Help needed to upgrade Capacitors in a Marshall DSL 40C

[sohosteve]

This thread seems to be traveling off at some odd tangents now which I'm finding quite entertaining though somewhat confusing.

At first I thought one of the comments made by pdf64 related to the design of the amp this thread is actually about, namely the Marshall DSL 40C.
I have since realised that it related to the schematic chosen by J M Fahey, merely to illustrate that no component brands or colours were used in a circuit diagram.
It wasn't championing the design featured.
I understood that.
I also understood that it wasn't the schematic for my amp.
I like pdf64's joke about the tubes 'warming up quickly' :-)

tedmich has taken me on a totally different journey altogether!
Entertaining, though not entirely accurate.
Not that philosophy ever was...
Though I am not an electronic engineer, I have been playing electric guitar for over forty years (thirty professionally) and despite the dangers, do still have ears that work, albeit within a slightly limited frequency range.

The Fromel mod that I performed on my Fender Blues Deluxe almost transformed it into a different beast altogether.
It sounded and responded totally differently to how it did pre-mod. Tones that I had struggled to find it in before became easy to dial in, or change to something different but equally pleasing. It also felt like a small time delay had been removed from the signal chain (guitar straight into amp).
Difficult to explain but everything seemed to respond much faster making everything sound and feel more immediate. Notes seemed to fly off my pick and chords became much more glorious and expansive.
This was not something that my (failing - lol!) mind conjured up because I wanted it to happen out of 'expectation'.

I'm sure that some mods are a load of old cobblers, but others do actually bring positive results.
I know because I've also seen/heard both sides of the coin.

I tried an A/B test by recording a Tube Screamer pedal with different JRC4558 chips in, comparing Burr Brown, new 4558s and a 4558 I'd pulled from an early 80s Ibanez multi-effect - the one that people seem prepared to kill each other to obtain due to how the incredible 'mojo' of this little IC will bring you so much closer to SRV.
I recorded the same guitar part, with the same settings with only the chips swapped, on different tracks (straight through a Benchmark ADC to DAC converters in 24 Bit) and switched directly between them and I could not hear ANY difference between them whatsoever.
In fact it didn't even sound like I was switching between solo'd guitar parts at all. They were that close.

I concluded that the only way the vintage 4558 will bring you closer to SRV is if you hold onto one while peeing into 100 Watt Marshall head running at full power...

Meanwhile...

If anyone does have any real world suggestions for upping the DSL 40Cs game I'd be interested to hear them...

Cheers!

[g1]

Sorry to go off topic again, but it may be insightful to further look at the mods you did to the Fender Blues Deluxe as they created such a noticeable difference.
Was this a basic Fromel kit? Was the speaker changed and if so was it at a different time than the mods or all together?
You mentioned "power transistors", I think this is a typo. Power transformer or something else?

P.S. thanks for the new sig, classic!

[Enzo]

If you didn't already think of it, record your guitar directly, then play THAt back through the screamer or whatever else you might be comparing. That way the input will be identical. No matter how hard you try to play the same thing repeatedly, it will always differ. Then the multiple output recordings will be truer comparisons.

[tedmich]

Good call Enzo, such "reamping" is a much better test ! Eminence did this with their guitar speakers at one point and its was such a better way to pick the sound you preferred.

[The Dude]

Agreed. Whether you do it knowingly or not, you tend to "play for the amp". There's a natural tendency to play differently with different guitars and/or amps to achieve the best sound.

[Tom Phillips]

A good guitar looper pedal is very useful for this kind of testing since it allows you to make a test "recording" without the need to mic an amp.

[The Dude]

I have prerecorded clips that I sometimes use- some DI'd right off the guitar. It's useful when doing repairs or testing. I don't have enough hands to play guitar and run a DVM at the same time.

[sohosteve]

Yeah, I get that.
However these were very basic parts I put down and I've been gigging for forty years and playing sessions long enough to play a riff, strum some chords or play a lead lick EXACTLY the same way twenty seven times without even listening to what I'm playing.
I deliberately didn't 'work off' the sound because I wanted a 'flat' performance.
That said, I understand what you're saying.
I don't own a looper, but I've got enough kit here to record dry and re-amp if I really want to go that anal on it next time.
But I appreciate your suggestion.

If you didn't already think of it, record your guitar directly, then play THAt back through the screamer or whatever else you might be comparing. That way the input will be identical. No matter how hard you try to play the same thing repeatedly, it will always differ. Then the multiple output recordings will be truer comparisons.

[J M Fahey]

I have prerecorded clips that I sometimes use- some DI'd right off the guitar. It's useful when doing repairs or testing. I don't have enough hands to play guitar and run a DVM at the same time.

Do you have a link to some site holding such DI MP3s?
Most I find are demoing a pedal or something and are not raw or generic enough.
Thanks.

[The Dude]

I don't, Juan. I couldn't find any either, so I just made some myself. I plugged a guitar into my soundcard (through a mic preamp to get a decent level), hit record, and started bangin' away. I use the volume control on my PC to dial it down to a reasonable level for guitar amp(s).

[Justin Thomas]

I find almost any Boss DD-_ to do a perfectly suitable job for this simple task - main difference being loop times available. And I thought EVERYONE had one of those, except me (I sold mine years ago). Clean, clinical, perfectly cloned, sterile, did I say clinical, reproduction, every time! Wouldn't work so great with the Echoplex...

Justin

[Chuck H]

This thread seems to be traveling off at some odd tangents now which I'm finding quite entertaining though somewhat confusing.

Maybe a little. But for the most part I think it's been intermingling discussions about capacitor brand vs. value because you said:

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.

And there wasn't any mention of cap value changes. The inference being that a cap of different construction could make a mediocre amp into a good or great amp. To put it into a nutshell then, even though I get that you've got it already, Cap type won't change much, cap value can. So, to keep this on track with what I figure to be your original goal... You want mods or cap value changes that may get this amp closer to what you want. You can ignore the Sprague 715P as a necessity. Though there's certainly nothing wrong with those caps if you'd like to use them. Well, nothing wrong with them other than the price. I used them happily until they started to get stupid expensive.

[Mick Bailey]

The easiest components to change to improve tone are speakers and tubes. You've already got an upgraded speaker, but don't mention what tubes are fitted and how old they are.

[tedmich]

So you've heard this guy right?

If it sounds great to you by all means swap in the 715P caps. Be carefeul to not overheat the PCB traces, a low wattage adjustable iron is needed, and a solder sucker works quite well. Good luck!

PS people like the C19 lift mod too.

[Enzo]

Just always keep in mind that just because a cap says 0.02 on the side, doesn't mean the actual value of the cap is 0.02. So when we think we are not changing the value by replacing some wrong color 0.02 with an orange color 0.02, we may still be. The old one might measure as 0.016, and the new might measure out as 0.024.