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150.148.0.27
In Reply to: RE: AC Power Regulator for Joule Electra VZN-100 posted by pepillotur on January 05, 2009 at 01:08:51
The general consensus is that AC voltage regulation does some damage to the performance of a hi-power tube amplifier, by constricting the instantaneous power. This has been said in connection with use of conventional audiophile devices. It might be possible to employ an industrial strength regulator, however, that could do the job. I've never had any experience with such devices. It seems that you are in a place that uses 220V-240V standard. Here in the US, I have had a lot of success and satisfaction with just using dedicated lines for all my audio equipment. That way the system is relatively insensitive to power variations caused by the current draw of other devices in my home. We use a 3-wire system here; this also makes it possible to adopt balanced power lines, which I have not tried yet. Have you discussed your issue with Judd Barber?
On another level, it's not ideal to have your AC line voltage changing value, but it ought not to upset the amplifiers enough to make them "unstable". In what way are they unstable? A jump from 222VAC to 230VAC is less than a 5% variation, not so bad, really.
Peps issue is that he is getting short term (like over a period of several minutes or less if I understand correctly) line voltage variations which can cause the filament string voltage (the number that is read out on each amps LCD meter display) from around 63 to 68 volts. Biggist I have ever seen a volt or two at most gradual change during the day (several hoours of operation) here in the states (i.e. of minor consequence).
With the kind of variation that pep is getting, the bias of the tubes can vary a fair amount. Not so great that its going to harm the tubes IMO, but enough to move the bias out of the preferred general zone (sweet spot if you will) were the amps sound thier best. Is this noticeable/audible - to be honest I don't know? (if the change in voltage is short enough in time and settles back to a certain normal value, there may not be enough time for the bias to drift out of that sweet spot - in which case the listener may not notice anything) .
Monster makes a big power conditioner which is essentially a mutli=tap autoformer (i.e. it monitors voltage and switches in or out additional taps on the transformer to keep line voltage from sagging or surging) that will fix the issue.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
Rich, I have been reading several reviews about the Monster AVS2000 voltage stabilizer you recommend me. Specially the Chip Stern review in the Stereophile.com web page. I'm afraid for the fact that it's said there that it works with a servo-motor, then, as the reviewer says: " I could actually hear a mechanical clacking as the servo-motor scrambled to stabilize the voltage" .
Knowing how variable is the voltage in my actual home going up and down, that would mean that I would hear that clacking each very few minutes. I imagine that if I do not play the music always loud or I do not install the Monster in another room, to hear that claking could become really a bit disturbing. Then, do you know of other voltage regulators out there that would work fine feeding the VZN-100's but in a different and more quiet way?. It would be interesting to know other options.
Thanks in advance.
We've been looking at building the AC power regulator of the MA-3 as a stand-along product. It would easily handle the VZN-100. It is continuously variable and does not use taps- instead an automatic variac. The cost would be about $3000 for such a device....
Sounds like it would be just the right thing. Got a link or something I can read to get a better idea of what you are mentioning?
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
http://www.atma-sphere.com/products/ma3.html
The amplifier uses an AC regulation system. Response is not instantaneous, but its pretty fast- within 1/4 second or so. Just about any power supply will store energy well enough that it would be effective. We've thought about building it as a stand-alone product for some years, Right now I'm at CES, and such a thing is really handy with the wall power being variable and often too low!
I'm at CES too Ralph.. working with Bobby P (Merlin) over at the Venetian. If I get a chance I'll try to make it over to the show and say hello.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
Yes Rich, that's exactly what happens. As you say, as a consequence, the bias of the tubes also move out of his adequate working values (26 to 28), more or less going up until 33 or going down to 23. In the past, I used to try to compensate those variations just turning up or down the variac, and doing the same with the bias of each 6C33C tube. But that was really frustrating and a final sonic disaster. Actually I learned to leave the things as they are, with that voltage oscillation just happening, not touching or trying to compensate anything, and the sonic results are clearly better than before.
I think that Monster voltage stabilizer and power conditioner you recommend me could be a good thing, and not only for the VZN-100's, I guess my Joule LAP-150 would also benefit from it. I will try to contact with them, because it seems this Monster company do not have distributors or dealers in Spain or Europe.
Thanks to both for your help.
Sort of on topic - I was looking at a broken 'mains conditioner' at the weekend - nothing built in to regulate the volts, just to clean it up.
Seeing the UK mains incoming on a scope, it's amazing how 'dirty' it is - the waveform is nothing like a nice clean sine wave you get from an audio oscillator . .it's distinctly mangled at the peaks.What effect this does to the sound on any equipment driven by the mains is anyones guess - but it can't do it much good !!
Just another thought - if an OTL is push-pull - then it's bound to draw constant current form the mains - so any instantaneous current limiting by a regulator shouldn't affect anything . . .
Edits: 01/06/09
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