London Power Saving for Uni/Bi-Valve?

[Stu Blue]

Just wondering if Andy and co at THD have considered London Power Saving as an alternative to the "attenuator" in the Uni/Bi-valve since so many people on this forum find the tone changes too much with very low volume use. The clips that Manu posted a while back were very impressive...

[stephen sawall]

Last I talked to Andy and Ed (6 weeks ago) they were not releasing the next amp or anything else new till the economy gets better. There was a lot less people at the shop then the last time I was there. I do not know if this is a effect of the economy or not.

The Hot Plate in My Bivalve I was told is a watered down version of the Hot Plate. It has no switches / etc. They did not put it on the Flexi because the thing was "melting". It does not sound near as good as my other / separate Hot Plate with the Bivalve.

Personally I never liked the sound of London Power Saving (or what ever it is called) on any amp I have played with it. (Taste)

If I remember correctly that is done in the phase inverter. A lot of the sound of THD amps is in the power amp. I do not know if it would help with the amp or not ?

All the Hot Plates sound best when used with less attenuation.

To my taste the Hot Plate on the Bivalve sounds best above 1 o'clock.

But who knows ?

[Stu Blue]

Yes ... it's London Power Scaling... I thought it worked by reducing voltage to power valves... here's the manu101 thread ... www.univalve.net/vbulletin/showthread.php?t=2997

[stephen sawall]

The amps I have played I felt were kind of lifless for a better word for it.
Only a few I have tried and I never heard them with out it. So it could have been the amp ?

[DavidB]

I have never tried an amp with the London Power scaling feature. The Maven Peal wattage control, which I understand operates differently, sounds very good in Maven Peal amps -- brings otherwise unbearable loudness down to manageable levels. Unfortunately, Maven Peal amps aren't made anymore and apparently noone has licensed the technology, unlike London Power.

[rubrshrk]

I'm a fan of both Power Scaling and attenuation, but both have some limitations. At more extreme volume reduction, some tone is stripped off. One can compensate by careful tube choice, but only to a point.

Much of the tonal difference that happens with loudness is explained by Fletcher-Munson curves (the modern term is Equal Loudness Curve, which describes a more scientifically derived response) and Steve here did a very useful and informative illustration of this effect with attenuators a while back.

[manu101]

I'm still very happy with my decision to mod my Bivalve with Power scaling. To me, the built-in attenuator was useless at high attenuation and, being a basement player, 30 watts of EL34 power, even at medium gain, is way too loud! Granted, the power scaling mod is not THE magic recipe. But it is an unexpensive alternative. And once you've learn how to use it properly, it does the trick very nicely!