Problem: Static/crackling noise in my Mod50

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jarrett

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As you probably know from reading I love my VX/EG5/6L6 equipped Mod50. I use it on 1-4 gigs every week. Occasionally on the gig, I will get a static/crackling noise coming through the speakers. It's very intermittent and doesn't appear to be tied to anything directly. It sounds like when you roll a faulty cable, but it isn't as I've checked all of those. I've also looked for microphonic preamp tubes and no luck there either. When it happens, I click through all the modules and channels on the footswitch to see if its isolated to one and its not. Could it be a power tube thing or an electricity thing? I wanted to throw it out to the forum and see what else could this be and what are some potential solutions for it? Thanks in advance.
 
Dude, I have the same thing!! It is intermittent as well. I've changed out the power tubes, cable, V1 and V2 pre too. Most of the time it's really quiet, but at times I get that same "crackly" sound. So I'm interested too.
 
Sweet, I'll give it a try! Thanks. I did change it out with another AT7!

donbarzini":ccbd2 said:
I had the same problem. Most likely it's the fx loop preamp tube, the 12AT7, change it to a 12AX7. Frank at Egnater told me to do this, ever since, there has not been a problem.
Click to expand...
 
Interesting... I occasionally have this problem with my RM50B... wondering if it could easily be fixed with a tube swap as well.

--B
 
Please phone me at our shop 248-541-9100 when you have problems? If you don't get an answer, please leave a message and I will call you back.

So....you switched channels to try to isolate to one or all modules but didn't say what you found.

Use this process next time it makes the noise.
1) Step through the modules to see if it gets worse as you go to the higher gain ones.
2) If so, the problem is probably the first preamp tube which is closest to the input jack.
3) If the noise is only on one module, one of the two tubes in that module are probably the culprit.
4) If the noise is constant but is unaffected by switching modules, it is likely the effects loop buffer tube located in the back row on the right end. We ship with a 12AT7 but a 12AX7 will work just fine.
Note: We did have static noise issues with the Sovtek EH series tubes. They would be fine for a week or so and then start that intermittent static noise thing.
 
Great advice Bruce and thanks. Very common sense. I may have actually traced some of the culprit to one of my speakers!! I"ll keep testing though, but I'm almost certain.
 
Thanks Bruce. I thought it might beneficial to post here in case others were having the same problem. Apparently, it was a good guess :)

Based on what Bruce said, it appears to be the Mullard 12AT7 I have in my FX loop. I knew I shouldn't have gone NOS :) What if it only happens at a certain gig site? Are there power issues that could cause something like this? If it is the loop, would it only occur when something was in the loop or even when no effects were being used? Thanks!
 
Well, I still seem to be having the problem on an intermittent basis. I've swapped tubes, cables, speaker cables, speaker cabs and it's still happening. After the static, if I don't play for a second, the sound cuts totally out, then if I just make the slightest touch on the strings, the basic amp noise starts again. So it's really cutting in and out. It happens on both modules as well. If I swap power tubes, it seems like it goes away for a while, then returns. I'm going to go back down and swap out some more things. If I can't track it down, I may have to send it up to Bruce. I'm leary about gigging it tonight now.......darn.

Man, it's a tough one. I changed the tubes in my EG5 and it helped, but it's still there a bit. Not much on the SL2 but barely. I do get some pops through the speakers when I'm turning the bias knob as I'm biasing the amp if that means anything. All controls are at 0. Now I get this fluttering/ringing when I'm using pretty high gain. It keeps going even when I mute the strings. I have to turn the gain knob down and then it will stop. Weird.

May have to gig the build amp tonight. No solo boost...........
 
Buckeyedog":2ccbc said:
Well, I still seem to be having the problem on an intermittent basis. I've swapped tubes, cables, speaker cables, speaker cabs and it's still happening. After the static, if I don't play for a second, the sound cuts totally out, then if I just make the slightest touch on the strings, the basic amp noise starts again. So it's really cutting in and out.
Click to expand...

I had the same thing happen a few weeks ago; the crackling and sound cutting out. I thought at first it might be the new tung sol 5881 tubes I put in but I tested by plugging my guitar into the serial effects return and the crackling and cutting out wasn't happening.

I replaced all three preamp tubes in the back of the amp one at a time and determend it was the effect buffer tube (which was a ruby ax7) and replaced it with an at7 and it did seem to correct the problem.

The sound cutting out really freaked me out though... Its been fine since.
 
Marco, I've changed them all out and I just changed them all out again just to be sure. Still had the problem although it does seem to be after it warms up a bit.

OK, it seems when I tap on top of the amp head I can make it crackle a bit. On the T/D, perfectly clean it started to crackle and I wasn't playing at all. I tapped the top of the amp and it quit for a minute or two. So I started tapping the top and it would crackle every time I tapped it.....not hard, just a little open hand tap. Seemed to be anywhere on the top, but maybe more so over the pre amp tube area and the speaker out jack area. Sounds like there may be something loose in there?
 
Try plugging your guitar into the serial effect return and see if it still does it. Then you can at least rule out the power section.

bruce egnater":45f16 said:
Note: We did have static noise issues with the Sovtek EH series tubes. They would be fine for a week or so and then start that intermittent static noise thing.
Click to expand...

Sovtek EH series tubes??

Well at least you have the class build amp, it could be worst; you could be stuck running through a POD. :confused:
 
Well at least you have the class build amp, it could be worst; you could be stuck running through a POD. :confused:[/quote]

You got that right!! My singer/guitar player wants me to get a POD since he has one. Man I just can't stand those things.

I'm going to try the Mod, but have my build in case. Off here in a few minutes.
 
Well, it was cutting in and out last night. Mainly on the EG5, but at times on the T/D as well. I'm sure it's in the amp somewhere. I may just send it to Bruce for a check up. I have the chassis out and I can't see anything loose anywhere. I left a message for Bruce at the shop, so hopefully I'll hear back tomorrow. The sound guy loved the amp though. Said it had great tone.....of course we all know that!
 
It happened to me again today as well and it was during the time I had the EG5 in there. It started happening well after the amp was warm. And while it was going on, I switched channels on the footswitch and it was on every channel but I did notice that it seemed to vary with the EQ setting on the module, ie the static had less highs on the darker module/channels. It didn't happen when I had the SL2 module in there, but several times with the EG5. At the end of the set, I stayed around for five minutes trying to recreate it, but could not. Its completely intermittent and seems to just happen in the middle of the set for some reason. Does this point to anything particular? Something with the EG5 perhaps?
 
bruce egnater":f2d1a said:
Please phone me at our shop 248-541-9100 when you have problems? If you don't get an answer, please leave a message and I will call you back.

So....you switched channels to try to isolate to one or all modules but didn't say what you found.

Use this process next time it makes the noise.
1) Step through the modules to see if it gets worse as you go to the higher gain ones.
2) If so, the problem is probably the first preamp tube which is closest to the input jack.
3) If the noise is only on one module, one of the two tubes in that module are probably the culprit.
4) If the noise is constant but is unaffected by switching modules, it is likely the effects loop buffer tube located in the back row on the right end. We ship with a 12AT7 but a 12AX7 will work just fine.
Note: We did have static noise issues with the Sovtek EH series tubes. They would be fine for a week or so and then start that intermittent static noise thing.
Click to expand...

I went back and read what Bruce wrote about this and it sounds like it could be the Sovtek tubes. I retubed the whole head and modules with Tung Sol Reissue 12AX7s and a Mullard 12AT7 (got talked into NOS) but when I compared the Tung Sol to the Sovtek 12AX7s in the EG5, I prefered the Sovtek. If its the Sovteks in the EG5 module that are causing my problems, would the static also be there when I switch to my VX module as well?
 
Does it mean anything that the static only happens in the middle of the set? Its not at the beginning and not at the end. It just starts happening about 45 minutes in or so and then stops before the end of the set approximately 45 minutes later. I can't make it start or stop on cue and it gets louder based on the module/channels volume. Any more ideas?
 
Hey, are you using anything in the serial loop? I was and removed it the other day and had the random cutting out thing happen again. Being the only thing I changed was removing my Xppression form the serial loop I tried using a short patch cable in the loop and all was normal. So, for shits and giggles, try putting a short patch cord in the serial loop and see if it makes a difference. report back!
 
MarcoR":0594b said:
Hey, are you using anything in the serial loop? I was and removed it the other day and had the random cutting out thing happen again. Being the only thing I changed was removing my Xppression form the serial loop I tried using a short patch cable in the loop and all was normal. So, for shits and giggles, try putting a short patch cord in the serial loop and see if it makes a difference. report back!
Click to expand...

Man that could be something. I literally have 40 foot of cable in my serial loop. I'm running my Boss GT-8 in the loop. Next time it happens, I will yank the cables from the loop first to see if that stops it. I need to go to a rack/midi pedal setup, but I really like having the tuner and all that built into the GT-8. Might have to give that up for the greater good though.
 
Im not sure if this is the same thing or not but this weekend I started getting static as well with the EG5. It did not happen on any other module and was not related to FX loop (I took everything out of the loop). The strange thing was that it was only noticable when I played a G chord and when I played LOUD. Anyway, I swapped out the Sovteks in the module with some EH 12AX7s my buddy had lying around and bingo, problem solved. As a side bonus, we both actually think the EHs sound BETTER than the Sovteks as well! Just more even and full. Maybe a little smoother as well.

Maybe there is something funky going on with these Sovteks...
 
I figured I had two issues......one with the EG5 and one with the amp. I'd even get little quiet pops through the speaker when biasing with all the controls on 0. So I went ahead and shipped the chassis and EG5 up for Bruce to check out. Must say I'm missing my amp badly though............ :aww: :cry:
 
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