BALANCED POWER??  more snake oil or is there something to it?? - Page 1
Forum section: electronics / general

author: OhmSweetOhm
author_rank: Newbie
timestamp: July 14, 2013, 12:00:43 am
content: Balanced power seems to be all the rage for uber high end audio and recording studios.... is there really something to this balanced power idea or is this more nonsense?Thanks Dave!!-Don

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: July 14, 2013, 01:35:13 am
content: I've never heard of it, despite being a musician and an audio enthusiast.My only concern is to keep power cables away from signal cables. The miles of crap cable running through your home isn't going to be disregarded easily.

author: c4757p
author_rank: Super Contributor
timestamp: July 14, 2013, 01:45:58 am
content: I'm not an audio guy, but it looks like "I don't understand what causes AC hum" voodoo bullshit to me. As far as I can tell, the premise is that because of the differential supply, there will be an equal amount of interference in both directions, which will cancel out. Looks like a fundamental misunderstanding of why things like LVDS reduce EM emissions. The current is what causes the interference, not the voltage, and this is already differential. Every mains outlet and inlet has exactly one line and one neutral, it has to be. You don't run power out of one outlet and back into the other.Electrostatic (capacitive) couplingwouldbe reduced by this, but capacitive coupling should only be a problem if you run signal and power wiring very close together. Just a few mm distance between them should be enough to reduce capacitive coupling below significant levels.

author: IanB
author_rank: Super Contributor
timestamp: July 14, 2013, 01:58:41 am
content: I've no idea what this is about, but in the old days the power supplies for valve (vacuum tube) equipment did not have voltage regulation. They had a smoothing capacitor and a filtering inductor and that was it. They relied on the amplifier circuit to have power supply ripple rejection so that power supply ripple didn't make it into the output.Every well designed circuit should have inherent noise rejection.

author: c4757p
author_rank: Super Contributor
timestamp: July 14, 2013, 02:00:54 am
content: Quote from: IanB on July 14, 2013, 01:58:41 amAC mains -> center-tapped isolation transformer, center tap grounded. Now the power is balanced about ground. A magic charm against mains hum.

author: c4757p
author_rank: Super Contributor
timestamp: July 14, 2013, 02:05:18 am
content: By the way, OhmSweetOhm, your username is brilliant.

author: IanB
author_rank: Super Contributor
timestamp: July 14, 2013, 02:15:16 am
content: Quote from: c4757p on July 14, 2013, 02:00:54 amWell I could see how that might work. Every positive going ripple on the +ve rail would be balanced by a -ve going ripple on the -ve rail. Assuming your output was referenced to ground, then the ground voltage would stay anchored while the +ve and -ve rails moved symmetrically up and down around it.

author: c4757p
author_rank: Super Contributor
timestamp: July 14, 2013, 02:20:25 am
content: Still, unless you ensure that both "phases" (dear god, let's not get into that discussion again) are always an equal distance from all signal lines, you're not doing much for voltage-induced hum, and nothing at all for current-induced hum. The only way you're going to ensure equidistant wires is if the power is transmitted on coax.If the audio people weren't always so convinced that DC-DC converters were the spawn of Satan, you could solve these stupid hum issues by powering everything from a ground-referenced, regulated DC power supply. But then you'd see them running the DC supply at 60V and regulating it to 3V with a linear regulator strapped to an engine block for heatsinking...

author: TerminalJack505
author_rank: Super Contributor
timestamp: July 14, 2013, 02:33:06 am
content: Nitro2k01 asked about this inthis thread.It doesn't look like it was ever settled in that thread but at least Nitro2k01 had hearsay evidence that it eliminated hum.

author: C
author_rank: Super Contributor
timestamp: July 14, 2013, 03:38:47 am
content: In the past, a lot of things were done single ended mode. This is a down to a cost thing, not a good thing.Single ended puts the return path into a noise path.Today the other thing is everyone wanting to connect grounds. And by doing this end up making things worse.From a Safety point of view all that is needed is to keep differential signals from floating up to some high voltage such that the high floating charge could be a hazard.There are many types of grounds and they should not all be connected every place possible.Safety ground at the wall is just that A connection for power safety purposes. That does not mean that a RF ground should be connected every place possible to the power safety ground.A great Scope would have a differential input on each channel. This at one time was a high cost thing to do. Now if you look at most high speed chips it is almost a no cost thing to do.If you want a low noise switcher supply you could use a common mode choke in place of the inductor in one side, but this has a side effect to the circuit such that it also will need to handle the voltage difference in the signal path that the second half of the common mode choke will create.. If you then slap ground connections to each end of this signal path like some want to do then you have a case of instead of helping reduce noise, the common choke is preventing the original inductor half action due to the added UN-needed ground. You should still have a ground path, just not every where as this shows.C

author: JuKu
author_rank: Frequent Contributor
timestamp: July 14, 2013, 07:26:59 am
content: This is the first time I hear that particular term. But generally talking about high end audio power supplies, EMI (usually), lenght matching, magnetics etc have nothing to do with it. Sure, in high speed digital circuitry or RF all those are important, but in audio, the important frequency range is several orders of magnitude off. It is about plain old PSRR.Example, a careless design: Take a very good audio op-amp, and you might have 80dB PSRR to work with. A plain 78xx power supply, well done, and you still easily might have 10mV riding on supplies. That's 1uV noise per supply times two (both rails). Your simple design might have three op-amps. Now there is 6uV noise/hum/distortion on your signal from power supplies alone. Although the design is good solid engineering, uses good parts, works great and to the datasheet performance, it stll isn't exactly high-end.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: July 26, 2013, 07:03:25 pm
content: AFAIK it's about having a "clean", noiseless power supply. Some hi-fi people will swear that running everything from a battery results in better sound.Personally I'm more concerned with the music than the sound quality (a major chord is a major chord, regardless of the device), and am a lo-fi enthusiast, but I've seen some pretty freakishly awesome hi-fi setups that make you feel as if you were in the recording room*, so I can definitely say that there is some meaning in all their gimmicks - even though there is a lot of superstition going on there.* - awesome as it was, it CERTAINLY isn't worth the $10000 that it cost, by any standard.

author: free_electron
author_rank: Super Contributor
timestamp: July 26, 2013, 07:52:23 pm
content: anyone knows that serious audio equipment runs off 3 phase supplies ...

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 27, 2013, 05:21:51 am
content: Had to search abit, but yeah, sure;http://www.pknc.com/3phase_eng.html(kind of awesome; 40kw coming from a 19" 1HE unit. 2x20kW into 2.6ohms, sort of a modulated welding thing [130A(pk)/ch] )Hope you don't mind I omitted the 'high-end' from the contextThis gear is for big raves and concerts. For serious work

author: SeanB
author_rank: Super Contributor
timestamp: July 27, 2013, 06:12:37 am
content: Now that is one serious power amplifier. I remember seeing plans to build a DIY 1kW power amplifier, and looked at the sheer number of high voltage high current output devices needed, and that the driver was a 15A power device on it's own. It also needed +- 100V power rails at around 30A per channel. That and a load impedance of 0.5R

author: DRT
author_rank: Regular Contributor
timestamp: July 27, 2013, 06:03:44 pm
content: Quote from: c4757p on July 14, 2013, 02:05:18 amAgreed, but Kraftwerk got there first!

author: rdnzl999
author_rank: Newbie
timestamp: August 29, 2013, 10:34:50 pm
content: I vote "not snake oil".However, improvement may be subtle, profound, or unnoticeable, depending on what you power with it.I have an Equitech 1.5RQ in front of my stereo and TV.Audible hum is gone from all transformers in the system. The only mechanical noise is the hard drive in the cable box. Sizzle in the picture (Plasma TV) is much reduced, blacker near-blacks. Absolutely no audible noise in the system listening at the speakers.Subjective improvements in sound were noted. You know, bass, image, etc, all seemed just a little more tweaked. The same things as noted by others.I bought the Equitech (used $1,000) from a studio upgrading to a whole-house balanced system.System:Speakers - MartinLogan ReQuestAmplification - Krell FPB 350 mcxPreamplifier - Krell KCTDAC - Benchmark DAC1 HDRVideo - Oppo 93Radio - Sony XDRF-1HDCD - California Audio Labs DX-2 used as transport and coaxial digital outUSB - from PC to DAC 92khzDigital Switch - Audio Authority 1177ADigital EQ - Behringer UltraCurve DEQ2496 (cheap but effective)TV - LG PK950 Plasma

author: Monkeh
author_rank: Super Contributor
timestamp: August 30, 2013, 07:58:06 am
content: Please come back after you've proved it with a double blind test. Until then, you're just convincing yourself you got something worthwhile out of your $1000.

author: rdnzl999
author_rank: Newbie
timestamp: August 30, 2013, 09:05:53 pm
content: "Please come back after you've proved it with a double blind test. Until then, you're just convincing yourself you got something worthwhile out of your $1000.I have nothing to prove to you. No double blind needed when the audible transformer mechanical hums are no longer audible even with a stethoscope.It's my system, my observation, my comment, my money. Go cry on somebody else's shoulder.

author: c4757p
author_rank: Super Contributor
timestamp: August 30, 2013, 09:17:47 pm
content: Quote from: rdnzl999 on August 30, 2013, 09:05:53 pmNo test needed? Horseshit. By adding a transformer, you've completely restructured the way your devices are powered. Ground loops are going to change, you have no way to know that it's the balanced power that did it. Try again, and this time rewire that thing so the power runs through the transformer without shifting the level. I bet the hum is still gone.Quote from: rdnzl999 on August 30, 2013, 09:05:53 pmWhat is it with people who say this? It's my comment, you can't touch it? What reason could you possibly have to post this to a public forum other than seeking responses? This isn't an audio forum, we're not going to all just masturbate to the equipment. (It takestest equipmentto getushorny...)

author: madires
author_rank: Super Contributor
timestamp: August 30, 2013, 09:25:41 pm
content: Quote from: rdnzl999 on August 30, 2013, 09:05:53 pmBalanced AC power prevents mechanical hum of transformers? I suddenly feel that the universe collapses into a void.

author: c4757p
author_rank: Super Contributor
timestamp: August 30, 2013, 09:29:35 pm
content: Oh boy, I didn't even notice that gem...

author: rdnzl999
author_rank: Newbie
timestamp: August 30, 2013, 09:57:03 pm
content: Look guys...I'm sitting here with Balanced Power running my Audio and Video system.I can assume from the comments that none of you are.The original post asked "Is it snake oil?"My answer (from my direct experience with the equipment) is "I think it is not."What's wrong with that?

author: c4757p
author_rank: Super Contributor
timestamp: August 30, 2013, 10:00:43 pm
content: Quote from: rdnzl999 on August 30, 2013, 09:05:53 pmThis is what's wrong with it.

author: rdnzl999
author_rank: Newbie
timestamp: August 30, 2013, 10:10:04 pm
content: Well, EXCUUUUUUSE me!

author: dr.diesel
author_rank: Super Contributor
timestamp: August 30, 2013, 10:12:15 pm
content: Quote from: rdnzl999 on August 30, 2013, 10:10:04 pmThere is no excuse for deliberate BS.

author: rdnzl999
author_rank: Newbie
timestamp: August 30, 2013, 10:13:37 pm
content: Where's the BS? I posted my observation and comment on the TOPIC.Thenthe trouble started.

author: Bored@Work
author_rank: Super Contributor
timestamp: August 30, 2013, 10:16:51 pm
content: I have not yet decided if it is actually entertaining watching an audiofool making a fool of himself, or if it is just another boring rerun of the clueless-trying-to-convince-us-of-snake-oil show, episode 2574.

author: madires
author_rank: Super Contributor
timestamp: August 30, 2013, 10:24:33 pm
content: Quote from: Bored@Work on August 30, 2013, 10:16:51 pmObviously you got an affection for simple switchers :-)

author: rdnzl999
author_rank: Newbie
timestamp: August 30, 2013, 10:25:22 pm
content: Here's my "audio fool" system.

author: dfmischler
author_rank: Frequent Contributor
timestamp: August 30, 2013, 10:30:22 pm
content: Hey, is that an oscilloscope in the left rear corner? Tell us about it

author: Kjelt
author_rank: Super Contributor
timestamp: August 30, 2013, 10:47:28 pm
content: Not to defend it because I don't have the knowledge about this but there seem to be some patents on this stuff one of which shows that the transformers are kinda special in a sense that they are "bifilar wound" (see picture).Quote from: c4757p on July 14, 2013, 02:00:54 amThe whole (audiofool) idea behind this is also (if I got it right) is that they don't use the ground of the mains input on the secondary side but use a new (as they call it "clean") ground with it's own grounding pin (struck a lot of meters in the ground where even in dry summers the soil should be wet).But I don't see the extra advantage over a normal isolation transformer with seperate ground in this case?I try to keep an open mind, perhaps some transformer expert might shed some light on this.

author: madires
author_rank: Super Contributor
timestamp: August 30, 2013, 11:03:54 pm
content: Quote from: Kjelt on August 30, 2013, 10:47:28 pmBifilar winding in transformers reduces stray inductance and increases capacitive coupling. I'm surprised that such old technology gets patents granted.

author: Rerouter
author_rank: Super Contributor
timestamp: August 30, 2013, 11:06:11 pm
content: A bit of searching makes it seem bifilar windings, are used to reduce the leakage inductance of a winding, with another page also claiming it shunted fast emf changes into heat via the second winding,the first point is only really relevant to signal coupling transformers, though the second point and a physical separation of the transformer case from mains earth probably explain his sudden reduction in transformer hum :/seriously dont trust me on any of this, it was just my own attempt to understand it

author: madires
author_rank: Super Contributor
timestamp: August 30, 2013, 11:28:12 pm
content: Actually there are two ways of bifilar winding. The one we talked about is using two separated wires (primary and secondary). The other one is using one wire or two wires connected at the other end, like a bifilar wirewound resistor (to reduce inductance). The latter method used for a transformer would result in a resistor (wire resistance) because the current flows in contrary directions for both halves of the wire and therefore compensates itself.

author: rdnzl999
author_rank: Newbie
timestamp: August 30, 2013, 11:51:54 pm
content: Quote from: dfmischler on August 30, 2013, 10:30:22 pmYes, it is. Nothing interesting, an analog 50mhz Instek O-653 just for poking around and bought cheap from some failed business liquidator. My old old 35mhz Leader developed unreliable rotary switches on one channel.

author: Monkeh
author_rank: Super Contributor
timestamp: August 31, 2013, 06:44:32 am
content: Quote from: rdnzl999 on August 30, 2013, 09:05:53 pmThen why post here?QuoteCry about what? Doesn't hurt me that you're willing to believe there's a difference in sound quality after you put four figures into something, with no objective testing.

author: Corporate666
author_rank: Unknown
timestamp: August 31, 2013, 08:20:28 am
content: Quote from: rdnzl999 on August 30, 2013, 09:57:03 pmThat sort of rationale might fly in religion forums where people have a conclusion in mind and work from there, but in a place like this, people are always going to be more data driven."balanced power eliminated mechanical hum, I prove it to myself and that's all that matters" is the same as "prayer cured my cancer. I proved it to myself and that's all that matters".It's your opinion, and that's fine - but it's not fact, and it's not data, and it's also probably not true(not to say you don't think it is with all your heart).

author: rdnzl999
author_rank: Newbie
timestamp: August 31, 2013, 08:26:17 am
content: "Then why post here?"Once again, it was a reply to OhmSweetOhm's general query concerning whether balanced power in an audio system is "more snake oil" or not."Cry about what?"Somebody you don't know makes a comment about something with which you apparently have no direct experience so you cry about "no objective testing".It's my opinion that "there is something to it". Take it or leave it.

author: rdnzl999
author_rank: Newbie
timestamp: August 31, 2013, 08:27:31 am
content: Jeez, now you folks are calling me a liar.

author: GeoffS
author_rank: Unknown
timestamp: August 31, 2013, 08:37:05 am
content: No ones calling you a liar, they're just not willing to accept your assertions without some evidence.By evidence, I mean measured, proven results rather than just a 'gut feel'

author: Corporate666
author_rank: Unknown
timestamp: August 31, 2013, 09:04:52 am
content: Quote from: rdnzl999 on August 31, 2013, 08:27:31 amNot at all.I know a lot of guys who will change the oil in their car and will swear that it runs smoother, it's faster, and they can feel a noticeable performance improvement. But you could take vibration and sound measurements and horsepower measurements and see no difference. But it won't matter because they will "know" there is a difference.It's the placebo effect and it's not imaginary, it's a very real thing. There are a lot of people who will claim a higher end HDMI cable gave them a better picture, or crazy-expensive speaker cables made the sound better. But they will say they "know" they achieved these benefits using equipment in a room that is so bad for sound that the differences they are talking about are orders of magnitude less than would even be detectable in that scenario.Passion for one's hobbies is great, and feeling better about a result is great too. But we're talking feelings, not facts. Facts are measurable and measurement instruments are way more capable than the human eye or ear.

author: Redtailed
author_rank: Newbie
timestamp: September 01, 2013, 06:23:46 am
content: Quote from: Corporate666 on August 31, 2013, 09:04:52 amThis deserves an upvote, if there were such mechanisms here.