Marshall DSL15H Modifications

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marshallnoise
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Joined: Wed Jun 10, 2015 1:58 pm
Just the numbers in order: 13492
Location: Oceanslime, CA

Marshall DSL15H Modifications

Post by marshallnoise » Thu Apr 05, 2018 2:18 pm

I know this isn't the sexiest amp for this forum, but I love this place and George and this info is good for some people to have.

I bought a Marshall DSL15H for $350 brand new off Sweetwater and loved the idea of it: Marshall DSL but 15 watts with 6V6 tubes instead of stupid EL84s. It is a channel switcher. It has the Green channel (no boost) from the big amp and also has the Lead 2 from the Red channel from the big amp too. The problem is that the Green is a touch too clean and the Lead 2 Red channel is just over the top an pretty much unusable. However, the idea of this amp works and using the past 5 years worth of internet history, I performed some mods that really transform this amp into something special. Clips will come later.

What did I change?
  • R15 got lowered from 1.8K to 900K (two 1.8ks in parallel). This takes the Green Channel and gives it a bit more gain. It also affects the Red Channel a bit too but more on that later.
  • R40 was bumped up from 1.8K to 5.6K to drop the available Red Channel gain considerably. There is simply too much gain on tap in stock form.
  • R82 was missing from this board completely. Install a 150K resistor there.
  • C34 is an electrolytic that I inserted a 10K resistor in series from the negative lead to the trace where the negative lead of the cap was pulled. I am pretty sure this is the bypass cap for the V1B which is on the Red Channel
  • C75 received similar treatment to C34 except that it is not an electrolytic cap so either leg works AND the value is 10M. I am not sure what this accomplished, but the people who did this in the interwebs said it was a good idea.
  • C76 was changed from 470pf to 100pf to balance the overall brightness between the Green Channel and the Red Channel. This apparently makes the amp more usable as a channel switcher as opposed to having two channels that are good on their own but do not function well together.
ImageDSL15H Mod Area by Paul Abbott, on Flickr

C75 & C76 &R82 are at the top leftish of the picture. To the right of where it says BAR CODE.

C34 & R40 are at the bottom right of the photo. R40 is hidden behind the poly cap but you can see R43, R42 and R41 in a row so it is just to the right of that.

R15 is not on the picture but it is down below where C34 & R40 are.

marshallnoise
Senior Member
Posts: 169
Joined: Wed Jun 10, 2015 1:58 pm
Just the numbers in order: 13492
Location: Oceanslime, CA

Re: Marshall DSL15H Modifications

Post by marshallnoise » Fri Jul 24, 2020 6:06 pm

Many, many moons later I am back.

I was not thrilled with how this amp would still break up way too much for my liking. My goal was to get the green channel a bit hotter and then bring some lowend into the red channel and drop the gain some more. Here is what I did:

I dropped R15 down to 68 ohms. This increased green channel gain quite a bit. I would imagine with a hot humbucker and a distortion box it would be plexi-ish. With GFS Mean 90s, I can barely get some drive out of the green channel with it maxxed.

On C34 (low end filtering of the red channel), I wanted more bottom end so I put in a 15K in there to replace the 10K I had originally modded it. Now I feel like the red and the green channel have the same "whoompfh".

I confess to snipping out C75 completely. I put a silver mica 500uf cap in there with the 10M resistor. Again, not totally sure what it did, but I am not mad about it.

I highly recommend people getting an Eico RTMA Resistance Box to change values on the fly. It was really helpful to me.

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