Here's some 4 kva transformers that are new. Just about right for tube gear power levels. Makes a BIG difference (sonically) with tube gear.
Don't take my word for it (whether these are suitable or not), but if I was in the market, I'd try one of these. Nice case when the electronics are gutted. It -very- likely has an electrostatic shield as well.
Just use 120VAC on the 240 VAC input taps....and re-wire the output taps for 60-0-60 across the 120/240 output...and tie the '0' part to ground, to the electrostatic shield, and the ground of the input side. Re-wire the outlets..and presto! Balanced AC. Jus' like that. Buying that quality* of balanced AC anywhere else, commercially, will cost you about ..oh..$2k. may as well get it for a few hunnert instead.
Derate as is nessessary. (likely half rated, at max load, to be safe)
If you can't figure out how to use this puppy from that limited excursion into it's wiring, then leave it alone.
looks like he has lots.
http://cgi.ebay.com/PowerVar-ABC380...ryZ20315QQssPageNameZWD1VQQrdZ1QQcmdZViewItem
*PS, Powervar tends to use toroidals, exclusively, they make their own.
I'd bother, but..over in the corner of my living room, is a 600lb, 50Kva isolation transformer, re-wired for balanced AC...
And..for you transformer coupling freaks.. well..there's some 100khz telefunken stereo! 1:1 (high level!!) transformers on Fleabay right now.
You won't see those again.
Don't take my word for it (whether these are suitable or not), but if I was in the market, I'd try one of these. Nice case when the electronics are gutted. It -very- likely has an electrostatic shield as well.
Just use 120VAC on the 240 VAC input taps....and re-wire the output taps for 60-0-60 across the 120/240 output...and tie the '0' part to ground, to the electrostatic shield, and the ground of the input side. Re-wire the outlets..and presto! Balanced AC. Jus' like that. Buying that quality* of balanced AC anywhere else, commercially, will cost you about ..oh..$2k. may as well get it for a few hunnert instead.
Derate as is nessessary. (likely half rated, at max load, to be safe)
If you can't figure out how to use this puppy from that limited excursion into it's wiring, then leave it alone.
looks like he has lots.
http://cgi.ebay.com/PowerVar-ABC380...ryZ20315QQssPageNameZWD1VQQrdZ1QQcmdZViewItem
*PS, Powervar tends to use toroidals, exclusively, they make their own.
I'd bother, but..over in the corner of my living room, is a 600lb, 50Kva isolation transformer, re-wired for balanced AC...
And..for you transformer coupling freaks.. well..there's some 100khz telefunken stereo! 1:1 (high level!!) transformers on Fleabay right now.
You won't see those again.
Oh Yes......
One more thing. Balanced AC blows all other AC noise control methods completely out of the water. No current and no frequency extension issues with a simple transformer,as long as you stay well away from it's given limits for VA throughput. It is specifically beneficial to tube gear, as tube gear transformers are voltage MULTIPLIERS, not dividers, like SS transformers.
VERY sensitive to AC noise, them there tubes.
Now, what will it be like?
I predict, without blinking..that if you try good balanced AC power in your tube audio system..that will be it. Period. You will NEVER run your audio system without it again. You will use it....for the rest of your life, or as long as you are using an AC power grid. It will be a very important performance upgrade for each piece of equipment that is plugged into it. The effect, as you can see, will be cummulative, on all gear. Beat that.
That good.
One more thing. Balanced AC blows all other AC noise control methods completely out of the water. No current and no frequency extension issues with a simple transformer,as long as you stay well away from it's given limits for VA throughput. It is specifically beneficial to tube gear, as tube gear transformers are voltage MULTIPLIERS, not dividers, like SS transformers.
VERY sensitive to AC noise, them there tubes.
Now, what will it be like?
I predict, without blinking..that if you try good balanced AC power in your tube audio system..that will be it. Period. You will NEVER run your audio system without it again. You will use it....for the rest of your life, or as long as you are using an AC power grid. It will be a very important performance upgrade for each piece of equipment that is plugged into it. The effect, as you can see, will be cummulative, on all gear. Beat that.
That good.
balanced AC cancels line noise. It comes through, in most AC rectified gear. I'm being overly fair. OK..ALL AC rectified gear, it comes through. Tube transformers are voltage multipliers. Even though some of the inductance of the PS system, etc..will eat some of the noise, large parts of it come through..and are superimposed on top of your audio signal, destroying transient integrety.The transient line noise ALWAYS comes though.
The human ear works like diode, it is single sided. The only important part of the signal is the transient and it's temporal placement. Everything else, is nearly unimportant. Wasted space..tick, tick tick..your ear waits for the next transient to figure out what it is listening to.
If you analyse a given device in those terms and ways....specifically..you end up with a clear understanding of what it takes to make a given piece of gear sound good.
You can use other types of devices to try and cure this issue, but they always result in transient smear..as this is the point where they are least effective.
99.99% or so of the signal will be unaffected..and if you sit down in front of a bunch of measuring gear and measure such, you will get those smug feeling numbers thrown back at you..but a clear understanding that they DON'T relate to--what you HEAR. The measurement method, specifically the weighting and what parts are being looked at is horribly wrong.
Measure the bits that are important to the ear and you'll start to get somewhere.
The isolation/balancing transformer, if underloaded, like a line signal coupling transformer, will behave the same, in many ways. If you look at the specifications for a tube transformer, you will note that the frequency limts at either end of the audible spectrum get 'shorted up' as you increase the current field loading.
Since this balancing transformer is under similar loading, as the signal will modulate the current draw from AC, the same considerations apply when deciding what current ratings and VA ratings need be looked at when selecting one.
Over-saturate it, and it will blunt high current transients. Everything but the bass will be fabulous. It's OK to overload or near the limits with computer gear, but stick to underusing the transformer for audio equipment. The bigger, the better.
The transformer, as you are using the wiring and VA ratings in an odd way, require that you de-rate it's maximum loading by a factor of 2. (this, if it is a 120/240VAC Input-120/240VAC output) The reality is that it can be loaded to a factor of about 0.6 of it's proper rating, as some of the rating is thermal in nature. However, over-loading it will cause severe loss of bass power.
I have a mis-wired 600lb 50Kva tansformer, which is running a 250Wpc stereo set up. It is severely underlaoded, and thus, does not present coloration to the system, only the beauty of extreme AC cleanliness. I get the same level of noise rejection on the AC lines as I would if I was transmitting a balanced audio signal. In this case, the noise reduction is applied to the transinet noise of the AC power coming into the system. As for that AC noise..there is PLENTY OF IT. HUGE AMOUNTS.
As stated, doing it via filtering is a way to destroy the crap out of all the quality you fight for. A underloaded Isolation transformer, wired for balanced AC is one simple way to get your cake and eat it too.
Works wonders, try it.
If you live in a big city, this is an EXTREME upgrade to your system's sonic quality. Big time change for the better. Large amounts of treble harshness and indistinct transients, depth of image, etc, will all be cleared up and improve dramatically. All those strange words/things that audiophiles talk about will come to your mouth, like 'plosives', 'liquidity', 'transient integrety', 'drive', 'slam', etc.
The exact method of which by you physically hear will be the exact point of attack/issue that is cleaned up by running balanced AC. It is nearly impossible to target and attack..and succeed at fixing a more important aspect of audio reproduction, when allied to an understanding of exactly how one recognises and understands 'quality' in audio reproduction.
Get it?
Once again..seriously..once you try this, you are incredibly likely to never go back to any other type of AC use, period. Balanced power, all the way. Like a new limb growing out of your back, it will always be with you. That transformer or more like them, bigger, better, etc..will go with your audio set ups, everywhere. From that moment--without question.
Caveat: If you listen to music with crummy CD players with bad clocking, this isn't gonna do much for you. Garabge in, garbage out. If you only hear and understand a small and negligble improvment, well.. You might be beyond help..!
The human ear works like diode, it is single sided. The only important part of the signal is the transient and it's temporal placement. Everything else, is nearly unimportant. Wasted space..tick, tick tick..your ear waits for the next transient to figure out what it is listening to.
If you analyse a given device in those terms and ways....specifically..you end up with a clear understanding of what it takes to make a given piece of gear sound good.
You can use other types of devices to try and cure this issue, but they always result in transient smear..as this is the point where they are least effective.
99.99% or so of the signal will be unaffected..and if you sit down in front of a bunch of measuring gear and measure such, you will get those smug feeling numbers thrown back at you..but a clear understanding that they DON'T relate to--what you HEAR. The measurement method, specifically the weighting and what parts are being looked at is horribly wrong.
Measure the bits that are important to the ear and you'll start to get somewhere.
The isolation/balancing transformer, if underloaded, like a line signal coupling transformer, will behave the same, in many ways. If you look at the specifications for a tube transformer, you will note that the frequency limts at either end of the audible spectrum get 'shorted up' as you increase the current field loading.
Since this balancing transformer is under similar loading, as the signal will modulate the current draw from AC, the same considerations apply when deciding what current ratings and VA ratings need be looked at when selecting one.
Over-saturate it, and it will blunt high current transients. Everything but the bass will be fabulous. It's OK to overload or near the limits with computer gear, but stick to underusing the transformer for audio equipment. The bigger, the better.
The transformer, as you are using the wiring and VA ratings in an odd way, require that you de-rate it's maximum loading by a factor of 2. (this, if it is a 120/240VAC Input-120/240VAC output) The reality is that it can be loaded to a factor of about 0.6 of it's proper rating, as some of the rating is thermal in nature. However, over-loading it will cause severe loss of bass power.
I have a mis-wired 600lb 50Kva tansformer, which is running a 250Wpc stereo set up. It is severely underlaoded, and thus, does not present coloration to the system, only the beauty of extreme AC cleanliness. I get the same level of noise rejection on the AC lines as I would if I was transmitting a balanced audio signal. In this case, the noise reduction is applied to the transinet noise of the AC power coming into the system. As for that AC noise..there is PLENTY OF IT. HUGE AMOUNTS.
As stated, doing it via filtering is a way to destroy the crap out of all the quality you fight for. A underloaded Isolation transformer, wired for balanced AC is one simple way to get your cake and eat it too.
Works wonders, try it.
If you live in a big city, this is an EXTREME upgrade to your system's sonic quality. Big time change for the better. Large amounts of treble harshness and indistinct transients, depth of image, etc, will all be cleared up and improve dramatically. All those strange words/things that audiophiles talk about will come to your mouth, like 'plosives', 'liquidity', 'transient integrety', 'drive', 'slam', etc.
The exact method of which by you physically hear will be the exact point of attack/issue that is cleaned up by running balanced AC. It is nearly impossible to target and attack..and succeed at fixing a more important aspect of audio reproduction, when allied to an understanding of exactly how one recognises and understands 'quality' in audio reproduction.
Get it?
Once again..seriously..once you try this, you are incredibly likely to never go back to any other type of AC use, period. Balanced power, all the way. Like a new limb growing out of your back, it will always be with you. That transformer or more like them, bigger, better, etc..will go with your audio set ups, everywhere. From that moment--without question.
Caveat: If you listen to music with crummy CD players with bad clocking, this isn't gonna do much for you. Garabge in, garbage out. If you only hear and understand a small and negligble improvment, well.. You might be beyond help..!
There are two kinds of line noise. Common-mode and differential.
There's really not much point in fretting about differential because rectification generates so many more (higher amplitude) harmonics anyway. Having said that, toroids tend to be wider bandwidth and pass such noise more readily than old-fashioned EI transformers, so they're best avoided. Differential mode noise is easily filtered.
Common-mode noise is usually passed straight through the mains transformer via the interwinding capacitance from primary to secondary. It's actually transistor amplifiers that are more susceptible because their signal voltages are so much lower in proportion to the noise. By comparison, a valve amplifier has signal voltages typically 20dB higher, conferring 20dB more rejection to incoming power supply noise. The output transformer then steps down the signal (and any noise) to the same loudspeaker voltages that the transistor amplifier produced. An earthed foil E/S screen between primary and secondary of the mains transformer very nearly eliminates common-mode mains noise, but it isn't often fitted because it costs money.
Your point about saturating mains transformers is well made. Most mains transformers are run close to saturation because this is most efficient. (I'm afraid "efficient" has a very specialised meaning to a transformer manufacturer and is related closely to cost.) Such a transformer leaks a lot of flux. If sensitive electronics are nearby, they will pick it up and it's hard to screen it. Either keep mains transformers well away from sensitive electronics, or run the core at a lower flux density. Or both.
I suspect that the other reason that interposing an over-rated isolation transformer between the mains and domestic equipment is that there is often DC on the mains. DC easily saturates mains transformers (especially toroids), causing leakage flux. An over-rated isolation transformer would block the DC from saturating the poorly designed domestic transformers.
There's really not much point in fretting about differential because rectification generates so many more (higher amplitude) harmonics anyway. Having said that, toroids tend to be wider bandwidth and pass such noise more readily than old-fashioned EI transformers, so they're best avoided. Differential mode noise is easily filtered.
Common-mode noise is usually passed straight through the mains transformer via the interwinding capacitance from primary to secondary. It's actually transistor amplifiers that are more susceptible because their signal voltages are so much lower in proportion to the noise. By comparison, a valve amplifier has signal voltages typically 20dB higher, conferring 20dB more rejection to incoming power supply noise. The output transformer then steps down the signal (and any noise) to the same loudspeaker voltages that the transistor amplifier produced. An earthed foil E/S screen between primary and secondary of the mains transformer very nearly eliminates common-mode mains noise, but it isn't often fitted because it costs money.
Your point about saturating mains transformers is well made. Most mains transformers are run close to saturation because this is most efficient. (I'm afraid "efficient" has a very specialised meaning to a transformer manufacturer and is related closely to cost.) Such a transformer leaks a lot of flux. If sensitive electronics are nearby, they will pick it up and it's hard to screen it. Either keep mains transformers well away from sensitive electronics, or run the core at a lower flux density. Or both.
I suspect that the other reason that interposing an over-rated isolation transformer between the mains and domestic equipment is that there is often DC on the mains. DC easily saturates mains transformers (especially toroids), causing leakage flux. An over-rated isolation transformer would block the DC from saturating the poorly designed domestic transformers.
Re: Oh Yes......
You are talking of using this as an isolation transformer aren't you? Would your power transformer not be unaware of it? If you used it as the power transformer itself then it's a different story. Only then can I see the case for the power transformer not overloading, which by the way, I agree with you on.
I agree with EC8010 that valve amps often have elevated signals to go along with their elevated supply voltages.
Noise may also be transmitted through interwinding capacitance and this is not proportional to the turns ratio. AFAIK it is often loosely proportional to a transformers size, making a shield for this large transformer appear to be a must.
Is not normal RF filtering a good thing for line noise?
You do have me thinking of trying a larger power transformer. I like the idea of the filter caps not needing to take the lions share of the responsibility for power supply solidity. It just sounds right, if you take my meaning.
However, I do run class A all the way, and I have series resistance throughout my supply. Would I have less to gain here?
You are talking of using this as an isolation transformer aren't you? Would your power transformer not be unaware of it? If you used it as the power transformer itself then it's a different story. Only then can I see the case for the power transformer not overloading, which by the way, I agree with you on.
I agree with EC8010 that valve amps often have elevated signals to go along with their elevated supply voltages.
Noise may also be transmitted through interwinding capacitance and this is not proportional to the turns ratio. AFAIK it is often loosely proportional to a transformers size, making a shield for this large transformer appear to be a must.
Is not normal RF filtering a good thing for line noise?
You do have me thinking of trying a larger power transformer. I like the idea of the filter caps not needing to take the lions share of the responsibility for power supply solidity. It just sounds right, if you take my meaning.
However, I do run class A all the way, and I have series resistance throughout my supply. Would I have less to gain here?
In my experience of trying just about every kind of RF and EMI noise type filter under the sun..be it pro, consumer, audio, video, industrial, etc..every single one of them has been harmful to the 'sound' of the system. Ever last one of them. I was always happier with the audio quality with such devices removed, and I consigned myself to having 'audio quality' at only 3am, when the load was low, and thus the noise onthe AC line was low.
Not the world's most technical answer, but a general attack on the idea of RF filtering, as being 'effective'...but also ruining the audio system at the same time.
If one looks at the RF filter, you would find that it modulates the transient (current and voltage throughput, which is dynamic..as the nature of the power draw) as well as getting rid of any RF noise on the line. Thus, it goes right after and ruins the exact component of the signal you are looking to preserve.
Like pops and clicks on a record..they may be there and noticable, but the RF noise may be far less damaging than the RF filter is. Like the same way a pop and click remover for LP's may work, but it beats the crap out of the audio signal at the same time. One is better off without the RF filter --and better off without the pop and click remover.
Pardon my lack of a correct technical point of discussion, it does not invalidate the validity of my observations and the proposed cure. Both work.
Post #6
I have a related question:
In the US, we have 2 phase power to the house (120-0-120). Most people only use 120V, but 240V is available. So, is it balanced power already?
Can I just use a 2:1 isolation transformer and get 60-0-60 (120V) to power tube gears?
Sounds workable. This particular 'leg' of your AC power system is generally QUIETER, noise wise, as well. This, compared to the single phase 120 that comes into the house. However, not knowing the exact characteristics of the AC coming into US houses(I'm in Canada, we don't have 208 and 480, for example) , I'd be real careful here. Make sure of the of the phasing of those sine waves first.
Not the world's most technical answer, but a general attack on the idea of RF filtering, as being 'effective'...but also ruining the audio system at the same time.
If one looks at the RF filter, you would find that it modulates the transient (current and voltage throughput, which is dynamic..as the nature of the power draw) as well as getting rid of any RF noise on the line. Thus, it goes right after and ruins the exact component of the signal you are looking to preserve.
Like pops and clicks on a record..they may be there and noticable, but the RF noise may be far less damaging than the RF filter is. Like the same way a pop and click remover for LP's may work, but it beats the crap out of the audio signal at the same time. One is better off without the RF filter --and better off without the pop and click remover.
Pardon my lack of a correct technical point of discussion, it does not invalidate the validity of my observations and the proposed cure. Both work.
Post #6
I have a related question:
In the US, we have 2 phase power to the house (120-0-120). Most people only use 120V, but 240V is available. So, is it balanced power already?
Can I just use a 2:1 isolation transformer and get 60-0-60 (120V) to power tube gears?
Sounds workable. This particular 'leg' of your AC power system is generally QUIETER, noise wise, as well. This, compared to the single phase 120 that comes into the house. However, not knowing the exact characteristics of the AC coming into US houses(I'm in Canada, we don't have 208 and 480, for example) , I'd be real careful here. Make sure of the of the phasing of those sine waves first.
My Balanced AC tranny, in the corner of my listening room. Note the scale of the CD jewel box, at the left bottom corner. You can peer inside and see the transformer. A bit on the big side. You can also see the 10 guage power cables (black)
Should be enough clean current throughput for most folk. I paid $300 for it. And $400 for the shipping......
Should be enough clean current throughput for most folk. I paid $300 for it. And $400 for the shipping......
An externally hosted image should be here but it was not working when we last tested it.
Quick and dirty:
http://www.equitech.com/articles/origin.html
It's becoming a recognized technique in recording studios.
http://www.equitech.com/articles/origin.html
It's becoming a recognized technique in recording studios.
You'd be better off saving the $700 altogether...
I could expain in much greater detail, but EC8010 has done so. Balanicng could help in certain circumstances, but. you either hear (and measure) 60 Hz coming through your system or you don't.
As far as noise is concerned, a larger transformer will only increase the capacitance that couples common-mode noise in; it will do little for differential mode noise... given similar transformer construction.
I could expain in much greater detail, but EC8010 has done so. Balanicng could help in certain circumstances, but. you either hear (and measure) 60 Hz coming through your system or you don't.
As far as noise is concerned, a larger transformer will only increase the capacitance that couples common-mode noise in; it will do little for differential mode noise... given similar transformer construction.
Makes a noticeable difference in my system. Wouldn't be without it having heard it. Poobah, just wondering, have you ever listened to an amplifier fed by a balanced power transformer?
KBK, any idea the dB isolation of these transformers? I can't find a figure in the data sheet or on their website.
KBK, any idea the dB isolation of these transformers? I can't find a figure in the data sheet or on their website.
Tom,
I do have amps that run on 240, and its definitely eliminates hum problems in many cases. As I said though, you either hear hum or you don't. As EC has stated, a proper shield in the transformer makes this generally insignificant.
There is a small fallacy in the link to "balanced power". That is that the imbalance current is still being shoved into ground... just a few feet farther upstream. In the situation of a studio, where long runs of low signal are involved, I could see the balancing thing being a real help, especially if you had some liberty regarding the definition of ground.
Hum issues aside, I don't think any other sonic claims would stand up to scrutiny. If you have intractable hum issues (via a dirty ground), by all means do it. It makes perfect sense.
BTW, the explanations for this are all rather poor. "Reactive currents" and all cloud the issue. One need only draw a capacitor from the center of the primary winding to the secondary to understand this minor evil a little more clearly.
I do have amps that run on 240, and its definitely eliminates hum problems in many cases. As I said though, you either hear hum or you don't. As EC has stated, a proper shield in the transformer makes this generally insignificant.
There is a small fallacy in the link to "balanced power". That is that the imbalance current is still being shoved into ground... just a few feet farther upstream. In the situation of a studio, where long runs of low signal are involved, I could see the balancing thing being a real help, especially if you had some liberty regarding the definition of ground.
Hum issues aside, I don't think any other sonic claims would stand up to scrutiny. If you have intractable hum issues (via a dirty ground), by all means do it. It makes perfect sense.
BTW, the explanations for this are all rather poor. "Reactive currents" and all cloud the issue. One need only draw a capacitor from the center of the primary winding to the secondary to understand this minor evil a little more clearly.
Yeah Poobah, it's all posturing and conjecture - until you jump off that cliff.
Come on back, once you've tried it.
I've said it before: Once you've tried balanced AC, you will always use it, after that exposure. You will not have a 'serious' (a set up you love to listen to) audio system without it.
For example, we tried it yesterday on a rebuilt Ref T-amp and a panasonic DVD/CD player, in the office. Bith ahve crummy switch mode PS's. UG. Both were improved -- dramatically. It was jaw dropping how obvious it was and even non audiophiles, common dude of the street, the factory workers, they got it and in a single heartbeat. Ie, 5 seconds of the unbalanced vs the balanced AC, and the heard it, and they 'got it'. Zero proding or prepping of any kind. No suggestives or anything like that. Simply put balanced AC Topaz tranny in place listen..then remove. Compare. Clear as a bell.
Come on back, once you've tried it.
I've said it before: Once you've tried balanced AC, you will always use it, after that exposure. You will not have a 'serious' (a set up you love to listen to) audio system without it.
For example, we tried it yesterday on a rebuilt Ref T-amp and a panasonic DVD/CD player, in the office. Bith ahve crummy switch mode PS's. UG. Both were improved -- dramatically. It was jaw dropping how obvious it was and even non audiophiles, common dude of the street, the factory workers, they got it and in a single heartbeat. Ie, 5 seconds of the unbalanced vs the balanced AC, and the heard it, and they 'got it'. Zero proding or prepping of any kind. No suggestives or anything like that. Simply put balanced AC Topaz tranny in place listen..then remove. Compare. Clear as a bell.
Clarity, ease of signal presentation, correctness in dynamics, subtutly of minute signals, extreme drop in treble 'hash', etc, etc. Oh yes, mo'better bass. Odd, but true. But, better clocks in CD players always bring mo better bass..and likely for the exact same reasons in terms of clarity of signal.
One of the reasons it works so well, is that it improves all gear in a system, so it is like a 2-3-4x multiple of improvements in that single signal chain, which comes out to being a MASSIVE improvement, overall.
One of the reasons it works so well, is that it improves all gear in a system, so it is like a 2-3-4x multiple of improvements in that single signal chain, which comes out to being a MASSIVE improvement, overall.
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