Hi all,

I bought a new Mesa Boogie Recto Recording Preamp, and had it
shippined overseas from the USA.

My local area is 240V, so I have a 500VA step-down transformer to
supply 110V. I've had this tested, and it works ok.


The problem is that when I turn up any of the gains on this preamp
beyond about midday on the dial, I get VERY severe heavy distortion
and clipping. Just to be clear, this isn't the kind of distortion that
you want to hear, it sounds like capacitors are discharging when I
play, and then charge up (the volume actually decreases when I play
and then rises up again). To best describe the tones I get, if you've
ever turned off a valve amp and kept playing guitar and still heard
the sound slowly fading away.. it sounds all harsh and nasty like
that, but much louder!
I also get very loud squealing feedback when I turn all the gains up
too.

OK, so to make sure it wasn't the Chinese Mesa tubes supplied, I
bought all new tubes, but exactly the same thing is happening.

I got our my Voltmeter, and tested the supply voltage when I turn up
the gains and play, and from my observations, it seems a constant
110V. So the power side of things looks ok.

Speaking to a colleague of mine, he thinks it might be that the tubes
might be heated too low, leading to square-waveforms that equate to
the sounds I described. He also suggested it could be the preamp isn't
getting enough power, but given my stepdown is 500W and I measured a
consant 110V, it doesn't seem likely.


This preamp looks to be built beautifully, but I can't find any
variable resistors inside that could be used to change any settings..
no doubt because Mesa amps don't require biasing!

Has anyone have any ideas or experience with valve amps showing this
kind of effect?

What can I do?? I'm sure the amp is in good order.. something is just
fundamentally wrong.

Any responses GREATLY appreciated!

Zooper