Author Topic: Pulling Tubes to Pull the Punch... (Read 2512 times)

headtheball · « **on:** June 21, 2006, 10:22:34 PM »

Ok folks:

Some very knowledgeable valve amp "heads" on here, and I'd like to pick your brains.

is it safe for me to pull two of the power tubes from my Laney VC-30, in order to drop the power. In theory, it seems safe enough to me, and I've ran other amps (and other peoples amps) without the full load for a short time. It's just to do a half hour gig in a tiny venue, and I'd like to be able to get some tone out of it without drowning everything else out.

Any help much appreciated.

Bainzy · « **Reply #1 on:** June 21, 2006, 10:43:47 PM »

Is it fixed bias or cathode bias? In a cathode bias amp I'd think you'd need to change the cathode resistor after pulling tubes.

Searcher · « **Reply #2 on:** June 21, 2006, 11:22:57 PM »

I think you can pull two of them. I've done it before, but not with the same amp as you have. You'll probably have to pull either the two inside tubes or the two outside ones--as opposed to, say, doing the two on the left.

It's not gonna make all that much difference to your headroom though.

hunter · « **Reply #3 on:** June 22, 2006, 05:49:55 AM »

I would call the guys at Laney ... sometimes people can be surprisingly helpful

steve · « **Reply #4 on:** June 22, 2006, 09:21:12 AM »

It will put extra strain on the transformer and could cause damage.

headtheball · « **Reply #5 on:** June 22, 2006, 04:29:34 PM »

If only Laney had a phonenumber that works...

i'm gonna gig away as stock anyway. Sure so what if I rattle a few pint glasses?

HTH AMPS · « **Reply #6 on:** June 22, 2006, 06:10:23 PM »

This amp is cathode biased, you can't just pull two of the valves without adjusting the value of the cathode resistor. You will also need to change the reflected load to the OT by changing the setting of the impedance switch.

:twisted:

headtheball · « **Reply #7 on:** June 22, 2006, 09:30:17 PM »

No matter. I gigged it stock, it smoked everything else in the building. Half volume and it crunched like a beast. Nicest AC30/Rory sound outside of an actual AC30 wound to hell. I'll put it down to the BKP's that I hit more bum notes than a tramp's diary, but the whole place lit up after I finished.