The Amp Garage

Telefunken have the tell tale diamond shape on the bottom of the tube imprinted in the glass in the middle of the tube pins. I recently found some old tubes that were labelled Fisher electronics made in West Germany that had the diamond shape on the bottom which indicates they were made by Telefunke...

when was the last time you changed out the 100K preamp resistors? I'd also look at the ceramic disc caps and opto bug. has it been altered in anyway to Black Face spec? you may also have a bad tube that needs to be tested multiple times after being allowed to heat up. If you mean the 100K plate loa...

The E caps were changed in 2007, still very new looking Sprauge's so they should be ok though the amp was not played much for a year, stored in a closet. When I tried it again earlier it didn't squeal at all but the hum was still there. Over the span of a second or so, the hum starts quietly then sw...

I removed the PI tube and it didn't squeal but there was no sound at all which I wouldn't expect there to be anyway. I tried removing and then swapping out V1 and V2 separately but the amp still squealed however the quality of the squealing has changed to sometimes not being as long or loud as befor...

I have an old black faced SF Fender Vibrolux and tonight the amp squealed very briefly when I took it off standby and after a second or two the squealing stopped and it seemed to be fine and sounded really good. I flipped standby back on again, waited a few seconds and then turned standby off and it...

Dave, This is it, thank you so much! I found some of those Heathkit A7 schematics but never saw the ones with the UL taps, missed those last few variations. The wiring color code matches perfectly but I will double check the connections before I desolder the wires to make sure everything matches the...

Regarding UL OT, those taps can be wired to your power tube screens for reduced distortion operation. Used more often in HiFi plans than guitar amps. Some report that it makes for a too sterile tone. Others like it. Dealers choice! You could put an VAC signal on the OT primaries and measure the AC ...

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag.. :D OK Well the power transf...

This is from the newest issue of GP (August) on news stand now with Rob Ickes on the cover. The article was written by Dave Zimmerman of Maven Peal amps.

Yowza that doesn't make sense the 1M should go to ground not the pin. Did you mean to write grid leak? Either way this is not what Dana's instructions state to do. Yes surfsup is correct, I was wrong, my grid stoppers are back at the input jack not at the tube socket and the cap is after those stop...

The 1M resistor is after the 100nF cap, but before the grid stopper. I have the directions from Hall, but it's rather invasive, as the Baby Will 18W project uses a PCB and also uses two triodes in parallel. My Lightning has both triodes of V1 in parallel as well and it works fine just attach the ca...

If you scale the whole amp I think you also have to put a cap and resistor at the grid of the tube where the volume pot is connected. This is what the directions indicated for the VVR that I got from Hall amps and I don't have any DC scratch on my 15 watt Lightning clone.

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag.. :D I sure hope these transf...

OK well paying less money is even better! I'll offer up to $100 for the tubes and the amp. I'm only going to get the guitar/audio related tubes, I'm not going to buy all of them. I figure there might be a few more 12A_7 types buried in the boxes and who knows what else might be there. Thanks this is...

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag.. :D Thanks Cliff for spillin...