Uninterruptable power supplies versus hi-fi mains conditioning - diyAudio
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Old 3rd May 2004, 08:21 PM   #1
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Question Uninterruptable power supplies versus hi-fi mains conditioning

Hi all,

I am no electronics expert. I have a hi-end system which could benefit from eliminating mains problems because my actual CD player is not hi-end - it's a Pioneer DV757Ai with an apparent grounding problem! As a result I get voltage when a CD isn't playing coming out of the coaxial digital output. This ends up as hum in my system.

I have two choices:
1) Fix the player (which I will at some point)
2) Eliminate mains borne noise so that the player cannot propagate it

Given the supposed benefits of improving mains in a hifi system, I am wondering about the feasibility of using a continuous (not backup) UPS device over an expensive hi-fi power regenerator like the "PowerStation" from Isotek Systems (see www.isoteksystems.com) which retails for £2750 here in the UK.

From what I can tell, the Isotek unit is not doing anything particularly special over a normal continuous UPS. Both seem to take in mains power and compensate for voltage spikes/lags and over/under current, charging a reservoir/battery and then using a power inverter to allow pure regulated AC to be tapped of the reservoir.

I am hoping some hi-fi hobbyists who are technically competent in electronics can give me their opinion on this. I am thinking the unit I have seen here (http://www.dabs.com/uk/channels/hard...?quicklinx=DRQ) is just as capable and that if my amplifier draws too much power to be connected to the same unit I could buy two and still save a fortune!??

What are the pro and cons of this? And are there any technically proficient people out there who may have made there own mains conditioners?

Thanks.
RagingInsanity
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Old 4th May 2004, 04:56 PM   #2
Did it Himself
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The consumer-grade unit will probably not produce a sine wave with as low distortion as the audio-grade unit.

However, using either of these units would be a total waste of time if your problem is, as you feel, due to a grounding problem.

I do not think it's a ground loop problem, digital connections are supposed to be immune to that kind of thing. In fact I'd be a little surprised that any mains gunk is affecting the digital circuitry to such an extent that it's audible. More likely is that any noise is getting into the amp and affecting the analogue circuitry. I guess the UPS would help here, but a mains filter would be a heck of a lot cheaper.
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Old 4th May 2004, 05:04 PM   #3
tiroth is offline tiroth  United States
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You don't need any DC path at all for S/PDIF connection. Is your player/DAC not transformer isolated? As a cheap experiment try just capacitor coupling to see if it solves your problem. You can always upgrade to transformer coupling if it is warranted.
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Old 4th May 2004, 07:07 PM   #4
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hi guys,

Yes it is a grounding problem as I have examined the innerds of my DVD player and it appears the shop who sold it to me did not reconnect the earth wiring to the chassis on certain marked places on two of the PCBs and they didnt leave behind any wire for it. This particular area of the player (not talking about it when its open here) can tingle the fingers if leaned on for a few seconds, but only lightly - yes I know this is dangerous and needs sorting!

I can use the SPDIF connector and this eliminates the noise. I have tested the digital line using bare wire from coaxial digital out on the DVD player to signal in on my Chord DAC64 BNC input and this gives hum even with no CD playing. I have also done bare wire on the return side and I get the same. This eliminates any interconnect itself having a short or some self induced EMI between return and signal wires. So my conclusion so far is that the noise is mains noise which should be going to the (floating) ground and isn't. The digital out is on the PCB which appears to not be grounded properly and so the mains hum is getting onto the signal and return lines. Probably to much static buildup on the non-grounded PCB maybe?

Thing is, I got the DVD player online and never posted the warranty off. To send it back and have a techie look at it will probably cost about as much as I could get a decent dedicated CD player for off of eBay if I only use it as a transport.

Incidently, I very much want to use the coaxial digital out because to my ears, it stomps the SPDIF optical feed into the ground with ease. The cable is that silly $$$ Nordost Valhalla, but I got x2 3m runs for 600 and reterminated them with Neutrik silver plated XLR's. The XLRs are terminated as recommended here:
http://www.rane.com/note110.html

I also made up the digital lead from what was left of the Valhalla and the connectors of an Audience AU24 digital lead that gave up the ghost (shoddy build basically). Best sonic upgrade I ever made overall except now I can hear mains noise and it is definately coming from the player.

Thanks for the advice so far though guys.

richie00boy, will line conditioning have an impact on how much current I can draw/will it affect my amps dynamics? Pre and power are Chord Electronics and have served me well. They are run on SMPS, but would that have any bearing?

RagingInsanity

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Old 4th May 2004, 07:21 PM   #5
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One extra thing...

Tiroth, you lost me after your first sentence!! I am a hi-end audiophile trying to learn some DIY stuff as I have reached the end of my budget and don't earn what i did when I was an IT contractor.

All I can say is the DVD player is a Pioneer DV757Ai and has a 2pin IEC mains input, so has a floating ground. No ground pins on the back. My DAC is a Chord Electronics DAC64 and uses a 3pin IEC mains input. The correct cables are used with the amps, so they are grounded properly and Chord Electronics owner John Franks' expertise in all manner of power supplies (especially SMPS) and the attention given in the amps means it is highly unlikely they have any influence. In fact, they are guaranteed not to contaminate the mains themselves.

RagingInsanity
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Old 6th May 2004, 07:53 AM   #6
Did it Himself
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Quote:
I have tested the digital line using bare wire from coaxial digital out on the DVD player to signal in on my Chord DAC64 BNC input and this gives hum even with no CD playing. I have also done bare wire on the return side and I get the same.
This reads to me as though you have only connected one of the two wires at any one time. Both are required!

Because the DVD player is not (and does not need to be) earthed, I'm sure it's not an earthing problem, more of a problem with your player. This is reinforced by you saying that there are missing connections inside the player and you get tingles from certain parts of the insides.

Why have these connections been removed? Is this part of some so-called audiophile upgrade?

Quote:
will line conditioning have an impact on how much current I can draw/will it affect my amps dynamics?
It shouldn't make a blind bit of difference if it's done even half-well. However, I don't think mains noise is the problem; you would be wasting your time here IMO.

Please don't tell me any more how much you spent on cables!!!
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Old 6th May 2004, 01:20 PM   #7
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No, the DVD player was bought new and I haven't modified it. It was made region free before retail by ASK Direct.

I did do a single bare wire (signal to signal and then return-to-return) to see if I got the noise with something else other than the coaxial lead, but it is the only phone-BNC lead I have.

Don't tell me about being nuts for blowing that much on cables ... I know, but I never had time to make my own before, nor knew much about making my own. Never again is all I can say!

The whole mains things is due to the noise thing and the fact I get the old clicks and pops scenario when my boiler goes on and off (not talking the missus). I have a Russ Andrews silencer, but its 4 years old and dead I think, can't be sure.

RagingInsanity
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Old 6th May 2004, 03:59 PM   #8
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A mains filter will help a little with the pops and clicks from the boiler, but a transient supressor would probably be a better bet.

The best thing to do with any mains noise problem is to find the source and cure it, not put expensive mains 'conditioners' in just before your audio kit. All you probably need to do is apply supression caps and a transient suppressor to your boiler switch. The other possibility is that the high-energy piezo-generated spark (if your boiler is of this type) can be a source of RF noise that travels through the air. So no amount of supression or fancy mains filters will ever cure this as it's radiated energy and nothing to do with the mains.

I'm still of the opinion that the fault is with the DVD player. Can you try another unit, even just a more modest player. As long as it still allows you to utilise the same connection scheme.

For 600 I will make you as many cables as you want for life!!! Have you not seen ready-made ones for like 20?
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Old 6th May 2004, 05:19 PM   #9
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Hmm, EMP from piezo? My boiler is the other side of my listening room back wall. It also has a fireplace and cupboards, but I would think the boiler is about 9ft away in straight line and since the wall can't shield the energy you are probably right.

I am visiting my folks on the weekend to borrow back my old CD player. I am convinced the DVD player is the problem in some way too. I am weighing up the cost of fixing versus cost of getting an old player as a transport via eBay. But that won't stop the hum with DVD/SACDs.

I know 600 is ludicrous for cables!! Nordost charge way too much, especially for Valhalla, but it is the best sounding retailed cable I have ever heard. However, most people don't have the time/energy to source decent raw materials and make their own. I do now and will. I am sure pure oxygen free crystal-grain silver in flourine-free teflon with a weave will beat the silly money Nordost Valhallas for about 5% of the Valhalla price.

I have been able to hear a difference with every wire I have ever tried in my system (often major differences) and tried so many that ultimately I have ended up looking at Nordost's Valhalla and turning it down on price. If I told you the retail value of what my 600 got you will be using alot more of these->

I am about to source some audio silver wiring and build a whole range of cables for my system. Hopefully getting better sound than my Nordost Valhallas, which will let me sell the Valhallas on eBay and do something decent like decorate my new house!

RagingInsanity
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Old 22nd June 2004, 01:03 AM   #10
deltec is offline deltec  Italy
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I have a DAC64 too and to solve your problem I can suggest to put a toslink cable of good quality MIt or Wireworld with the buffer on DAC64 the toslink finally sound good like a coax really!!!
With DAC64 using coax cableon Bnc every time someone turn on the light music stops for a second (Ican hear the relais switching on the dac)and come back, that why I listen with an optical cable, people at Chord says this is a problem they had in some unit and that they fix but I need to change the inside eeprom.
Sorry for my bad english and I hope that could be of any help for you!
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