A gorgeous amp, built like a tank, sounds sweet, but no reverb. Slapping the tank didn’t bring forth any spring sound, so it’s time to get it on the bench for some minor surgery and some amp tech porn pics!
A visual check sometimes yields the quickest results. Nothing was out of the ordinary. But this clamp-on ferrite choke does not appear on the schematic. The red and white RCA cables go to and from the reverb tank. What’s going on here?
The other end of those red and white cables terminate in the bottom panel of the amplifier cabinet. The cables from the reverb tank plug in here. The signal passes through the amplifier cabinet through these bulkhead RCA connectors. Interestingly, the loudspeaker wiring goes through this quarter-inch jack, greatly simplifying service. Thank You VOX!
Space is cramped, so I took some time to set up this portion of today’s program. I removed some solder from the RCA bulkhead connector, so I can make a new solder joint. I’m using a pair of tweezers to get the wire lined up because my big fat fingers won’t go inside the amp here. And I don’t want to be anywhere near the hot soldering iron when I’m fixing this.
Ah, that’s much better. The original Chinese solder was that high-melting-point lead-free stuff, containing lots of tin. In my experience, the lead-free solder is a bit brittle, so this particular solder joint was at-risk since the day it came from the factory.
While I’m on a rant about lead-free solder, let me rant about this ferrite choke. This part has nothing to do with sound reproduction or tone, but was likely added in an effort to comply with FCC or UL regulations. The only support for this choke was the wires from which it was dangling, and you saw the damage it caused. Here, I’m using a tie strap to hold the ferrite choke away from anything delicate.
Now everything is hooked up again and the reverb tank really, well, reverbs! I think we’ve got it fixed now. This is a nice shot of how the signal path moves from one section of the amp enclosure to another.
Thanks for reading all the way to the bottom!
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