Author Topic: Pulling tubes in a VH100R (Read 4771 times)

Oli · « **on:** July 10, 2007, 12:31:58 PM »

So, my VH100R is doing the rounds in my rig again, but as usual, i have to have it on about 0.7 volume, and i'm fed up with it because it sounds really cr@p at those levels- really grainy and just rubbish. I've heard many a conflicting post regarding pulling tubes, so i'll ask here, as i'm more inclined to believe you guys rather than people who probably have little experience with tube amps anyway.

Can i safely pull two tubes from my VH100R to reduce the power output to 50w? If this is the case, does it matter if i pull the inner two or the outer two? Also, do i need to adjust the speaker settings; it's currenty pushing two 8ohm cabs, but again i've heard things like 'if you half the power, you need to double/half the impedance'.

Cheers for the help!

EDIT: to clarify- the volume pot has to be that low because above that, it 'jumps' to a really loud volume due to the pot being cr@p/dirty/old

steve · « **Reply #1 on:** July 10, 2007, 01:04:06 PM »

This could damage your transformer, so i would not reommend it.

LazyNinja · « **Reply #2 on:** July 10, 2007, 04:14:50 PM »

I asked the same question to Laney tech support and was told not to do that and also that you'd void the warranty. They told me to use a hotplate.

Two methods I know to attenuate the sound:

1. You can move the FX loop settings knob on the back to the middle position and use the dial next to it to control the output volume. This is basically making the preamp signal weaker so that the power stage has to work harder to produce the same volume.

2. Same idea but with an EQ pedal. Set the FX loop to serial and move down all the sliders on the EQ pedal to reduce the preamp vol. The benefit of this over the above method is that you can taylor the sound with the EQ pedal if you need to. Another benefit is that this can be done on any amp with a serial loop. I do this on my AOR and it sounds great.

Hell Hound · « **Reply #3 on:** July 10, 2007, 07:34:52 PM »

get a THD hot plate or weber mass, pulling 2 tubes wouldn't sound a lot quieter anyway, just minus 3Db wich is nothing. With an attenuator it'll sound better with a very acceptable volume.

HTH AMPS · « **Reply #4 on:** July 10, 2007, 11:14:27 PM »

just because you'll void the warranty doesn't mean it isn't safe to do. you can remove either the inner pair or outer pair, makes no difference (just don't remove both valves on the same side - a big no-no).

if you're currently running the amp into an 8ohm cab you'll need to set the impedance selector one notch down (4ohms) to change the reflected load on the output transformer. you should really rebias but it won't shift more than a few mA anyway - you'll be fine, this is rock & roll afterall.

:twisted:

HTH AMPS · « **Reply #5 on:** July 10, 2007, 11:19:28 PM »

Quote from: LazyNinja

Set the FX loop to serial and move down all the sliders on the EQ pedal to reduce the preamp vol.

I've done similar things with the KFK EQ I had except I turned the input and output gain down on the pedal - worked a treat.

You could rig up a pot in the effects loop to attenuate the signal and reduce the overall volume - I think there are a few guys on ebay selling such boxes for £9.99

:twisted:

JamesHealey · « **Reply #6 on:** July 10, 2007, 11:20:02 PM »

it mismatch with the transformer on amps of lesser quality might cause some damage it's not advised at all.. but it works.

Oli · « **Reply #7 on:** July 10, 2007, 11:37:57 PM »

Thanks guys for all your help, especially LazyNinja, whom with having the same amp, provided me with the solution i was after- the fx loop control 'trick'- worked like a dream :)

Nice to know about pulling the tubes though, but it's not something i'll likely do now, but thank you anyway :)

rock and roll, can now turn my amp up to 2.5!

lifted · « **Reply #8 on:** July 12, 2007, 07:55:35 PM »

oops, I pulled tubes on 1 side when I blew one t'other day. Have played it a few times like that. What damage have I done?

Woogie · « **Reply #9 on:** July 12, 2007, 08:00:43 PM »

Quote from: Oli

Thanks guys for all your help, especially LazyNinja, whom with having the same amp, provided me with the solution i was after- the fx loop control 'trick'- worked like a dream :)

Nice to know about pulling the tubes though, but it's not something i'll likely do now, but thank you anyway :)

rock and roll, can now turn my amp up to 2.5!

I find Laney's are very loud by nature.. my VC30 blows 100w transistors to pieces on volume 4/5 :D. I have had my 100w JCM800 up to 5!! That thing is insane.