Same old cable argument again...

Yes thats right - inappropriate and conflicting earthing arragements as noone considers the properties of the entire earth current network. I think this is why well constructed mains cables especially with filters can make a difference, in a system that has a problem.

I prefer to listen first if thats ok. If that works out are you prepared to do a quick dem in my own system as you live just up the road from me? If I want a custom unit made is it best to contact mfa or yourself? My experience from before is that I will be waiting for them forever. I plan to go pmc active and have three pairs of long cables runs from the crossover to the amps and run a single pair of 10cm balanced cables from the pre to the crossovers. Would it be possible to use the TVC unbuffered like this with the short cable runs - I assume crossovers are easier to drive than power amps anyway. Currently I have 3 pairs of 3m balanced cables between pre and power amps so the tvc unbuffered is a nono as I said before. Perhaps we should continue this via PM.

 

Hi,

Yes. The info on the ABX is scant but even what exists (including especially some tests Tom Nousaine published in the long dead "Audio" mag from the US) raises many issues, well past minor statistical or procedural quibbles.

Yes and no. I personally suggest that one determines the other.

I need to check anchient (late 90's) papers if I still have the stuff, but I had overall 8 - 10 formal subjects, most of them NOT audiophiles (I was at the time living in a doctors flat in the Nurses Quarters of a Hospital - most of my subjects where in fact nurses of both sexes who liked music, I kinda presented this as almost a game). In order to not strain their friendliness towards me I limited each subject to 6 Trials, weighted correctetly to make sure that different and same samples had equal numbers.

I did make sure to select cables that had broadly similar electrical parameters (100pF/m) but which I had a strongly contrasting sound. One was RG-214/Mil which was used as "normal" reference and the other steel cored, copperclad RG-58. Resitance differences and capacitance differences where near the limits of what I could/can measure with reliability and should not have influenced the signal at all. I should add that the steel core in the RG-58 does give rise to measurable distortion in audio terms, at the time there was a contention that the difference may be measurable but certainly could not be heard.

I was unable to discard outliers due to the limits of the dataset choose a significance level of .2 for analysis, which with the around 50 sample size gave similar risks of Type A & B errors for small differences. All subjects showed a reasonable identification of the "DUT" cable over the control, as much as of no chnage to the control. In fact, most commented that the "DUT" cable (steel core RG-58) sounded quite unpleasant (which confirmed my own impressions, it sounded completely horrid!!!).

No, no. What I am refering to is the significance level.

As my dataset was small I choose a significance level of .2, in other words, out of ten experiments absolutely identical to mine, but with no actual difference preset only two would return an answer suggesting a difference is actually present, statiscally speaking.

So, I am so to speak 80% certain that my subjects really heard an actual difference and need to allow a 20% possibility that in fact the results are purely due to chance while no actual difference existed.

Green?

Ciao T

 

Hi,

I am suggesting that as you around london you may be able to get a Home Demo from JB or HOS at MFA, if it's on their way and such.

I think I'll pick up as the Technician for the UK distribution.

It would be fine with long cable runs as well. The TVC merely passes on what your source puts out. If your source can drive what comes after the TVC, then so can the TVC... ;-)

I would not think that length and number of cables would be a problem. The problem would be to make a unit with 3 pairs of XLR Outs! The MFA PMP has space for 3 Pairs of XLR's, so you would give up all XLR inputs to get so many outputs.

Ciao T

 

Ah ok it was my understanding that for 3 pairs of 3m cable to drive, the tvc would need a buffer of some sort. Let me know when you have a window in your schedule. I am also interested in hearing the s&b based phono.

 

Hi,

No, we normally suggest up to 1nF capacitive load. If you have 3m cables they would usually clock in at 50-100pF/m, so three in parallel are below this limit. The problem you have is where to plug them in.... ;-)

I'll see what my time is like, busy for the next week or teo I'm afraid...

Ciao T

 

Thanks. I will now go away this weekend for further :rds2:.

 

An assumption that a very small quantitative change in perceived loudness (of approximately 2%) equates to a qualitative change. Is this the case?

If a bucket has one thousand holes how will plugging one of those holes make it appreciably less leaky? And how many of these supposedly EMI shielded cables include EMI gland nuts?

The continuing fascination of audiophiles with matters of such insignificant magnitude shows no sign of abating.

 

Hi,

Stop shifting goalposts. I am merely pointing out that any categorical statement "cables cannot make an audible difference" is wrong. As for personal preference in sound, perception of "better" or "worse", that is a totally different story.

Again the usual dismissing view.

If a cable will pick up (aerial action) less RFI across a given freqency range it will do so and the results will remain observable DESPITE other sources of RFI ingress.

Let us be very clear, the effect of a few mm gap in a shield vs a 1 meter aerial in terms of noise picked up are quite drastic, especially if the frequency are not GHz but Shortwave and related bands.

Look, you guys ask for reasons why cables may make "different sound", here they are. Don't like them, great. We knew that. They won't go away though.

L8er T

 

As I plan to switch to active then I would only be looking for a pair of baanced outputs driving 0.1m cable. Bearing that in mind demming it in my current system is going to be a bit tricky and pointless. Probably a better idea for me to bring along my phono and volco and compare in your system if thats ok. No hurry. I will have to wait for my xmas bonus to go active anyway

 

I'm not shifting the goal posts and I wouldn't support a categorical statement “cables cannot make an audible differenceâ€Â.

I was asking if you consider a fantastically small change in perceived loudness – at the very periphery of audibility – as qualification for the reams of superlatives and metaphor applied to cable sound and the like?

Usual and dismissing maybe but a view that's based on simple common sense and one that, because of this, does not have a satisfactory answer.

You suggest others have not properly thought about the problem:

His first fault was of course to bring in the "cheap wire in the wall" - "expensive cable at the Amp" argument, which is obviously irrelevant in any kind of logic, to the question "does it make a difference".

There's approximately 14km of power cable between my local electricity transformer and my wall socket. Let's suppose 5% of this power cable is susceptible environmental EMI – this would represent 700m or so of which the last meter would represent about 0.1%.

Objectively, do you think EMI shielding applied to one tenth of one percent of a circuit is likely to result in a measurable (read useful) reduction of conducted EMI?

On the other hand a hi-fi power cable with a loop inductance (across live and neutral) of 100uH or so might actually be useful. Unfortunately I don't think this is possible without using ferrous materials.

 

Think of the cable acting as a sink and the major source of mains pollution being the hifi component itself. Treat at source?

 

I'm afraid you misunderstand the nature of EMI Mick.

It presents in two basic forms; conducted - travels down wire and cables etc - and environmental - is all around.

A cable with a shield will reduce the ingress of environmental EMI to the conductors of that cable (and also reduce the outgress of radiated EM waves from that cable) but will not “sink†nor filter conducted EMI present on the conductors as a result of EMI ingress or causation elsewhere.

To reduce conducted EMI requires a reactive component such a wire wound choke on an iron powder core or a cable ferrite or some other type of mains filter.

 

Hi,

You may ask. Good thing I anticipated this question several days ago. Most simply put, the issue is "familiarity breeds contempt". I'm happy to enlarge on that, as well to present illustrations and parables in the context, but not right now.

The least common of the senses is what one should use if one is actually out of ones depth, it's other names are prudence, caution and carefulness.

No. I suggest that they DID NOT THINK AT ALL, but merely repeated dogma in their own terminology, a charge lesser in some view, but much more serious in another.

And all that cable concerns itself with is to conduct 50Hz power to where it conducts it to and to (undesirably) pick up common mode noise noise all the way from supra low frequency used in (nuclear missile) submarine communication to stuff in the FM range and above.

There is no audio or related signal there, merely power and noise. The place where the audio signal is involved is quite limited in actual loop size and usally is limited to the mains cable and the distribution plug board.

Objectively speaking I think you are being very lazy and you cannot be bothered to actually think. If you did, you would not have asked that.

There are all sorts of things to do. We can discuss them in different contexts. I generally tend not to be too worried about common mode stuff. Consider instead the loops formed by mains cables and interconnects (how about 2-3m per loop?) locally, where the induced and picked up voltages are not common mode, but differential mode.

Ciao T

 

Hi,

Well, that is easiest work possible for a TVC.

Ciao T