Is balanced power (+60/-60 or +120/-120) good for tube amps ? Most desginers critically listen to their creations using regular power.
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.
I have a regular tube amplifier that is hooked up to a balanced power transformer near the wall sockets. I'm just not too sure if the sound coming from the amp is what the designer has envisioned.
vizion said:
I'm not big on "visions". Why don't you listen to the amp with and without the extra transformer and see which one you like more, if you hear a difference. 🙂
I use 75V+75V+15V (165V total) in my 300W/channel amps, but they are hybrid, i.e. contain tubes and transistors.
leadbelly said:
Ah, sorry!
Isolation transformer may be a good thing to eliminate horrible ground loops, but input transformers in power amps would be safer, i.e. Regulations require the green wire (Safety Ground) to be properly connected.
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
But how will balanced power affect SET tube amps? Will the cathode now see the power supply noise? Will additional choke filters be needed on the negative voltage rail?
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.
i have an isolation transformer in my setup. but i'm not too sure if it adds/subtracts harmonics, etc.
Wavebourn said:
My guess is no. I think an input transformer will be sufficient. My guess is that any noise in the cathode will be reflected to the grid and canceled out. But I am not sure if that is true at all.
agent.5 said:
You and Wavebourn still have no clue what the original post is discussing. There is no negative rail. Read one of the links in the thread about balanced power conditioners.
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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