Anyone want to talk about DSL's?

[TheGreatGreen]

Well, we don't need to go into the rabbit hole on this. Fundamentally you are right, they are not identical as the TSL is a 3-channel preamp so the schematics is a bit different. Admittedly, not by much and only for the 3rd channel preamp part. The rest of the amps, and the power amp section is identical on these amps.

The reason you heard the TSL being leaner is most likely attributed to either trying an early revision (where Marshall ###ed up the PCB components, and people like me needed to replace the main PCB board when the fix became available), or just the normal component value drift/variation which can range in 10 to 50% or even more in many cases. All amps sound different from each other, one DSL can be as much different from another DSL as TSL vs DSL or TSL vs another TSL. That's why we all try different amps and grab the one that speaks to you.

For all seriousness, being leaner or fuller does not change the substance of the sound of an amp, and can easily be corrected by either the on-board EQ or an external EQ.

All I can say, neither my ears nor a lab spectrum analyzer could not tell a difference between my JCM800 and the TSL in the 800 model. Less so with the DSL vs TSL in the same room through the same speaker cab at the same time.

I don't think it was component drift as I A/B'd them in the store when they were brand new. And it wasn't just me. Two guys who were working there said the same thing as I was playing them. We all heard it. Each was wired into its own full stack, two 1960 A and B cabs, and they were sitting next to each other in a large room. The guys had the amps turned to so you had to yell over them to be heard, so the low frequency content of both amps was on full display. Come to think of it, while I've A/B'd tons of amps, I don't think I've ever A/B'd two full stacks against each other like that besides those JCM 2000's. I suppose that's why I remember it as well as I do even though it was so long ago. Back then I barely had any experience with pro level tube gear at all so I was kind of on cloud 9 at that music store that day.

If there was a unique situation where a bunch of TSL's were messed up from the factory, that could have been what I heard. However, nothing sounded "wrong" with it. It sounded pretty much the same as the DSL except that it had much less low frequency content post gain, like a poweramp depth control was turned way down (even though that amp doesn't have one of those), where it sounded more balanced with the DSL.

Again, I'm not stating a preference for one or the other by saying this, I'm just telling you what we heard when we had the amps right next to each other.

 

[Epiplatys]

The “messed up” TSLs sounded OK (you could not tell if anything was wrong with it just by listening), but what happened Marshall put wrong resistor values and in some places a wrong resistor types. The amps kept blowing fuses and overcooking the tubes with the runaway bias current overtime. In my case what was noticeable is the shorter tube life, and I could see that some days the amp ran hotter than others. There was no easy fix, aside from replacing the entire main PCB loaded with the proper components in the right places.
And as it goes, wrong resistor values in EQ filter circuits result in the amp sounding different EQ-wise.
A good TSL sounds just as good as a good DSL. Both amps are great. And either amp can be had for next to nothing these days.

 

[TheGreatGreen]

The “messed up” TSLs sounded OK (you could not tell if anything was wrong with it just by listening), but what happened Marshall put wrong resistor values and in some places a wrong resistor types. The amps kept blowing fuses and overcooking the tubes with the runaway bias current overtime. In my case what was noticeable is the shorter tube life, and I could see that some days the amp ran hotter than others. There was no easy fix, aside from replacing the entire main PCB loaded with the proper components in the right places.
And as it goes, wrong resistor values in EQ filter circuits result in the amp sounding different EQ-wise.
A good TSL sounds just as good as a good DSL. Both amps are great. And either amp can be had for next to nothing these days.

Oh yeah the runaway bias problem happened with the DSL's too. Word is Marshall resolved the issue in 2005 and all the ones before it are susceptible.