Speedball Troubleshooting - High OA/OB values
- Thread starter Justin
- Start date
Can you post some new photos? I suspect that one of the black wires that makes up the ground buss isn't well connected.
Can you also measure the voltage at A2 and A3 again carefully?
Can you also measure the voltage at A2 and A3 again carefully?
Figured it better to give you too many than not enough
Attachments
D
Deke609
Guest
What is that gray metallic wire crossing the amp that ends near the green heater wiring on the transformer? Is that your solder? If so, and based solely on its diameter, it looks a lot like plumbing solder not electronics solder.
Plumbing solder would cause strange things like this to happen. I'd also love to see a photo or two of your 12AU7, which sounds strange, but it's good to be sure.
No, the soldier is 60/40 rosin core for electronics. I'm not sure what you're needing to see with the 12UA7 pics but heres a few - let me know if you wanted to see a different angle. It came in an old RCA box with the amp, and I've tried a few others which will alter the high voltages slightly but not to within spec.
Attachments
Well, that's not a 12AU7...
If it came from us, it might've snuck into a 12AU7 box on accident.
(I feel less crazy now BTW)
If it came from us, it might've snuck into a 12AU7 box on accident.
(I feel less crazy now BTW)
Oh wow, okay. Then the others I swapped in were all 12AT7 equivalents as well maybe. The 5963, ECC83, and CV4024 I tried would just give me similar values to the 12AT7 I started with, right? I guess I don't have a true 12AU7 here to check if that fixes it. I'll let the forum know if that solves my issue when I get the right tube, but I gotta say it feels good to know you think that's it, Paul. I've got 98 extra 22.1k resistors with your name on them if you want them! ;D
This is a 12AU7Justin said:
This is not a 12AU7Justin said:
This is not a 12AU7Justin said:
You need to run the amp with the 5963/12AU7. The other tubes will destroy the amp. The other tubes you are trying are absolutely not compatible with the Crack.
Success! It's running fine with the 5963 in it. Thanks for sharing your expertise with the community, Paul. It really is an invaluable resource. For anyone reading who might have been on the fence for some reason, these amps are amazing and the Bottlehead team really does run their business with customers in mind. Truly grateful.
Justin
Justin
I'm glad you had a spare around to get it sorted!
-PB
-PB
