I second the 6AS7 at 100V 100mA. Run my PP amp at those setting and it sounds very well. SE may not be quite so good since its not a terribly linear valve, but people have built SE's with them and liked the results well enough. 6AS7 sound better at high current and low volts.
A stereo amp using just one 6AS7 and something like a ECC88 as a driver. Very nice, very cheap amp which has the elegant esthetics of just one big valve and one small valve.
Shoog
A stereo amp using just one 6AS7 and something like a ECC88 as a driver. Very nice, very cheap amp which has the elegant esthetics of just one big valve and one small valve.
Shoog
funny that it is also said better to use cathode bias with 6AS7 (or maybe it was only 6080)
and 6S19p appears to work best with fixed neg bias voltage
Sorry guys for being away , i've made some tests but nothing good in terms of efficiency , power and freq. response.
The main idea was to use a 100V line to 4-8 ohm transformer with primary tap for 10/6/3W so 1K-1K6-3K2, disassembling the E I core to introduce an air gap.
Anyway i can't get more than 1-1.5W down to 50Hz . Tested tubes are EL86/829/832/6AS7...i can get 5-6W starting from 200Hz and up. It sounds good but i have to apply a sort of feedback (using 832 tube in parallel SE with plate on the 1k6 primary and G2 tied to 1K primary i get a sort of UL connection and it sound well and natural but lack of bass and if you push it you can hear tha bass distorting)
In conclusion the core of OT is probably too small and saturates easily no matter the air gap.
I will try with a SRPP and see what happen, if anyone intrested or if anyone had some good results using a 10W 100V matching transfomer , let me know !
Thanks to all, you great
The main idea was to use a 100V line to 4-8 ohm transformer with primary tap for 10/6/3W so 1K-1K6-3K2, disassembling the E I core to introduce an air gap.
Anyway i can't get more than 1-1.5W down to 50Hz . Tested tubes are EL86/829/832/6AS7...i can get 5-6W starting from 200Hz and up. It sounds good but i have to apply a sort of feedback (using 832 tube in parallel SE with plate on the 1k6 primary and G2 tied to 1K primary i get a sort of UL connection and it sound well and natural but lack of bass and if you push it you can hear tha bass distorting)
In conclusion the core of OT is probably too small and saturates easily no matter the air gap.
I will try with a SRPP and see what happen, if anyone intrested or if anyone had some good results using a 10W 100V matching transfomer , let me know !
Thanks to all, you great
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Yeah , I know , i built an amp years ago using 6080 and ecc88 ,B+ was about 160V and Ia around 100mA , if you take in account the cathode resistor voltage drop, you know is ok, little pushed but not redplating yet
Really cheap , easy and good looking (i like 6080 RCA look, also Svetlana 6AS7 )
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