True Master Volume Mod

grolschie · Post by **grolschie** » Tue Oct 10, 2006 4:47 pm

Hey there. Got my Laney LC50-II (2xEL34) modified today. Got a Master Volume knob added to the rear of it. Means I can crank the clean channel to 10 and get distortion, and turn the MV down on the back to bedroom levels. Seems to work ok too. I found that changing V4 from a 12AX7 to a 12AT7, although gain reduced a little, it tidied up the bass notes when volume on 10 with new MV turned down low. Sounds reasonably close to what the amp sounds like unmodified on 10, but at bearable levels. Dirty channel still has Gain and Master knobs and also works good with the new MV. The mod cost < $100 too. I am now beginning to not regret not buying that LC15R a few years ago.

thehenderson · Post by **thehenderson** » Tue Oct 10, 2006 5:00 pm

I always thought that a 'master volume' mod is such a confusing name for it. You are infact adding a pre amp gain knob, right?

grolschie · Post by **grolschie** » Tue Oct 10, 2006 5:44 pm

thehenderson wrote:I always thought that a 'master volume' mod is such a confusing name for it. You are infact adding a pre amp gain knob, right?

It's basically the same amp controls. i.e. clean channel has still has a single "volume" knob and the dirty channel has it's own "Master Volume" and "Drive" (aka "gain") knobs as per usual. However, an additional master volume knob is added to the back of the beast. Basically you crank your amp to desired settings, then wind down the MV knob on the back to a reasonable level.

As I understand it, the MV is added to a later stage in the circuit, but still prior to the power-amp. It's technically not power-tube distortion, but sounds very close. The tech mentioned that it makes V3 distort. It's a clever trick. You obviously don't get speaker breakup at the lower volume level though - which is good for me cos the Laney speaker is crap.

thehenderson · Post by **thehenderson** » Tue Oct 10, 2006 5:46 pm

Hmm, interesting

You just need to attenuate that bitch, that would be my advice

grolschie · Post by **grolschie** » Tue Oct 10, 2006 6:12 pm

I heard a Fender HotRod Deville that had been modified by the same dude. He installed an extra transformer and a 4 way rotary switch to lower voltages (i.e. output wattage) of the power tubes. The beast went from 60w to 30w to 15w to 7.5w. The clean channel sounded insanely good set at 15w. Fully breaking up, raunchy rock tone! The dirty channel was ignored, cos they never sound good on that amp. Same tech reckons the MV mod was 90% as good tonewise. Most mods are kinder on the tubes and OT than an attenuater. The point of the MV is that an attenuator should no longer be needed.

thehenderson · Post by **thehenderson** » Tue Oct 10, 2006 6:14 pm

Sounds like the business man, now you just need to post some tone clips

grolschie · Post by **grolschie** » Tue Oct 10, 2006 6:21 pm

I gotta learn to play first. hehehe