mark V buzz

hi scratching my head what to do. I have had a mark V for about a year or so sounds pretty great racked up. However were trying to record now, and are finding a buzz behind most of the tones especially audible on clean and at certain lower frequencies. Ive taken it apart, tightened all screws up, valves ahve been replaced, running thru a clean mesa 2x12 cab which is pristine. it almost seems like part of the signal just buzzes on the decay. Is this normal. Not having heard any other mark V perhaps it is. it bascially means we have to use a lesser amp when recording which is stoopid. but at least it doesnt buzz..

any ideas? being in the UK there are 0 mesa specialsts apart from glasgow which is the other end of the country and hard to contact

bobwrighter said:

hi scratching my head what to do. I have had a mark V for about a year or so sounds pretty great racked up. However were trying to record now, and are finding a buzz behind most of the tones especially audible on clean and at certain lower frequencies. Ive taken it apart, tightened all screws up, valves ahve been replaced, running thru a clean mesa 2x12 cab which is pristine. it almost seems like part of the signal just buzzes on the decay. Is this normal. Not having heard any other mark V perhaps it is. it bascially means we have to use a lesser amp when recording which is stoopid. but at least it doesnt buzz..

any ideas? being in the UK there are 0 mesa specialsts apart from glasgow which is the other end of the country and hard to contact

Click to expand...

It could be one of the pre amp tubes, specifically the v1 tube. I would recommend getting a mesa spax7 tube for it or a normal tung sol in v1 to eliminate the noise.

It could be one of the pre amp tubes, specifically the v1 tube. I would recommend getting a mesa spax7 tube for it or a normal tung sol in v1 to eliminate the noise.[/quote]


* thanks. I have been fiddling around with the settings, and turned the loop switch off so now all three channels volumes are governed by the master on each channel, and the main volume knob does nothing at all. Now have nice clean tones on channel 1 without any buzz, but can still hear some of the buzz on channels 2 and 3. It almost seems like the after -buzz is part of the gain signal itself. I did change the preamp tube a few months ago, but I guess I can try one of these ones to see if it makes any difference. downside of this is that I can't use my pedals... I did try them in the loop before but they significantly cut the entire signal coming out of the amp... :|

Sometimes you may get tube sing... or signal vibrations in the power tubes. Some frequencies on the clean channel seem to enhance this characteristic that seems to be more prone to Sinul-Class amps than the Class A/B as I have experienced for the past 24 years of owning a Mark amp from the MKIII up to the MKV. You may try swapping the inner pair of power tubes with the outer pair if the buzz is coming from the power tubes. (Typically present at 45W or 90W but 10W drives the power tubes differently and will eliminate the tube sing issue).

If you are getting typical white noise or supply hum in the signal chain, you may need a AC power conditioner rated for your AC source. I am assuming you have an export model or are using a step down for 120VAC.

As for the loop, Mark V uses line level and not instrument level which will tend to overdrive the buffers on most pedals. Trick: Ebtech LLS-2 is a dual channel line level to instrument level shift transformers. Place this in the loop using the +4dB jacks and feed the pedals with the -10dB jacks. In essence you are stepping down the line level to a more reasonable instrument level for pedals that cannot be operated with line level signals, at the end of the effects chain, the signal is stepped up to line level to the Mark V return. This should give you more range of control on the signal level out on the loop without swamping the input buffers resulting in signal degradation, compression or tone loss due to clipping or damaging effects from driving the pedal buffers too hard. Something I wish I had seen before replacing all of my effects gear....

https://www.sweetwater.com/store/detail/LLS2. the pedal version does not require any power as it is just two transformers to step down and step up.
http://www.ebtechaudio.com/llsdes.html