Took the back off my DSL-40CR. PROBLEM SOLVED!!!

dotsdad

dotsdad

New member
I have the same complaints about the DSL40 combo everyone else seems to have - fizzy highs at low volume and flubby bass at high volume.

Solutions online seem to be removing the C19 capacitor and replacing the stock speaker, but I don't like either option. I don't want to void the warranty by clipping capacitors, and I am too cheap to buy a new speaker.

To test if a new speaker would even do any good, I rigged the Celestion G12M-70 from my busted '86 5210 combo up to the DSL's 4 Ohm output and disconnected the stock speaker. (Thanks, Marshall, for the multiple ohm outputs!) It sounded sooo much smoother in the mids and highs, but the bottom end was gone. Not tightened up, just missing. I still liked the sound better than stock, though.

I figured taking the speaker out of the old semi-open-backed combo and putting it in the new closed-back combo might get back some of the lows while keeping the smooth mids and highs. Makes sense, right? After all, they say to put speakers in the corners if you need more bass. Physics or something. blah blah blah.

I started pulling the back off when the epiphany came (and a touch of laziness as well)...I thought "hey, if closed backs have more bass, let's listen to the flubby stock speaker with the back off to hear the difference before effing with the speaker swap."

Well, guess what? The flubby bass is gone!! Yes, the high is a bit fizzy at low volume but, you know, it's an effin Marshall. The fizz goes away when you turn it the master up.

So there you go: "How to mod a Marshall DSL40CR combo without voiding the warranty or spending money 101." Seriously, folks. Leave the capacitors alone and skip the speaker swaps. Just take the back off and turn up the volume. Problem solved!
 
I’m actually surprised by this. Typically, closed back puts back pressure on the speaker, decreasing the settling time of the cone and transducer, pending it to reproduce more detail, highs, and less bass. Open back let’s the cone travel it’s full distance unhindered, which typically results in a looser flabby sound (like old tweed fenders). Glad it worked, but I am surprised how it worked.
 
Part of it could be that the back was made out of something even crappier than mdf. Like molded glue and sawdust or something. I don’t know what it is, but tone tapping it definitely doesn’t give that classic woody knock of old school birch. Maybe it sounds better because that sh*t isn’t vibrating?
 
That actually makes sense. If the softer material was putting a very uneven back pressure on the cone (like a poorly tuned passive radiator), it could have interfered with reproducing certain frequencies. Taking it off is letting it at least function normally and naturally.
 
Personally I'm just not a fan of 112 closed-backs no matter what quality the back is, although there are some huge 112 cab-only boxes on the market now which I've never tried.

With the bigger cabs maybe a c90 or k100, or even a t75 might really kick *ss.
Usually the only way I like a 112 is as a ported design like the thiele.
 
beaubrummels said:
That actually makes sense. If the softer material was putting a very uneven back pressure on the cone (like a poorly tuned passive radiator), it could have interfered with reproducing certain frequencies. Taking it off is letting it at least function normally and naturally.
Click to expand...

Hmm...so now you've got me wondering if I should fit some baltic birch back there.
 
I prefer open backs
all my external cabinets are convertible
I open each on and save the door in a closet
 
Is that the ~20 watter with 84's? If so I had one long long ago. Great sound but the thing ran REALLY hot. Like , put a on a fan it at club level hot. Great sound but didn't last but a few years.
 
dotsdad said:
Hmm...so now you've got me wondering if I should fit some baltic birch back there.
Click to expand...

FWIW I just put a plank of ply on the back of an old Randall RG-80 combo cabinet I use as an extension speaker and it definitely tightened and brightened up the Celestions I used in there, though I was using the Greenback / Historic / Vintage line. (I swapped out 3-4 before settling on a ‘historic’ whatever reissue of a Vintage 30. I wanted to love the Hendrix 50hz I had, but in the end Vintage 30 was an all around improvement.)
 
Do they even do t75 in any new version of these anymore?
I really tend to like t75 and k100 the best in small combos, especially with el34 amps.
 
Love hearing about mods that are reversible and low/no cost! Often we throw cash at our problems instead of just tinkering with stuff. Way to go!
 
I liked it more as an open-back. I'm sure there is more of a difference in the room than in the clips, always is.
Most 112 closed-backs sound stuffy to my ears, especially in most combos because they're usually not thick birch like a good 112 dedicated cab, nor are they usually as deep in combo form.

I'd probably suggest making a slot or port back for it, but keeping the stock back as is. It might sound better fully closed if you get near band volume.
 
Well, that mod was easy! Have to keep that in mind.

Glad it worked for you. I like DSL 40's period. DOn't own one.
 
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