JCM 2000 idle buzz/hum

[felipevsw]

I got this JCM 2000 DSL50 used recently. It is from 2001 and had the dreaded bias runoff problem that I got fixed last week.

It has this static-like noise even when all knobs are at zero, but only when its off standby. When I engage standby, the noise stops.

I thought this would be somehow related to the bias problem, but even after the fix, the noise continues.

This is my first experience with this amp, so I'm not sure if this is just the way the amp is, or could that be some other problem, known or not known, that I should have checked?

I have changed all tubes, specially the power tubes, to see if it would stop the noise, but it's still there.

Anyone had this before?

 

[Tatzmann]

"Firstly, the "biasdriftproblem" was just in your imagination, the 50's don't have it!"

That is what the JCM2000 fanbois are going to tell you when they come along, don't listen, let them on.

But back to your problem, i had more than a few noise sources on my problem DSL.

Bad solderjoints all over, problems with the DC preamp heaters, lousy connectors and the amp seems to be a little picky bitch when it comes to preamptubes.

 

[felipevsw]

"Firstly, the "biasdriftproblem" was just in your imagination, the 50's don't have it!"

That is what the JCM2000 fanbois are going to tell you when they come along, don't listen, let them on.

But back to your problem, i had more than a few noise sources on my problem DSL.

Bad solderjoints all over, problems with the DC preamp heaters, lousy connectors and the amp seems to be a little picky bitch when it comes to preamptubes.

Oh, mine sure had it, and it was pretty bad! It didn't even had to be super hot to develop it, just a few minutes off standby, and the bias would runoff like my dog when I leave the door open. Now it's fine after the hole drilling on pin 5 fix.

I was suspecting the DC heaters might have something to do with the noise, since these early boards material is a mess... I'll check that. I did remove all preamp tubes at one point, and the noise was still there though. It might be more than one problem...

Are you referring to the flat cables connectors that are lousy, or the jacks, or both?

Also, what kind/brand of preamp tubes does it like? I have some at my disposal, but nothing fancy... Some JJs ECC83S, some Sovteks 12AX7WB and WA and an LPS that was in PI when I got the amp, some Sino 12AX7Bs, a couple PSVANE gold pins... what would you recommend?

Thanks for your reply.

 

[Kuga]

Yeah! You are right some DSL50 has bias drift issues because insulating board material become conductive.

Maybe It have loose screws from PT transformer. Do you can record this static noise?

 

[felipevsw]

Yeah! You are right some DSL50 has bias drift issues because insulating board material become conductive.

Maybe It have loose screws from PT transformer. Do you can record this static noise?

Hello,

Here's the link to the recording I just did. Try to listen to it with headphones if you can.



Thanks

 

[Kuga]

I think It have a faulty on a electronic components. Maybe more than one. I think It needs a visit to the amp tech. You can check If all is properly tight. Maybe It has a bad connection. If you feel confortable cheking inside but take care with HT residual voltage.
Best of luck.

 

[Doomguy]

I never heard anybody claiming that DSL 2000 is dead silent when the standby is not engaged, even with all knobs on 0.

Mine does have some noise too, (the 100watt version) but it doesn't get through my playing.

I have a Boss NS2 in the loop and it does help a little bit with the noise

 

[Kuga]

I never heard anybody claiming that DSL 2000 is dead silent when the standby is not engaged, even with all knobs on 0.

Mine does have some noise too, (the 100watt version) but it doesn't get through my playing.

I have a Boss NS2 in the loop and it does help a little bit with the noise

You are right but I think it's a bit to much noise for a 50W amp.

 

[Doomguy]

You are right but I think it's a bit to much noise for a 50W amp.

I didn't find the noise to be that loud in the video, the OP seemed to be talking not very loud. I just turned on mine out of curiosity to check. These are more than 20year old high gain amplifiers and they are a bit noisy when not on standby

@felipevsw does it get in your way when you play?

A noise suppression pedal in the loop helps. My boss ns2 reduces the noise to half, but it doesn't completely erase the noise

 

[Kuga]

I didn't find the noise to be that loud in the video, the OP seemed to be talking not very loud. I just turned on mine out of curiosity to check. These are more than 20year old high gain amplifiers and they are a bit noisy when not on standby

@felipevsw does it get in your way when you play?

A noise suppression pedal in the loop helps. My boss ns2 reduces the noise to half, but it doesn't completely erase the noise

I undestand He is recording the noise using a mic throught interface. I think it's a noticiable noise.

 

[Doomguy]

I undestand He is recording the noise using a mic throught interface. I think it's a noticiable noise.

Maybe... I can't say for sure. The noise on mine I could call it noticeable too. The thing is that everyone on this thread who owns this amp has admitted to have that kind of noise, it doesn't look unnatural for this amp.

As long as it doesn't interfere with the playing, I posted my suggestion before to make it less annoying.

Also no, it doesn't have to do about the bias drift issue that the OP was asking at the first post. Mine doesn't have bias drift (I check the bias regularly) and I do have hiss when not on standby.

 

[felipevsw]

It is my first experience with this amp, as I had never played one or heard one person before, so I couldn't tell if this was the way this amp is or not, which was one of my questions.

It seems this amp is like this, so be it, I just wanted confirmation.

My other amps, older single channel Marshall amps, don't have this static-like noise, only the traditional Marshall hiss when the volume is turned up, but usually are dead silent when the volume is turned down either on the amp or in the guitar (minus the normal hiss).

I'm used to noise, since I've been playing for almost 20+ years now, but usually the Marshall hiss, not this static hum.

Either way, the amp has a visit to the tech due next week, and it will be thoroughly reviewed and checked for cold solder joints, failing caps and resistors. Later I'll put it to good use.

Thanks for the help fellas.

Cheers

 

[Tatzmann]

I watched the video.

You could have worded the header better. If you had said "hum" instead of "static" i could have givin you the following info earlier.

This varying level hum that is always present with the 2000 is just another little "feature" of the DSL, and probably TSL amps. Marshall implemented this feature starting with the 900 series, to a little lesser extent there usually.

The source is mechanical vibration inside the powertransformer. Learn to live with it, otherwise you'll have to throw serious money at it, which i'd not recommend.

 

[felipevsw]

I watched the video.

You could have worded the header better. If you had said "hum" instead of "static" i could have givin you the following info earlier.

This varying level hum that is always present with the 2000 is just another little "feature" of the DSL, and probably TSL amps. Marshall implemented this feature starting with the 900 series, to a little lesser extent there usually.

The source is mechanical vibration inside the powertransformer. Learn to live with it, otherwise you'll have to throw serious money at it, which i'd not recommend.

I apologize, English is not my first language, so I meant hum when I said noise.

I've heard about the PT being a source of hum on this amp... As long as it doesn't increase too too much when I increase the volume, it's okay, I can only notice when everything is dead silent around me, hardly the case in a band scenario. I was just worried it might be something else since my other amps don't do that, and I never had a 2000's DSL before.

My 900 Mk3 doesn't do that thankfully, but I think it has Drake PT, the DSL has Dagnall PT, only the OT is Drake.

Thanks again for the confirmation.

 

[What?]

Sounds like a buzz to me, not a hum. Same sound as when you aren't touching any grounded point on a guitar that is plugged into an amp. Like Ninnttt, not Hmmm.

 

[Tatzmann]

Actually i pondered to change my wording from "hum" to "buzz" after i wrote it, because yes, it's technically more of a buzz.

I remember when i had my first DSL on the bench, that buzz was quite irritating, its not felt as much when the chassis sits in the headbox, ofcourse.

 

[What?]

@felipevsw My 1997 JCM 2000 DSL 50 does have a slight buzz when off standby, in case it is helpful hearing from others who own this amp.

 

[felipevsw]

@felipevsw My 1997 JCM 2000 DSL 50 does have a slight buzz when off standby, in case it is helpful hearing from others who own this amp.

Yeah, thanks, this was one of the points of my thread, trying to determine if this buzz was "native" to this amp or it was a problem specific to mine. So it's like @Tatzmann
said, it's a "feature" of this amp it seems. Of course, in a band/gig scenario, where the noise flor is higher than a silent studio/bedroom, it's unnoticeable.

 

[dslman]

The 100 watt JCM2000 DSL heads hum/vibrate more than the 50 watt 2K DSL head I use to own. It was quite a difference.
I owned around 5 or 6 2K 100 waters, and the hum could get irritating when practicing at lower volumes.

 

[6StringMoFo]

My 100 is noisy, always has been. Playing makes it go away