HiFi (Chifi) tube amp build - but my own design. - Printable Version
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RE: HiFi (Chifi) tube amp build - but my own design. - RodB - 04-03-2025
Tim,
I have some bakelite sockets in my work shop that I can dig up. I believe quite a few are NOS. I will take photos tomorrow and if you're interested you can have them for the cost of shipping.
RE: HiFi (Chifi) tube amp build - but my own design. - RodB - 04-04-2025
Tim - Photos of 8 octal tube sockets. (Top and bottom)
Send me a PM if you're interested.
RE: HiFi (Chifi) tube amp build - but my own design. - TV MAN - 05-04-2025
Thanks Rod for the offer but I don't think those would work. There's some differences in the sizing and mounting holes between China (slotted screw holes) and NOS USA tube sockets. I've tried some others and nothing lines up. I'd have to pull parts and grind my tube socket holes larger. I do have some ceramic ones coming in from over seas that measure correctly. I ordered several different types so hopefully I'll get something that will work.
RE: HiFi (Chifi) tube amp build - but my own design. - TV MAN - 06-07-2025
I got some new ceramic octal tube sockets installed and also tried some different coupling caps.
The results:
The good - both tubes light up
The bad - sounds awful!
Ok, so just why? Maybe my coupling caps. I tried some generic yellow .33 caps that came with a kit. I wasn't super pleased with the brown drop caps I had in there previously, so I tried those. So, I'll try something else. Maybe some of those highly sought after leaky bumble bees
I'll also use some socket adapters and check voltages so I can see if the new sockets are working. Voltages at the pins check ok. May be time to break out the scope again. It'd be great for a guitar player - just the right distortion, but for HiFi - not so much.
RE: HiFi (Chifi) tube amp build - but my own design. - RodB - 06-07-2025
You sound guys are never satisfied.
RE: HiFi (Chifi) tube amp build - but my own design. - TV MAN - 06-07-2025
Well, maybe - maybe not
It's been an interesting project so far! Something so simple, yet so cranky. The 1st one worked perfect, aside from some static from those lousy tube sockets, a little wiggling and it clears up. THIS ONE, been a challenge. Identical, but not identical. The 1st one worked so good that I don't want to touch it, then there's this one. Probably some dumb simple thing that I've overlooked. Well, it's like this - only a real car guy can understand! You never really finish a classic car! There's always something else 
RE: HiFi (Chifi) tube amp build - but my own design. - TV MAN - 06-07-2025
Well, found muh culprit. After using socket test adapters and finding voltages all ok, swapping 6V6s, no avail, swapped the 6GH8a with a good Phillips 6U8a and bingo! Clean as can be! Junk Jap made 6GH8 tubes! Well, I kinda think they may all be junk. Anyway, the couplers are fine. It hadn't been sounding very good and with one output tube having to be flipped or moved to get it to light up, figured the sockets were the main problem. Wrong! Stupid tube failed! Same with the china made ones. Don't last. That said, I'd observed some weird effects putting my meter/oscilloscope probes on the lower 6V6 G1 (cathode side of the phaser), so I swapped in a 10k stopper (left the 1K on the other tube) and that stopped the weird effects/oscillations. Read that needed to be done on some circuits using the 6U8/6GH8 driver instead of 7199 in AK. Well, must be something to that since it seemed necessary in this adaptation. I can elaborate if anyone would like the reason for this.
RE: HiFi (Chifi) tube amp build - but my own design. - RodB - 06-08-2025
So, here's Prince on stage halfway through Purple Rain when he stoops down to his tech and says "Rod, pull out that 6GH8 and replace it with a 6U8." That's genius. Good find, Tim.
Television circuits would use ferrite chokes to reduce parasitic oscillation. Is that a possible solution?