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Old 5th February 2012, 10:08 AM   #1
Mike B is offline Mike B  United Kingdom
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Default Made to Measure Audio Interconnects

I was repairing an old tuner & it got me thinking about interconnects; what’s it interconnecting?
Internally the circuits go through various short wire links, PCB tracks, circuit components & the grounds mostly all common & coming from different directions. It made me wonder why so much effort & importance is placed on IC design. What does 1m or 1.2m of cable do that is so magical considering the apparent chaos of the equipment internals.
If the cable has an effect then is that not implying the cable acts as a filter, but if as I suspect a well-designed “good sounding” cable does nothing, then surely less of nothing might be better than 1.2m worth.

So what will the shortest & simplest possible cable do for us?
I looked around the interweb & selected a cable that has the lowest possible capacitance, good dielectric and minimal resistance etc., in other words less of anything that could have an effect on sound.
I chose Mogami 2549, XLPE, 76pF/m core-screen & 11pF/m core-core
I acquired a length (from USA, not available in these parts) & some Neutrik 5-pin DIN’s.

The cable is a simple 2 channel twisted pair with a wire spiral screen, I selected this deliberately as a 2 channel signal & return screen ground is electrically the same as the source & pre-amp PCB wiring – 2 channel signal & 1 common ground. I considered star-quad (using a double insulated return) but with the very short cable lengths its noise rejection advantages would not come into play.

The cables where made to fit exactly between sources & amp. The CDP is 18cm long, the tuner is 30cm.
After a few days listening I am confident my logic has some merit, I am not making claims on how it (they) sounds, but enough to say I am pleased.

Any thoughts from our eminent forum members.
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Old 5th February 2012, 11:03 AM   #2
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What are you comparing them to? Unless you have enough of many materials and design, incremental changes that cables seem to make, cannot be heard.

My suggestion is that you try these A New Interconnect Design
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Old 5th February 2012, 11:31 AM   #3
Mike B is offline Mike B  United Kingdom
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Sam, 1st point is I am not a cable believer, the reverse in fact, cables cannot "improve" sound. I am an electrical engineer with a quite few years experience in the discipline of R&D & all over the real world with training & hands on trouble shooting experience. Exotic cable designs is also what my post is suggesting are maybe unnecessary.

I'm comparing them to standard length commercial cables, all DIN-DIN. I'm doing this primarily in my own Naim integrated amp/CDP/tuner set up but also with some friends with multi-box set ups and using their cables. My own cable for comparison are Naim standard "lavender", AR Sounds Skylink & FlashBackSales PP. Loaned cables are Naim HiLine, Chord Anthem & Cadenza.
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Old 5th February 2012, 11:46 AM   #4
AndrewT is offline AndrewT  Scotland
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Yes, the interconnects create filters.

I would suggest that the cable characteristics be chosen to ensure the filters so created do not remove nor alter the audio signal.

I would guess that short cables are better than long cables for interconnects.

But, in my opinion speaker cables have a much bigger effect on the behaviour of the attached amplifier and on the behaviour of the attached speaker, than interconnects do for sources and receivers.
Moving on from there, I believe that short speaker cables are more important than short interconnects to get the biggest benefit from choosing the cables' characteristics.
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Old 5th February 2012, 12:02 PM   #5
Mike B is offline Mike B  United Kingdom
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Hi Andrew, agree on the speaker cable lengths until - like me - you have Naim amps.
Naim, Linn & NVA whilst they have a classic zobel cap & resistor in shunt across the output, they do not have a HF ringing stabilisation inductor incorporated inside the amp. Instead they use the inductance of the speaker cable. Hence Naim need a minimum of 3.5m preferably of their own NACA5 at 1uH/m
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Old 5th February 2012, 12:07 PM   #6
AndrewT is offline AndrewT  Scotland
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Yes, I knew Naim did this.
I did not know that the same applied to Linn & "who?".

3.5uH is quite a lot for the output L//R.

Does the amp really perform that well if it is designed to need that much output inductance?
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Old 5th February 2012, 12:38 PM   #7
Mike B is offline Mike B  United Kingdom
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NVA - Nene Valley Audio - NVA Index Frame
They seem to be more concerned with using low capacitance cable which I don't see as the way to fix HF osciliation stability issues.
A typical power amp zobel will have a shunt connected 100nF cap in series with a 10r resistor, but I believe they don't have this anyway.
But a typical speaker load has uF (micro) values, considerably more so if its an electrostatic, so in my book a few extra pF (pico) of speaker cable will hardly have much effect on controlling HF stability issues.

Naim recommend a minimum of 3.5uH (3.5m) optimum is 5 to 8, up to a max of 20.
Their modern amp designs are far more tolerant of low L high C cable designs as they appear to have a designed rolled off within the audio circuit, this comes in above 50kHz so they tend to avoid output stability issues anyhow.

Typical classic built in series inductors are around 5uH with a 10r shunt to damp L/Q.
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