DSL100 head issue

[GibsonMarshallGuy47]

I've had my DSL100 head for about 8 years now... 90% of the time it works great. I've had occasional had issues where it would suddenly cut out or have a sudden volume drop, but that usually clears up within a matter of seconds, and those incidents thankfully have been extremely rare.

last night I went to band practice... we took a break from playing for about two months, so this was our first jam session after the break. my amp generally sits in our singer's basement most of the time, which is where our jam room is. while its there, it doesn't get touched at all, ever. at last night's band practice, after letting it sit on (on standby) for a few minutes, I turned my amp on, and immediately got a very unusual static-y humming noise. it clearly sounded like something was wrong. I turned it up to normal volume and played, but almost nothing was coming out. only about 5% of how loud it should be. then the power suddenly died. it just turned itself off. I opened the fuse compartment and replaced the fuse that was in there with the spare. even though visually, the fuse did not look burned out at all. I turned the amp back on and kept it on standby for a few minutes. I flipped the standby switch and heard the same troublesome static-y loud humming (this is on the green channel with the gain on 2 and the pre-amp on 2 as well). barely any audio coming out of the amp at all. I flipped the standby back on. I looked at all the tubes. they seemed to be all glowing normally. I then decided to flip the pentatode switch from 100 to 50 watts... it then emitted a loud whiney squealing noise (sounded like a theramin), so I put it back on standby and flipped it back to 100 watt mode. I let it sit for a few more minutes, and got the same results... I then turned it off for 15 minutes, turned it back on, and still no difference. I messaged a friend of mine who is a very experienced music engineer, and guitarist, and knows a lot about guitar gear and amps, explained the situation to him, and he thought that it almost certainly is an issue with the power tubes, with about 90% certainty. I've never re-tubed an amp before. all I know is that I very well may need a brand new, matched 4-set of EL34 power tubes. I plan on bringing it to an amp tech nearby sometime soon to have it checked. I've estimated that I'm probably going to be out roughly 300 bucks, approximately (considering the cost of the tubes and the work).

that being said, does anyone else here have any input about this? anyone else had this same problem? does it seem like the tubes or possibly something else? I was thinking about spraying all the jacks with some DeOxit to see if that helps at all. I've had a similar issue happen before with another amp, and DeOxit cleared it right up.

 

[Adrian R]

90% of the problems with *tube* amps is *tubes*. I suggest buying a new quad and install them yourself. Biasing a DSL is easy. Get a multimeter, set for mV DC (200 range)..shoot for about 70-72 mV per two tubes. Before doing that though, clean all your tube sockets and jacks. Shuguang makes reliable tubes. They're sold under a few different names. TAD, Ruby, GT, Sino....You want their EL-34B. Another great sounding, reliable tube is the Electro Harmonix EL-34.

 

[Adrian R]

I've had my DSL100 head for about 8 years now... 90% of the time it works great. I've had occasional had issues where it would suddenly cut out or have a sudden volume drop, but that usually clears up within a matter of seconds, and those incidents thankfully have been extremely rare.

last night I went to band practice... we took a break from playing for about two months, so this was our first jam session after the break. my amp generally sits in our singer's basement most of the time, which is where our jam room is. while its there, it doesn't get touched at all, ever. at last night's band practice, after letting it sit on (on standby) for a few minutes, I turned my amp on, and immediately got a very unusual static-y humming noise. it clearly sounded like something was wrong. I turned it up to normal volume and played, but almost nothing was coming out. only about 5% of how loud it should be. then the power suddenly died. it just turned itself off. I opened the fuse compartment and replaced the fuse that was in there with the spare. even though visually, the fuse did not look burned out at all. I turned the amp back on and kept it on standby for a few minutes. I flipped the standby switch and heard the same troublesome static-y loud humming (this is on the green channel with the gain on 2 and the pre-amp on 2 as well). barely any audio coming out of the amp at all. I flipped the standby back on. I looked at all the tubes. they seemed to be all glowing normally. I then decided to flip the pentatode switch from 100 to 50 watts... it then emitted a loud whiney squealing noise (sounded like a theramin), so I put it back on standby and flipped it back to 100 watt mode. I let it sit for a few more minutes, and got the same results... I then turned it off for 15 minutes, turned it back on, and still no difference. I messaged a friend of mine who is a very experienced music engineer, and guitarist, and knows a lot about guitar gear and amps, explained the situation to him, and he thought that it almost certainly is an issue with the power tubes, with about 90% certainty. I've never re-tubed an amp before. all I know is that I very well may need a brand new, matched 4-set of EL34 power tubes. I plan on bringing it to an amp tech nearby sometime soon to have it checked. I've estimated that I'm probably going to be out roughly 300 bucks, approximately (considering the cost of the tubes and the work).

that being said, does anyone else here have any input about this? anyone else had this same problem? does it seem like the tubes or possibly something else? I was thinking about spraying all the jacks with some DeOxit to see if that helps at all. I've had a similar issue happen before with another amp, and DeOxit cleared it right up.

If it's a JCM 2000 model it could be a speaker ground issue as well.

 

[GibsonMarshallGuy47]

well, I brought my DSL100 head home with me from our jam spot, so after work I'm gonna hook it up to my 2x12 cab that I have there and see what's going on... but first, I'm gonna De-Oxit all the jacks and see if that does anything... I've had that stuff magically resolve similar issues more than once before. its worth a shot, although I am not hopeful at all.

 

[PelliX]

Shuguang makes reliable tubes.

Actually, they haven't for a few years now, the factory/plant shut down. Also, while I do like Shuguang valves, their EL34's were somewhat plagued by quality issues.

Another great sounding, reliable tube is the Electro Harmonix EL-34.

Those are made in the New Sensor plant. Today you effectively only have New Sensor and JJ. As you pointed out, these two manufacturers are relabeled and rebranded under all sorts of names, but that's all there is out there, really.

If it's a JCM 2000 model it could be a speaker ground issue as well.

Good point, though that wouldn't usually explain the squeal OP mentioned. Certainly worth having checked while the amp is a the tech, though!

90% of the problems with *tube* amps is *tubes*. I suggest buying a new quad and install them yourself. Biasing a DSL is easy. Get a multimeter, set for mV DC (200 range)..shoot for about 70-72 mV per two tubes. Before doing that though, clean all your tube sockets and jacks.

^ This, very much. If you get stuck or decide to take it in anyway, you're going to pay for new valves, so you might as well score a good deal yourself and hand them to the tech if it comes to that.

 

[Adrian R]

Actually, they haven't for a few years now, the factory/plant shut down. Also, while I do like Shuguang valves, their EL34's were somewhat plagued by quality issues.



Those are made in the New Sensor plant. Today you effectively only have New Sensor and JJ. As you pointed out, these two manufacturers are relabeled and rebranded under all sorts of names, but that's all there is out there, really.



Good point, though that wouldn't usually explain the squeal OP mentioned. Certainly worth having checked while the amp is a the tech, though!



^ This, very much. If you get stuck or decide to take it in anyway, you're going to pay for new valves, so you might as well score a good deal yourself and hand them to the tech if it comes to that.

Most techs are going to way under bias the DSL...as Marshall themselves recommend a range that was far too hot. I do all my own service....and have been using DSLs for over a decade. The speaker ground is well known within the 2000 series.

 

[jgcable]

Try tubes first. Swap them out one at a time. Do the pencil test first. Tap each tube with a pencil and see if it makes noise. Be careful. High voltages are everywhere. If its not tubes try cleaning out your send and return jacks. Try plugging your guitar into the effects return to see if you get a clean guitar signal. If you do.. the problem is in the preamp section. Most likely a tube.
If none of that works it could be bias drift. DSL100's especially the old ones are prone eventually to bias drift. Amp techs repair them all the time. Very common.

 

[PelliX]

Most techs are going to way under bias the DSL...as Marshall themselves recommend a range that was far too hot. I do all my own service....and have been using DSLs for over a decade. The speaker ground is well known within the 2000 series. The H m

Is that a thing, yeah? I do my own service, too, so I don't have much experience with techs, but I would assume that biasing a couple of pairs of EL34's isn't rocket science to most.

Agree on the speaker ground issue, though!

 

[GibsonMarshallGuy47]

I watched a video tutorial about how to replace & bias power tubes on a Marshall DSL100 head. it looks like the testing pins for the tubes are way inside, on the circuit board. I honestly don't know if I wanna open my amp all the way up like that, and start fiddling around on the circuit board. I would much rather pay an experienced professional to do all that... anyway, I talked to the amp tech guy in my area - I live in the Philadelphia suburbs, and this guy is apparently THE main amp tech that ALL the guitar shops in the entire southeastern PA area use. he's been doing his thing for the past few decades... I'm gonna hang on to the amp this weekend, give it the DeOxit treatment and see what it does... if it doesn't change anything, I'm going to drop it off at the guy's shop on Monday. he said the turn-around time (if its something fairly straight-forward, like just the tubes) is about a week and a half... I'm going to assume that the damage (for diagnostic, power tube replacement, biasing) is going to run me at least $300.

 

[GibsonMarshallGuy47]

UPDATE:
well, guess what??... I brought my amp home, sprayed all the jacks (input, speaker outs, effects loop send/return, footswitch port) with DeOxit D5, worked it in there with some in & outs using an instrument cable, waited 10 minutes, powered on the amp and left it on standby for another 10 minutes to let the tubes warm up (which I inspected closely - they were all glowing normally), then I turned it on, with anticipation and anxiety...

it works perfectly fine... its functioning perfectly normal... absolutely no noise issues at all, and my guitar signal is coming through loud and clear, like it should. and to think, I was ready to bring it to an amp tech, leave it there for a week and a half, and spend probably two to three hundred bucks on diagnostic tests, and quite possibly a power tube quad replacement & biasing. I've said it before - DeOxit is pure liquid magic... legit, raising amps from the dead sorcery. every single guitarist and bassist needs to have a can of this on hand at all times. I've had similar issues with this amp, and others that I've had, and almost every single time, spraying some DeOxit into all the jacks fixed it.

aside from all that, I'm fully aware that with my amp being 8 and a half years old, it will more than likely require a complete power/pre amp re-tubing, and re-biasing sometime in the near future. for that reason, I may decide to invest in the replacement tubes sooner rather than later.

 

[Mitchell Pearrow]

@GibsonMarshallGuy47
That’s fantastic you got it going with just the dirty Jack cleaning.
And as you said a new set of replacement tubes is a must have for your amp.

Cheers

 

[Mike_LA]

Congrats bro, I was just about to tell you to do that.
I've learned with my 6101s (7 preamp tubes) that quite a lot of issues can come from tubes that need to be reseated and it usually arises after sitting for a while.
Always check the easiest thing first.

 

[Leonard Neemoil]

Cool, glad you solved it and reported back. Thanks.

Crank it!

 

[don550]

Congrats on a easier repair.. Get some new tubes in it, set the bias and then let that lion roar!

 

[Old Punker]

UPDATE:
well, guess what??... I brought my amp home, sprayed all the jacks (input, speaker outs, effects loop send/return, footswitch port) with DeOxit D5, worked it in there with some in & outs using an instrument cable, waited 10 minutes, powered on the amp and left it on standby for another 10 minutes to let the tubes warm up (which I inspected closely - they were all glowing normally), then I turned it on, with anticipation and anxiety...

it works perfectly fine... its functioning perfectly normal... absolutely no noise issues at all, and my guitar signal is coming through loud and clear, like it should. and to think, I was ready to bring it to an amp tech, leave it there for a week and a half, and spend probably two to three hundred bucks on diagnostic tests, and quite possibly a power tube quad replacement & biasing. I've said it before - DeOxit is pure liquid magic... legit, raising amps from the dead sorcery. every single guitarist and bassist needs to have a can of this on hand at all times. I've had similar issues with this amp, and others that I've had, and almost every single time, spraying some DeOxit into all the jacks fixed it.

aside from all that, I'm fully aware that with my amp being 8 and a half years old, it will more than likely require a complete power/pre amp re-tubing, and re-biasing sometime in the near future. for that reason, I may decide to invest in the replacement tubes sooner rather than later.

In the past I've had similar issues to what you describe and I've also 'fixed' those problems using the same DeoxIT (or isopropyl alcohol). I usually check my guitar, all pedals in chain, cables, then clean jacks on amp. If that doesn't work I start looking at tubes.

I have also noticed these sorts of minor issues arise after letting gear sit for a while in my basement. Actually, if you keep your amps in the same room as your guitars, basement or otherwise, and you keep the air humidified enough for your guitars, then these oxidization issues can happen, IMHO. Sometimes even just unplugging/plugging from jacks can fix it.

 

[GibsonMarshallGuy47]

I guess I should've known that some DeOxit treatment would more than likely make it good as new... I've actually had similar issues with this amp a couple of times over the years (sudden volume drops, cutting out intermittently, weird noises, etc.), and DeOxit has fixed it right up. I even had an issue with another solid state amp head that I have, which I hadn't used in a few years. I turned it on one day and it emitted a piercingly LOUD squealing noise whenever I turned it on. once again, DeOxit completely cured that.

considering that my tube head is about 8 and a half years old, I recently did some research and apparently the life span of most tubes, from what I read (depending on frequency of use), is supposedly: 3 to 5 years for power tubes, and 5 to 7 years for pre amp tubes. I don't know how accurate this is, but obviously, based on this info, I am definitely overdue for a complete set of new tubes (power amp tubes, at the very least). what I might do is invest in a full set of each (power & pre) just so that I have them when they eventually fail, which I'm sire will happen within the next year or two.

with it being a Marshall, naturally the power tubes are four EL34's. I was doing some online research about other compatible tubes to EL34's, and apparently a lot of people seem to like KT77's, saying that they are less compressed, and have better, more pronounced, tighter low end. I might opt to get those. there's also 2 different companies that make them that even sound different - JJ and Genalex/Gold Lion, JJ's being the more inexpensive of the two... I'm still in the process of looking up different info on preamp tubes... can anyone recommend a different preamp tube other than a 12AX7, that might be considered an upgrade? or are there certain companies that make the best of the best 12AX7's?

 

[GibsonMarshallGuy47]

so... after a week and a half, I finally brought my amp back to our band rehearsal spot for practice, and I immediately realized that something is definitely very wrong.

the amp turns on, and there is sound coming out, but the tone sounds very brittle and thin and spikey - not as full sounding as it usually is - and I also have to turn up the pre-amp volume a lot higher than I usually do ... normally, band practice volume is at 2, but now I have to turn it up to almost 4 to get it as loud as I need it to be. I was able to get through band practice ok, but basically, the amp just sounds wrong, compared to how its supposed to sound normally.

any suggestions as to what this might be, OR for a simple thing I can do to get it to work properly, or something I could easily check myself?.. does this sound like a power or preamp tube issue? I read somewhere that this is very consistent with a bad power tube.

just tp be clear, I have no replacement tubes, or a multi-meter, and I am not experienced at all with working on amps... and before anyone says it, YES I will most certainly be taking it to an amp tech to get it checked out as soon as I'm able to.

 

[shredless]

Tubes, these are wear items, like brake pads or even oil and filters on a car. Think of them like that, they wear out. Change them before you do damage to non wear items like transformers, wiring or pcbs. You have been lucky so far.

 

[lyates1987]

Doing exactly this is what fixed a red plating issue on one side of my SLP100. Tube sockets get old and contact isn't so great. Took a EL34 I had sitting around and sprayed with contact cleaner and ran it up and down each tube socket. Amp works like a champ now.

 

[GibsonMarshallGuy47]

so, a week ago I brought my DSL100H to the well known amp tech guy who is supposed to be THE legendary amp doctor around here - he pretty much handles 90% of all amp repairs & maintenance for the entire southeast Pennsylvania area. this guy has been the go-to amp wizard in the Philly region for the past couple of decades that all the guitar shops defer to. he is supposedly going to be getting back to me any day now.

I'm prepared for either:
1.) he checks out the amp and confirms that it just needs a thorough cleaning, and air blasting of the tube sockets & circuit board, maybe re-soldering a few old points of contact, etc... that should be somewhere in the range of 60 to 80 bucks, I'm guessing.
2.) he checks everything and confirms that I need new power tubes. depending on how much a new quad set is going to be (somewhere between $120 and $150), I'm assuming the cost of everything are going total somewhere in the range of 200 to 220 bucks. hopefully no more than that.

we shall see...
UPDATE: I'm not kidding... literally the exact moment that I posted this comment, the amp tech guy called my cell... crazy coincidence.
so the verdict is - a new quad set of EL34's are what is needed. I think the amp guy has an Electro Harmonix set. I'll be out about $220, and the amp will be ready in a few days.