NAD: 2002 DSL50

[Gunner64]

Stock transformers and other parts in that amp?

Heyboer transformers, that's what came with that kit. A lot like the classictones, which are alot like the old drakes. Other than a few minor changes mostly parts mojo sent. I have a thread here on the build as I was doing it, you can look at it in the building the classics section of the forum here.

 

[nortiks]

Congrats!

I have a 2001 JCM2000 DSL50 and the bias is rock steady. No bias issues at all.

Maybe Marshall had a similar problem to what Firestone had back in the 1970's...Some, but not all of a particular model of tire would fail spectacularly while the rest were perfectly good. Turns out some dude was peeing in the rubber while it was liquid causing the bad ones. True story, lol.

 

[dslman]

Wish I never sold my DSL50, it was quiet out of the box compared to the many 100 WATT DSL heads I owned over the years. (transformer hum) I added a choke, OT, MOD tank, and did the speaker jack fix. The amp became a bit faster after the choke,OT, and slightly quieter at idle. . I'd probably leave it stock if I had it to do over, but I'd do the speaker jack fix if you ever use the 8 OHM output jack. I'm sure you know all about that. These amps are awesome for running stereo via the FX-Loop and any stereo, delay pedal, what a huge sound. Happy for you on acquiring a great amp!!

 

[Adrian R]

Wish I never sold my DSL50, it was quiet out of the box compared to the many 100 WATT DSL heads I owned over the years. (transformer hum) I added a choke, OT, MOD tank, and did the speaker jack fix. The amp became a bit faster after the choke,OT, and slightly quieter at idle. . I'd probably leave it stock if I had it to do over, but I'd do the speaker jack fix if you ever use the 8 OHM output jack. I'm sure you know all about that. These amps are awesome for running stereo via the FX-Loop and any stereo, delay pedal, what a huge sound. Happy for you on acquiring a great amp!!

Hey Dude, like I have had 3 DSL100s modded them with trannys and a choke, and two DSL50s...one I sold off because I put to hot of a PT in it. The other one I sold off in 2010 because of a 1989 2204 I had, This current DSL50, man it sounds KICK ASS...totally stock. Really ballsy, tons of gain in the red OD1 channel...Keep the preamp at about 11 am and it has plenty of gain, but it sounds like a 2204 with an OD pedal. Real fat and warm, super crunchy with good fidelity, and when you turn the guitar down, it chimes like an 800. It's early yet, you know honeymoon and all, but I am beginning to like it more than the 100watters...with the mods! It destroys all of the 900s I have/had...in fact the DR50 I did all this work to...choke and OT EL-34s new caps, proper bias network, sounds good, this DSL kills it. Way more organic, and cutting, more dynamic...sounds like a proper 800 but with more gain...

So just like the 800 scenario, they're all good, but some are special. This may be the case with this DSL50. I have a 3H 250mA choke in the wings...was gonna put it in, but I don't know, it sounds so good now...Perplexed.

BTW..The orignal Sylvanta tubes are staying in. I tried four different pairs...of other basically new matched duets... These Sylvantas outperform all of them.

 

[What?]

Yea, ~50 watts is a good power level for an amp. More than enough power for a bar band, not heavy in weight, less expensive to retube. My main amps are all in that range (45-50 watts). And I haven't heard any reason to upgrade the transformers in my DSL 50. It seems fine as is. If you ever crank the green channel with the crunch button disengaged and push it with an eq as a boost for some more dirt and shaping, it sounds fat and huge for a low'ish to mid gain sound. That tells me that if you want the red channel to sound bigger, it's not the transformers, it's some channges in the preamp that you're looking for. More recently than when I first got the DSL 50 I have come to terms with the red channel with the gain set low, and I really enjoy playing it on the red channel. I currently have a pair of JJ KT77's in it, and I like them just fine, more than the winged C's that were in there previously and the JJ E34L's. The KT77's sound less compressed and less strident in the upper mids.

 

[dslman]

Ri

Hey Dude, like I have had 3 DSL100s modded them with trannys and a choke, and two DSL50s...one I sold off because I put to hot of a PT in it. The other one I sold off in 2010 because of a 1989 2204 I had, This current DSL50, man it sounds KICK ASS...totally stock. Really ballsy, tons of gain in the red OD1 channel...Keep the preamp at about 11 am and it has plenty of gain, but it sounds like a 2204 with an OD pedal. Real fat and warm, super crunchy with good fidelity, and when you turn the guitar down, it chimes like an 800. It's early yet, you know honeymoon and all, but I am beginning to like it more than the 100watters...with the mods! It destroys all of the 900s I have/had...in fact the DR50 I did all this work to...choke and OT EL-34s new caps, proper bias network, sounds good, this DSL kills it. Way more organic, and cutting, more dynamic...sounds like a proper 800 but with more gain...

So just like the 800 scenario, they're all good, but some are special. This may be the case with this DSL50. I have a 3H 250mA choke in the wings...was gonna put it in, but I don't know, it sounds so good now...Perplexed.

BTW..The orignal Sylvanta tubes are staying in. I tried four different pairs...of other basically new matched duets... These Sylvantas outperform all of them.

Right on! I remember not enjoying having to solder that choke to those fragile traces, and hoping I chose the right spot to mount it, but by chance, or fortune it all worked great. Also those spade connections on the OT were so tight, I just knew I was gonna break the board, or something…lol

I wish I knew how to add a resonance knob to the amp instead of the tone switch button, but it could be opening a can of trouble to try .
I can’t remember what I did to get the lead channels to match the clean channel in fullness, seems like a capacitor somewhere, but it definitely helped, in my amp.
Sounds like you don’t need to worry about it with yours, so that’s a big plus.
I love my DSL100H , but the JCM2000 DSL heads sure have a rich, organic tone that’s very appealing, and 800esque.
I’ve been looking for another one just for that reason alone, and to run in stereo with the 100H.
A stock DSL50 is a fantastic amp.
Hope she serves you well for many years.

 

[Marshall Stack]

Yea, ~50 watts is a good power level for an amp. More than enough power for a bar band, not heavy in weight, less expensive to retube. My main amps are all in that range (45-50 watts). And I haven't heard any reason to upgrade the transformers in my DSL 50. It seems fine as is. If you ever crank the green channel with the crunch button disengaged and push it with an eq as a boost for some more dirt and shaping, it sounds fat and huge for a low'ish to mid gain sound. That tells me that if you want the red channel to sound bigger, it's not the transformers, it's some channges in the preamp that you're looking for. More recently than when I first got the DSL 50 I have come to terms with the red channel with the gain set low, and I really enjoy playing it on the red channel. I currently have a pair of JJ KT77's in it, and I like them just fine, more than the winged C's that were in there previously and the JJ E34L's. The KT77's sound less compressed and less strident in the upper mids.

I have found that a Boss GE-7 in the loop works great. I have tried various overdrives into the amp but I think it sounds better without one.

 

[dslman]

https://www.marshallforum.com/media/20160816_183954_1475578275233.8529/full?d=1475578414

 

[PelliX]

Maybe Marshall had a similar problem to what Firestone had back in the 1970's...Some, but not all of a particular model of tire would fail spectacularly while the rest were perfectly good. Turns out some dude was peeing in the rubber while it was liquid causing the bad ones. True story, lol.

LOL! No, actually it was a lot simpler. The actual root cause of the issue was the boards being stocked with the wrong parts. They were using negative temperature coefficient resistors. That in turn meant that things would warm up (as they should normally) but spiral out of control. This obviously had or has the potential to cause cascading failures like heating the board beyond reasonable levels and causing the valves to redplate, etc. I *believe* the JCM2000 50 watters had the issue too (at least, some of the early ones), but if one prevents the problem by replacing those resistors, one has actually tackled the source. In addition there were a couple of other components that were a little underrated, but these - to the best of my knowledge - never really caused any problems on their own.

 

[What?]

LOL! No, actually it was a lot simpler. The actual root cause of the issue was the boards being stocked with the wrong parts. They were using negative temperature coefficient resistors. That in turn meant that things would warm up (as they should normally) but spiral out of control. This obviously had or has the potential to cause cascading failures like heating the board beyond reasonable levels and causing the valves to redplate, etc. I *believe* the JCM2000 50 watters had the issue too (at least, some of the early ones), but if one prevents the problem by replacing those resistors, one has actually tackled the source. In addition there were a couple of other components that were a little underrated, but these - to the best of my knowledge - never really caused any problems on their own.

I never heard this about the negative temp coefficient resistors. Do you remember were you saw that from? I do remember seeing something about some wrong resistors values and an underrated cap.

 

[What?]

I have found that a Boss GE-7 in the loop works great. I have tried various overdrives into the amp but I think it sounds better without one.

I'm generally not a fan of overdrive pedals. Most of them have fixed roll-offs in the lows and highs, which I prefer to have control over.

 

[PelliX]

I never heard this about the negative temp coefficient resistors. Do you remember were you saw that from?

Various places, though I'd be hard pressed to recall where I came across it first. Here's what appears to be a first hand pretty detailed description, though I can't vouch for that particular case:

JC Maillet Marshall TSL 122 Article

Eurotubes Marshall Tech Article

www.eurotubes.com

I do remember seeing something about some wrong resistors values and an underrated cap.

Yup, sounds about right.

 

[nortiks]

I never heard this about the negative temp coefficient resistors. Do you remember were you saw that from? I do remember seeing something about some wrong resistors values and an underrated cap.

I read that somewhere as well, can't recall where I saw it since I read so many different places. It may contribute to the drift, but its primarily the epoxy in the boards. But since I replaced those resistors when I did the air gapping job, I can't say just how much they contribute. But I can say the board is definitely conductive since I also had a severe hum in the green channel due exclusively to the board and had to air gap V2 grids to fix it.

And I did read somewhere that Marshall fessed up to the epoxy problem at some point, but you know how it is on the internet, no way to know if its rumor or real. The "wrong" resistors are the 220K grid blockers on the output tubes of the earlier models. Hard to call it wrong since that value is what shows on the schematics for those models. But regardless, the "conventional" value used in prior and subsequent models with EL34 in them is 5.6K and to my ears it sounds a lot better with the "conventional" value. As for underrated caps, those are the power tube HF damper caps, and its more like "marginally rated" than underrated.

As to why the DSL100 is more well known for the bias drift problem than the DSL50, I theorize its because it has twice as many EL34 cooking the board, and the problem happens over time as the board experiences heat. None of them had the bias drift problem when they went home with the original buyer (presumably), it developed over time as the board got cooked by the EL34s. And unfortunately, since the problem causes the tubes to drift hotter, once the problem begins, its a dog chasing its tail. The more the bias drift happens the hotter the tubes get and the more the board gets cooked, causing it to drift even more. So yeah, the DSL100 is going to do this moreso than a DSL50 will. But judging from mine, a 50 can get cooked and its just as much of a problem as the 100.

 

[dslman]

I read that somewhere as well, can't recall where I saw it since I read so many different places. It may contribute to the drift, but its primarily the epoxy in the boards. But since I replaced those resistors when I did the air gapping job, I can't say just how much they contribute. But I can say the board is definitely conductive since I also had a severe hum in the green channel due exclusively to the board and had to air gap V2 grids to fix it.

And I did read somewhere that Marshall fessed up to the epoxy problem at some point, but you know how it is on the internet, no way to know if its rumor or real. The "wrong" resistors are the 220K grid blockers on the output tubes of the earlier models. Hard to call it wrong since that value is what shows on the schematics for those models. But regardless, the "conventional" value used in prior and subsequent models with EL34 in them is 5.6K and to my ears it sounds a lot better with the "conventional" value. As for underrated caps, those are the power tube HF damper caps, and its more like "marginally rated" than underrated.

As to why the DSL100 is more well known for the bias drift problem than the DSL50, I theorize its because it has twice as many EL34 cooking the board, and the problem happens over time as the board experiences heat. None of them had the bias drift problem when they went home with the original buyer, it developed over time as the board got cooked by the EL34s. And unfortunately, since the problem causes the tubes to drift hotter, once the problem begins, its a dog chasing its tail. The more the bias drift happens the hotter the tubes get and the more the board gets cooked, causing it to drift even more. So yeah, the DSL100 is going to do this moreso than a DSL50 will. But judging from mine, a 50 can get cooked and its just as much of a problem as the 100.

I sent you a question about C19, and C20, on the front control board.Do you think these silver mica caps are the cause of popping issues when changing channels on these JCM2000 heads?
Many complaints about this issue.
Thanks.

 

[What?]

I read that somewhere as well, can't recall where I saw it since I read so many different places. It may contribute to the drift, but its primarily the epoxy in the boards. But since I replaced those resistors when I did the air gapping job, I can't say just how much they contribute. But I can say the board is definitely conductive since I also had a severe hum in the green channel due exclusively to the board and had to air gap V2 grids to fix it.

And I did read somewhere that Marshall fessed up to the epoxy problem at some point, but you know how it is on the internet, no way to know if its rumor or real. The "wrong" resistors are the 220K grid blockers on the output tubes of the earlier models. Hard to call it wrong since that value is what shows on the schematics for those models. But regardless, the "conventional" value used in prior and subsequent models with EL34 in them is 5.6K and to my ears it sounds a lot better with the "conventional" value. As for underrated caps, those are the power tube HF damper caps, and its more like "marginally rated" than underrated.

As to why the DSL100 is more well known for the bias drift problem than the DSL50, I theorize its because it has twice as many EL34 cooking the board, and the problem happens over time as the board experiences heat. None of them had the bias drift problem when they went home with the original buyer, it developed over time as the board got cooked by the EL34s. And unfortunately, since the problem causes the tubes to drift hotter, once the problem begins, its a dog chasing its tail. The more the bias drift happens the hotter the tubes get and the more the board gets cooked, causing it to drift even more. So yeah, the DSL100 is going to do this moreso than a DSL50 will. But judging from mine, a 50 can get cooked and its just as much of a problem as the 100.

I appreciate the info. I check my DSL 50 once in a while for any signs of bias drift. Knock on wood, I haven't seen any yet, including the amp having been played daily for hours on end in a very small building during hot spring and summer a couple of years back. It was hot enough in there to sweat so bad that it dripped heavily on some pedals and killed one. I have no idea what the difference might be between the amps that end up drifting and those that don't. I also figured that the DSL100's were prone to drifting due to more heat from 4 power tubes. vs. 2. I have considered being proactive about possible drift, but I would hate to go hacking on the pcb until I see some sign on it. It has been a very reliable amp as is.

 

[nortiks]

I have considered being proactive about possible drift, but I would hate to go hacking on the pcb until I see some sign on it. It has been a very reliable amp as is.

I'd think that anyone who has one from the "drift years" that has had a lot of use and isn't drifting by this point is probably fine. (just remember that to see it, check bias cold then again after 30-45 minutes of playing at volume or on a bench with signal and load)

But the best proactive thing to do for heat build up is probably a computer fan to cool the EL34s. I read in an old tube book by a guy that was a tube guru in the 1950's that extra cooling could increase useful lifespan by double. Heck that alone makes it worth fitting a fan in and its no problem to do it in a 100 reversable way as much room as there is to work with. A lot of the newer computer case fans are super quiet (as if noise is an issue with a 50-100 watt head, lol).

 

[Mitchell Pearrow]

Congratulations
HNAD

 

[rolijen]

Great amp! Probably my favorite all-arounder. Rock on!