Music pros are not immune from bull

[71 dB]

IMO he is clearly biased.

Yes, he is biased in favor of science against snake oil nonsense.

 

[bfreedma]

EMI susceptibility of the cable.

The original reason cables had a "direction arrow" was to show which end had the shield connected to. Unbalanced cables which adhering to one of the conventional instrumentation theory wiring conventions generally have a ground and live wire twisted around each other, with a shield braid surrounding them and attached at one end only. This is so the shield can dump any interference into one of the connected pieces of equipment, and not the other. So it makes sense to label that so you can get it the right way round.

Of course the audio community who did not understand this, (perhaps through a lack technical knowledge, or more likely some manufacturer inventing reasons to fit in with the marketing nonsense that surrounds some parts of the industry), could hear the difference in some circumstances, and "invented" directional copper. Then I suspect they imagined speaker cables are directional next, and the whole thing got ridiculous.

This null test is a great leveller, and has enormous merit. However you ask "What do you believe null testing of these wires fails to account for?": It cannot fully qualify differences in RF shielding and conduction. This can occasionally make a difference, especially in the era this started, before CE approval, as things get a little difficult to predict. However I never pay a lot for audio cables. I just get decent quality microphone cable, and solder it carefully in decent RCA plugs, marking the end with the shield connected.

(Before the usual suspects flame the above, this instrumentation theory comes from an AES lecture on grounding)

Wouldn't the differences in RF shielding and conduction show in a null test? Theoretically, I see your point if we took the same cables that nulled out in location 1 and moved them to location 2 without again performing a null test, though I haven't seen evidence of this happening in the real world. At least not without unusual circumstances.

 

[gregorio]

I have seen interviews with big time musicians with horrifyingly cheap systems\boomboxes ect in their living rooms....i guess if you are used to the sound of live music, the sound of reproduced music can become a bit of a lost cause?

I don't think it's quite as simple as that. In a sense, big time musicians are NOT used to the sound of live music! What they're used to is the sound of their instrument a few inches away, to which they are physically connected and additionally, they're used to the sound of the ensemble they're rehearsing and performing with from the aural perspective of being inside that ensemble. The sound they are used to is substantially different from the "sound of live music" (the overall performance as heard/experienced by the audience). Experienced musicians know this and it means that what we're ultimately dealing with is not what the musician is actually used to hearing but some idealised subjective concept of what they want to sound like (to an audience). Musicians not experienced with recording/audio will invariably make the same initial statement when hearing the first playback of what they've just recorded: "Is that me?" or "Did I do that?".

Additionally, as I mentioned before, many musicians simply don't know very much about audio and due to these two factors we therefore find a pretty wide spread amongst musicians that's not dissimilar to the general public. Many musicians are reasonably satisfied with typical consumer systems, some are audiophiles and believe the same audiophile myths as other audiophiles and a very small minority want to know the actual facts and have accurate rather than "subjectively pleasing" systems.

G

 

[dexter3d]

Ok so couldn't help it and asked the guy about it. He stands by it 100%, said did some blind tests with his wife switching cables etc, differences in depth timbre cold hot or whatever. So sad.

 

[jagwap]

Wouldn't the differences in RF shielding and conduction show in a null test? Theoretically, I see your point if we took the same cables that nulled out in location 1 and moved them to location 2 without again performing a null test, though I haven't seen evidence of this happening in the real world. At least not without unusual circumstances.

It is possible the null test could show them, but unlikely. Unless the null box demodulates the RF to audio frequencies (which is predominantly what we are concerned with) equally accurately, the difference between the RF behaviour in each will end up as a difference way beyond the audio range, and likely suppressed in the circuit. There are no apparent EMI precautions in the schematic shown, but it is unlikely to be the real one if it is a commercial project. It would be interesting to produce an RF null tester, where the RF is deliberately demodulated.

Another limitation is that the null tester cannot be used to compare active or AC coupled circuits, as the creator alludes to in the video when he mentions phase shift. Any tolerance in capacitance would cause a phase error which would swamp the nulled signal. Many have tried, with varying success. Brunel University Audio department had an interesting project, and NAD research did some work in this area, twice.

 

[bfreedma]

It is possible the null test could show them, but unlikely. Unless the null box demodulates the RF to audio frequencies (which is predominantly what we are concerned with) equally accurately, the difference between the RF behaviour in each will end up as a difference way beyond the audio range, and likely suppressed in the circuit. There are no apparent EMI precautions in the schematic shown, but it is unlikely to be the real one if it is a commercial project. It would be interesting to produce an RF null tester, where the RF is deliberately demodulated.

Another limitation is that the null tester cannot be used to compare active or AC coupled circuits, as the creator alludes to in the video when he mentions phase shift. Any tolerance in capacitance would cause a phase error which would swamp the nulled signal. Many have tried, with varying success. Brunel University Audio department had an interesting project, and NAD research did some work in this area, twice.

Interesting, thanks. How likely is it that those scenarios create an audible difference in real world conditions? I'll see if I can find the research and give it a read.

 

[Glmoneydawg]

Interesting, thanks. How likely is it that those scenarios create an audible difference in real world conditions? I'll see if I can find the research and give it a read.

With the high levels of pre-amplification required for record playback,unshielded cables easily pick up 60hz(Canada)powerline humm from badly placed power cords...shielded cables clear this up.Try moving your phono preamp patch cords around the power cords in your system.....easy experiment.No it has no effect on sound quality per se,but definitely reduces line frequency humm.

 

[bigshot]

I never had problems with power cords with my turntable, but I did have trouble if the cables dangled over a TV set.

 

[Glmoneydawg]

I never had problems with power cords with my turntable, but I did have trouble if the cables dangled over a TV set.

Yep...you have to have some unfortunate cable placement to make it happen...and the fix is as simple as moving the cables a couple of inches.When you consider the tiny electrical signal from your cartridge being amplified up to line level and how low that signal is before amplification it's amazing it doesn't pick up more noise.

 

[bfreedma]

With the high levels of pre-amplification required for record playback,unshielded cables easily pick up 60hz(Canada)powerline humm from badly placed power cords...shielded cables clear this up.Try moving your phono preamp patch cords around the power cords in your system.....easy experiment.No it has no effect on sound quality per se,but definitely reduces line frequency humm.

No phono here to try that with, but I don’t doubt an unshielded phone cable would be susceptible.

 

[jagwap]

No phono here to try that with, but I don’t doubt an unshielded phone cable would be susceptible.

It really needs to be a shielded cable which has a separate ground inside the shield for the pickup reference. This is because the output from a cartridge is balanced, and it is especially important to separate the ground to the cartridge and the shield dumpling the turntable noise. This is also why decent turntables have an extra and separate chassis wire to attach to the chassis of your preamp. When Rega dropped the wire to save money, they caused huge problems.

 

[bigshot]

It's easy to make your own ground wire. Just attach a wire to the chassis of the turntable and run it to ground.

 

[jagwap]

It's easy to make your own ground wire. Just attach a wire to the chassis of the turntable and run it to ground.

Sure, but

1. People won't
2. Rega already connected the chassis to the left channel screen.

There was a lot of hum, and customers blamed the amps not the turntable.

 

[bigshot]

I had a Dual that had grounding issues. I connected a wire to the chassis and then attached the other end of the wire to the screw in the center of the wall plug. Fixed it right up.

 

[Don Hills]

...Musicians not experienced with recording/audio will invariably make the same initial statement when hearing the first playback of what they've just recorded: "Is that me?" or "Did I do that?". ...

Hands up anyone who has not been surprised at how different a recording of their own voice sounds.