Issue Mark V 35: Buzz/sizzle (presence)

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espcustom-fr

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Hi everybody.

Very very happy owner of a Mark V35 head + Rectifier 1x12 cab that i've been waiting for 8 months here in FR. Couldn't be happier except for one issue.

The amp has a strange noise, like a buzz or some sort of static electricity coming from the speaker. I mainly play channel 2 so the gain overcovers it, but in channel 1 it is perfectly audible and i realized that yesterday.

Even with master and gain at 0 i can hear it. When i switch off the speaker with the cabclone feature of course it disapears. It happens with or without my guitar plugged

Funny thing is it reacts with the presence knob, the more i put some presence the more i can hear this noise. The amp and cab are brand new and the overall sound is great, no power problem or else.

does this ring a bell to any user?

In the instruction manual it says that presence control "can put extra stress on even borderline microphonic preamp tubes". So it would be a normal behaviour? do my preamp tubes need replacement?

thanks for any input.

Can't put my own samples, so it sounds a bit like this :mrgreen: but more piercing/squeaky (from 0'50):

https://www.youtube.com/watch?v=afwYMdN43Mc
 
Hi,

I had the same problem on my Mark V 35. At first, it did not always appear but it started when I got a text and my phone was placed on my amp. Over time it got worse and really annoyed my band and me. I had to switch to standby between songs during rehearsal.

My first attempt was putting a shielded Mesa tube in V1, the SPAX 12AX7 thing. That did nothing. I found that it also happened when I plugged my Helix into the FX return so it was definitely a power amp problem. I found that the powertubes were mismatched (one was blue and three were gray). When putting the mismatched pair (grey blue) to the inner sockets the noise vanished in 25W and 10W mode. That pretty much confirmed that this was the problem. Also, the blue tube looked kind of burned inside so I guess it got a lot more wear for some reason.

I got on the phone with the German Mesa service and explained the above. They sent me a new set of power tubes and since my amp is silent.

In short: Try cycling the poweramp tubes and see if it vanishes in 25W mode with any tube arrangement. Then replace with properly matched tubes.
 
Hi!

I've got my Mark V:25 a while ago and I have noticed the same thing recently. The buzz noise wchich is most audible on the clean channel and master volume all the way down so there is no other noise except of that buzz. It does change only with the presence knob movement. I have actually replaced all tubes with original Mesa ones and it didn't help. Does anyone have similar issue? I'm sure it's something in the power amp section but not no idea what it might be. If not the tubes than I was thinking maybe dirty sockets, some capacitors, transformer or grounding issue. Any suggestions much appreciated :)
 

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