The Amp Garage

OK, that makes sense --- it's just the Channel vol pot, not the MV pot

Also Tube Depot:

https://www.tubedepot.com/t/tubes/preamp-tubes

This is "My Opinion Only": I do use Old Production 12ax7's in some amps and I believe they can make a difference --- But not always, in every amp In a Classic Hiwatt DR504 or DR103 (or good clones) a Blackburn Mullard ecc83 (12ax7) is a thing of beauty --- but not "magic" in every case NOS 12ax7's c...

I built myself a 5F6A based clone head several years ago Except it has: 1) A PPIMV 2) A Raw control 3) Is only a single channel (and a single guitar input) with a 12ax7 in V1 --- both halves of V1 running in parallel, going to a dual ganged Vol pot, and mixed by resistors after the Vol pot This head...

What kind of resistors did Marshall use, in their prime years, to make Marshall amps ?? Mostly 1/2 watt Carbon Film resistors When I look inside my '79 Marshall 2104 head (was originally a 2x12 combo) I see mostly 1/2 watt Carbon Film resistors So when I build Marshall type amps I use 1/2 watt Carbo...

I suspect that DR504 is a UK-made Hiwatt made during the time Musicground owned the rights to the Hiwatt name (the Harrison clan) I doubt they sourced their iron from Heyboer (I've used many Heyboer Partridge clone transformers in Hiwatt-type builds) I believe the Harrisons sourced their Partridge c...

Here is a schematic (w/voltages) of one 1983 Marshall 2204 (owned by mhuss) These are typical voltages of a 1983-era 2204 amp --- This does not mean that EVERY 1983 2204 will match these voltages exactly --- this does not mean that EVERY Marshall 2204 ever made will match these voltages (my '79 Mars...

Years ago I followed some of the many SIR #36 schematics you posted (on another forum) and built many similar amps, usually 50 watt These heads were sold to musicians in my local area and were well received --- your schematics helped me to learn to modify Marshall circuits But most local musicians, ...

I did some tweaking to a 25 watt 2204-type build I did recently --- I put the 470k/470pF !st Treble Peaker back in (i had a 68k in there) to give it more treble response when the MV is cranked above 5 --- this worked well, I'd gotten into the habit of building 2204-type amps without the 1st Treble P...

I recently serviced this amp for a friend --- It is a 6550 spec amp that had EL34's installed (which biased the EL34's so cold that it barely operated at all) I quickly measured all the resistors in the amp (initially looking for the "problem" before I realized it was a 6550 amp) and I found that th...

Here's a 100 ohm/5 Watt Metal Oxide Power Resistor that Mouser currently has in stock --- It has better specs than the other 3 similar resistors they have right now: https://www.mouser.com/ProductDetail/YAGEO/RSF500JT-91-100R?qs=sGAEpiMZZMvmQ%252BOLa8n%2FM0VaQqJq%2FX2CratbCum5YeFYTqqG54ZAZA%3D%3D Bu...

Why not build your own Mini-Plexi ?

I just built two mini-2204's (6L6GC x 2, 25 watt scaled iron) one stock-ish and the other Hi Gain with a plate driven tone stack and other mods

You can build your mini-Plexi and make it however you want it

https://mhuss.com/Plexi6V6/Plexi6V6.gif

I built two DR504 clones in 2006 without heat shields ---- One I still have and it is still running fine --- The other was sold to a touring band that has been using it since then playing all over the SW USA, Mexico, and parts of South America --- They brought it back to me once for a "tune up" and ...

I just saw a YT video that said Reptilian Space Aliens have a military base in Antarctica from which they fly most of the craft that people report as UFO's It went on to say that they've been having navigation problems (because they're Space Aliens) and have hired Elvis Presley to pilot their craft ...

I must agree If the OP's amp has Stray Voltage on the main Eyelet Board then no parts swapping will fix the hum problem until the Stray Voltage is eliminated I'd also take a very close look at the grounding of everything on the front panel of the amp ----- Make sure everything is Clean, Tight, and S...