Mark V - odd noise

[sheehanje]

I've been through my share of odd noises from squeals to flub - but I got a new one that just started.

I've eliminated cables (both speaker and instrument), power sources, cabinets. Happening with 2 different guitars. The head was retubed with SPAX7's and EL34's, but I'm getting the noise with both 6l6's and EL34's.

Here is a link to a sound clip:

https://soundcloud.com/john-sheehan-21/amp-noise


I'm palm muting the notes and lightly hitting the strings cause it makes it more pronounced, but it's noticeable with regular playing (just not as much).

Any ideas?

 

[SamuelJ86]

That's a new one. It sounds to me like the rattle is coming right after the pick. So the sound is causing the rattle. That's what I hear anyway. Hmmm. Idk man. I've never heard a tube make that noise. If the sound is coming out of the speaker maybe something is rattling against a preamp tube. Maybe try re seating the pre amp tubes. That sound is coming out of the speaker, isn't it? Could something be loose inside a preamp tube maybe? If you got a spare, start rolling.

 

[Nicklotsaguitars]

Sounded to me like a fuzz coming in. Like if a fuzz pedal was leaking a bit of effect into the signal.
If there are no effects plugged in. Does it do that on the clean or middle channel? Does it do it as you increase the gain control on those channel to maximum?
If not, if it only does it on the high gain channel, I'd suspect a diode on that area of the circuit. Maybe even a dirty valve socket. I've heard them sound like that before

 

[sheehanje]

That is the guitar plugged straight into the amp - nothing in the effects loop. For this recording I went through a Torpedo Reload loadbox to record - so there was no speaker involved (although it happens with speakers hooked up too).

It's mostly on channel 3 - although Channel 2 has a little "static", and channel 1 I can't seem to get truly "clean".

I bought the amp new back in September - as I said, I just did a tube refresh trying to eliminate other noise (squeals/whistles).

The odd thing with this noise is it isn't always reproducible - at least not at the same volume. Sometimes it's there, and sometimes it's not - or not as bad, no matter what the variables (cables, cabinets, guitars) are.

 

[sheehanje]

So I went home at lunch today to be able to really crank my amp without the attenueator and I didn't notice the noise. I really can't play long at that volume though.

I hooked the attenuator back up and for a while didn't hear anything - but eventually that noise started creeping back in, although not near as bad as last night. Really scratching my head on this one. I wouldn't mind rolling the tubes, but it's going to be hard to diagnose because it seems intermittent.

I'm considering bringing it back to the music shop I bought it from and have them give me an opinion. It's not just this noise that has me wondering, but Channel 1 has never sounded near as good as I've seen others get from the Mark V. I don't know if I'm doing something wrong or maybe there is an issue with my amp. I thought replacing all the tubes would help, but I still have issues. I don't know if they are perceived or real issues, but might be worth it having another set of ears listen to it.

 

[Nicklotsaguitars]

If the problem isn't happening without the attenuator, then the problem is the attenuator. Not the amp.

I use an old Marshall Powebreak myself. Though I've never plugged it into my MkV. All attenuators affect sound. However that sounds a bit serious for an attenuator to affect the amp that way. Like it isn't sitting right with the output transformer.
You are using speaker cable, not instrument cable to go into and out of the attenuator?

If it was happening without the attenuator, I'd be looking at something very early on in the input circuit. Reason being the noise is obviously amplifying as the gain stages increase.

 

[sheehanje]

If the problem isn't happening without the attenuator, then the problem is the attenuator. Not the amp.

I use an old Marshall Powebreak myself. Though I've never plugged it into my MkV. All attenuators affect sound. However that sounds a bit serious for an attenuator to affect the amp that way. Like it isn't sitting right with the output transformer.
You are using speaker cable, not instrument cable to go into and out of the attenuator?

If it was happening without the attenuator, I'd be looking at something very early on in the input circuit. Reason being the noise is obviously amplifying as the gain stages increase.

I'm using speaker cables, and good quality (planet waves) ones. I've swapped out cables to (both speaker and instrument).

I'm not sure where it's happening. It's intermittent, and when I first hooked the attenuator back up I had no noise. After a few minutes it started creeping back in. Unfortunately I can't blast my amp (apartment) for long periods of time.

I may roll the tubes tonight - like I said, I'm having other issues (squealing in mark IV mode, channel 1 seems very thin and tinty). If I get nowhere I'll bring it to the shop where they deal with Mesa Boogies all the time... I'm definitely not an expert. I will say this - the Krankenstein+ sounds better on the clean channel then the Mesa - and that shouldn't be...