanks
I have recently aquired tube preamplifier from one of my friends, he claims that he got it from Singapore, i saw same design on ali excpress though. Anyway, pre is very nice, in very good shape, sounds amazing, however, i noticed small shhhhh sound when i put my ears next to speakers, this shhhh were audible on my solid state preamp before also, but was twice lower,
This preamp is pushing allot of power to my power amp were i need to raise volume only on 1 ( 8 o'clock ) , i will try attaching some videos and photos for the pre and willing to get your kind openions.
Tube pre (unnamed)
Power amp (krell kst 100)
Speakers ls50
https://photos.app.goo.gl/RxKK8sPHEoCdSdrY9
Thanks
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Paid Member
Are they triode strapped? A resistor connecting pin #6 to pin #8 (G2 to plate)? Can't tell from your pics.
jeff
https://frank.pocnet.net/sheets/049/6/6SJ7.pdf
Gain in triode is indeed around 20. The pinout is odd, unfortunately, so less obvious to find a lower gain alternative.
I would consider rewiring it for a 6G6G. Only 125mA at 6.3V so no problems there. I've used this in triode, gain 9.5, and I liked the sound. It's very clear. But it would have to be rewired by somebody who knew what they were doing.
If it were mine I'd fit a UX5 socket and use a 37 tube. Gain around 9. Very good sound. I use 37 or the 76 myself. Not easy to find these tubes though. The 6G6G is still fairly common and cheap.
Gain in triode is indeed around 20. The pinout is odd, unfortunately, so less obvious to find a lower gain alternative.
I would consider rewiring it for a 6G6G. Only 125mA at 6.3V so no problems there. I've used this in triode, gain 9.5, and I liked the sound. It's very clear. But it would have to be rewired by somebody who knew what they were doing.
If it were mine I'd fit a UX5 socket and use a 37 tube. Gain around 9. Very good sound. I use 37 or the 76 myself. Not easy to find these tubes though. The 6G6G is still fairly common and cheap.
Triode strapped 6V6 would be a little more heater current - 900mA instead of 600mA. Probably OK but who knows.
Same pinout as the 6G6G anyway, and with that pinout a 6P5GT could also be used, gain 14 and a true triode. Not so common any more though.
I've been playing around with all these tubes and the 37/76 are the stars of the show. Higher output impedance than 6V6 and 6G6G though so would expect to see 100K input impedance on the amp.
Same pinout as the 6G6G anyway, and with that pinout a 6P5GT could also be used, gain 14 and a true triode. Not so common any more though.
I've been playing around with all these tubes and the 37/76 are the stars of the show. Higher output impedance than 6V6 and 6G6G though so would expect to see 100K input impedance on the amp.