Help needed to upgrade Capacitors in a Marshall DSL 40C

[sohosteve]

Hi there
I have just bought a secondhand Marshall DSL 40c 40 Watt Valve Combo.
It has already had a speaker upgrade and I've performed the C19 mod to balance up the channel switching tones which has worked very well.
Now I'd like to dig a little further to see if I can further improve the tone by replacing some of the main capacitors with Sprague Orange Drop 715P capacitors as per this chap.

https://www.youtube.com/watch?v=WqMSlj4dnPc

I feel that I should mention that I am NOT a trained electronic engineer.
However I have safely carried out quite a few modifications on valve amps (replacing all major caps, tone stack mods, etc etc) working from graphic instructions.
So I know how to safely discharge the caps without electrocuting myself and use an electronic toolkit without stripping tracks or melting components.

What I require is some assistance with identifying the parts that I need to order from Watford Valves so that I can replace the components now in place

The twelve capacitors that I wish to replace are marked as follows


Six x 223J400
Four x 102J1000P
One x 102J630P
One x 333K400

Because I'm not trained I don't know how the equivalent parts are described!

This is where I'll be ordering them from as I'm based in London https://www.watfordvalves.com/products.asp?ID=3&man=72

Thanks

[tedmich]

Search these numbers at Mouser, they all come back as decent polyester film caps. Because of this replacing these with (same value) orange drops will do almost nothing to the overall sound of the amp IMHO. If you're set on this, please record before and after clips and post them here as an experiment.

[Dave H]

Search these numbers at Mouser, they all come back as decent polyester film caps. Because of this replacing these with (same value) orange drops will do almost nothing to the overall sound of the amp.

I agree. Also the pin spacing of orange drops is too wide and the board would have to be removed to fit them. You could end up doing more harm than good.

[Justin Thomas]

I didn't hear anything in that clip not doable by pickup switching, or other much less risky surgery on a complex and expensive piece of nice gear. Weigh the possibilities against the risks; I wouldn't, based on THAT youtube clip. Just seemed like two still shots with music over it.

If this was an old Fender or something I'd say experiment away. Not on PCBs. Not trying to discourage you, but an old SF Bassman or something would be better as a mod/tone cap taste test bed.

Justin

[sohosteve]

Ah, ok.
Fair enough everybody I appreciate your opinions.

I just thought I may be able to bring some extra 'mojo' to it with what I thought may be a capacitor 'upgrade'.
The reason I thought this may be the case is because last year I performed the Fromel Electronics mod on a mid 90's American made Fender Blues Deluxe combo - which was all PCB too.
In that case swapping out most of the major caps and power transistors totally transformed the thing.
This made it far more responsive, tonally rich and tightened up the bass quite considerably.
Difficult to explain, but it made it sound more 'expensive', for want of a better word.
It seemed to jangle more like an old Fender Twin and had some great grunt to the break up.
Though maybe Fender were using cheap components at the time it was built.

It would seem to be the consensus of opinion here that I'd be wasting my time and money and possibly endangering my new purchase.
So I'll let sleeping dogs lie and put it through it's paces as is.

Thanks again for all your kind help!

You guys are truly fantastic :-)

[tedmich]

The Fromel kit may indeed use different value caps, which is a much more direct way towards modifying an amps sound.
Fender Blues Deluxe Reissue Modifications ? Fromel Electronics
while capacitor material changes (such as ceramic -> mica, polyester-> polypropylene) with the same values changes sound VERY subtly, if at all.

[J M Fahey]

Check this factory original Marshall schematic.

Check *all* Marshall schematics.
Then *all* Fender/Vox/Ampeg/Orange/you_name_it .
All the killer amps which define Rock Guitar sound.

All state value (capacitance) and if necessary, voltage.
NONE states ***BRAND*** or ***COLOUR***
Guess why?

Maybe it's irrelevant to sound?

[DrGonz78]

This made it far more responsive, tonally rich and tightened up the bass quite considerably.

Now I would say go back and look at that cap upgrade you did on this other amp. I would guess that it had you change the microfarad rating on some of the main filter caps on the power supply. Perhaps that tighter bass response was due to an increase of capacitance and it smoothed/tightened up the low end response of the amp.

[dai h.]

from what I (vaguely) understand, comparing things like this is tricky and not necessarily that simple to do if trying to do something scientific. It seems you need to know thing to know (if that makes sense).

So, (for example, say) did you know that the caps you swapped were close enough in value to make for a valid comparison (were they measured?). Did you know that slight volume differences can have an influence on perception? (Louder tends to sound better to the human ear.) If you changed something like an old filter cap, was the perceived improvement due to an "upgrade" (kind of loaded terminology), or was it more a matter of restoring the performance? Was there some esoteric (or -ish) thing going on, where there was a bit of C or L from cap positioning influencing the outcome and when the "upgrade cap" was introduced, this relationship changed?

If someone puts a lot of effort and time into "an upgrade" I think there is going to be a tendency to be biased about the outcome also. Not to say anyone shouldn't try to improve things, but perhaps some things to think about?

[sohosteve]

Aha!
That makes much more sense to me to me now.
I didn't realise that the Fromel kit actually corrected component values to bring out the best in the basic amp design.

The Fromel kit may indeed use different value caps, which is a much more direct way towards modifying an amps sound.
Fender Blues Deluxe Reissue Modifications ? Fromel Electronics
while capacitor material changes (such as ceramic -> mica, polyester-> polypropylene) with the same values changes sound VERY subtly, if at all.

[sohosteve]

As previously mentioned, I'm not an electronics engineer, but I've successfully performed mods on my amps (and FX pedals) in the past with very noticeable and pleasing results.
And often these mods have been more to do with upgrading to more expensive, higher quality components than changing values.

As I have understood it, this was because corner cutting was done during manufacture to save money with cheaper components.
So I assumed, evidently wrongly, that I could improve the tone and response by 'upgrading' to Orange Drop caps (as I noticed online that someone else had performed this mod).
Even though I can't read or understand a schematic, I do realise that they do not mention the brand or colour of components.
However, due to the huge amount of online discussions comparing Sozo, to Mallory to Sprague etc etc etc I was tricked into thinking that 'upgrading' quality/brand could have some kind of positive effect on the tone and response of an amplifier.
They certainly do when swapping out the tone cap in a guitar without changing the value.
Also when using a cheap pot or a more expensive one.
Consequently I thought it may follow that by changing to more expensive/higher quality capacitors in an amplifier circuit would have a similar effect.

I realise now, due to the numerous comments made here, that this is not the case...

Anyway, in my humble opinion, the Marshall DSL 40c is a great little amp with a sound much larger than it's box would suggest it is capable of and I'm quite happy with it.
I just wondered if there was a way to squeeze even more out of it with minor modification.

I've been using Marshall valve amps since 1979 and have enjoyed great tones from a variety of configurations.
More recently I have been using an 1985 JCM 800 100 Watt Combo that sounds absolutely astounding but I just can't physically cope with the weight of it any longer. Especially as I live on the fourth floor of an apartment block and have had a few serious back problems over recent years.
The DSL 40c is the closest thing I have found to a manageable replacement albeit it something of a compromise tonally.

So that sent me on something of a tone quest, in the hopes that with a little bit of tweaking, I could raise it's game as much as possible by swapping out a small amount of components without spending a fortune.

Someone has already upgraded the speaker and I performed the C19 mod yesterday which has definitely upped it's game.

If anyone has any suggestions for mods to take it further into the realms of 'tone heaven' I'll be happy to check them out.
Meanwhile I guess I'll just work with it as is.

Thanks again to everybody here for all your input.

Check this factory original Marshall schematic.

Check *all* Marshall schematics.
Then *all* Fender/Vox/Ampeg/Orange/you_name_it .
All the killer amps which define Rock Guitar sound.

All state value (capacitance) and if necessary, voltage.
NONE states ***BRAND*** or ***COLOUR***
Guess why?

Maybe it's irrelevant to sound?

[Chuck H]

JM posted that schematic because it DOESN'T specify cap brand or dielectric material. But you could certainly use it as a component value mod guide where applicable. See... Everyone raves about the crunchy el34 Marshall sound of rock! When you can actually get 90% of that sound without ever overdriving the power tubes. The PI clips very shortly after the power tubes and largely influences the actual shape of the final wave form. I don't know that amp and I couldn't find a schematic quickly. But you mentioned replacing some SS output devices so I thought I'd mention this.

[pdf64]

Check this factory original Marshall schematic.

...

Ha, you picked one of the 'duh' specials, in which the bias supply is taken after the standby switch.
I guess it helps the power tubes to warm up quickly.

[tedmich]

Humans are simply TERRIBLE at A/B testing, that's why the scientific method was invented! Expectations are almost everything to humans, if you send your amp off to Voodoo (or other modder) with a fat check you are damn well gonna think you died and went to heaven when it returns in a couple weeks...its human nature. Now if you could consistently measure something we'd be well on our way to a science, because the plural of anecdote is NOT data, sadly.

[J M Fahey]

Oh, I just picked the very first straight "image" Google offered, actually the 5th suggestion because the earlier 4 were .PDF which open in a separate window and to boot from Elektrotanya which makes you wait 1 minute, or sign in, or solve Electrical puzzles written in Hungarian
But I could have posted any of the about 200 .jpg or .gif from Dr Tube,any and all would have shown the same.