The Amp Garage

Man, that is a very goofy circuit, and the patent is pretty weird too. The owner's manual devotes 2-and-a-half pages as to why Randall Smith will not grant you a bias control, because the evil tube vendors have a conspiracy to sell you their defective tubes, but Mesa of course, have absolutely perfe...

It's a guitar amp.

Any references to engineering terms, real or imagined, are purely conjecture and ad-speak.

"It's class-A"

"Wow, is it true class A?"

"yup, truly, the finest sounding amp ever, best in class, so that makes it an A!"

This amp has a couple of weirdnesses going on with the -27v supply. Preamp tubes V1 and V2, have their filaments wired in series, and are powered by the -27V DC. If a tube The 12AX7 V3 and the EL84 filaments are powered by the 6.3VAC power, that also powers the pilot lamp. The schematic is a hot mes...

The symptom kind of points at filter capacitor, or other power supply issue.

Perhaps revisit the previously replaced main filter caps, particularly inspecting the work. Also, just because they were new doesn't always mean they haven't failed or faltered. It happens.

So towards hi-fi land, without going that far. The experience I did on LPTI and power amps in that field can come handy, as with the SE version. I would like to try two approaches, one with 12ax7 and one with ecc88 or similar (so andriver with more or less capanility to drive the output tubes). Has...

FWIW, I'd say this is indeed the plan. Somebody mentioned designer handbags, which is a good analogy. Artificial scarcity, pricing far above manufacturing costs and narratives to generate and maintain cachet. All aimed at driving profit margin up. Curiously, my wife and I just strolled through a ve...

Why stop there? Parts have tolerances; wouldn't a true clone be identical circuit, original appearance and materials, and NOS parts, whereby on a location-by-location basis, each part in the circuit measures the same value as the part Dumble used in that particular location? But if it isn't an RN60...

Consider the power amp and choice of speaker, EV12L, which is capable of high power and sound pressure levels without a lot of cone break up. It appears the philosophy was to keep the power amp and speaker quite clean, with most of the amp's character coming from the preamp stages. It is interesting...

I have a B&K 1655A unit that includes a meter, a safety-current-leakage detector and even a separately controlled outlet for a soldering iron, that I use with my thermal wire strippers.

Long discontinued, but really nice and you can find them on eBay and the like.

harleytech wrote: ↑Tue Oct 06, 2026 5:10 pm "I heard on That Pedal Show the new ODS goes for $25,000. Consider me uninterested"
That goes for me too..

Interested, but under-funded.

No, because it would be "by Smitty"

DPS has the legal rights (as far as I know) to do that. I don't know if HAD trademarked his name, trade dress and or anything else.

DPS has the rights to the name and the trade dress. They can't "clone" the originals. They can make copies or good reproductions. They could even make really, really good new amps, with some philosophical lineage, since they were apparently in close contact with Mr. Dumble in his later years and wor...

Neither and the poll is broken. They're copies at best. You can't clone the Mona Lisa, because the artist has left this world long ago and the materials used then are not readily available today. You can't clone a Dumble because the artist has left this world, and the places where he got most of his...

I didn't write up the whole list, being that it is a voltage doubler power supply, you'll want to change those. If you can figure out how to mount these, these are 10,000 hour @ 105c rated, 68uf @ 350v, very high quality parts, and they're $2.52 each in qty 1 units. https://www.digikey.com/en/produc...

I could not find caps that cheap anywhere. I stuck with normal uf values in the spec and ended up close to $100 for all 14 caps plus a few spares. 10 20uf/50v caps where right around $50, I did buy vishay/sprague tva series for these so maybe there was a cheaper option out there. You can get 10 of ...