Balanced Power

PaulBrewer

Does anyone have any experience of using Balanced Mains Power ?

Savman

In what way? You talkin' about three phase distros etc?

PaulBrewer

No - actual balanced power a +110V a centre tapped earth and a - 110V

Savman

Right. These go to eleven.

alan kelly

Having an electrical backround i have a "VAGUE" idea on what your talking about.

3 phase systems try to balance the loads equally but i think what your on about is single phase (230v) something that might limit electrical interference in electronic circuits... Ie less noise might mean cleaner music... Not sure this is where you are going with this...

If you are looking for just a steady 230v supply which certain machines need for a better output ups systems are often used. This means you have a back up supply and also a perfect sine wave...

Apologies if i am going off in a tangent Paul. This might not be what your on about. Also apologies to anyone else who is reading this and thought this was a music production forum....:D

studiorat

It's meant to cancel out noise in power lines by way of CMR. I looked at it before but didn't follow up on it.

It raises issues about grounding when using unbalanced audio signals. Also it presents a situation where you now need to fuse both legs of the power supply. In a regular system you only need one fuse on the live side, if both legs are live then you need to fuse both, obviously.

There's a company called Equitech which have a unit that might be worth looking at. But since we have twice the voltage and since we will probably use more power than the average audiophile type I'm not sure how it's rated.

EDIT: In fact the mains power supply in Morocco is like that, opposite voltages on each leg. Using gear that wasn't set up for it certainly presented a few surprises during the recording, every chassis in the system was live including the power switch on my laptop. Had to do the recording sessions using a phase tester to press the go button.

madtheory

Unless you're working in the US, it's not a good idea with our 240v system:
http://www.soundonsound.com/forum/showflat.php?Cat=&Board=MRT&Number=344373&Searchpage=1&Main=340360&Words=%26quot%3Broger+nichols%26quot%3B&topic=&Search=true#Post344373

I've never worked in the US so I have no experience with it.

alan kelly

:rolleyes:Never heard of a fuse on both legs... Every day is a school day..

studiorat

alan kelly wrote: »

:rolleyes:Never heard of a fuse on both legs... Every day is a school day..

Yeah, I dunno how you'd do it. But since theres juice on both sides, I would have thought it made sense. Unless the fuse blowing on the positive side would cut the negative side but I don't see how that would happen.

I guess theres trip switches and stuff available but it's a whole kettle of worms I wouldn't fancy getting into.

It would appear to some that a balanced supply is a quick fix for bad earthing. Perhaps a dedicated technical earth rod would be a better idea.

PaulBrewer

A customer of mine bought one and reckons it's the most significant single improvement to his overall sound he's ever had.

The unit has all the necessary protection included.

alan kelly

I agree that its something i dont fancy getting into. I could be wrong but dont think a dedicated earth rod will make much difference either.. Also technically there is power on both positive and negative .. Usually a larger current on the negative because of the load.. I think mr brewer opened the can and left the room before the worms escaped...:D

PaulBrewer

madtheory wrote: »

Unless you're working in the US, it's not a good idea with our 240v system:
.

Nonsense -

It's used in quite a few UK Studios, Mark Knopfler's British Grove being one I'm familiar with.

studiorat

PaulBrewer wrote: »

A customer of mine bought one and reckons it's the most significant single improvement to his overall sound he's ever had.

The unit has all the necessary protection included.

A power conditioner? Talking about balanced power usually refers to the installation of the whole gaff not just parts of it.

What's connected to it and how? Are there multiple trips or if one unit trips the whole lot is shut off?

Is the whole faculity connected? What happens if you connect something that isn't on the balanced system? Like a mic in the other room or something?

PaulBrewer

Well earth is still earth so there aren't any issues that way.

Here's what they have to say -

"Our range of balanced power units safely transform and filter a nominal 230v 50Hz AC single phase supply to 115-0-115v balanced power. The core of each unit is a precision wound oversize toroidal transformer with unusual characteristics and a very accurate secondary centre tap. Comprehensive internal component, supply and load protection is incorporated to ensure the final system is even safer than a conventional unbalanced supply system. We currently offer an 8kVa model for rack mounting and a free standing 2kVA version. We also offer a 58-0-58 4kVA 50Hz system for imported equipment, usually from the USA.
What are the advantages? Balanced power enhances audio visual and data system performance principally by significantly reducing the system noise floor. This directly leads to:
• Increased sonic transparency and dynamic range • Improved perception of positioning of sound sources within the stereo/surround sound
field • Increased clarity in video picture presentation with reduced artefacts • Can improve clock jitter in non-optimal digital systems • Maximised bit resolution for A-D and D-A conversion leading to better
performance/utilisation of compression algorithms in the digital domain • Increased data transfer rates and reduced errors between interconnected digital
equipment
As system engineers, we expect (and indeed insist) on balanced interconnects, routing and patching for analogue/digital audio and synchronous/asynchronous data transfer between equipment wherever possible. This reduces susceptibility to interference, both radiated and conducted. Now we can apply this balancing technique to the system distributing the raw power.
How does it work? The conventional unbalanced power distribution system amounts to a “rubbish” highway – huge numbers of non-linear loads with commutating rectifiers in their power supplies react with the less than perfect power distribution system to produce a cacophony of non-linear, phase shifted currents at frequencies from 50Hz into the 10’s of Mhz. Many manufacturers limit this supply- derived interference just sufficiently to comply with EMC standards, some even selecting the most lax version applicable to their particular product. How do you know which manufacturers are doing this? Many manufacturers also test all parameters of each piece of equipment in isolation on a test bench; at Westwick Installation, we as system integrators often find performance is compromised as the equipment is concentrated in racks and then interconnected.
The Balanced Delivery System exhibits several beneficial effects: • Study the circuit of a typical IEC mains inlet filter and you will see it is a balanced component forced to work at reduced performance in a 0-230v Live-Neutral distribution system. By supplying 115-0-115v balanced power, you can realise each filter’s full performance in both directions (general conducted interference entering the equipment and commutating rectifier and digital processing noise leaving the equipment to pollute
adjacent equipment. • When a typical IEC input filter is operating in conventional unbalanced mode, the
enclosed live-earth capacitor directly injects a small current from the live pin directly in to the earth system. This is principally in phase and additive with the currents from all the other filters fed on that distribution circuit/phase; this current can build up to amps; this current also flows through the metal cases of the installed equipment and the cable screens interconnecting them. Feed it with balanced power and most of that current cancels out. The balancing transformer creates that optimal cancelling condition locally and primarily needs the distribution earth as a fault current safety route and earth reference, not a poorly performing interference current “dump.”
• EMC compliant equipment should reject the interference caused by circulating earth currents; it can not however annihilate the effect. Balanced power significantly reduces the cause of earth currents; AV equipment manufacturers can only address the symptom, and with varying degrees of success – also, they tend not to routinely test in adverse installation environments.
• Conventional toroidal power supply transformers are wound for maximum efficiency and minimum cost. Simply adding a centre tap to the secondary does not work – we tried! Our manufacturer uses unconventional winding techniques, core materials and construction to achieve a transformer optimised for balancing and interference reduction. Inductance and capacitance characteristics are different to a conventional transformer – they have been optimised to exhibit substantially improved filtering properties – in both directions.
• A useful by-product of the design process for our models is a much reduced primary inrush current – wiring for a Surge-Gard power thermistor is included but this is almost always linked out. There is a connector for an optional internal current measuring Tx.
• Digital data transport, particularly but not exclusively rack-to-rack, benefits from the reduced noise floor of balanced power. Although data leaves the source equipment as 1’s and 0’s, our intense desire to obtain high bandwidth coupled with cable/connector induced reflections leaves us with plenty of data recovery work to be carried out at the destination. We are prepared to argue that this recovery is quite an analogue process – when does the 0 become a 1? System noise can only degrade the recovery performance – leading to lost data for serial digital audio, packets requiring retransmission for IP data.
• These systems have comprehensive input and output over current protection, output residual current and over temperature protection with 220, 230, 240, 250v input taps.
We advocate the use of meshed earthing systems, PECs (parallel earth conductors), STP Ethernet cables and eradication (in almost all circumstances), of the “One End Only” cable screen termination rule. In our experience, our balanced power system can significantly reduce commissioning time. Legacy audio equipment (and sadly some equipment of current manufacture) possessing an XLR “pin 1 problem” is identified at commissioning and dealt with locally.

madtheory

PaulBrewer wrote: »

Nonsense -

It's used in quite a few UK Studios, Mark Knopfler's British Grove being one I'm familiar with.

It depends:

http://www.soundonsound.com/forum/showthreaded.php?Cat=&Number=341828&page=&view=&sb=5&o=&vc=1

PaulBrewer

madtheory wrote: »

It depends:

http://www.soundonsound.com/forum/showthreaded.php?Cat=&Number=341828&page=&view=&sb=5&o=&vc=1

It's not very expensive -

£350 for a 2kva.

Anyway that wasn't my question.


Does anyone use it or has heard what it does ?

madtheory

So it reduces the noise floor. So is it better to:
(a) Have all the grounding in order so the mains borne noise doesn't get to the audio in the first place.
(b) Reduce the mains borne noise level with the Equitech.

(a) Makes more sense to me, because you can potentially achieve zero noise, whereas with (b) you can "only" get it very very low. Doing both would be a belt and braces approach .

Seems to me that noise is a bigger problem in the US because of the low supply voltage. With 240v the SNR is over twice as good.

PaulBrewer

madtheory wrote: »

So it reduces the noise floor. So is it better to:
(a) Have all the grounding in order so the mains borne noise doesn't get to the audio in the first place.
(b) Reduce the mains borne noise level with the Equitech.

(a) Makes more sense to me, because you can potentially achieve zero noise, whereas with (b) you can "only" get it very very low. Doing both would be a belt and braces approach .

Seems to me that noise is a bigger problem in the US because of the low supply voltage. With 240v the SNR is over twice as good.

Does anyone use it or has heard what it does ?

Paolo_M

Haven't used it but I come from an electrical background.

Most mains noise is from electromagnet interferance and harmonics on the line.
A centre tapped supply will help with neither.
Can't imagine what benifit it would have in an audio system.

CMR doesn't exist in a power supply. CMRR is a property of an audio system such as a humbucker guitar pickup or an amplifier. All amplifiers run from DC and ac power is completely isolated from that with the exception of a common ground usually.

I build high gain valve amplifiers where the valve heaters do run from ac. A transformer centre tap will never be accurate and will cause noise. That's just a property of a transformer that cannot be avoided.
The inside of a high gain vale amplifier is a harsh environment for noise with gains of over 1,000,000 in the preamp. Main cable is run right to the power supply in there. A bit of filtering (2c cap) and twisting the wires produces absolutely zero mains noise in that environment.

Audio system noise is almost never to do with the power supply but rather the grounding scheme.

madtheory

Thanks Paolo. I tend to agree.

However, the Hammond Novachord appears to uses cancellation as a means of achieving smoother rectification in at least one of the supply rails:

http://www.novachord.co.uk/restoration.htm

That's my understanding of it anyway. Perhaps you could shed some light on it?

PaulBrewer

Have you heard it in action Paolo ? Is there anything in the quote above you think is incorrect?

madtheory

Notwithstanding the curious example of the Novachord PSU, balanced power can't work, because the "noise" is not created in the same way as the noise a balanced audio circuit is meant to eliminate. It's pseudo science. Just get the mains installed to spec, and keep the audio signal ground isolated from earth by using balanced lines throughout.

Here's how you do it correctly.

Here's the Rane note on how it is done. (Rane notes are probably the best free advice for sound engineering purposes):

What makes a ground loop current annoying is when the audio signal is affected. Unfortunately, many manufacturers of balanced audio equipment design the internal grounding system improperly, thus creating balanced equipment that is not immune to the cabling's noise currents.

If you have unbalanced equipment (who doesn't) that article shows you how to integrate it.

And here's an interesting approach by Tony Waldron from CADAC.

So the choices are:
1. Spend STG£350 on something that probably doesn't work at all, but makes you feel better.
2. Spend an hour reading the above linked articles, and another hour tidy up your wiring. This will probably make you feel better.

PaulBrewer

madtheory wrote: »

balanced power can't work,

There you go with that UnScience you're so fond of.

Did you not learn your lesson with the Clocking thread ?

If you haven't heard it in action it's just speculation on your part.

I take it you haven't ?

That was my initial question after all.

madtheory

If you take the time to read the articles I linked to, you will see that my opening statement is not "unscience".

What lesson was to be learned with the clocking thread? Did you read Hugh Robjohn's article?

This issue is much more clear cut, it's electricity- well understood, not contentious like jitter. Why would I need to "hear it in action" that is a flawed argument. I know it doesn't work. For example, I know ear candling doesn't work either, it isn't necessary to try it to know that. I've already made it clear that I have no experience with balanced power, stop trying to make an issue of that. I have no experience with ear candling either.

I didn't find anything on the Equitech site that convinced me. If you can find something, I'd love to read it. I'm always open to persuasion, but not endorsement.

tweeky

With respect to all it's a bit like the discussion as to whether a car aerial impedes the performance of a BMW? Yawn, lets get back to work and make music!

A bit like this gem for hi-fi nerds

http://www.russandrews.com/product.asp?lookup=1&region=UK&currency=GBP&pf_id=1549&customer_id=PAA1360063410580UKZGRLTGZXIQPSKM

madtheory

tweeky wrote: »

lets get back to work and make music!

Stop posting on the tinterweb so :P

Paolo_M

PaulBrewer wrote: »

Have you heard it in action Paolo ? Is there anything in the quote above you think is incorrect?

No I have not heard it in action.

However I, and any other Electrical Engineering with experience of both audio systems and power distribution, will tell you that it will not benefit you in any way.

If there is any improvement it will be down to the method of grounding that's used, and nothing whatsoever (I can't stress this enough!!) to with balanced lines or CMR or noise cancellation in the lines.

I'm nerdy enough to have already studied the Rane articles that Madtheory posted and while it doesn't address powering the devices the information regarding ground isolation and proper shielding techniques for audio devices is spot on.

I've used some of these techniques on my amp. It is recordable quiet at full gain (we're talking 5150 level here) and normal unbalanced crummy old mains is run right inside the amplifier. The heaters have high current (think electomagnetic interferance) ac carried right up to the intrument level inputs as that's the nature of a valve design.

Proper grounding schemes eliminate all audable mains noise within an audio system; FACT.
Balanced lines were designed and are still implemented because of savings that can be made in copper.
They can also provide dual voltages; American homes have have 120Vac from hot to ground but many also use 240Vac from hot to hot for utilities like cookers etc. but have nothing to do with noise reduction in audio systems.

PaulBrewer

Isn't there a possibility that all the above doesn't explain what's going on ?

That there COULD be an improvement as declared by my client and Knopfler's techs that isn't being explained by the theories offered ?

Hearing is the only way to know.

The explanation comes after the event, not before it, in my mind.

Isn't that how real Science works ?

madtheory

Anything is possible, if a difference is audible there must be a reason. However, this electrical stuff is not theory, it's fact. Has been for at least 60 years. Maybe the technician concerned could explain the benefits they've realised, over and above standard grounding practice?

PaulBrewer

madtheory wrote: »

if a difference is audible there must be a reason.

Exactly -

so the logical process is find is there a difference and if there is, explain it. (or maybe not)

Of note in the manufacturers info was the improvements in digital systems - of which most studios are these days.

If there are benefits to be had with it in a digital system then it's an 'across the board' one i.e. everything sounds better, which to my mind is a very desirable outcome for £350, if it is the case.

Anyway it's clear that despite quite a few posts no-one has experienced the difference, if there is one.

Paolo_M

PaulBrewer wrote: »

Exactly -

so the logical process is find is there a difference and if there is, explain it. (or maybe not)

Of note in the manufacturers info was the improvements in digital systems - of which most studios are these days.

If there are benefits to be had with it in a digital system then it's an 'across the board' one i.e. everything sounds better, which to my mind is a very desirable outcome for £350, if it is the case.

Anyway it's clear that despite quite a few posts no-one has experienced the difference, if there is one.

I re-read the manuifacturers blurb.

Balanced lines would reduce earth currents as he has described.
A well designed audio would not benefit from this however as the audio ground and shields SHOULD be well clear of the protective earth from the supply. Not all audio systems follow good grounding practise however.
Reducing earth current would benefit a poorly implemented audio system grounding scheme.
As I mentioned earlier, this benefit is for poorly grounded systems and nothing to do with CMR or balanced lines etc.
It would have no benefit for a complete audio system made up of all quality pieces of kit.

Computors do throw a lot of crap onto the line also, but a well designed audio devices interal power supply will filter this and will not affect the audio signal inside.
Having a main supply that filters that crap out is good practise, that's what a power conditioner does so it's nothing revolutionary. I'm presuming most studios have this anyway.

If it were me, I'd remove each audio device one at a time and see if any noise improvement happens. Then either replace the offending device or, if you're really attached to the device a supply like this would be beneficial.

PaulBrewer

Paolo_M wrote: »

if you're really attached to the device a supply like this would be beneficial.

I think most people select units because they do a certain job well and are unlikely to want to dump boxes.

Also some users (Mixer Cenzo Townshend for example) drive there 'personal' stuff with balanced power as they sometimes move around to different studios and it removes a variable.

It will be interesting to hear what difference there is.

My client in Longford is plagued by mains and RF noise and even a dedicated technical earth and star quad cabling hasn't given him the result he says balanced power has.

madtheory

That sounds like a real pain for your client. If balanced mains is working for him that's great. However, I remain sceptical. The balanced audio line and standard procedure such as putting balancing trafos on the i/o of unbalanced gear is well proven methodology after 60+ years. My technician has seen so- called technical earths at venues, one where there was no actual rod in the ground, and another where the new rod was so close to the old one it was exactly the same. Not all electricians care or know about this stuff. Local radiating power transformers, electric fences and mobile phone masts are other common issues that can be addressed with old fashioned electrical engineering. The Equitech might be useful for location work, but IMO nothing beats EE know how and some investigation at a venue where problems are occurring.