Channel Switching popping issue & Tubes rattle issue

[Phano36]

I've been having that Channel load Popping issue when switching from OD to Clean. From about one year now ! The noise in question also affect something in the Reverb tank because it's sound similar that when you hit your amp with alot of reberb. One thing for sure this noise or transiant is cause by a deffective component.

I've recently changed the JFET (TR145) as suggested by Steve D that's control the mute when switching channels and unfortunataly it didn't fixed the issue. Maybe it's something deffective in the reberb circuit ? But witout a schematic.. it hard to tell wich parts control the reberb circuit.

I also experience another issue this time with a rattle noise that's comming from the power tubes. Specialy when I hit the "A" string or any that "A" note on my guitar.

After reviewing some previous post from other participants in this forum I find out that i'm not the only one that's having both of these issues.

So my questions... Did finaly someone found a cure from both of those issues ?
And by the way, please dont tell me to bring my amp to the nearest service center... I Already did it and they dont have a clue of what is causing those issues !

[jagermike66]

hey phano,

Firstly sorry if my suggestions have already been given!

With the tube rattle, are they the original stock tubes? Sounds like you're getting a bit of resonance from the A string. Try some different tubes, see if that solves it. Ive had a few different sets in mine and some have rattled more than others. At gig volume i dont notice it though.

As for the pop, are you 100% sure its the amp itself? not the footswitch? Also stick your reveb on minimum, and disconnect the phono cables from the tank itself. On my old DSL, i used to get a reverberant pop when going from OD to clean just as you are, but only when there was actually reverb in the signal (i hardly ever use reverb so I just left it).

M

[Phano36]

Hello Jagermike66

Thanks’ for your suggestions, any help will do : ) !

First, about the tubes rattle issue, unfortunately for me, I've already tried some other tubes and the problem doesn't go away.
What I noticed during troubleshooting is that if I put my hand on the tubes during the rattling it's stop. No surprises...
Those tubes catch the harmonic frequency vibrations coming from the speakers that are amplified by the metal chassis where the tubes sockets are installed. Hope that it’s make sense for you? English is not my mother language : )

Last week I’ve also installed some rubber grommets under each of the tubes socket screws hoping this would cut some of that vibrations but it didn’t work.
I though next to remove the actual base type tubes retainers and replace then with the spring type. Maybe it's just an illusion but it look to me that the Spring type retainer would help preventing some of that vibrations since they hold the tubes by the tip instead of by the base. I believe that it could help dissipated some of that vibration. But first I wanted to see if some of the forum guy’s had already found a solution for this annoying issue.

Second, about the channel popping issue. Even with the reverb knob at 0 the problem is still present. I also tough of unplugging the reverb tank but…. I paid for an Amp with a working reverb even if like you, I never used it! It’s not normal to have it unplugged no?

It’s been more then one year that I am participating in the present forum and I noticed that some other follows are experiencing the same two issues. I’m sad to say that Marshall’s Quality assurance team is not doing the job. When you have more then two similar issues in the field it’s should be consider as a trend and Marshall should investigate on it and submit a fix.
And this doesn't improve the MA reputation.

[Beck-Ola]

I though next to remove the actual base type tubes retainers and replace then with the spring type. Maybe it's just an illusion but it look to me that the Spring type retainer would help preventing some of that vibrations since they hold the tubes by the tip instead of by the base. I believe that it could help dissipated some of that vibration.

I found that replacing the stock "bearteeth clamp" retainers with spring types on my VM combo (different amp but same issue) offered a little bit of improvement although it didn't cure it totally. Made it much more bearable though. In fact, for a few weeks or months the rattle was so slight that I thought it was fine. But gradually with higher volume levels it has crept back in---in a very narrow frequency band, which interestingly enough is around 140Hz-150Hz and not the deeper place it usually resides (i.e., around the 4th fret of the low E....100Hz or so). Anyway, keep banging away at it. You have a better chance using EL34s than I do using KT-66s. But it is worth the effort because the tone is so good.

[Phano36]

Thank's for this advices Beck-Ola.

A question ... are you also using those rubber o-ring that goes between the spring retainers tip and the tubes ?

[Beck-Ola]

Thank's for this advices Beck-Ola.

A question ... are you also using those rubber o-ring that goes between the spring retainers tip and the tubes ?

Nah, just the retainers themselves. I've never tried the rubber deals.

[Phano36]

I just received an E-mail from Marshall service center in Montreal Canada. They say's that the loud popping noise issue is related to the way the amp is design and their is nothing they can do ! To sad ... I guess my only option left is to unplug the reverb.

[jagermike66]

wow that is aweful :( bad times mate

[washburn 1]

Hi guys

Very interesting that i have just seen this post as i have had the beast cranked up today and noticed (huge understatement) that my head has the same problem with the valve (or whatever) rattle/buzz!! The noise is so prominent that it is Clearly audible when the amp is turned up to number 6 or so.In fact it seems to be just as loud as the amplified sound! For me the noise was SLIGHTLY reduced when putting pressure on top of the valves but it really seems that there is a serious chassis buzz/vibration but i can`t seem to locate where it is exactly or how to stop it. It sounds as if its coming from inside the chassis when its in the casing (head). Was just wondering if anyone had experienced the same type or amount of noise (its ******* horrible) and any solutions that have worked for you.
Cheers, Kev.

[Phano36]

Hello Washburn 1

Yep, for me also the Tubes rattle go away when I put my hand on the tip of the tubes. It's obvious that it's comming from somewhere in the chassis. Unfortunataly I wasn't able to pin point the exact source (note that I own a combo) Anyway I just ordered some spring ratainers and O-rings. I dont know if you are familiar with the o-ring ? They goes between the tubes and the retainers, should cut out some extra vibrations. Will see. Should received them in about 9 days from now.

[washburn 1]

Hi Phano

Yeah , have seen the o rings, will prob get some but most seem to come from HK/ China or USA and i`m impatient and want them now!!! I WILL find the cause of this buzz/rattle somehow and let you know what i find. Will also try isolating the head from the cabs with foam or something.I cannot put up with that noise!!
Any other ideas anyone?? Steve??

[Phano36]

Washburn

Since you're going into deep dive investigation : ) and you're going to open the beast anyway, try to ad extra strip of insulating foam between the chassis and the cabinet ? I noticed that the actual foam seems a little thin no ?

[washburn 1]

Hi Phano

Checking out the buzz today, isolated the head from the cabs with fairly dense foam and noticed that the back of the top cab was vibrating along the top of the back panel. When pushing in the panel the buzz seemed to reduce a lot, so until i can really seal the edge dead tight i cant hear what the amp is doing but i dont actually think there is much problem with the head. Will let you know. Kev.