Mike Fortin Marshall DSL mod Youtube clip added.

[FortinAmps]

Hey Jason,

Are you able to do any clips?

Cheers,
Mike

 

[tonmazz]

I might just be falling for nostalgia because I went from a DSL50 which I did have modded to a hot rodded Caswell JCM 800 and honestly the 800 blew it out of the water in a side by side. Even with the DSL mod, which I was less than satisfied with for several reasons that I won't go into, there was a thinness with the DSL. Maybe this mod would be different and make a difference. Keep in mind that the mod I had done included new Mercury output transformer as well as board changes and in comparison it was still weak. That being said the clean was to die for and I still miss that. I should probably be happy with what I have instead of looking back...

 

[jasonP]

I might just be falling for nostalgia because I went from a DSL50 which I did have modded to a hot rodded Caswell JCM 800 and honestly the 800 blew it out of the water in a side by side. Even with the DSL mod, which I was less than satisfied with for several reasons that I won't go into, there was a thinness with the DSL. Maybe this mod would be different and make a difference. Keep in mind that the mod I had done included new Mercury output transformer as well as board changes and in comparison it was still weak. That being said the clean was to die for and I still miss that. I should probably be happy with what I have instead of looking back...

I actually thought the MM OT sounded thinner then the stock unit. For right now I wouldn't change anything on my amp it sounds great to my ears. Mike's mod really opened up the red channel and now selling my DD because of that. Really smokes.
I'm going to try and get some video by the weekend.

 

[tonmazz]

I can't wait to hear it. Might make me think twice! I was always a third channel guy.

 

[jchop]

JasonP messaged me about this post at the metro forum.

I have a DSL 100 also and have done the same mods as JasonP ( Marstran C1998 Output Tranny and 3Hchoke).
I've also lowered C12 on the input board to 180pf, which is a treble bleed. Also did all of the mods listed here to solve thermal runaway or a bias drift. (besides the single bias control) http://www.lynx.bc.ca/~jc/TSL122.html

I was having and am still having some troubles with the bias drifting really bad. My dsl 100 is a 1998 model. I've tried everything listed in the link, tubes ect. still no luck.. From what I've heard apparently Marshall used a cheap plastic PCB and over time as it ages begins to act as a thermisistor. In 2003 Marshall took note of the problem and started making all post 2003 Valve PCB boads out of good glass fiber and also made some changes to the circuit layout in the preamp section. This seemed to address the issues with thermal runaway bias problem many where having.

Needless to say I'm going to have to order a new Valve PCB. Marshall says I will have to order it through a dealer here in the US. I was quoted $200 from an online Marshall dealer. I've heard on other forums the part is actually only $50 us dollars .

Anyone know of a Marshall dealer that will not charge so much to order replacement parts through?

I want to try these mods also, but I need to address these
other issues first.

 

[jasonP]

Update.
I also changed up the tone stack when the mid shift button is used just to add something different. Changed out R36 resistor to 15k, jumped C22 and left C19 stock. According to Mike this is close to a VHT tone shift. If I wanted less of a change I would just jump C19. Now when pushing the mid shift it is not such a huge change. So the change makes the amp more modern sounding, tighter and scoops the mids a little.
Going to play out the weekend and see how the amp does.
Jason

Update #2
After playing the amp against others I found it still freaking rips. But I want to change some small things about the amp.
Mike sugested that I jump C11,C10,R19,R20 on the input board. He actually told me to do this right away but I wanted to see how it sounded before. Now when backing the gain down it goes from aggressive to compressed. Just like he said it would. Sounds fucking ripping! Wish I would have done this before like Mike sugested.
I am extremely happy with the way this turned out. Sounds so bad ass! Even took it to the next step above what it was.
So anybody doing this I would say...
.1uf for C12 on the main board
Jump C11,C10,R19,R20


UPDATE #3. These are the values I think sound the best and have used for a while now. So I'm going to post them up.
Hey Mike,
I wanted to give you an update and I would totally recomend this after trying a couple different values.
I would still do the depth mod. I add in about 15 percent just to give it a little more lower mids if you don't use the deep switch. But sounds great with out as well.
Pretty much the best sound out of my amp so far with these values.

Main
I've tried both 220pf and 470pf over R23. Much prefer the 220pf.
1uf for C12 for less mids. . The .68uf is just to much, I like this value if you are going to keep .022uf on C8.
R12=22K I like the stock 68k, as it tames some of the gain.
R13=100K
C17= .001UF
C13= 2.2UF
C8=.0047UF I like .022uf as it adds a little beef back to the amp
C16=.0022
C6&C7= .1UF
Input
C10/C11/R19/R20 all jumped. More gain and like the voicing of the amp more like this.
R36 15k, C22 Jumped, C19 470p Left Stock. Mid scoop option is not a dramatic before and is way more usable. Great for more modern tones, chords, drop tunings.
C12 .0047 I love this. Amp gets aggressive when down and compressed when gain turned up, I also like .001uf if don't want such a drastic change in brightness when lowering the gain knob.

Output Jack Schematic:
R19 IS THE FB RESISTOR, TRY IT ON THE 8 OHM TAP INSTEAD OF 4 OHM.

 

[skoora]

I think the DSL's are pretty good too. I always thought the bass response between the two channels was way out of balance. The green channel has so much more low end you can never get the channels to balance. Plus I wish the green channel when the boost was engaged was tighter and sharper, sounding like a true JCM800. This is more so when using humbuckers. I agree with previous posters that the red channel is too thin when the preamp is lower and I would have to use that to get JCM800 type tones that the green channel didn't quite get. Also the channel switching always had a slight delay or morphing quality to it. It never seemed instant.

 

[jasonP]

I think the DSL's are pretty good too. I always thought the bass response between the two channels was way out of balance. The green channel has so much more low end you can never get the channels to balance. Plus I wish the green channel when the boost was engaged was tighter and sharper, sounding like a true JCM800. This is more so when using humbuckers. I agree with previous posters that the red channel is too thin when the preamp is lower and I would have to use that to get JCM800 type tones that the green channel didn't quite get. Also the channel switching always had a slight delay or morphing quality to it. It never seemed instant.

If you where using the reverb then you would hear a ramp up when switching channels. Although I never thought the balance between bass was that huge the green channel does have more and the red channel being thinner. I've always ran the bass boost on so that helps thicken up the red channel. I've found that boosting the green channel got the amp really tight.

 

[ratter]

Talked to Mike said it was ok I post the values of his mod.

That's VERY cool of him.

 

[tweed]

clips!!!!!!!

 

[Brain Becker]

Mike's a very cool guy. He hooked me up with some schematics I needed over at TGP. I didn't even know he was a member here.

 

[blackba]

Did you guys discuss doing adding a choke as well?

the mods sound pretty cool. The hardest thing with PCBs IMO is getting them out of the amp, but then again I solder to PCBS alot in my job. I was surprised to see the power amp PCB is double sided FR4. That is good since they did board mounted tube sockets (which I am not a big fan of)

 

[jasonP]

Did you guys discuss doing adding a choke as well?

the mods sound pretty cool. The hardest thing with PCBs IMO is getting them out of the amp, but then again I solder to PCBS alot in my job. I was surprised to see the power amp PCB is double sided FR4. That is good since they did board mounted tube sockets (which I am not a big fan of)

Yes we did talk about that. R71 is the choke resistor location. I already replaced it with a 3H before doing this. Also replaced the OT with a Heyboer.

 

[skoora]

I think the DSL's are pretty good too. I always thought the bass response between the two channels was way out of balance. The green channel has so much more low end you can never get the channels to balance. Plus I wish the green channel when the boost was engaged was tighter and sharper, sounding like a true JCM800. This is more so when using humbuckers. I agree with previous posters that the red channel is too thin when the preamp is lower and I would have to use that to get JCM800 type tones that the green channel didn't quite get. Also the channel switching always had a slight delay or morphing quality to it. It never seemed instant.

If you where using the reverb then you would hear a ramp up when switching channels. Although I never thought the balance between bass was that huge the green channel does have more and the red channel being thinner. I've always ran the bass boost on so that helps thicken up the red channel. I've found that boosting the green channel got the amp really tight.

I noticed the ramp up on switching with the reverb off. I know boosting the green can sound good (OCD especially) but then if you want to use both channels you're doing a lot of tap dancing. Plus the green channel is very boomy if you use the bass boost. Now if there was a way to put a pot on the bass boost and have it channel assignable that would be sweet.

 

[jasonP]

I think the DSL's are pretty good too. I always thought the bass response between the two channels was way out of balance. The green channel has so much more low end you can never get the channels to balance. Plus I wish the green channel when the boost was engaged was tighter and sharper, sounding like a true JCM800. This is more so when using humbuckers. I agree with previous posters that the red channel is too thin when the preamp is lower and I would have to use that to get JCM800 type tones that the green channel didn't quite get. Also the channel switching always had a slight delay or morphing quality to it. It never seemed instant.

If you where using the reverb then you would hear a ramp up when switching channels. Although I never thought the balance between bass was that huge the green channel does have more and the red channel being thinner. I've always ran the bass boost on so that helps thicken up the red channel. I've found that boosting the green channel got the amp really tight.

I noticed the ramp up on switching with the reverb off. I know boosting the green can sound good (OCD especially) but then if you want to use both channels you're doing a lot of tap dancing. Plus the green channel is very boomy if you use the bass boost. Now if there was a way to put a pot on the bass boost and have it channel assignable that would be sweet.

I think the older DSL might of had this channel switching problem but I know mine doesn't do this.
It is hard to set both channels to sound good with one eq as in any amp with the same setup.
I found the bass can get loose or boomy when using a very warm spongy sounding humbucker and stock the amp is more forgiving and spongy already. Although I think when putting a boost in the front it makes the amp sound very tight.

 

[jasonP]

Here you go. Only on 2. Sorry for the shitty ass playing. Hopefully it sounds alright. Fast forward to around 1:00 so you don't have to listen to my stupid ass talk.

 

[Marshall Law]

sounds good, someone fixed your youtube

 

[cyndicate]

Wow that sounds great

 

[Juggernaut]

 

[stephen sawall]

That is the best I have heard a DSL sound ... very cool.