Friday, January 17, 2014

1971 Vibrochamp

Okay, sorry for the crap photo:

This came in for some TLC. It was cutting out and sounding weak when it was working. Simple solutions on this one. Power switch was dying and replaced the 2 12AX7 preamp tubes as they were weak. Also replaced the cathode caps which helped the background noise. On the 6V6 470 ohm cathode resistor someone had replaced it with a Sprague Atom 25@25V. I've had those pop in the past in that position so I replaced that with a 25@50V cap.

The back panels were missing:

Had a new set made by Mojo Musical Supply. They do great work:

Added some "tube teeth" to prevent the 5Y3 and 6V6 tube from falling out:

It's not uncommon for these tubes to fall out during a performance no matter how much you re-tension the sockets. This was no exception. Amp has a heavy glass JJ 6V6. Gravity dig?

Here's some shots of the inside of the amp:

The infamous "brick drop" 70's CBS caps. These tend to be leaky but not in this case. I prefer to leave signal caps alone in an amp unless they are leaking or dead. Better to maintain the integrity of the amp.
And in this case, this is easily the best sounding VibroChamp I've had the pleasure of working on. Big and warm, full bodied tone. These can sound really scooped in the mids but this one is just majic.


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