If you are inquiring about using symmetrical supply rails, it is rare in tube amps. There aren't N and P channel tubes, only N channel. Also, most are transformer coupled. So it is pretty much pointless to have a symmetrical supply as ground will make a better voltage reference than a negative supply rail. The only time you really see symmetrical supply rails is in OTL's (output transformerless) that are based on a totem pole type topology.
as far as I was aware, balanced mains just reduced the 'grunge' coming in on the power line. (Does something else happen too?)
By all accounts this generally is reported to sound 'better'. And it's almost certain that the manufacturer would have designed and auditioned their product sans balanced mains input (given the very few households that would have it). But I, as a designer, would want to hear how my product held up in a 'normal' (somewhat sub-optimal) environment anyway (and design accordingly). If it sounded good there, it'd (surely) just sound better with balanced power(?)
By all accounts this generally is reported to sound 'better'. And it's almost certain that the manufacturer would have designed and auditioned their product sans balanced mains input (given the very few households that would have it). But I, as a designer, would want to hear how my product held up in a 'normal' (somewhat sub-optimal) environment anyway (and design accordingly). If it sounded good there, it'd (surely) just sound better with balanced power(?)
hmm, I would have thought the theoretical explanations would have been well known. The real question is whether the theory translates into any actual practical or audible advantages.
But a quick google turned up the following:
Tech stuff from Equitech (a Bal-pow manufacturer)
- Origins
- future
and a random review (the first I happened to stumble across) of one balanced power component
I'm sure there's plenty more -- both yay and nay -- out there too.
I suppose it would be nice if the power came through twisted pairs, but with grounded neutral this wouldn't work!
I have wondered about Pyro cable. For those who do not recognise the name, this is fireproof, but the point is is consists of a copper tube inside which is a pair of copper conductors contained in a sort of powdery ceramic material. Since obviously the tube is grounded I would think that this would provide some protection from radiated rubbish - well at least that which is radiated nearby.
7N7
I have wondered about Pyro cable. For those who do not recognise the name, this is fireproof, but the point is is consists of a copper tube inside which is a pair of copper conductors contained in a sort of powdery ceramic material. Since obviously the tube is grounded I would think that this would provide some protection from radiated rubbish - well at least that which is radiated nearby.
7N7
agent.5 said:
Also, will balanced vacuum in tubes be needed?
Ground loops cause undesired feedback modulated by EMI garbage that distorts the sound. Unfortunately the most audiofile armor I saw contain unbalanced inputs and outputs, unlike studio equipment that is balanced, but anyway ground loops cause some troubles for studios as well since most of modern gear has electronically balanced ins/outs to save costs on quality transformers.
leadbelly said:
Of course there is an negative rail. Balanced power is +60V -- 0 -- -60V. the total is still 120V.
Let say that a normal tube amp has a ground at 0V and B+ at 400V. If you connect this tube amp to a balanced power transformer, you will have B+ at 200V and the ground (of this tube amp) at -200V.
agent.5 said:
No. Even though the isolation transformer and amp power transformer provide galvanic isolation for the power, the multiple grounds need to be connected all the way back to the AC outlet ground for safety. If your tube amp is constructed properly, the circuit ground will be tied back to the chassis ground, and so it will remain 0V.
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