@@HeadfirstAmps Sounds great! I mean the amplifier definitely does the heavy lifting but the suhr pickups always sound great! May have to try some soon.
I've got a 78 JMP 50w like this that's in immaculate condition, however the Volume pot is still letting a small signal through when it's at zero, and it jumps up REALLY loud in just the first part of the rotation (way more than it should). I suspect it's a bad pot, but don't want to disturb the factory Red dye on the connections if it's not the Pot. Otherwise I'd just swap it out to see. Is it likely that it could be a failed component that feeds the pot? What could I test?
Hey im scoping a 100 watt 68 spec superlead.....ok on my scope at 1k sine wave that big brite cap puts garbage on the wave.....but if you go up to like 2.5k or 3k sine wave it clears up.....plus i can barely turn the volume up before distorting the wave......if i go through my normal channel the 1k sine wave is good all the way to the phase inverter.......i would probably have to bias it there but still cant get much volume travel....does this all sound normal
@@HeadfirstAmps I seem to be getting it better....I had old iskra resistors and old src treble caps in it and it made it mushy so I changed the resistors to the modern carbon film and the src to modern silver micas....I think the cheap black silver micas sound better for it.....I put about 288 pf on the mixers and 556pf on the tone stack with a mixture of synergy and mustard caps....I'm still tweaking it but it's getting better......it's funny how my bright cap dirties up the 1k sine wave and not a 3k sine wave
YES!. I have a bunch of amps but one that sticks out is the 77 Master Volume 2204 I have with vintage Mustard caps. I have the original cab similar to what you have here with G12H-30 55hz greenbacks. I also have a 79 after they switched to the red Mallory box caps. The difference is night and day the 79 sounds good but it's relatively lifeless compared to the 77. They're otherwise identical. I have a custom Friedman BE100 Deluxe hand made clone point-to-point amp that's phenomenal. It's got Sozo GenII Mustard caps and after about two years they sound almost identical to the vintage Mullard Mustard caps. They take a little while to break in before they get crisp and sweet they will sound a little boxy and dry at first. Once they break in they're so nice to me almost exactly like vintage Mustard caps.
Sound absolutely legendary. A question: I have an original JMP MK2 1986 from '75 that I had professionally converted to a 1987. I am kind of considering mod'ing it further to a 2204. Would that be an awful idea? It's definitely not mint - it already has holes in a back (currently made master volume and negative feedback control). I quite like it as it is but it's not fun being forced to run OD's in front of it to reach heavy metal compatible gain.
Jason, what modern capacitors are the closest to those mustards. I'm in the middle of building a 2204 from Modulus Amplification. And that amp sounds unreal. Great work, as always.
The Mallory M150s are good. USA Synergy if you can get them are the best - valvestorm sell them. Vishay mkt1813 like Marshall use in the 1959hw are cool.
@@scottwilcox6313Sozo, Mojotone Dijon or Jupiter caps are very close, perhaps a touch clearer in the highs vs Phillips Mustards, not to mention well made and robust. We are spoiled with choices nowadays
Look for a cap that has same basic construction. You are looking for a film and foil polyester cap with sprayed metal ends, copper (not steel) leads. There are very few available these days, most being Metallized Polyester (Mallory 150 / MKT1813 etc etc etc etc) and many of those having steel leads. Sozo don't say what their construction is and charge a bomb.
I look forward to these videos. I've been a digital guy for over 25yrs. You've given me a new found love for antique circuitry.
My plan is working. Lol
@@HeadfirstAmps The take over for ultimate control! Awesome....
Jeez Jase, those open chords at the beginning are THE SOUND of rock. Iconic tone there mate! Sounds incredible.
Thanks Mike! Hard to beat these old classics man!
Killer as always Jason, just got a Marshall JMP 2203 1979, your channel show me too many amazing amp and I end up looking for old Marshall's 😂
lol, that’s awesome
Right there is the tone that people look for for decades and spent a lot of money to try and get. Awesome tone yet again!
They are classic circuits, just need to be tuned in right!
The issue with NOS mustards is break-in time.
What 100+ hours?
Something to think about before investing in the upgrade.
Are there bigger differences between the pre-rockerswitch era JMP non-mvs and these mid-to-late-70s amps?
Sounds awesome Jason! Love these videos! What kind of pickups are you using in the Suhr?
Bone stock Pete Thorn sig, so those are a Thornbucker+ set.
@@HeadfirstAmps Sounds great! I mean the amplifier definitely does the heavy lifting but the suhr pickups always sound great! May have to try some soon.
no grid resistors yet I didn't hear any blocking distortion and it still sounded great lol
All tones were after the grid resistors were added!
@@HeadfirstAmps I bet you already had mentioned something about it and I failed to notice the fine print 😆 great work though, it's now a real amp!
I've got a 78 JMP 50w like this that's in immaculate condition, however the Volume pot is still letting a small signal through when it's at zero, and it jumps up REALLY loud in just the first part of the rotation (way more than it should). I suspect it's a bad pot, but don't want to disturb the factory Red dye on the connections if it's not the Pot. Otherwise I'd just swap it out to see. Is it likely that it could be a failed component that feeds the pot? What could I test?
what current production tube you like in the PI.? i use 12AX7LPS for all my PI. JJ dont sound as good there
I use JJ throughout and love them. Depends on the circuit I suppose.
Hey im scoping a 100 watt 68 spec superlead.....ok on my scope at 1k sine wave that big brite cap puts garbage on the wave.....but if you go up to like 2.5k or 3k sine wave it clears up.....plus i can barely turn the volume up before distorting the wave......if i go through my normal channel the 1k sine wave is good all the way to the phase inverter.......i would probably have to bias it there but still cant get much volume travel....does this all sound normal
I guess the question is, how does the amp sound?
@@HeadfirstAmps I seem to be getting it better....I had old iskra resistors and old src treble caps in it and it made it mushy so I changed the resistors to the modern carbon film and the src to modern silver micas....I think the cheap black silver micas sound better for it.....I put about 288 pf on the mixers and 556pf on the tone stack with a mixture of synergy and mustard caps....I'm still tweaking it but it's getting better......it's funny how my bright cap dirties up the 1k sine wave and not a 3k sine wave
Killer! I just got a 2203 and my Lester sounds massive through it. So much that I have not even tried my Anderson super strat thru it yet!
YES!. I have a bunch of amps but one that sticks out is the 77 Master Volume 2204 I have with vintage Mustard caps. I have the original cab similar to what you have here with G12H-30 55hz greenbacks. I also have a 79 after they switched to the red Mallory box caps. The difference is night and day the 79 sounds good but it's relatively lifeless compared to the 77. They're otherwise identical. I have a custom Friedman BE100 Deluxe hand made clone point-to-point amp that's phenomenal. It's got Sozo GenII Mustard caps and after about two years they sound almost identical to the vintage Mullard Mustard caps. They take a little while to break in before they get crisp and sweet they will sound a little boxy and dry at first. Once they break in they're so nice to me almost exactly like vintage Mustard caps.
It's just awesome learning from some of the masters in the industry.
Sound absolutely legendary. A question: I have an original JMP MK2 1986 from '75 that I had professionally converted to a 1987. I am kind of considering mod'ing it further to a 2204. Would that be an awful idea? It's definitely not mint - it already has holes in a back (currently made master volume and negative feedback control). I quite like it as it is but it's not fun being forced to run OD's in front of it to reach heavy metal compatible gain.
Not a bad idea, there is little difference between a 1987 and a 2204, and you can always convert it back again!
Do you determine polarity/outer foil of caps before installing?
Yes, I use my scope
Jason, what modern capacitors are the closest to those mustards. I'm in the middle of building a 2204 from Modulus Amplification. And that amp sounds unreal. Great work, as always.
The Mallory M150s are good. USA Synergy if you can get them are the best - valvestorm sell them. Vishay mkt1813 like Marshall use in the 1959hw are cool.
@HeadfirstAmplification Thank you will do some searching. Nos mustards are just too hard to find and expensive.
@@scottwilcox6313Sozo, Mojotone Dijon or Jupiter caps are very close, perhaps a touch clearer in the highs vs Phillips Mustards, not to mention well made and robust. We are spoiled with choices nowadays
@@eyedunno8462Mojotone Dijon are Polypropylene Film. Not saying they are bad but they are not Polyester Film.
Look for a cap that has same basic construction. You are looking for a film and foil polyester cap with sprayed metal ends, copper (not steel) leads. There are very few available these days, most being Metallized Polyester (Mallory 150 / MKT1813 etc etc etc etc) and many of those having steel leads. Sozo don't say what their construction is and charge a bomb.
Hey you know how the 100 waters have the center tap grounded between the mains caps.....would you ground those at chassis too?
The CT is connected between the filter caps, but not grounded.
@@HeadfirstAmps ok I didn't know if you could ground those like the 50 watters