Amp in good working order,=, Has been fully checked over prior to sale. Tuves were measured with bias setup.Visual condition is pretty good with some marks of usage as shown in the photos. Amp was manufactured in Unnited Kingdom in 2003.Specification:All-tube guitar amp.Channels: 2 Classic Gain oraz Ultra Gain.Switches: Clean/Crunch on clean channel and Lead1/Lead2 on overdrive.Independent Gain and Volume controls for each channel.Controls: Bass, Middle, Treble, Presence.Tone Shif read more.
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TL:DR - Fixed a Marshall JCM2000 DSL401 from completely dead to 100% working better than factory. The long version: I'm not an amp tech by any stretch. However, more than 10 years ago I was involved in a pretty catastrophic vehicle accident that left me unable to walk for two years.
I posted this over on the Amp Garage forum but have received no responses, so I'm re-posting this here for some added help.I came across a great deal on an older Marshall JCM 2000 DSL 50 head and am trying to make the best of it. It's yet to display the runaway bias drift issue, and other than having a noisy reverb circuit it sounds pretty good, especially with NOS Mullard, Telefunken, and RCA preamp tubes.I removed the reverb and that took care of that issue.amp is quiet and feels pretty good. However, I'd like to make this amp the best it can be within reason, and have used Sozo caps in past builds with great success, observing they provide a very clear, clean, 'right' sound.So, I'm looking for help in choosing which coupling caps in the JCM 2000 DSL 50 I should replace for most bang-for-the-buck improvement in tone and feel.
The.022uf caps in the tone stack seem like obvious ones, as well as the.022uf coupling caps in between preamp stages as well as after the phase inverter. Maybe a cathode cap or two as well? I'm not too up on the gainier side of that circuit and have not used Sozo's in high-gain circuits, so I'm open to suggestions/input.Would one of you be willing to take a look at the JCM 2000 DSL 50 schematics out there and let me know what caps you'd suggest swapping with Sozos? It'd be much appreciated.Schematics:Thanks in advance,David. Was having a harder time picking the specific caps on this schematic.I'm not used to working with PCB amps. PTP/Turret Strip/Eyelet Board stuff, sure, but not so much PCB.Was hoping someone else may have done this before me and have the specific caps itemized.
If not, I'll have to dig through the other schematics and compile a list of caps.Good info on leaving the cathode caps. I was thinking tone stack and coupling as well, just not clear which 'numbers' they are in the schematic.
Well heck, it fired up and worked without incident!!!!When does that ever happen (to me)???Love it.Interesting difference, though.with the 'stock' setup, the amp was more modern sounding, versatile, even-keeled. After installing a 3hy choke (Classic Tone) and replacing the major coupling caps with Sozo NextGen caps, the amp went way toward the vintage realm. Very interesting.I'm not yet sold on the Green Channel after the swap, but oddly enough, the Red Channel has been improved.
Odd, as I preferred the Green Channel by far before the mods.To sum up the Green Channel tone change post-choke-and-Sozos, it's like the amp went from Green Day to 'It's a Long Way to the Top if (You Wanna Rock and Roll)', as the Green Channel seems to magically want to sit, tonally, in that mid-'70s, scooped, (JMP?) tone range. Not sure JMP is the best way to describe it, but I'm tired and that's the first thing that comes to my gut instinct.Anyway, I'll give it a go and let the caps break in some more before giving a final judgement.
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One thing is for sure, there is LESS hum now, clearer bass, and more articulate top end present than before. It's not necessarily, qualitatively 'better' to my ears at this point, but it sure isn't worse. Very interesting. Thanks for the information, I have always wondered if it was really useful to replace caps in modern high gain Marshalls. In my limited experience with new Marshalls, I'm convinced that Marshall at times spends a lot of ear time tuning their amps to sound 'Marshally' with the caps they choose to use in production. The stock Vintage Modern I own sounds exactly like I would want it to even if the caps would be replaced, so I see no reason to mod it. It sounded so good I wouldn't even pull the chassis out of the wood for over a year as I didn't want to change anything.IMHO much of the tone of older Marshalls is in the mustard caps; they tend to have a near low pass effect in that they generally let the brightness through while taming the sizzle, kind of like a well broken in Greenback or G12-65.
And I installed Sozos in an amp I built years ago after fighting its tone for a long time; the Sozos were the missing ingredient to give it the Marshall mids/treble harmonic contour. I'm a big believer in Sozos in the right application.The problem with many amp/guitar mods is that the person doing the mods may not have a clear idea of what they hope to achieve. That approach can get frustrating and expensive at times. But information such as is in this thread is helpful in one's decision on whether to do cap mods or not, you know what the results are with a particular amp. These Sozos have already started to break in after a couple of hours.or, my ears are adjusting to them. IIRC there is an 20 hr break in period for these. I've had them in the past, and always appreciate their airy, balanced tonality.Odd thing.I find that I DO NOT need to use the Deep switch any longer on the Green Channel, whereas before the choke/cap swap I found I needed the Deep switch engaged on the JCM800 settings (not so much on the Plexi settings).
As well, I actually PREFER the high gain, Red Channel with the Sozos.they seemed to smooth that channel out, especially in the low end.There is still some hash/grainy-ness in the OD with the MV turned up on the Green Channel, but, the clean tones are much better already.Once finances allow I'll install a Classic Tone OT as well.done the Heyboer/Mercury Magnetics/etc.etc.highendtransformer thing in the past, and am curious what a 'budget' upgraded OT will do to the sound. These Sozos have already started to break in after a couple of hours.or, my ears are adjusting to them. IIRC there is an 20 hr break in period for these. I've had them in the past, and always appreciate their airy, balanced tonality.Odd thing.I find that I DO NOT need to use the Deep switch any longer on the Green Channel, whereas before the choke/cap swap I found I needed the Deep switch engaged on the JCM800 settings (not so much on the Plexi settings). As well, I actually PREFER the high gain, Red Channel with the Sozos.they seemed to smooth that channel out, especially in the low end.There is still some hash/grainy-ness in the OD with the MV turned up on the Green Channel, but, the clean tones are much better already.Once finances allow I'll install a Classic Tone OT as well.done the Heyboer/Mercury Magnetics/etc.etc.highendtransformer thing in the past, and am curious what a 'budget' upgraded OT will do to the sound.
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