Marshall Vibratrem

[andy]

I've owned this pedal for ages, and been pretty unimpressed with it. I did once use the Vibrato setting on a session, but the range of some of the pots is rubbish, with the lower 50% being in effect 'off', and with the effected signal mixed in with the unaffected, making the trem into a mild blipping sound within the original sound.

I played through it again today, and decided to put it on ebay, but after packing my gear down, I thought that there may be a couple of trim pots inside which could turn this hunk'o'junk into a beautiful wobbly joy to play through, and, on the off chance I opened it up.- Voila, lucky me found a couple if tiny trim pots staring back from the bottom of the PCB.

Has anyone else here had a fiddle with these and found that they help? And what the pots might do?

I may not have the chance to try it for a day or two...

[ashcatlt]

I did a search. Found a number of folks with the same complaint. None of them mentioned the trim pots. Couldn't find a free schematic online, either. Maybe you could take a guts shot and we can RE that puppy into submission?

[andy]

Thanks for looking all the same, ashcatlt.

I hunted for ages to find some info or a schematic, but likewise, nothing to be seen.

I might just take some photos, as I found some time to have a go with the pots, and one (PR2, for those with this pedal) seemed to be a voltage fine tuner of some kind- in the right spot, the effect can be made to work, and within that the range of the depth control can be improved, but only within a tiny point on the pot. Too far to one side and you only get the 'effected' tone without the effect, too far to the other and the tone becomes emaciated and weak, and without the effect. Pot PR1 made a barely audible difference, though to one side the tone was a bit rawer (in a negative digital-like way) and to the other it sounded subtly smoother and fuller.

I am interested to find out what the function is, but I think that may be the only reason that this pedal has saved itself from the horrors of Ebay for a couple of weeks more. Oh, that and the fact that it is a pretty cool looking thing...

Photos to follow if I can get the time/close up focus!

[andy]

I haven't got round to taking any photos yet, but I just thought I would pass on the great knowledge which was imparted to me by the Marshall support team when I asked what the functions of the trim pots were...

Hi

They set up the tremelo

Cheers

Marshall Service Team

...

[cynical1]

May 12, 2008 7:19:45 GMT -5 andy said:

Hi

They set up the tremelo

Cheers

Marshall Service Team

...

...did they mention if it goes to eleven?...