Tuesday, October 13, 2009

What's Happening et al

Lots of good things happening lately on the bench. A 1970 Twin Reverb came in awhile back with a large growth installed in it. Said growth turned out to be a Ross Distortion pedal that some well-intentioned soul attempted to permanently install in the amp. To the left is a picture of the mess I had to contend with. The pedal's innards are buried in that wad of relatively expensive gaff tape. The distortion and level controls from the pedal took the place of the intensity and speed control for the amp's vibrato. So, I had to re-establish the vib section of the amp on top of straightening out the mess on the input jacks. There was some other nonsense happening elsewhere in the amp; but, nothing too major to fix (although the huge hole in the side of the cabinet that sports a useless fan is unrepairable short of getting a new cabinet for the amp). The amp had two beautiful - and highly collectible - EV alnico SRO 12" speakers in it. Those speaker just love to be driven hard. When I got the amp done, I demo'd it with my Les Paul and promptly had the windows in the house shaking (all that came to halt when my 7-yr old appeared in the spare room with fingers in her ears hollering something or the other...). The only problem now is that something happened to the reverb in transit. So, I have Brian bringing the amp back out to Blacktown Sound Labs for a check-up (pray for Brian's intestinal tract because that is also the heaviest Twin I have ever worked on).

Currently on the bench is Sean's head. This puppy is one of my favorite creations. I built it 8-yrs ago on the chassis of an Elk head (Elk was a Japanese company that made knock-offs of Fender amps in the 60's and 70's). Its basically a 40w Fender AB763 circuit with a tube-buffered effects loop and hair too much gain. Sean reports some strange noises coming from it. I re-tubed it last December and it was running fine at that point. So far in limited work, I've found one bad power supply cap (it had puked its white, powdery, guts out). That has to be fixed before I can proceed with the rest of it.

I have a schematic together for a 22-ish watt amp that combines the preamp from a classic JCM800 Marshall with the output section of Fender Deluxe. This will be the first amp I've built that intentionally creates distortion in the amp circuit. I'm normally not a fan of "buzz box" -i.e. Boogie - amps. But, I've always had a soft spot for the early 80's JCM800's. That, combined with my favorite Fender output section (the Deluxe), might yield an interesting amp....or a total tonal turd. Only way to find out is to build it and start tweaking. But, that is on-hold until I get caught up on other projects. I have a Deluxe Reverb sitting in my garage that needs a power transformer and probably new a cabinet. That should come first...


  1. You should post more posts. What about satan's marshall's?

  2. Nothing wrong with that 800. It just needed a foot-switch and a new back panel. His '79 Twin on the other hand has been a nightmare. I finally figured out that two of the power supply caps that were replaced prior to me were the wrong value. They were making it hum. With that fixed, a brand new preamp tube promptly crapped out. Grr...