VVR..

[jcat5503]

I've got a Dr Z Mazerati V2 (cathode bias el84 quad) that I'm going to add a VVR to. I bought the kit from Dana Hall

My question is, what's the best way to do it? Scale the whole amp, just the power section, or the power and PI..

Any help is much appreciated! Cheers!

Btw the amp has negative feedback.. Not sure if that matters..

[xtian]

You can review my notes on putting Hall's VVR in my Rocket:

http://ampgarage.com/forum/viewtopic.php?t=17584

After installation, I had DC on my controls, but was able to remove it by installing one additional cap.

I'm not sure if the NFB will make a diff.

[Reeltarded]

If you are going to scale a whole amp you might as well starve it with a variac to see what you think first. The heaters will drop too, but you know.. similar.

I would rather add a PI B+ node and scale only the output if I was going to get busy in there.

[gingertube]

How much you scale depends upon what you are trying to achieve. If you just want to be able to get "full bore" tone at lower volume then just scale output tube B+ and Screen supplies.
I would probably do this as a starter. You can later try also scaling the Phase inverter supply - my experience was that I prefered not to scale the phase inverter but I had a post PI master which allowed be to adjust drive into the output tubes along with the scale level (KOC's "Drive Compensation" control). Never tried scaling the supply to the preamp because I automatically ASS UME D it would sound rubbish.
Cheers,
Ian

[sliberty]

I have only ever installed VVRs so that they scale the whole amp. It is an easier install, as the other way often requires a MV (which seems silly on a VVR equipped amp). I like the results a lot for bring jamming levels under control. I don't find it (or any other solution) useful for bedroom levels.

[jcat5503]

I will probably end up scaling the whole amp, since there's no master. I don't feel like adding a PPIMV either..

Hopefully it retains the feel and tone, just reduces the volume some.

[Firestorm]

Scaling the preamp can change its character. If you don't want to install a master, try scaling the whole power amp including the PI.

[vibratoking]

My experience says scale the whole amp.

It will change the character of the pre, but that change is dwarfed by the impact of not pushing the speakers - when using it for big reductions. I like a fully scaled VVR over just the output section. IMO VVR works best when used for small volume reductions. I hear almost no difference when used that way. If you want bedroom levels, it functions, but does not sound great due to no push on the speakers. VVR is much better than a speaker attenuator IMO.

[chief mushroom cloud]

I would rather add a PI B+ node and scale only the output if I was going to get busy in there.

+1

[KellyBass]

If I'm not mistaken (dreaming), you can switch two resistors in the VVR and adjust the amount of roll off (attenuation). I ended up doing this and choosing just a bit of attenuation instead of bedroom volumes. Worked great!! I ended up labeling the knob as "loud" and "louder".