Mark 5:25 noise issues.

[schwa6970]

Hi All,

I got a new Mark 5:25 in May. I absolutely love the amp but am having noise issues Buzz,Hiss, and when I turn it up with no guitar plugged in at about noon in both channels I get a weird ringing feedback noise. :x I am guessing its a tube problem but being a new Boogie user I would like some experienced input.
Any help would be appreciated.
As much as I payed for the amp and the cabinet I am hoping its simple as a preamp tube swap.

 

[Monstercastle]

Yes, it's most likely a preamp tube. You will need to pull the chassis to get to many of the preamp tubes. The manual has a page that lists the functions of the tubes. Each preamp tube has an A & B side. You might be able to narrow it down based on what modes it happens in. Another approach is to switch around the tubes and see if the symptoms change.

 

[cherbst]

What kind of settings are you using? I found the 5:25 to be geared way hotter than the full size MkV. On the full size I had the gain around 2:00, on the 5:25 around 11 for similar feel.

 

[cherbst]

Oh and this:

'when I turn it up with no guitar plugged in'

don't do that Never run a tube amp with guitar or speaker unplugged, all bets are off then, it's damaging too

 

[persist]

Hi All,

I got a new Mark 5:25 in May. I absolutely love the amp but am having noise issues Buzz,Hiss, and when I turn it up with no guitar plugged in at about noon in both channels I get a weird ringing feedback noise. :x I am guessing its a tube problem but being a new Boogie user I would like some experienced input.
Any help would be appreciated.
As much as I payed for the amp and the cabinet I am hoping its simple as a preamp tube swap.

Hi. Understand the noise issue when guitar is not plugged in but what about when you're playing?

If you haven't fixed the noise issue, here's a quick checklist:
- make sure reverb cable is fully seated (bottom of amp)
- check that you are using speaker wire (and not a guitar or patch cables) to connect amp and cab
- disconnect from power source/amp has cooled down and check that tubes are all fully seated (may have to remove chassis from cab); you could try swapping tubes to see if it makes a difference . . . .

Good luck.

 

[schwa6970]

Hi all thanks for your responses. To further answer your questions about my problems. I always use a speaker cable. I have been using tube amps forever and this is the most important thing other than never running without a load.
I have never heard of turning a tube amp on without a guitar plugged in being damaging I dont believe that to be true.
as quoted from the gear page about the guitar not plugged in thing
"It doesn't hurt an amp to turn it on without a guitar attached".
"It CAN hurt an amp to turn it on without a speaker attached."
Yes I turned it on without my guitar plugged for about 10 seconds to check to see if I had bad cord or some kind of noise issue with my guitar. only to diagnose the problem nothing more.Never have I turned any tube amp on without a speaker attached.
I havent tried reseating the tubes yet thats my next step.
Even with my guitar volume turned all the way down I still get the squeal at 12 on the master and an enormous amount of white noise(hiss).I am starting to lean towards the tube running the loop.
If I have nothing in the loop or into the front of the amp except guitar it is a lot quieter but the hiss is still there. I really hope I didnt sacrifice my pre Cbs Fender Deluxe to get an amp that has noise issues I would cry .

 

[Monstercastle]

You need to pull the chassis and start swapping preamp tubes until you find the bad tube(s). Yes, always have a speaker attached while the head is on. Makes no matter if a guitar is plugged in or not.