White Little Rock

JXG

Hello all, just picked up a White Little Rock 50 combo, made in Sunderland early 80s, the preamp is loosely based on a Mesa mark II, they managed to squeeze 50 watts out of a quad of el84. I've heard they work the 84s very hard - anyone got experience of one? Worked on one? A very long shot, but if anyone has a circuit diagram that'd be great. Only had a very quick play and peek inside - looks like it's been modded for adjustable bias, sounds biased too cold to me.

Cheers, John 

koneguitarist

I could not get a circuit diagram for love no money, mine was a 1x12 tweed combo, nice sound, very punchy. Any pics?

ICBM

I've worked on a couple, although not recently. They are very hard on valves, yes - if I remember correctly they use very high plate voltages and need to be biased cold or they'll fry them in short order. I don't have a diagram but I don't remember them being particularly complicated.

If you're interested in warming it up you might want to look at reducing the screen voltage a bit relative to the plate voltage, which should let you warm up the bias a bit without blowing the valves. I'd probably go with something tough like JJs if you don't want to spend on NOS EL84s.

JXG

Thanks guys, much appreciated. I've got some old Mullards to go in it, hopefully get chance to have a poke about in it soon 

Cheers, John

koneguitarist

Got any pics yet ?