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Old 25th January 2020, 02:25 PM   #9271
male42 is offline male42  Russian Federation
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Quote:
Originally Posted by boywonder View Post
Male42....superb!



What are the driver tubes with the top caps? Did you machine the transformer covers? How did you get the text on top plate?
The text on the top panel is laser engraving. Transformer covers are fast rotation with abrasive treatment.387A_WE, Tube 387A_WE; Rohre 387A_WE ID35019, Vacuum Pentode
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Old 25th January 2020, 05:29 PM   #9272
6A3sUMMER is offline 6A3sUMMER  United States
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Wow!
Good looking amplifier.

The 387A link you provided says that the 387A was the forerunner of the 717A.

I have a pair of 717A tubes.
If I get the time and energy I will try using them. Same look, except no top cap.
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Old 25th January 2020, 08:33 PM   #9273
male42 is offline male42  Russian Federation
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Originally Posted by 6A3sUMMER View Post
Wow!
Good looking amplifier.

The 387A link you provided says that the 387A was the forerunner of the 717A.

I have a pair of 717A tubes.
If I get the time and energy I will try using them. Same look, except no top cap.
387A as well as 717A wonderful pentodes. The 387A of 1935 has an incomparable sound .717A uses Yamamoto in its amplifiers. which cost 8500 dollars. probably not casual. I made this amplifier in the image of "darling" only the 1626 triode I replaced with 45. in order to increase power. acoustics I have an open box on a 12" broadband. With a sensitivity of 98 dB. 1 watt is enough for it for a good return
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Old 30th January 2020, 01:04 AM   #9274
AllenB is offline AllenB  Australia
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Old 30th January 2020, 01:30 AM   #9275
audiowize is offline audiowize  United States
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Originally Posted by cyclotronboy View Post
This is a 1625PP amp, with Edcor cxpp60-ms-4.2k iron. Uses 6SN7's as cathode followers to drive the grids of the 1625s into AB2. 1625 biased at 50mA quiescent.
I have finally stashed away enough iron that I'd like to do something similar. Have you found that a 6SN7 wired as a cathode follower is working well to deal with the grid current on those AB2 peaks?

I have been staring at that 80W operating point in the 807 datasheet for a while wondering if it's actually possible...
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Old 30th January 2020, 05:37 AM   #9276
Diabolical Artificer is offline Diabolical Artificer  United Kingdom
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Nice work lads. I'd be interested in seeing a schematic of your OP section cyclotronboyI presume the 1625's are fixed bias, if so where did you bias them.

Andy.
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Old 3rd March 2020, 07:58 AM   #9277
showdown is offline showdown  Norway
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KT88 SE amp, the Abdellah/Gendrano/Kegger/Blueglow (phew!) circuit. Power supply is a little different, with a 5U4GB and CLCRC filter. The chassis is an old handmade mahogany drawer that I reinforced with aluminum angle bar and freshened up with a bit of shellac, the top is 3 mm aluminum diamond plate.

Telefunken ECC85 driver, James OTs, 440V B+ and 78mA on the KT88s. Sounds fantastic!
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Old 3rd March 2020, 08:19 AM   #9278
mhouston is offline mhouston  Australia
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Originally Posted by showdown View Post
KT88 SE amp, the Abdellah/Gendrano/Kegger/Blueglow (phew!) circuit. Power supply is a little different, with a 5U4GB and CLCRC filter. The chassis is an old handmade mahogany drawer that I reinforced with aluminum angle bar and freshened up with a bit of shellac, the top is 3 mm aluminum diamond plate.

Telefunken ECC85 driver, James OTs, 440V B+ and 78mA on the KT88s. Sounds fantastic!
Not the first time a draw has been used as a base. Mahogany, now thatís classy. Amp looks good. A KT88 SE UL is on my list probably as a wine box amp.
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Old 3rd March 2020, 08:40 AM   #9279
kissabout2002 is offline kissabout2002  Italy
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Quote:
Originally Posted by showdown View Post
KT88 SE amp, the Abdellah/Gendrano/Kegger/Blueglow (phew!) circuit. Power supply is a little different, with a 5U4GB and CLCRC filter. The chassis is an old handmade mahogany drawer that I reinforced with aluminum angle bar and freshened up with a bit of shellac, the top is 3 mm aluminum diamond plate.

Telefunken ECC85 driver, James OTs, 440V B+ and 78mA on the KT88s. Sounds fantastic!
Wowww that's a beauty congrats, I built too recently amp in a bamboo drawer but yours is really posh, you also been lucky to find a James OTs if I remember they out of business since 2018....anyway enjoy the music :-)
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Old 3rd March 2020, 08:45 AM   #9280
spirakos is offline spirakos  Greece
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Default PSL86 SE

With CCS loaded triode, pentode mode, two local fbs, stabilised voltages
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