Tube Amp Archive

Thanks ISOTone!

Thanks fellows...I was afraid of that....will have to reverse engineer this but I too am guessing the 6dq6s were swapped out in favour of the EL84s. This doesn't strike me as anything to be concerned about. If the wiring matches EL84, just go with the flow. If you don't care for how EL84's sound in...

Thanks fellows...I was afraid of that....will have to reverse engineer this but I too am guessing the 6dq6s were swapped out in favour of the EL84s.

A friend brought in this interesting amp the other day. Made in the U.S. by Standel circa 1960s. There's no model number on the amp but some research I've managed to conduct indicates it's a piggyback Artist 50? Found very little info on this amp anywhere including at the Standel Amp website. The PT...

As promised here are gut shots of the chassis. Pleasantly surprised to find it in such nice shape sans the usual thermal deterioration found in most amps of the period ( no brittle wiring, melted wax caps etc) Nicely laid out and implemented IMO...it will be relatively easy to work on. The Trafos ar...

H303A model shows a transformer despite suspicious tube filament voltages. http://www.el34world.com/charts/Schematics/files/harmony/harmony_h303a.pdf :oops: Hey jjman....some mea culpa here on my part...you know the saying "sometimes you can't see the forest for the trees?" Well I must be totally b...

Boring is fine as long as it's stable and reliable. :) Many "out there" builds but usually unstable as hell... What I've noticed of late, is a lot of guitarists (blues, jazz and R&B anyways) seem to be looking for something with a distinct tonal character without a lot of superfluous stuff (amp circ...

I am inclined to try and modify this rather than strip down....converted an old Bell 2122a mono amp for a friend who owns a Tiny Terror and a Dr. Z M12 and just loved the unique sound of the old Bell feeding his 1X12. Will keep everyone posted how this old organ amp does.or does not develop. Iron te...

Cygnus X1 wrote:Are you going to update this widowmaker?

Yes...including a proper chassis grounding scheme to circumvent this classic example of the circuit of death

But that aside, any hints about what may be going on with my volume pot?

H303A model shows a transformer despite suspicious tube filament voltages. http://www.el34world.com/charts/Schematics/files/harmony/harmony_h303a.pdf Yes, but this is not the H303A....it is an H303...most definitely no transformer the tube complement is almost a dead give-away for transformerless d...

OK...Hard as it may seem to believe just had another wickedly strange amplifier dropped on my doorstep. That German amp of some months ago seems pretty ordinary compared to this IMO In this case it is a Minshall Mono Organ Amplifier Tube complement is as follows: 5V4G Rectifier 2X 6L6 Outpu tubes 2X...

Ok gang...have an issue that's driving me a little nuts. I have a Harmony H303. Tube complements consists of 35Z5 Rectifier 50L6 Output and 12SQ7 pre-amp tube. For the first 5-10 minutes everything is tickety-boo but then the volume pot cuts out completely whenever I attempt to take it past 8....I c...

Well I promised to keep you posted on the progress of this strange amplifier. As you may recall everything powered up but no signal output on any of the 4 input pots.... Checked the continuity for opens on the OT and it checked out fine. Replaced all the Wima Mica Caps with Sprague Orange Drops or c...

Got an Ampeg M12 Amp in the other day. Brought it up slowly on a variac after testing all the tubes and am getting sound through Channel 1 and 2 Inputs, volume and tone pots work too. The issue I have is that the tremolo footswitch has one loose wire and I don't know where it should be placed. In re...

Well slow progress on this amp ( and others :oops: ) seems every time I start troubleshooting in walks something more pressing. But I have managed to discover that their is a very very low audio hum coming out the speakers. However nothing I plug in or no matter what pot I adjust the level of hum re...