The Official Marshall DSL40c Information Thread

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Pulled the new 34's out and put the originals back in to check the bias, and those read at 15-ish each...

Put the new 34's back in an rechecked the bias on those to 12 each again... and just for the hell of it, I wanted to see what the range was on the trim pots per min and max... my minimum was 4.2mV, and my max was 31.8mV...

so with the originals still reading fairly low like that, I'm gonna guess that there is something in/on the board itself that is causing the issue - possibly the scooping issue too when the gain is max'd out... I'm also curious that since I set these lower than the stock ones, if that's causing the "scooping" issue to decrease...

Either way, its going to get dropped off, checked out and fixed. Its still totally worth it for me to have it done.
 
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And as I believed I mentioned in one of my earlier posts, the board and everything internally looks good - nothing burnt, broken, damaged, etc... I know that doesn't always mean thats the case, but usually if something is burnt/broken and you can physically see it, then that is your starting point. Here's the pics of everything inside the chassis...

Also, here's something interesting with the stock EL34'S... There's a sticker on them from and by Tube Amp Doctor!!! I'm guessing this is a 2016 model, from what I can see of the stickers in/on it... 20201126_112756.jpg 20201126_112809.jpg 20201126_112819.jpg 20201126_112827.jpg 20201126_112834.jpg 20201126_111111.jpg 20201126_111048.jpg
 

tmingle

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Hey guys! So another update on my DSL40C resurrection...

*I bought a new set of tubes for it. I bought 3x Sylvania 12AX7's for V1, V2 & V4, a GE JAN 12AX7WA for V3 (per Marty's recommendation...), and a set of TAD EL34B-STR's for the power tubes.

*My new head cabinet came in from Mission Engineering, and it's absolutely beautiful! My project tomorrow after digesting Thanksgiving dinner, is to re-arrange my amps and cabs to set the Marshall on top of my 4x12.

However, there is something I am puzzled by when checking the bias on the new tubes... I know the general numbers are 37/38mV each tube. When I checked mine, it read 11.8 on each... ??? So I went to start adjusting it up to the normal 37 or 38, it maxed out at like 24... when I saw that the other tube was the same reading - 12mV - I set the other tube back down to 12 to match...

With this being said, what do you guys think it could be thats causing the readings to be so low??? After re-inspecting everything inside the chassis, and making sure the tubes are seated correctly and all the way in, nothing looks out of place or damaged & all the tubes are all the way in...

I am going to put everything back together and test it out playing it and see if I'm still getting the "scooping/pulling the blanket off the front of rhe speaker" sound issue I've been having or not with the new tubes in it...

But I am looking for any suggestions or ideas as to why the bias readings are so low. Any help is greatly appreciated! I will also follow up with an updated pic of the head and my setup(s)!

Thanks as always guys!!
Are you measuring the bias in 1/2 power mode? It may affect your readings. Personally, I never cared for the 1/2 power mode on this amp.
 

Ren Furtado

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Hi, guys! New member here. I was wondering if you guys could give me input on preamp tubes for my DSL40C.

I'm thinking on using Sovtek's 12AX7-LPS for v1 and v4 and keep the stock Marshall tubes on v2 and v3. Is that ok or should I replace them all?

After watching many comparison vids on youtube the Sovtek tubes still sound the best for my ears. But, I'm open to suggestions.

In my country, I can also easily find EHX, Mullard and JJ.

Cheers from Brazil!
 

Ren Furtado

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Be careful about comparos of on-line videos. The mics are unknown (as are the clipping and other recording attributes) to give it much credence beyond a start prior to FtF listening.

Thanks, Bownse. And, yes, you're absolutely right.

I'm thinking on replacing the v1 and v4 tubes and keep the stock Marshall's on v2 and v3. Is that ok? Do I have to replace all four tubes?
 

Mitchell Pearrow

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Hi, guys! New member here. I was wondering if you guys could give me input on preamp tubes for my DSL40C.

I'm thinking on using Sovtek's 12AX7-LPS for v1 and v4 and keep the stock Marshall tubes on v2 and v3. Is that ok or should I replace them all?

After watching many comparison vids on youtube the Sovtek tubes still sound the best for my ears. But, I'm open to suggestions.

In my country, I can also easily find EHX, Mullard and JJ.

Cheers from Brazil!
Welcome to the forum
Your ears are going to be the final answer for the positions you are going to put them in (preamp tubes)
I put a 12AT7, in V2
5751 in V4
And that sounds pretty good on my Dsl40c’s, it vastly helped out the red 2 ultra channel.
Cheers
Mitch
 
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Ninjaking67

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Hey guys!
I'm a once in a while visitor but regularly see Mitch Pearrow on TTR! I have a question for you "all knowing" types. I hope it wasn't already answered somewhere within the 529ish pages of this thread and I just missed it!
I have an older DSL40C that I performed the C19 mod on. I was unhappy with the fizziness of the OD before the mod but now I am not pleased with how dark the OD sounds.
I read that putting a 100pF cap in place of the existing C19 should be the sweet, happy medium. Any idea what voltage value this cap should be?
Thanks in advance for any advice! Cheers.

EDIT: I should maybe note that in addition to the C19 mod, the amp has an Eminence Redcoat Governor speaker.
The tube compliment is currently ECC823 in V1, 5751 in V2, ECC83MG in V3 and 5751 in V4. It still has the stock Marshall branded power tubes.
 
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Bownse

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I did the C19 mod, swapped in a 75 Creamback and noted the darker tone but felt it was better than with the C19. I then moved it all into a 2-speaker closed back cab with separate head. The Creamback and the OEM speaker went into the new cab and the overly-bright OEM speaker compliments the other mods.

I'm not saying "do like me" but maybe that experience can form a game plan: (different speaker(s))? Higher rated C19 (which has been discussed here at length).
 
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So FINALLY, I have an update for you guys about my DSL40C...

On my last post, I had put new tubes in it and had an extremely low bias reading on both the new and the original tubes. I also had an issue what seemed to sound like a blanket being pulled off the front of the amp itself in the very first few milliseconds of playing it. This is the result since I had it dropped off about a month ago...

Apparently, a few of the pots had been pushed in from the front of the amp, which had loosened some of the contacts where they solder to the board and loosened the pots themselves (pot casings started becoming unclipped...). They were all re-seated, reconnected any and all loose connections, burned in the new tubes correctly and re-biased to proper numbers. Despite all of this, I still noticed the sound issue its had before I dropped it off...

But here is what I found interesting... I had stopped at GC for a set of strings, and tried out a guitar thru a brand new DSL40CR. I instantly noticed that the CR has the same sound issue as my 40C does... So I'm thinking it has something to do with the design and construction of the circuit of the amp itself...

So even with all the new parts, tubes and work that went into rescuing this amp, it's not one I'm gonna hang on to... It does sound good in both channels and both modes withing each channel, but that sound issue is enough for me to not want it...

As a result, I have both the amp and the head conversion cabinet I had made by Mission Engineering up for sale on Reverb. I *MIGHT* see if GC will give me an even trade on the amp for the Jackson 7-string I tried out while I was there yesterday. So ideally, the head cabinet is up for grabs if anyone wants to do a conversion on thier DSL40C...

Thanks for all the help and insight guys, I really appreciate it. You have gotten me in the right direction with the amp, but its unfortunately just not the right amp for me. Hope you guys keep rocking, and stay safe during these insane times we all face right now!

Josh in NY
 


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