Just to be sure. Do you have the monitor switch set to "Input?"

Have you checked the tubes in the phono circuit of the preamp?

Possibly. I'd check for dirty pin connections since it's easy and free. The small signal tubes can last decades, but do fail eventually, though not always eventfully.

Gently pull the tube of the socket with a slight rocking motion. Check to see if the gettering is opaque on the top of the tube. If the tube looks really cloudy, it's almost certainly bad. You can wipe the pins on the tube with a little steel wool to help with connectivity and reinstall, paying attention to the orientation of the pins in the socket. Don't force anything.

Your tube is probably a 12AX7 or variant in the phono section. They're pretty inexpensive.

You should also get a can of spray contact cleaner and spray the contacts of the input selector switch while rotatiing it.

Be sure that the contact cleaner says that it is safe for plastics.

That's great! You should get around 8-10 thousand hours of life on most decent quality 12AX7 tubes.

You might want to take a close look at the old tubes.

They might be 12AU7s. I have run into this a lot. Some people think they are interchangable, which they are NOT!!!

The 12AU7 has the same pin connections, but only about 10% as much voltage gain, which would explain your problem.

But maybe one of your old ones was just bad...lol.

ejbrooks13 wrote:

Thank you for all the help! It ended up being my tubes, swapped them out for some new 12AX7 and everything works great!