My Modded Marshall 1959slp 100w Photos

Re: My Modded Marshall 1959slp 100w Photos

joelap said:
So that's the beast I've heard so much about? :)

Looks pretty good man. I gotta figure out what the heck I'm going to do about my money situation. I literally have 35 dollars to last me until the second week of June, so my AC30 is on hold. I've got the sozo caps in and the chassis, just waiting for the resistors, silver mica, and filter caps to come in from Ceriatone, then I'll build a mock board out of cardboard to keep myself occupied until I get the money to start ordering the parts and whatnot. Has anyone on the metroamp forums done the caswell mod yet and recorded a clip of that amp cranked? last I checked the only clip had the PPIMV low and it was all preamp gain and sounded more like early van halen than GnR. Just curious about the concensus on the mod over there?
Click to expand...

I think that there haven't been any more clips made with it than the one you described, which is a bit disappointing as last time I tried some of the values in my amp, I got scarily close to the AFD sound.

One cool thing is, I've got in contact with a guy who has Caswell working right now on an amp mod for him, and together we're gonna work out exactly what he did to his amp. So even if that spec I showed you is slightly different to the original mod, we'll have 100% confirmation of what it actually was soon.
 
Re: My Modded Marshall 1959slp 100w Photos

shredaholic said:
Thanks Jeff :D, the reason it still sounds like an original Marshall is because I've tried out all the different values that old plexi's used, taken the best sounding ones (to me anyway), and put those values together into my amp. The only thing in the tonal path right now that was never in a plexi made from 1967-1969 is the 100k NFB resistor.


By lessening the NFB I managed to make it more powerful sounding, and increase the power amp gain; most amps lose the Marshall character because they add gain through the preamp and compression. This type of gain is totally the opposite - it's huge, open sounding gain and sounds almost the same as power tubes being driven hard. It makes the amp more responsive to guitar volume changes, and seems to increase the harmonic content and controllable feedback.
Click to expand...

So would you say (and remember I don't know a damn thing about amps except what I like to hear, and how to use the on/off switch :laugh2: ), considering your mods ( using the "hodgepodge" of values from various plexis ) this is more like a "metalface" than a true plexi? Cos to me that's what it sounds like based on the real deal stuff I've played. Many of the early Plexis are a bit sweeter and a little "farty". Your amp is a little crunchier, tight & bright...more like the 72-75-ish amps I've played. Its like Hendrix tone vs. MKIII DP era Blackmore (I know he used Majors, but hopefully you'll get gist).
 
Re: My Modded Marshall 1959slp 100w Photos

shredaholic said:
Yeah the main reason it's messy is I've used the same board so many times, and have never really "cleaned it up" so to speak. I don't own any de-soldering braid so I need to get some of that. When I first did the PTP board last year, I wasn't that good at soldering, and I used the lead-free stuff which makes the joints look dull. Even though I'm now using the 60/40 leaded stuff, a lot of the joints still have the old solder on them.

The capacitor that looks most strange is the .68uf on V1b's cathode - the reason that and others look that way is because I used some of the caps for an experiment where I tried to replicate the mustard coloured covering on the old Mustard caps. After finishing the experiment, the caps were cleaned up with paint stripper, which unfortunately took off the writing on them and damaged some of the yellow wrapping outside. They still work and sound fine though - I call it character :)
Click to expand...

Get one of those Radio Shack solder suckers....The one you plug in and looks like a soldering iron but has the red rubber bulb on top of the soldering Iron tip....Use the desoldering braid also....I also use silver solder on all of my projects,including all of my pedal mods....The amp sounds great though buddy,and that's all that really matters....I think if you clean up those connections,your amp will have better longevity and reliability later on down the road...It's alot of work I know,cause I converted my own PCB over to PTP,but it was really worth the effort.....I went with Trace at Voodoo Amp's Custom MM Output transformer and choke and one of these days I'll do the PT,but it doesn't really even need it...My amp seems to sound better and more open each time I Play through it,in fact it sounded amazing the other night with my band!
 
Re: My Modded Marshall 1959slp 100w Photos

They didn't use 100k until the 2203 (MV's, JCM800's) came out if my memory serves me right. Lessening the negative feedback is such a killer mod on a Marshall, and makes the amp have more poweramp gain.
Click to expand...

You're speaking about the 1959 model,but my 73 50 watt 1987 model came with the 100k to the 4 ohm tap...That's where I've kept it,but I've installed a resonance control on mine...
 
Re: My Modded Marshall 1959slp 100w Photos

JeffB said:
So would you say (and remember I don't know a damn thing about amps except what I like to hear, and how to use the on/off switch :laugh2: ), considering your mods ( using the "hodgepodge" of values from various plexis ) this is more like a "metalface" than a true plexi? Cos to me that's what it sounds like based on the real deal stuff I've played. Many of the early Plexis are a bit sweeter and a little "farty". Your amp is a little crunchier, tight & bright...more like the 72-75-ish amps I've played. Its like Hendrix tone vs. MKIII DP era Blackmore (I know he used Majors, but hopefully you'll get gist).
Click to expand...

In some ways yes, but most of the values in the amp are actually early plexi values. I won't go into the details but most of the values are more thicker and fatter sounding, and then I had to use one or two thinner ('69 circuit values) sounding ones to get the crunch and loose the flub. The cap on the presence control was more common on MV marshalls, that's where that upper mid cut comes from. I'd say it's half a 1967 plexi (with bass values), and a few metalface-esque tweaks.

Bear in mind I am using a strat, which is pretty thin sounding through most Marshalls - if you plugged it into the high treble high impedance input of say, a '69 or later Marshall, it'd sound very thin and weak. I'm using that input in these clips with my amp too. Through my amp it sounds more like a humbucker equipped strat, so using humbuckers in my next clips will probably demonstrate it better I think, or using the strat with less gain. With less gain on the amp's controls, the amp is effectively a sweeter sounding earlier Plexi and does that sound very well.

I haven't tried the amp for a while with the VHII's actually, most importantly not since lessening the NFB. I'm expecting it's gonna sound pretty huge. Like Van Halen I type gain. One source that has reputedly seen his amp claims that he had a variable NFB control in his amp, which would explain that a lot. Or maybe his NFB resistor had drifted up in value? To me anyway, his amp sounds like it had a lot less NFB than the 47k/8ohm tap combo.
 
Re: My Modded Marshall 1959slp 100w Photos

STRATDELUXER97 said:
You're speaking about the 1959 model,but my 73 50 watt 1987 model came with the 100k to the 4 ohm tap...That's where I've kept it,but I've installed a resonance control on mine...
Click to expand...

Cool - I absolutely love that NFB setting! I was gonna install a variable NFB control in the amp, but I don't think I'd ever change it so I didn't bother! :D
 
Re: My Modded Marshall 1959slp 100w Photos

shredaholic said:
In some ways yes, but most of the values in the amp are actually early plexi values. I won't go into the details but most of the values are more thicker and fatter sounding, and then I had to use one or two thinner ('69 circuit values) sounding ones to get the crunch and loose the flub. The cap on the presence control was more common on MV marshalls, that's where that upper mid cut comes from. I'd say it's half a 1967 plexi (with bass values), and a few metalface-esque tweaks.

Bear in mind I am using a strat, which is pretty thin sounding through most Marshalls - if you plugged it into the high treble high impedance input of say, a '69 or later Marshall, it'd sound very thin and weak. I'm using that input in these clips with my amp too. Through my amp it sounds more like a humbucker equipped strat, so using humbuckers in my next clips will probably demonstrate it better I think, or using the strat with less gain. With less gain on the amp's controls, the amp is effectively a sweeter sounding earlier Plexi and does that sound very well.

I haven't tried the amp for a while with the VHII's actually, most importantly not since lessening the NFB. I'm expecting it's gonna sound pretty huge. Like Van Halen I type gain. One source that has reputedly seen his amp claims that he had a variable NFB control in his amp, which would explain that a lot. Or maybe his NFB resistor had drifted up in value? To me anyway, his amp sounds like it had a lot less NFB than the 47k/8ohm tap combo.
Click to expand...


I really like the .68 across the Presence pot...You need to try that if you haven't already....Unless you no longer have presence because of the PIMV? I disconnected the PIMV on mine,as it sets up an oscillation over notes..I Like my amp without that in the circuit...
 
Re: My Modded Marshall 1959slp 100w Photos

Bro, that is sweet. Just listened to your clip. Sounds incredible. Gotta love them Marshalls. :D
 
Re: My Modded Marshall 1959slp 100w Photos

shredaholic said:
Cool - I absolutely love that NFB setting! I was gonna install a variable NFB control in the amp, but I don't think I'd ever change it so I didn't bother! :D
Click to expand...

The more stuff we add to our Marshalls though,the more chance of problems with oscillation and stray antenna effects from extra wire and components and neighboring parts of a circuit...Sometimes less is more brother...I just love the 4 ohm tap with the 100k fb resistor...With the transformer,much better choke,and nice components and tweaks throughout,I'm very very happy with my amp...Wish I had the time to post clips,but I really can't be bothered with it...:smack:
 
Re: My Modded Marshall 1959slp 100w Photos

Yeah I took another listen as well, and then I switched into Kev's Stramp clip as well....I LOVE CRUNCH:D
Hehehe especially that old huge Marshall one, I think that I will get one of our amp tweakers to make me one late Plexi 1959 for me...I love that big glassy sound.
 
Re: My Modded Marshall 1959slp 100w Photos

ErikH said:
Bro, that is sweet. Just listened to your clip. Sounds incredible. Gotta love them Marshalls. :D
Click to expand...

Old Marshalls literally "Rockl Erik...:banana:
 
Re: My Modded Marshall 1959slp 100w Photos

STRATDELUXER97 said:
Old Marshalls literally "Rockl Erik...:banana:
Click to expand...
Yes, yes they do. :D :banana:

Mine may not be one of those old classic models, but it'll rattle the windows a few blocks away. :D
 
Re: My Modded Marshall 1959slp 100w Photos

Nice tone, plexi and not plexi.

Nice chops.

Need to clean up those circuits.
 
Re: My Modded Marshall 1959slp 100w Photos

shredaholic said:
I think that there haven't been any more clips made with it than the one you described, which is a bit disappointing as last time I tried some of the values in my amp, I got scarily close to the AFD sound.

One cool thing is, I've got in contact with a guy who has Caswell working right now on an amp mod for him, and together we're gonna work out exactly what he did to his amp. So even if that spec I showed you is slightly different to the original mod, we'll have 100% confirmation of what it actually was soon.
Click to expand...
Jackpot, keep me updated and let me known when it's all said and done.
 
Re: My Modded Marshall 1959slp 100w Photos

shredaholic said:
In some ways yes, but most of the values in the amp are actually early plexi values. I won't go into the details but most of the values are more thicker and fatter sounding, and then I had to use one or two thinner ('69 circuit values) sounding ones to get the crunch and loose the flub. The cap on the presence control was more common on MV marshalls, that's where that upper mid cut comes from. I'd say it's half a 1967 plexi (with bass values), and a few metalface-esque tweaks.

Bear in mind I am using a strat, which is pretty thin sounding through most Marshalls - if you plugged it into the high treble high impedance input of say, a '69 or later Marshall, it'd sound very thin and weak. I'm using that input in these clips with my amp too. Through my amp it sounds more like a humbucker equipped strat, so using humbuckers in my next clips will probably demonstrate it better I think, or using the strat with less gain. With less gain on the amp's controls, the amp is effectively a sweeter sounding earlier Plexi and does that sound very well.

I haven't tried the amp for a while with the VHII's actually, most importantly not since lessening the NFB. I'm expecting it's gonna sound pretty huge. Like Van Halen I type gain. One source that has reputedly seen his amp claims that he had a variable NFB control in his amp, which would explain that a lot. Or maybe his NFB resistor had drifted up in value? To me anyway, his amp sounds like it had a lot less NFB than the 47k/8ohm tap combo.
Click to expand...

Thanks for the detailed info. One of the absolute best sounding amps I've heard here on the board. I like plexis but many I'v3e played just don't have "it" (for me). Yours does. You done good :bigthumb:

Now get to work on those clips with the VHII pups ;) :D
 
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