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jolon

Why digital seems to be affected by power and cables

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Are you one of these people that need "verified" (by who?) tests before you can make a decision, Steve?

 

Why not do experiments off your own bat - based on recommendations from others - and decide as a result of them?

 

That's what I have done. ;)

 

Andy

 

 

 

Andy

Hi Andy

I have done the blind test about 3 times over a couple of years about 10 years back when i had a bit of time on my hands with friends and fellow enthusiasts. I wanted to believe, would have had lots of fun with cables. But at the end of the day they proved not to be effective. Some of them looked really great though.

 

Cheers 

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No.  This thread is about power cables (as well as interconnects such as those used for SPDIF).  Please do not attempt blind tests with power cables in which one is a coat hanger.  It is very silly and more than a bit dangerous.

 

Ummm, did I mention coat hangers, Tex?

 

No - I was responding to Steved's (possibly off-topic) post about speaker cables.

 

 

Andy

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Guest Doppler Effect

Ummm, did I mention coat hangers, Tex?

 

No - I was responding to Steved's (possibly off-topic) post about speaker cables.

 

 

Andy

Like a coat hanger being used for SPDIF, I think you missed some bits.

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Hi Andy

I have done the blind test about 3 times over a couple of years about 10 years back when i had a bit of time on my hands with friends and fellow enthusiasts. I wanted to believe, would have had lots of fun with cables. But at the end of the day they proved not to be effective. Some of them looked really great though.

 

Cheers 

 

OK ... that's good, Steve.

 

Me, I don't do 'blind tests' (although one of the people who I always involve in such tests is half blind! :D ) but I do do tests.

 

 

Regards,

 

Andy

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Like a coat hanger being used for SPDIF, I think you missed some bits.

 

Haha - anyone who tries to use a coat hanger as an SPDIF cable is definitely missing a few bits, Tex! :D :D

 

Andy

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No.  This thread is about power cables (as well as interconnects such as those used for SPDIF).  Please do not attempt blind tests with power cables in which one is a coat hanger.  It is very silly and more than a bit dangerous.

 Hi Karri, was not referring to anything of digital transfer but but the general topic of placebo.

 

Cheers

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Guest Doppler Effect

i think you were getting your wires crossed.

Edited by Doppler Effect

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i think you were getting your wires crossed.

Funny, witty  and true  :D  ;)  :thumb:

Edited by Steved

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I'm someone who wants to know why things sound different.

 

Starting off subjectively, way way back in the 80's I was using a Quad power amp and a pair of KEF (I think Chorale's).  I was running QED C38 speaker cable.  However, I had an option on a pair of Apogee panels, and wanted to try some other cable.  So I borrowed some Kimber 8TC.  In the end I didn't buy the Apogee's, but I tried out the 8TC on my system.  Mrs S was out at the time - but I was "gob smacked" at the difference.  Mrs S came in, I plonked her in the sweet spot with the C38 in place.  Then without telling her what I did, I swapped to the 8TC.  "OMG - what did you just do - it sounds fabulous!".  "Um - I swapped one bit of copper wire for a different bit of copper wire"

 

I'm still uncertain what the physics of this is.  I have some plausibility arguments, but that is all.  First is that many amps are only marginally stable.  Old NAIM amps were a prime example, and you needed to use their cables to prevent the things bursting into oscillation and smoke coming out.  A current example is NVA, which have no protection circuits or Zobel or series inductor on the output, and high capacitance cables blow the amps up - you absolutely need NVA's single wire cables, and you space them apart to minimise capacitance.

 

The second plausibility argument is related to RFI.  It is alas a fact that RF getting back into the output of most power amps causes very odd behavior.  It gets into the feedback loop and can either cause instability or some sort of modulation artefacts which make the amp sound poor.  In practice, how much RF does it need to trigger this behaviour, and is this level present in most domestic environments?  Dunno.  The general cable solution if this problem exists is to use something that is woven, like Kimber - but that is very high capacitance (and astonishingly low inductance) and does not suit all amps - see stability above.  The other thing is the put external Zobel networks at both end of the cable.  In principle these need to be matched to the cable, but in practice 100nF in series with 10 ohms or so seems to work OK.  The other good thing is an air core series inductor at the amp end. 10uH or so.  Most good amps have one anyway - the inductor and output Zobel are intended to prevent instability and stop RF from mucking things up.  BUT some tweaky manufacturer's (like NVA) reckon that sort of thing detracts from the sound in some way.

 

Anyway, the upshot is that the detailed construction of the cable can change the performance of the power amp.  Plausibility remember, or isolated results and not hard physics.

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The second plausibility argument is related to RFI.  It is alas a fact that RF getting back into the output of most power amps causes very odd behavior.  It gets into the feedback loop and can either cause instability or some sort of modulation artefacts which make the amp sound poor.  In practice, how much RF does it need to trigger this behaviour, and is this level present in most domestic environments?  Dunno.  The general cable solution if this problem exists is to use something that is woven, like Kimber - but that is very high capacitance (and astonishingly low inductance) and does not suit all amps - see stability above.  The other thing is the put external Zobel networks at both end of the cable.  In principle these need to be matched to the cable, but in practice 100nF in series with 10 ohms or so seems to work OK.  The other good thing is an air core series inductor at the amp end. 10uH or so.  Most good amps have one anyway - the inductor and output Zobel are intended to prevent instability and stop RF from mucking things up.  BUT some tweaky manufacturer's (like NVA) reckon that sort of thing detracts from the sound in some way.

 

I can vouch for that, Craig.

 

I run 3-way active Maggies.  About 7 years ago, I changed my 6x AKSA monobloks for the then-current version of Hugh Dean's amps - Lifeforce.

 

After implementing the amps, I found I was getting a buzzing from my 2x 5 sq ft bass panels.  I couldn't figure out what the problem could be and eventually had to get the designer over to diagnose the problem ... and what it turned out to be was that the bass panels were acting as antennae and picking up RFI ... which was getting into the output of the amp via the speaker cables and interacting with the feedback loop (even though it didn't have much FB.

 

The solution was to put a 3.3nF film cap across the bass amp terminals - to short the RFI to ground.  For safety's sake, I also put a 1nF film cap across the output of the mid panel & ribbon amps; Hugh subsequently made this part of the circuit.

 

 

Regards,

 

Andy

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You blokes keep talking.  I'm learning good stuff here!

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RFI and magnetic fields affect digital through PC's. The answer is madscientist PC or Black Discus products. Guys you are not going to believe the difference for the good. His digital spdif cable is another winner. Checkout his products and be glad you did. 30 day MBG after he measures and blind tests. Brilliant.

 

 

charles

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Don't you just love people who laugh AT you while taking your money?

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Hello everyone. I love and am very interested in this topic but most of the read hurts my brain. I have a very good system IMHO. That said the weakest link in my system by a country mile are my Power Cables both for my amps and my Dac. I am looking at getting some Voodoo Cables in the Middle of the year. The Black Diamond for my amps and the Electra for my PS audio Dac. I hope I won't be wasting my money. One thing I will say is I did have good Power cables for my amps on loan and sadly had to give them back, It was like night and day as the Sound stage went out the window as well as the bass.

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Correct me if I'm wrong that the mad scientist reflections rather than 75 Ohms matters more. Got me. We used a CEC01 transport and a Weiss Medea DAC. No rubbish there.

     It appears for reasons I just do not know the MS cable just was better sound all around. The rest of the system are Pipedream speakers, Arion class "D" hybrid with Duelund output caps, a Loesch & weisner preamp, Kuzma TT, Triode Wire Labs cabling except digital, Lector CDP and a BSG QOL.

 

 

charles

Hi Rollo, I looks like have the same amps as you with the Dueland cast caps. :)

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Hi Rollo, I looks like have the same amps as you with the Dueland ,

 

   Great amp and the Duelund caps are just special. I use either Triode wire Labs or Mad Scientist power cords. TWL Digital All American well for digital TWL 7+ for Piaudio Uberbuss [power conditioner, two] and Mad Scientist PC for Preamp and TT.

   We use TWL and MS cords at the audio shows. The PIAudio Digibuss is a conditioner dedicated for digital. A game changer IMHO. I sell them in the States. The Uberbuss is a conditioner/power correction device. Both do no harm and bring out every bit of music noise and hash free. No loss of dynamics with amps either. Win, win.

 

 

charles

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Don't you just love people who laugh AT you while taking your money?

 

 

   Not when they offer a 30 day money back guarantee and the products are affective. When not no money from me.

 

charles

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That is the key - 30 or 60 day money back guarantee.  That way you can't lose, provided you have loadsa money to pay for whatever if you want to keep it.

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Hello everyone. I love and am very interested in this topic but most of the read hurts my brain. I have a very good system IMHO. That said the weakest link in my system by a country mile are my Power Cables

 

No it's not.  It's your speakers and their relationship with your room.

 

Notice how I don't even know what speakers and room you have?! .... That's how big a "country mile" is   ;)

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Hello everyone. I love and am very interested in this topic but most of the read hurts my brain. I have a very good system IMHO. That said the weakest link in my system by a country mile are my Power Cables both for my amps and my Dac.

No, they are not. Power cable differences are utterly insignificant.

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I took some measurements of an optimised SPDIF link.  

 

The first picture shows the set up.  This is from an old, but still excellent Meridian 200 transport with modified (by moi) output to a Metrum Octave DAC, again modified.  The small silver box is a Minicircuits 75 ohm power splitter so that the real time signal passing through can be picked off for display.

 

The second picture shows the picked off SPDIF signal.  This is displayed on a Tektronix 7854 scope with 7A29 plugin, and a 75 to 50 ohm impedance convertor.  I have measured the bandwidth of that combination using a tunnel diode pulser with 30ps rise time, at 740MHz  That is way overkill and shows small ripples on the waveform that are invisible at lower bandwidths.  The measured rise and fall time are equal at 1.3ns.  The signal amplitude is 60mV and is lower than the required 400mV as a result of insertion losses in the power splitter and impedance convertor.

 

attachicon.gifSPDIF-setup.jpg

attachicon.gifSPDIF-signal.jpg

I miss my 7854. I don't miss the bench real estate I got back. Fabulous CRO. I retained my 7A22 plug-in though. I'll find something to use it with.

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I miss my 7854. I don't miss the bench real estate I got back. Fabulous CRO. I retained my 7A22 plug-in though. I'll find something to use it with.

 

Alas one of my "hobbies" is test equipment.  My original background was in electronics at at time when the 7000 series was current, and house mortgage price.  Now you can buy them for not much.  So I have almost all the 7000-series mainframes and most plugins (many of them twice).  That is not counting HP, General Radio, AVO and Fluke.

 

My long suffering wife reckons that there is a fine dividing line between "hobby" and "mental illness".

Edited by CraigS

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Alas one of my "hobbies" is test equipment.  My original background was in electronics at at time when the 7000 series was current, and house mortgage price.  Now you can buy them for not much.  So I have almost all the 7000-series mainframes and most plugins (many of them twice).  That is not counting HP, General Radio, AVO and Fluke.

 

My long suffering wife reckons that there is a fine dividing line between "hobby" and "mental illness".

LOL! Same here. I've started my collection with some nice pieces. I recently acquired a couple of these:

http://www.ebay.com/itm/131657437692

Astonishingly complicated mechanical masterpieces. I'll seek out the matching chart recorder.

I did, finally, acquire an AVO 8 recently. I recall lusting after one 45 years ago, but could not hope to be able to afford one. They're cheap as chips now.

I do miss the 7854 though. A formidable instrument.

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Alas one of my "hobbies" is test equipment.  My original background was in electronics at at time when the 7000 series was current, and house mortgage price.  Now you can buy them for not much.  So I have almost all the 7000-series mainframes and most plugins (many of them twice).  That is not counting HP, General Radio, AVO and Fluke.

 

My long suffering wife reckons that there is a fine dividing line between "hobby" and "mental illness".

Is your wife into shoes?

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