Mesa Roadster noise issue

[twostring]

Hello all...

http://www.youtube.com/watch?v=WAMQ8y1PEeo

I'm having an issue with my Roadster and need some insight into what could be causing this. To avoid typing everything all over again, I'll just paste what I've already outlined on the Youtube posting...

A quick video to demonstrate a noise issue I'm having with my amp. Depending on how certain notes resonate in the amp, I get this horrible arcing sound. I'm curious to know if this is a sign my power tubes are going out, or if there is something far more serious going on within the amp. This problem just crept up on me one day about two months ago. Here's what I've done...

1. Isolate the amp by moving it off of and away from the speaker cabinet. The amp is also resting on a pillow to dampen as much of the vibration from the speaker as possible.

2. Check all channels and modes of operation. This problem occurs in both Bold and Spongy modes, 100 watt and 50 watt, rectifier or diode and no matter if the effects loop and reverb are on or off. The noise also occurs in all 4 channels.

3. I've done a brief "tap" test on each of the rectifier and power tubes. Tapping on the rectifier tubes does nothing. Tapping on each of the power tubes results in a brief "burp" noise similar to what you'll hear towards the end of this video. I haven't bothered to check any of the preamp tubes because at this point I don't believe they are the problem.

4. The noise sustains no matter if there is a signal going through the amp or not, meaning once this arcing starts, I can cut the volume on the guitar or even unplug it and the noise continues. I can sometimes turn down the volume on the amp and the noise will suddenly cut out, but at times I've had to switch the amp over to standby in order to get the noise to stop.

Here are the settings on the amp as played in the video...

Channel 1
Power - Bold/100 watt
Diode Rectifier
Effects Loop - Off
Voice - Clean
Master - 3 o'clock
Presence - 2:30
Bass - 2:30
Mid - 1 o'clock
Treble - 2:30
Gain - 8 o'clock
Reverb - noon

I'm playing a stock '60's reissue Strat (apologies for the background noise, I've got electronics in the room and I'm dealing with a single coil guitar through the amp at a pretty high volume).

Video shot with Nokia N95 8GB

[155]

bye bye power tube!

[twostring]

So that's one vote for power tubes. Anyone else have an opinion?

And remember, the noise occurs if I tap on any of the 4 power tubes.

Thanks to 155, and I appreciate any opinions on the matter.

[mike80]

That sounds a little more serious than a tube. More like something internal. My best advice is to get that amp to a Mesa certified tech and get it looked at ASAP. I don't think the Roadsters are 5 years old yet, so it should still be under warranty.

[155]

yeah could be anything really get some new powers and see if thats it, if not try the pres if thats not it warrenty time but sounds like once the power tube gets crankin is when it goes apeshit, I have a roadster and blew a power tube a coulple weeks ago and there was wierd shit happening before it went.

[HHB]

could be a tube but it sounds more serious to me, was it a new purchase? sucks cause the Roadking is a great amp when working properly

[twostring]

Yup, purchased new in 2007 via Guitar Center (not a floor model, shipped to GC where I picked up the sealed boxes).

[Supertgtr]

Always check the power tubes FIRST. Always.

[twostring]

Originally Posted by Supertgtr

Always check the power tubes FIRST. Always.

Meaning? The amp ran fine for a year and a half and suddenly aquired this noise. Trust me, if this was present from day one, I would have already dealt with it.

[mobis8]

I think it sounds great!!!!!!

Seriously, may be a bad tube causing arcing? Best bet I would think would be to send it in to Mesa under warranty. Worst thing that would happen is they would send you a new one... Or they fix it...

[HHB]

call Mesa and find the local authorized repair guy, he could tell ya in a second ( and fix it )

[Supertgtr]

Quote:
Originally Posted by Supertgtr
Always check the power tubes FIRST. Always.

Meaning? The amp ran fine for a year and a half and suddenly aquired this noise. Trust me, if this was present from day one, I would have already dealt with it.

No that is not what I meant. What I meant was, whenever there's a strange hum or noise that occurs in a tube amp, Always check the tubes first. Swap out the tubes with a known good set first, before paying shipping costs to ship it somewhere, or incurring an amp tech's bench fee. Most of the time it's a bad tube.
I get about two years of use out of a quad set of 6L6s in my dual rec before they start to go south.

[twostring]

Originally Posted by Supertgtr

No that is not what I meant. What I meant was, whenever there's a strange hum or noise that occurs in a tube amp, Always check the tubes first. Swap out the tubes with a known good set first, before paying shipping costs to ship it somewhere, or incurring an amp tech's bench fee. Most of the time it's a bad tube.
I get about two years of use out of a quad set of 6L6s in my dual rec before they start to go south.

Yeah mang, I had no intention of dropping this thing off to a tech without knowing what the possibilities are. I've had rather bad dealings with some amp techs, and the only good one I know won't touch Mesa stuff (they are not an authorized service center and don't want to get into claims if they should happen to work on an amp). I'm about due for new tubes if 2 years is the typical life span. The amp sees a lot of action. A set of replacements has been ordered and is on the way. Tonight I'll try to switch it to 50 watt mode and move the middle pair to the outside and see if I get the same problem.

PS - Yes, mobis, I love the sound of the amp, but it's the horrible GLARRRGGHHCHCHHSHSSHHHSHHSHSHHS at the end of the video that I'm trying to get rid of. Up until that point, I was happy, but in my head I'm thinking "any minute now, this amp is going to shat a mutant horse".

[mobis8]

And that was the sound I was talking about. Many people would pay good money to emulate that in a pedal!!!

(just joking of course)

[twostring]

swapped tubes around (inside pair to outside, outside to inside) and the noise is still present. Interesting discovery...on spongy mode, I can tap on the PTs and the noise is only present on one of them instead of all of them. So hopefully this is a good indication of a power tube failure instead of something more serious. The replacement tubes will be here soon.