Picked up an old SIR Marshall

Samhain said:
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Frank Levi worked at SIR NY and later SIR LA.
Was Frank that reworked all the Caswell amps in LA.
Everyone wanted Franks amps. Levi was hired by RATT on the road as an amp tech in the early days.
Billy Squire & many more as well. I knew Squire's amps were different because of that kerrang first time i heard them.
Whatever he worked on seemed to turn to gold. Very low key guy.
Frank & I were friends, love telling his story RIP.
Your amp looks stock what i can see.
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You've said this before, and you are wrong on anything related to Caswell's amp, the famous #39. That amp was in high demand for years BEFORE Levi ever got out to LA. Period.
The truth is, when Levi got to LA Caswell had gone and SIR asked Levi to CLONE #39 into a few more of their amps so that they would also be reserved for years straight, like #39 was. He did that. Now, after Levi noticed all the accolades Caswell was getting all of a sudden Levi chimes up and 'claims' to be the real magic behind #39. Lol.
I'm sure he was a great tech in his own right but he's full of shit on all accounts when it comes to #39. In an interview he states that the Caswell amp was a terrible mess and sounded bad. So he had to 'correct' lots of things. Well, then why was that amp rented out for YEARS STRAIGHT before Levi got there?
Must've sounded pretty good since Lynch rented it for the whole ULAK tour. Which was long before Levi got there.
 
Chris6870 said:
It has new cap job and new tubes. Work appears to be well done. Weird thing is this amp is clean as a whislte as in zero breakup, no overdrive even when cranked. I would think this thing should do AC/DC type gain all day long.
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Could be a Superbass circuit...those are fairly clean until you get the volumes really cooking. My Tremolo is like that.
 
Is Caswell still in business? You could maybe get the #39 mod from him? Someone might be able to clone the #34, #36 mods also.
 
Racerxrated said:
Could be a Superbass circuit...those are fairly clean until you get the volumes really cooking. My Tremolo is like that.
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I don't see a bright cap on the Bright volume but my computer won't zoom in very far (EDIT: OK I think there is a dark brown silver mica on there but looks like a lower than stock value). The Presence cap should be large-ish and I don't see a large cap there. There's a few components that aren't stock such as bias swap to EL34s. And that purple wire that appears to be connected to the speaker jack ground looks...different. Purple is usually NFB which would be connected to speaker jack positive or the impedance selector.
 
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Chris6870 said:
It has 6550s in it currently
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Then maybe it was swapped back or it's the original mod to 6550. Those 2 tan resistors in bias circuit are the two resistors you would swap to go between EL34/6550 (to do it right) and maybe those are the original mod to 6550s for US distribution.

It's strange for it to be that clean when cranked. I have a Superbass with no bright cap and generally low gain circuit and I put a 12AY7 in V1 sometimes and it still gets pretty dirty when cranked.
 
Check all the preamp tubes to make sure they're all 12AX7/ECC-83's and that someone didn't put an 12AT or 12AU 7 in there.
And maybe swap some other 12AX7's.
Id also make sure all your power tubes are working too.
 
Samhain said:
Check all the preamp tubes to make sure they're all 12AX7/ECC-83's and that someone didn't put an 12AT or 12AU 7 in there.
And maybe swap some other 12AX7's.
Id also make sure all your power tubes are working too.
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I did that. Swapped in New 12ax7s and no different. The guy who did the cap job is right in my town. Spoke to him and he said it should be nice and crunchy. He doesn't remember doing the work specifically as it was a few years ago but said he'd take a look at it and get it sounding like a Marshall should. Other option is to take it to a better know guy an hour away with a long wait list. I might just take it to the local guy and see if it's something simple.
 
SpiderWars said:
Then maybe it was swapped back or it's the original mod to 6550. Those 2 tan resistors in bias circuit are the two resistors you would swap to go between EL34/6550 (to do it right) and maybe those are the original mod to 6550s for US distribution.

It's strange for it to be that clean when cranked. I have a Superbass with no bright cap and generally low gain circuit and I put a 12AY7 in V1 sometimes and it still gets pretty dirty when cranked.
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I had a 78 fawn headshell 2204 that was just like this in terms of clean sounding. It came from a studio out of Tennessee and was mint, I assume it was for country music. I recapped it and couldn’t sell it fast enough - too mint to mod, to shitty sounding to keep.
 
So I took it to a local tech and he said everything looks perfect circuit wise, all voltages are good and basically stock. He said he could get some break up at ear splitting volumes but it was fairly clean. He suggested going to EL34's which might get a little more crunch out of it. Kinda torn. Not sure if I should mod it or just sell it to someone who wants an original circuit.
 
Racerxrated said:
You've said this before, and you are wrong on anything related to Caswell's amp, the famous #39. That amp was in high demand for years BEFORE Levi ever got out to LA. Period.
The truth is, when Levi got to LA Caswell had gone and SIR asked Levi to CLONE #39 into a few more of their amps so that they would also be reserved for years straight, like #39 was. He did that. Now, after Levi noticed all the accolades Caswell was getting all of a sudden Levi chimes up and 'claims' to be the real magic behind #39. Lol.
I'm sure he was a great tech in his own right but he's full of shit on all accounts when it comes to #39. In an interview he states that the Caswell amp was a terrible mess and sounded bad. So he had to 'correct' lots of things. Well, then why was that amp rented out for YEARS STRAIGHT before Levi got there?
Must've sounded pretty good since Lynch rented it for the whole ULAK tour. Which was long before Levi got there.
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Frank & I were friends. We all have our stories now don't we ?
Frank had the amps everyone wanted. And still do.
Caswell went to solid state hybrids and preamps & shit, everything opposite of the original SIR amps LOL.
Caswell has been riding Franks coattails about 45+ years now.
One thing is for sure the original SIR amps disappeared a long time ago, nobody know where they are and the one's that do ain't talking.
Bet Lynch knows.
 
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Samhain said:
Frank & I were friends. We all have our stories now don't we ?
Frank had the amps everyone wanted. And still do.
Caswell went to solid state hybrids and preamps & shit, everything opposite of the original SIR amps LOL.
Caswell has been riding Franks coattails about 45+ years now.
One thing is for sure the original SIR amps disappeared a long time ago, nobody know where they are and the one's that do ain't talking.
Bet Lynch knows.
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Again, wrong on ALL counts. Funny how right before Frank was supposed to introduce his home brew amp, that he does an interview and tries to change reality. Frank was hired to COPY Caswell’s modded 71 SuperTrem, #39, the amp EVERYONE wanted and was impossible to get. SIR wanted more like it for obvious reasons. Lynch himself tried to buy it…and instead rented it for the ULAK tour. In an interview Lynch states that he finally found out who modded 39…Caswell….and had him mod a few more for him.
These are the facts, and true history of that amp. Not the made up bullshit by a guy who decided right before he started his own amp line(which never materialized btw) that he’d tell a tall tale to drum up business for himself. In Levi’s interview he states that no one wanted to rent #39….what a joke. There’s at least 5 interviews where Lynch, Slash and others talk about #39, and how it was ALWAYS unavailable.
Levi turned into a good liar, that’s for sure. It’s too bad because he did some cool mods…but his half ass attempt to change history is sad at best.
 
Chris6870 said:
So I took it to a local tech and he said everything looks perfect circuit wise, all voltages are good and basically stock. He said he could get some break up at ear splitting volumes but it was fairly clean. He suggested going to EL34's which might get a little more crunch out of it. Kinda torn. Not sure if I should mod it or just sell it to someone who wants an original circuit.
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Have you tried a pedal or two in front of it? My 72 is a damn monster that blows the doors off any amp I’ve owned or played, when I double boost it. Better than either Wizard or C+ coliseum I had. It’s also a fairly clean tone like a SB.
 
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