Jump to content

Sign in to follow this  
jolon

Why digital seems to be affected by power and cables

Recommended Posts

I don't understand. Do power cables make a difference or not?

 

Well I've tried quite hard, but clearly

 

0HYDjTy.jpg

Share this post


Link to post
Share on other sites
Guest Muon

Small power transformers like source components generally have (up to 160VA) generally don't show mechanical hum from the transformer itself.  Rod Elliott has an explanation for this on his web-site.

 

However, large power transformers in power amps having linear power supplies can certainly buzz - and, yes, it appears a DC component on the AC mains is the problem,  The culprits (producing the DC) can be a number of things - your (or your neighbour's) solar power inverter ... and SMPSes powering washing machines / routers / PCs / TVs / Foxtel boxes / wifi devices ... .

 

You can stop DC getting into your power amp(s) by plugging them into a 'device' which is then plugged into the wall-socket:

  1. a 1:1 isolating transformer, or
  2. a DC blocker.

The problem with #1 for a power amplifier - if it's 100w or more - is that the transformer needs to be a big one, so that it doesn't restrict the power flow into the amp.  Big transformers are a. physically large and b. expensive.  You would need to experiment whether the isolating transformer had a negative effect on SQ which outweighed the benefit of removing the transformer buzz.  I would suggest you'd need a transformer which has a minimum of 10x the VA rating of the amp, to not get any current restrictions.

 

So #2 is probably more appropriate for power amps.  Rod Elliott has a design on his web-site which @@guru used as the basis for his product (as I did).  With the correct choice of parts, these can pass 10a continuous - so they should be appropriate for most power amps out there.

 

 

Regards,

 

Andy

Rod never met my Telefunken Double C core transformer in my phono then....I think It's 50va.

 

As you might know a little DC blocker was the answer for it.

 

I'll move along now and not disturb :)

Share this post


Link to post
Share on other sites

I'm  a real fan of the pro audio company Rane.  Their technical note http://www.rane.com/note165.html describes precisely this problem, where a few cm of inappropriate ground wire gives RF breakthrough.

 

The problem is best solved by employing an additional RF ground plane, connected via 104 ceramics to the signal earth node and various rail distribution points. 

 

Not only is the amplifier more immune to RFI, but performance is potentially improved too. 

Edited by Slartibartfast

Share this post


Link to post
Share on other sites


Rod never met my Telefunken Double C core transformer in my phono then....I think It's 50va.

 

As you might know a little DC blocker was the answer for it.

 

I'll move along now and not disturb :)

 

Rod never met my Telefunken Double C core transformer in my phono then....I think It's 50va.

 

As you might know a little DC blocker was the answer for it.

 

I'll move along now and not disturb :)

 

Aah, that is interesting to know.  So small transformers can suffer, too.

 

Thanks,  :thumb:

 

Andy

Share this post


Link to post
Share on other sites

I don't understand. Do power cables make a difference or not?

 

Just try a few really different cables and listen for yourself.  You make up your own mind.

 

Two here it seems hear no difference, but the majority of us do and I hear significant differences.

 

Just because it is expensive, does not mean it is better though!!!  Sometimes simple works a treat.

 

I do like the idea of the zobel on speaker cables or output of an amp, that has a lot of merit and I have not explored with that before.

Share this post


Link to post
Share on other sites

I don't understand. Do power cables make a difference or not?

No. However, if you must decide to experiment, here are a few things to keep in mind:

* The IEC connector causes far more problems than any cable difference. In fact, this is why a captive power lead is a vastly superior option to any detachable cable. The best cable connections eliminate any kind of plug and socket. If you must use IEC connectors, make certain the IEC connectors are identical and provide a secure connection (not all do).

* When performing a power cable test, use a standard double blind protocol. Failure to do so will render any opinions completely invalid. I know of no power cable difference proponent that has allowed themselves to be subject to a double blind test. That should tell you all you need to know. Double blind testing is THE standard for all tests, from pharmaceuticals, wine tasting and to audio equipment. People who disparage double blind testing are charlatans or ignorant.

Share this post


Link to post
Share on other sites

Just try a few really different cables and listen for yourself.  You make up your own mind.

 

Two here it seems hear no difference, but the majority of us do and I hear significant differences.

 

Just because it is expensive, does not mean it is better though!!!  Sometimes simple works a treat.

 

I do like the idea of the zobel on speaker cables or output of an amp, that has a lot of merit and I have not explored with that before.

Zobels should be employed by the amplifier, NOT the speaker cable.

Share this post


Link to post
Share on other sites


so don't waste money on fancy looking power cables for my amps but do get a good one for my dac?

Share this post


Link to post
Share on other sites

so don't waste money on fancy looking power cables for my amps but do get a good one for my dac?

Power cables make no difference for ANY product. Prove it for yourself: BORROW a fancy power cable and do a blind test.

Edited by Zaphod Beeblebrox

Share this post


Link to post
Share on other sites

The general rule is - power cables for small signal stuff first.  Then power amps - but fancy cables have made little difference to the sound of the power amps I have used.  Then speaker cables, and lastly small signal ones.

 

Digital cables is a whole different debate - dealt with earlier in the thread.

 

Others have a different order, and run the gamut for mains cables that they can't possibly make a difference to of course they do.

Share this post


Link to post
Share on other sites
Guest Eggcup The Daft

I don't understand. Do power cables make a difference or not?

Clearly they do, though through what mechanism (I have to include the "arrogant" statements about placebo effect/confirmation bias etc, here, please take all that stuff as read and disagreed with in your personal case, everyone!).

 

My point would be that they shouldn't matter for those cases that can be anticipated by the builders/designers/engineers producing audio product - or, if they do for reasons of cost, they should be noted and explained in the product manuals for our benefit. Mains power supply is not exact in the way that, for example a specified digital input standard is, but much of what goes on is known and can be allowed for.

 

What there should not be is either a reliance on luck, or on purchasers having either a perfect mains supply, an infinite supply of potentially "fortuitous" power leads, or the knowledge to mess around with the mains in ways that are potentially dangerous and possibly illegal.

Share this post


Link to post
Share on other sites


Guest Muon

Aah, that is interesting to know.  So small transformers can suffer, too.

 

Thanks,  :thumb:

 

Andy

Seems so :)

Share this post


Link to post
Share on other sites

Just so's you know that I put my money where my mouth is.  I run actively crossed over speakers, with four channels of power amplification on each side.  I built my own, using designs by Douglas Self (his Blameless approach).  Overengineered, with too-large heatsinks that only get tepid after an ear bleedingly loud session.  But better than the other way round.

 

Balanced inputs, largely to get around any hum loop problems.  Neutrik EMC series XLR's all round for RF garbage control.  Mains power to each amp is using Neutrik Powercon 32A connectors and 20A pro-audio (ie regular) mains cable 15mm diameter.  Those are terminated in industrial AC power connectors.  the mating sockets are wired to a high current IEC in a wooden box I made myself.  That is connected to a Russ Andrews Powerblock using a Superkord-500 (ie one of my own designs).  In fact the mains wiring for all my components goes via Superkords to one of the Russ Andrews distribution boards.  All the Superkord and Andrews distribition stuff is all to do with mains RF management.  All mains transformers are silent - but I did specify them all myself and had them manufactured by people who know what they are doing.

 

The main source is a Logitech Transporter, either from a Synology NAS with my ripped CD's or live streaming from Tidal HiFi.  That connects to a Tortuga Audio balanced LDR passive pre, basically like this http://www.tortugaaudio.com/products/ldrxb-balanced-passive-preamp/ but built using a kit of bits that the guy supplies.  Other inputs from CD player, TV and record deck temporarily go through an Audio Research LS3B for conversion to balanced and hence to the Tortuga.  Record deck is a Garrard 401 in a slate plinth, with a SME series 1 arm and a Zu Audio hotrodded Denon DL103 http://www.zuaudio.com/phono-cartridges/standard cartridge.

 

Signal cabling is mainly pro-audio balanced (the sort of stuff that there are miles of in any recording studio), except the links between the Transporter, Tortuga, and active crossover which are Kimber Select balanced.

 

There is a completely separate headphone rig in the bedroom.  That is an ancient Meridian CD200, hotrodded by moi, and a Audio Synthesis DAC.  Both of these have highly modded SPDIF as discussed earlier in the thread.  That feeds a clone of the best STAX electrostatic headphone amp of all time, the SRM-T2 - total madness, it pulls over 200W out of the mains.  Phones are old generation SR-Lambda and newish SR-007 OmegaII.  Mains cables are regular Russ Andrews into a small RA power block.  Signal cables are Kimber select, unbalanced.

Share this post


Link to post
Share on other sites

Those power cords you are using Craig, the cheapest is a mere 455 quid x 8 off, pretty cheap really. :sarc:

 

Not all of us can afford that, in fact not many of us can hence why we need to find something that can work for us and not break the bank.

 

I like your use of 32A plugs and the industrial stuff.  I believe it's all about "CURRENT CAPABILITY".  Headroom for a cable if you like, and the weakest link in a flexible cord is the plug on either one or both ends, it's surface contact area and the grip on that contact area.

 

Gold plated, rhodium, copper?  I have no opinion there what is best or if one is better than another.

Share this post


Link to post
Share on other sites

Those power cords you are using Craig, the cheapest is a mere 455 quid x 8 off, pretty cheap really. :sarc:

 

Not all of us can afford that, in fact not many of us can hence why we need to find something that can work for us and not break the bank.

 

I like your use of 32A plugs and the industrial stuff.  I believe it's all about "CURRENT CAPABILITY".  Headroom for a cable if you like, and the weakest link in a flexible cord is the plug on either one or both ends, it's surface contact area and the grip on that contact area.

 

Gold plated, rhodium, copper?  I have no opinion there what is best or if one is better than another.

 

I totally agree on the cost thing.  But my audio expenditure is not ridiculous, because my gear changes very slowly, and much/most of it is built by me.  Bought amps and speakers have lived in my system for many years, sometimes decades (like the LS3B).  And in the past I have gone to the extent of hardwiring the gear into the wall, getting rid of mains connectors entirely.  It is a real PITA if you want to change anything, or move a component around.

 

But on mains, recall an earlier post where I said I had had excellent results using the same wiring that is in the wall (twin and earth) for a mains cable.  If you are competent in wiring mains power (or know someone who is) that is a ridiculously easy thing to try, and costs almost nothing.  Here's one I made a while ago

 

post-153047-0-51592100-1456402987_thumb.

 

And on signal cabling, I generally just use balanced pro cable - most of my system is wired using this http://www.canford.co.uk/FST-HD-FOIL-SCREENED-STRANDED-CONDUCTOR-TWIN-CABLE-Heavy-duty , which as you will note is seriously not expensive.  But remember that everything you listen to has already gone through hundreds of metres of this sort of stuff in recording studios and live venues.

 

Regarding rhodium/gold/silver/bare copper the key thing is not what is on the surface, but what is underneath.  Most platings require either an adhesion layer to make sure that the plating sticks to the base metal, or a barrier layer to prevent the base metal from contaminating the plating.  For gold it is generally nickel (because gold dissolves in copper - got the badge on that one).  For rhodium it is either gold, or bronze - but it may go onto brass without an underlayer.  Silver or silver plating is prone to tarnish, which is why silver jewelry is often rhodium plated.  Bare copper is of course prone to tarnish, and in any event all mains plugs that I know of use brass pins.  Standards labs often strip the plating from spade terminals where the base metal is copper to prevent thermocouple voltages during precision DC measurements, but that has no relevance for the time-varying signals in audio.

 

I must admit I use Deoxit on all connections.  Since I have a Kelvin Bridge that can measure down to micro-ohms I can attest to the fact that using deoxit significantly reduces contact resistance.  Dunno how - Deoxit's website is full of snake oil explanations, but works and I've proven to my satisfaction that it does so.

Edited by CraigS

Share this post


Link to post
Share on other sites


Those power cords you are using Craig, the cheapest is a mere 455 quid x 8 off, pretty cheap really. :sarc:

 

Not all of us can afford that, in fact not many of us can hence why we need to find something that can work for us and not break the bank.

 

I like your use of 32A plugs and the industrial stuff.  I believe it's all about "CURRENT CAPABILITY".  Headroom for a cable if you like, and the weakest link in a flexible cord is the plug on either one or both ends, it's surface contact area and the grip on that contact area.

 

Gold plated, rhodium, copper?  I have no opinion there what is best or if one is better than another.

Good quality SOLDERED, captive mains cables are VASTLY superior to ANY IEC connector, regardless of how much they cost. In fact, I would argue that the cost of hard wiring a mains lead is far less than some of the insanely priced, inferior, IEC connectors.

Share this post


Link to post
Share on other sites

So what are you going to solder it to?  Unless you are going to bypass the on/off switch, power fuse, soft start etc and hard wire to the transformer primary.  If you don't, all you are doing by soldering is removing one connection in a long chain of connections.

Share this post


Link to post
Share on other sites

So what are you going to solder it to?  Unless you are going to bypass the on/off switch, power fuse, soft start etc and hard wire to the transformer primary.  If you don't, all you are doing by soldering is removing one connection in a long chain of connections.

You're making assumptions which may not be based on facts. Some of the things mentioned may not exist. Either way, removal of one, often seriously problematical, connection by using a captive power lead is simple, cheap and logical. It was, once, the way all power connections were made. Persuading consumers to spend nonsensical sums on over-priced connectors (and cables) is a solution in search of a problem. Captive power leads eliminate one major source of frustration and potential expense.

Share this post


Link to post
Share on other sites

You're making assumptions which may not be based on facts. Some of the things mentioned may not exist. Either way, removal of one, often seriously problematical, connection by using a captive power lead is simple, cheap and logical. It was, once, the way all power connections were made. Persuading consumers to spend nonsensical sums on over-priced connectors (and cables) is a solution in search of a problem. Captive power leads eliminate one major source of frustration and potential expense.

 

Don't get me wrong - I agree in principle.  IEC's aren't locking, the contact pressure is relatively low, and they can randomly pull out particularly if the lead is heavy.  My old Audio Research power amp had a captive lead, as did many old bits of kit - that is if they didn't use the hokey little bulgin 3-pin like Quad. That is why, if you have the choice, the big Neutrik Powercons work so well - they lock. Push it in and then rotate until the latch clicks home - and a reliable <=3 milliohm contact resistance.  And because Neutrik make them by the million they are cheap, unlike esoteric IEC's.  Neutrik have just announced their 1 billionth XLR since company foundation.

 

But on captive leads most people don't have the electrical skills to open up a piece of kit, survey what to do and how to do it safely, select the correct strain relief and drill or punch the hole for it etc etc.  And if it is a relatively new product, invalidate the warranty.

 

Back in the day, you used to be able to get wire straps that fitted to the IEC mounting holes that clipped onto the IEC to prevent 

Edited by CraigS

Share this post


Link to post
Share on other sites

 

I found them at a place here in Melbourne for $28ea.

 

I have never seen them before.  For the legal eagles, I am not sure how they would comply with our AUSNZ Standards 2007 code.  More investigation req'd there.

 

But then if you are worried about this, then don't forget about the legalities of a "flexible cord" either.  No more than 5 conductors with no less than 7 stands/ conductor and no conductor bigger than 4mm sq.  (or something like that- it's been a couple of years)

 

...So there go 70% of our audiophile cords!

 

If these  powerCONs work, they are a bargain, of course you will need to fashion an adpator plate if you don't want to cut new holes in your chassis to mount it's counterpart.  Easy for me as a metalworker.

 

Thanks for the tip Craig.

Edited by Red MacKay

Share this post


Link to post
Share on other sites

Would it be silly to ask if a Power Cable from the wall to my PS Audio P10 would be a waste as the power is being cleaned from the P10 not the mains power?

Edited by SdP

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Classifieds Statistics


    Currently Active Ads

    Total Sales (Since 2018)

    Total Sales Value (Last 14 Days)

    Total Ads Value (Since March 2020)
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...