Mod an amp????

[alfredpunkjazz]

have anyone done this?

I'm thinking of putting a switch on my SVT-VR to turn off a pair of tubes, but don't know if this is possible and if its worth... and if its secure!

(I'm thinking that would kill the guarantee... but living here in México, I think that doesn't really matters, LOL!)

What do you guys think?

 

[anyonefortennis]

Someone did that mod to a mesa 400+ but this mod depends on how the tubes are wired. Not sure if you will be able to pull it off with an SVT.

Edit - Found the link - Tber Anderbass has done this. Check out the switches on the right turn on/off tube pairs.

 

[alfredpunkjazz]

That's exactly what I want. Thanks.

 

[JGR]

the svt has an extremely complex output section design, and even if it didn't, i would highly recommend against modding it.

i assume you want to be able to crank it to get more output distortion. consider looking into lower gain preamp tubes as one alternative.

you can also use a power attenuator - weber makes one rated for 150 watts rms and has a 200 watt model on the way - either should be fine so long as you don't go crazy with the level of attenuation.

JR

 

[alfredpunkjazz]

I want to be able to reach the sweet spot at some lower level, sometimes it exceeds the needs of a rehearsal... or maybe... it always exceeds!

LOL

The SVT-VR doesn't has any gain knob, so that makes it hard.

But, what do a power attenuator does?

Thanks for the answer man.

 

[JGR]

a power attenuator is connected between your amp head and a cabinet. it dissipates a portion of the amps output into heat.

check out tedweber.com

i dont know what cab you are using, but you may want to consider a smaller one so you can drive the amp harder.

for clarification, the svt-vr has a gain knob but no master volume.

JR

 

[alfredpunkjazz]

Oh...

Didn't know that about my own amp... LOL

I use the matching 8x10 enclosure.

It's almost new, and it sounds great, but sometimes, at some tunes more acoustic, its hard to get it sounding right, plus it gets into the acoustic guitars, and that its something annoying, lol.

Thanks for the tip man!

 

[anderbass]

Here's the link to the above mentioned amp mod thread:
http://www.talkbass.com/forum/showthread.php?t=238662

I'll just add that this modded Mesa has seen lots of hard use at half power,
and is still seems to be working perfectly.
(I've been playing this 400+ again, because my V4 is currently awaiting repair)

 

[alfredpunkjazz]

Thanks!

 

[anderbass]

Quote:

With something like an SVT or other 300 watt tube amps on the market that are even LESS stable, an attenuater can be recipe for fireworks. With tubes running at their limits to get high power and volume, attentuating the output and running them flat-out can overheat their internals. They could and probably will short and take out a good portion of the amp with them.