Tech help with an Engl Fireball 100

[Drumzilla]

Hey guys. I've encountered a problem with my amp and I'm wondering if any of you guys have advice or technical knowledge you'd be willing to impart.
Just to get it out of the way, I live in a small mountain town in Canada and money is an issue so sending my amp to a qualified Engl tech isn't in the cards right now and the local "Amp Tech" charges an arm and a leg and doesn't exactly inspire confidence.

On to the problem. I've encountered a strange noise on my lead channel. It's only detectable while palm muting and letting the note ring out/fade away. It's kind of a mix of buzzing and almost grinding, and seems to get louder as the noise of the guitar fades away. This is not normal amp hum. Way too loud.
It's there with or without the noise gate engaged. It's not audible on the clean channel.
I had the tubes tested and according to the local "expert" they're fine.
Here's the weird part: In the local music store I couldn't get it to make this noise. It sounded perfect. I take it home again and it's back. I've been running it through a Marshall 2x12 and borrowed an EVH 4x12 to make sure it wasn't the cabinet. I moved the head from one cab to the other and it seemed to go away, but slowly came back over the course of a jam.

I picked up a replacement pre-amp tube and was going to try and troubleshoot this thing to see if one is faulty, but not faulty enough to test negative. This being my first 'real' guitar head and me being primarily a drummer I thought before I start mucking about with things I really don't understand, I'd ask the community and see if anyone one out there would be so kind as to assist me in my ignorance.

Any advice would be great. I'm in over my head here.

 

[spaghettipomodoro]

What guitar do you use? Your strings may be ringing out at the head of the guitar. Not sure if that's the sound you're describing but my guitar does that too when there isn't any foam muting the strings.

 

[Drumzilla]

I usually play a Schecter Tempest through it, but I spend a lot of time playing drums while my guitarist plays my Telecaster through it. You think it could be the guitar? It seems pretty loud.

 

[Wizard of Ozz]

Might be bad wiring in your home causing this. I had a similar issue with my Fireball 100. Are there dimmer switches for the lights anywhere in your house? If yes, make sure they are all turned off.

Take your FB100 to a friend's house or another place, and see if the noise is still present.

Also, turn off the noise gate... and it can sometimes make some unusual sounds.

 

[spaghettipomodoro]

Possibly, does it sound almost like feedback? I mean you don't hear it in cleans which makes sense as there isn't enough gain to make it audible (To my understanding... correct me if I'm wrong)

It would be these parts of the guitar that ring out, I'm quite gifted at MS paint as you can tell....

Try sticking some foam in between the headstock and the strings and see if it helps at all. May be a noise gate thing as well depending on how loud you are. If it's the amp I have no suggestions but it sounds more like ringing out to me. Any more info?

 

[Drumzilla]

It's sounds like a grinding buzz. I'm going to do some guitar swapping and try cranking the gain on the clean channel to see what happens.
As far as wiring in the house, I'm in a small ex-mining town in the Purcell Mountains and almost all the houses here are 65+ year old pre-fab junk that miners bought from the company that owned the mine. I have absolutely no doubt the electrical is total garbage. Thank fuck I'm only renting.
I'll see if I can record it and get it up here.

 

[spaghettipomodoro]

Yeah a recording would help the most. Best of luck!

 

[Drumzilla]

Well, it's definitely not coming from a guitar. Tested it with a Tele, the Tempest, and a Schecter Blackjack tuned to B. It's present across the board.
I cranked the gain all the way on the clean channel but couldn't get it to kick in, but it's there for sure on the lead.
I also played with the gate, and all the way off it's still there. It seems to come up as the 'chug' fades out, but it fades shortly after the guitar stops. The best way I can describe the sound is that it sort of sounds like a small, thin disc of metal vibrating against a table or similar hard surface.
It also seems to get worse the longer I play which I why I'm leaning towards a tube, but like I said: I don't know what I'm doing.
Could it be an inactive pedal in my signal path?

 

[Drumzilla]

Nope. Ran straight in with a high quality Lava cable. This thing seems to come and go. I'll see if I can record it tonight. Thanks for the help guys.
I wouldn't have been surprised though. My roommate likes running a few pedals in front of it and how I put up with a Metal Zone in front of an Engl and a Behringer flanger sitting next to my Decimator G String is beyond me.
Friends don't let friends buy Behringer.

 

[Quitty]

Have you tried it with a different cab?
It sounds like the extra 'chug' on the lead channel might be causing a loose (or torn) speaker to buzz around.

Edit: sorry, missed that part about the EVH.
It's strange, though, that switching cabs made the problem go away, even temporarily.
Does it only happen in high volumes? Does it still happen if you cut the bass lower?

 

[Drumzilla]

More so at higher volumes it seems. I wonder if jostling it while moving it from cab to cab adjusted a loose tube or something.
It seems to be more prevalent the more I boost the low end, but it's so subtle I might be imagining it.

 

[Quitty]

A random thought - maybe something's loose in the amp and it's sitting on the cab, making it rattle?
Try putting it next to the cab, rather than on top.

 

[Drumzilla]

Thanks dude. I'll test that out.
You guys are awesome for helping me out. I love this board. Low percentage of D-bags.

 

[wakjob]

Good suggestions so far.

Try a different cable other than the Lava, even a cheap one. And nothing else. No pedals in front or anything in the FX loop.

Set the head away from the cab and cushion it by putting a pillow or folded up blanket under it so it isolates vibrations.

Could be dirty power. IN4007 rectifying diodes don't usually go bad but...

And yeah, CLIPS!!!

 

[Drumzilla]

Alright guys, here's the problem. What do you think?

20120411 141800 by helephant on SoundCloud - Create, record and share your sounds for free

 

[Quitty]

That 'kheek' sound at the end of the last three chugs?
That sounds like tube trouble to me.

Also, 'Faeak!!1'

 

[Wizard of Ozz]

Tube issue. One or more of the preamp tubes is microphonic... what you are hearing is the tube rattling or ringing. Replace them all to be sure.

 

[Drumzilla]

That's the one. I've got an engl preamp tube and a Groove tube I can replace with. Do I just start swapping tubes to see if it goes away? Should i re-tube the whole thing?

 

[Wizard of Ozz]

That's the one. I've got an engl preamp tube and a Groove tube I can replace with. Do I just start swapping tubes to see if it goes away? Should i re-tube the whole thing?

You can actually tap on all 4 preamp tubes (take off the metal covers first) with a pencil and listen for which one rings. If it makes noise, it's the culprit. Only thing is, tapping only identifies the bad tube sometimes... depending on how microphonic the tube is.

 

[Drumzilla]

Well guys, there were two preamp tubes making noise and thanks to the Engl people in grand old Der Fatherland I was able to replace them both with the tubes supplied with the amp when I bought it. Fired it up and it sounds metal as fuck once again! No buzz.
Thank you guys so much for your help. If I died right now you'd need a jackhammer to get the smile of my corpse. Thumbs up and positive reps all around.
I know this is a pretty basic problem but everyone need to start somewhere and without your troubleshooting I'd be out a ton of cash I can't afford. I can't say thanks enough.