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aberdeen-music

Bias Laney VH100R


darkeale
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Does the Laney have bias points on the rear panel? I know they've got switchable bias between the two different types of valves it can host (5881's and EL34's). If it does, your life is comparitively easy as all you'd need was a way of reading your mA readings (generally a multimeter with 2 probes across the points) and knowledge of the optimal current ratings for your chosen valves.

Otherwise it's going through something like this very very carefully.

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i think for that model of amp, you need a bias probe with sockets that plug into the tube sockets. the tubes then plug into these. You power up the amp with the chassis removed. find the bias pot and adjust to the relevant bias depending on the plate voltage, you can do the calculations to what the (mA) setting is when you find the plate voltage with the bias probe.

or you could do it by measuring the plate voltage the hard way, which is measuring it from the tube socket pins

easy as pie but bias probes are hard to find in the UK, you can get them from the german store (tubeampdoctor) though. oh and don't touch anything else in the amp while doing this and wear rubber soled shoes. also have someone near you with a defib as well (just in case :D)

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