• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

RCA cables make no difference, that's what they say

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
.... really???

So, this is the "real life" test setup, very simple, however addressing common issues.

Class I analog audio generator is the signal source, yes class I so the signal ground is connected with mains PE. Then we have RCA to RCA cable and USB soundcard, that is connected to the PC notebook (with SMPS of course) that is also class I. So we have the usual ground loop as many users are experiencing every day. Small -40dBV generator signal is used. Now the results:

1) RG-59 cable 50cm
RG-59_50cm.png


2) Monster Interlink 250 shielded twisted pair, shield connected at one end only, 35cm
Monster_35cm.png


3) "Generic" cable 1m (something supplied with DVD player)
Generic_1m.png


4) Profigold with EMI suppressor, 1.5m
Profigold_150cm.png

Profigold.JPG


5) Pseudo-balanced RCA to XLR, big mismatch of 600ohm to 1.5kohm/1.5kohm, 50cm
Pseudobalanced_50cm.png


Measuring system background noise

system_noise.png



Conclusion

Monster Interlink 250 twisted pair is the worst, though shortest. It verifies that twisted pair or Kimber-like wire for single ended link cable is a nonsense. Even highly mismatched RCA to XLR pseudo-balanced is a winner.
 
Last edited:

thewas

Major Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
4,189
Likes
9,215
Most knowledgeable audio people say that cables don't make an audible difference (except for example capacitance in phono cables or long distances in noisy EMF environments) which actually also your measurements show, namely that those differences under -100dB are not audible but of course they are measurable.
 

VintageFlanker

Major Contributor
Forum Donor
Joined
Sep 20, 2018
Messages
2,960
Likes
8,924
Location
Paris
Well, I guess just everybody's agree on: different cables don't measure the same.

Sounding different is another story. Based on your measurements, I don't see how there may be any matter in the acoustic realm.

-100dB THD+N at 50Hz could not be audible by anybody on Earth.;)
 
OP
pma

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
Most knowledgeable audio people say that cables don't make an audible difference (except for example capacitance in phono cables or long distances in noisy EMF environments) which actually also your measurements show, namely that those differences under -100dB are not audible but of course they are measurable.

Frankly, I do not agree. It is just one specific case and quite "optimal", because the generator and PC share the same mains outlet. First.

Second, take into account it is a link level. Add a power amplifier with typical gain of 26 - 29dB to all the interference spectral lines, and you are in the range of audible signals, if you cover complete 20kHz range. At least you have different kind of audible buzz.

Now my question stays as always, why isolated component ultra SINAD debates if the short RCA interconnect between two class I components destroys it completely? And are you sure that the resulting amplified (power amp gain) difference will be inaudible? Or is it just another kind of unsupported belief, not very different from audiophile beliefs?
 
OP
pma

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
Well, I guess just everybody's agree on: different cables don't measure the same.

Sounding different is another story. Based on your measurements, I don't see how there may be any matter in the acoustic realm.

-100dB THD+N at 50Hz could not be audible by anybody on Earth.;)

Again, this is a link level with short cables and same outlet plug. Add at least 26dB power amp gain and consider the buzz over whole audio band. You guys should think deeper, at least, and present some real life results. Why do you think that so many members complain of buzz and "noise"? You have the answer here.
 
OP
pma

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
I don't think anyone is saying RCA vs XLR makes no difference in ground loop conditions. But even in your tests (with short cables) the differenece is inaudible to most people.
Same answer, add 26dB gain of the power amplifier.
 
OP
pma

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
OK guys, I will leave you for some time. My many decades experience says that RCA cables may make a difference which strongly depends on the system setup and grounding of individual components, including safety classes.
 

tonycollinet

Major Contributor
Forum Donor
Joined
Sep 4, 2021
Messages
2,097
Likes
2,969
Location
UK/Cheshire
Same answer, add 26dB gain of the power amplifier.
Point taken.

But still - I don't think many claim there is no difference between RCA and XLR. And the difference between the different RCA cables is marginal even for the monster cable with disconnected shield and twisted pair.
 

thewas

Major Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
4,189
Likes
9,215
Frankly, I do not agree. It is just one specific case and quite "optimal", because the generator and PC share the same mains outlet. First.
As I wrote already in noisy EMF environments it is not difficult to hear the difference between for example a shielded and non shielded one but this is not what audiophiles usually claim under "cable sound".
Second, take into account it is a link level. Add a power amplifier with typical gain of 26 - 29dB to all the interference spectral lines, and you are in the range of audible signals, if you cover complete 20kHz range. At least you have different kind of audible buzz.
The distance to your 1 kHz tone would still remain more than 80 dB and make them rather inaudible/masked.
Now my question stays as always, why isolated component ultra SINAD debates if the short RCA interconnect between two class I components destroys it completely?
Have you seen me writing anywhere about the audible importance of very high SINADs? Most knowledgeable audio people just like them to be very high as a proof of technical effort and excellence, but not because they audibly sound better.
 

ZolaIII

Major Contributor
Joined
Jul 28, 2019
Messages
1,858
Likes
1,072
Of course that everything makes a difference that's why we have standards in the first place. You need better shielding for better EMI rejection, you need ticker conductor for longer cable, you need a termo and generally more durable cable for field use while you will certainly go grounded not to chase loops especially for equipment that is moved and reconnected regularly.
But hell you don't need magic, stiff one's made of unicorns horn all you need is deacent ones and that's all what this whose about in the first place.

Example (edited): I switched to ProCab CLA RCA one's recently because those ware cheap and widely available where I live. AWG is an thin side but I doubt I will ever need a more than 5 meters long one in my use case so that whose not the issue and connectors are deacent while cable is flexible. Tested the 5 m long one by wrinkling it into bunch of power cables on the floor and putting it upon large working plate capacitor, cable whose plugged to working power amplifier while I held other end in my hand. As it remained silent (I couldn't hear anything) it whose future proof enough for what I want it to do.
 
Last edited:
OP
pma

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
So this is the "winner" of the test. Another "Generic" cable, now #2, 1m long. Again supplied with a DVD player.

Generic2_1m.png


Please anyone, do not tell me that RCA cables cannot make a sound difference as a general statement.

The cable looks like this and we call it a shoelace.
Generic_cable_No2.JPG
 
OP
pma

pma

Major Contributor
Forum Donor
Joined
Feb 23, 2019
Messages
2,905
Likes
5,797
Location
Prague
Hi @pma. In my opinion, this is a valuable research, thanks for your time. Do you have some studio brand (Cordial, Sommer, Klotz, etc.) RCA cable to test? It would be nice to see how they perform. Thanks!

Hi @xaviescacs , thank you. I have such cables, but only XLR-XLR and TRS-XLR. As you have already stated, they are intended for professional use. I normally run 10m of XLR-XLR and 3m of TRS-XLR without smallest issues and interferences, but yes, in balanced links. I would need to cut some of them and solder the RCA's. Or I might try to put XLR-RCA adapters behind the XLR's
 

MusicNBeer

Senior Member
Forum Donor
Joined
Jan 20, 2019
Messages
310
Likes
446
The only difference is noise immunity. That's why I simply put my ear up to each woofer and tweeter to make sure the cable is shielding correctly. If quiet, it's good. Those distortions aren't signal dependent. There's no harmonic distortion being added by the cable.
 

SIY

Master Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
8,279
Likes
18,586
Location
Alfred, NY
I'm not seeing anything here approaching real world audibility, even accounting for power amp gain (from your first DVD interconnect, there would be roughly -80dBV at the speakers, translating to about 20 dBSPL at one meter from an extremely sensitive horn, in a frequency range where hearing is not very sensitive). I can construct an edge case (expensively treated and isolated room, horn speakers, close in listening by a 12 year old), but that's hardly real world. As @MusicNBeer says, the real test is audibility in situ. I routinely use interconnects like your DVD ones with no audible noise from listening position or even from one meter. Cheap Amazon cables are a theoretical step up. That's what's in my system now and I would challenge anyone to hear an ill effect.

The very worst interconnects I've used were from Morrow, pretty expensive had I paid for them, audible buzz from 2-3 inches away, but zero from two meters. No real shielding, but that's not in accord with your strawman ("do not tell me that RCA cables cannot make a sound difference").
 
Top Bottom