The Amp Garage

Regarding the 18n, Valvestorm has been selling 18n NOS Mustards for a long time. Also 27n and 39n but sometimes they aren't available. Then they come back sometimes. 22n NOS Mustards have gotten quite expensive, these oddball values are relatively cheap. Also, the little red 47pF dogbones sound real...

This will probably be of no help but I tried building a mini-Major. A 2x KT88 Marshall Major type of thing. I got custom transformers from Chris Merren and he said with the ~500v power supply that his PT would provide that 100W output was no problem. The amp never sounded that good so I sold the OT,...

Just a guess but maybe try separating that blue wire that is above the board and those other wires zip-tied to it. Move them around and see if it affects the oscillation.

Marshall's are my wheelhouse. In my experience, the optimal combination varies from amp to amp. Some amps sound great with an 820R on the split cathode Bright channel while other get too loose/boomy in the lows. It also of course depends on your target tone. Is it at the dirty end of the spectrum li...

Just curious but what is that stacked, cylindrical thing in the bottom picture? Is that a switch of some sort? If so could it somehow be shortened?

Same for plates, because 100k vs 110k in parallel with 220k doesn’t make that much difference. It's really about double that increase. The 82k is increased to 100k and the 100k is increased to 110k+10k pot. And since the 82k was increased so much you'll almost always have to crank that 10k pot to y...

What about the standard Dumble PI vs the Bluesmaster? Can you give me a reference link of the two specific schematics you want to be compared? As for the bandwidth, generally the high Zout of the amp makes the speaker and cabinet control it in a good percentage. Coupling cap, presence control and o...

Thank you. Looking at the materials you shared, I realize that the component values ​​I had in mind for the SLP circuit were exactly those of the '68 model. Since I built it referencing the Mark Huss Plexi 6V6 and the 1959/1987x reissue schematics, it seems I effectively built it to '68 specificati...

I went down this rabbit hole too, not long ago. The article from Roe is excellent, also see the massive amount of historical data here: https://marstran.com/Historic%20Data%20Base.htm I am not sure why, but the database only contains 50W models. Still, it should give you a pretty good idea of typic...

I went down this rabbit hole too, not long ago. The article from Roe is excellent, also see the massive amount of historical data here: https://marstran.com/Historic%20Data%20Base.htm I am not sure why, but the database only contains 50W models. Still, it should give you a pretty good idea of typic...

What about the standard Dumble PI vs the Bluesmaster (i.e. Marshall PI if I've got the terminology right)? What is the difference in drive level and bandwidth?

The Super Lead schematic at the link above marked early, ca. 1967 doesn’t have any treble peaker caps, while the Unicord schematic dated 1970 has one of the channels shown with a 500pF and a bright cap on the volume. Yep and what was actually in the amps was another thing sometimes. The earlier JTM...

- V1 cathode configuration (split vs. shared) - Bright channel coupling capacitor value - Bright channel bright capacitor value - Presence of V2 cathode bypass - NFB (Negative Feedback) value split 820r/330uf - 820r/.68uf 2n2 5n ? 47k a 1967 by contrast would have shared 820r/330uf 22n 100pf or 5n ...

Tom Bukovac (Uncle Larry) made a comp to a real Tweed Deluxe a while back.