the_equalizer
1000+ Head-Fier
- Joined
- Jul 5, 2009
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Quote:
Hi everybody and many thanks for this thread.
Here’s my build. I modified the circuit a bit to use 6J6 tubes that are still abundant and available at ~$2 a piece. The modification is straightforward: one will need two 39 Ohm 10W resistors (mouser part# 71-CP10-K-39) and two 150 Ohm resistors (286-150-RC). The latter replace the heaters while the former connected in series with two "real" heaters make them work.
An obvious drawback of this scheme is extra heat produced by the ohmic voltage divider. But one can live with that taken into account the tubes availability.
I also added diode protection to the output (2 x 2 x 2 = 8 diodes = forward/reverse 2.4V threshold protection for two channels). I used blue LEDs so they flash nicely when the power is on.
Now about the sound: it's very nice. I made a test using the same source and different outputs: Harman Kardon AVR75 amplifier, new tube amp and internal headphones amp of the player. The new amp definitely outperforms Harman Kardon though this amplifier works very well with the speakers. The internal amp, though, is very competitive. If one compares apples to apples (same volume level) then it’s difficult to tell what is better. Perhaps, the tube amp is softer (in a good sense) in the mid-frequencies. An obvious advantage of the tube amp is higher volume level. The sound is distortion-free and rich. Overall, I'm very pleased
Nice work! Congratulations on getting a 6J6 variant up and running!
Quote:
I'm going to be starting this project soon. I'm building the 12AU7 version. I wanted to order almost everything from one place to save on shipping. Mouser has everything I need except .22uF 250v and .22uF 63v capacitors. They only have 50v 100v and 200v. Will any of those work as replacements? Otherwise, where I else should I order from?
Thanks
0.22 uF @ 100v will do nicely for C2, C4 and C3a, C5a
EDIT: of course, 0.22 uF @ 200v will also work perfectly.
cheers!