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RCA to XLR trouble


Seems like an anti-snake oil article. What's wrong with that quote?
The first part is technically correct, but meaningless in practice for a decent DAC. The signal is reduced while the noise floor remains the same (so reduced SNR) but when the noise floor is inaudible (as it will be for any decent modern DAC) or below the noise level of the monitor's ADC, you can't hear a difference. For the 'blind test' I'd love to see the details of the test. It's certainly possible for the OS or application to have poorly implemented volume control, or for the analog volume control to have audible distortion that might be preferred, but if both are done well you're unlikely to hear the difference. We have whole threads on these issues, like:
https://www.audiosciencereview.com/...olume-control-vs-analog-volume-control.20512/
https://www.audiosciencereview.com/...nding-the-windows-audio-quality-debate.19438/
 
The first part is technically correct, but meaningless in practice for a decent DAC. The signal is reduced while the noise floor remains the same (so reduced SNR) but when the noise floor is inaudible (as it will be for any decent modern DAC) or below the noise level of the monitor's ADC, you can't hear a difference. For the 'blind test' I'd love to see the details of the test. It's certainly possible for the OS or application to have poorly implemented volume control, or for the analog volume control to have audible distortion that might be preferred, but if both are done well you're unlikely to hear the difference. We have whole threads on these issues, like:
https://www.audiosciencereview.com/...olume-control-vs-analog-volume-control.20512/
https://www.audiosciencereview.com/...nding-the-windows-audio-quality-debate.19438/

I don't know if this applies to lower end subs, but Genelec have this to say:


Supposing it applies to the 7040/7050 or F One subs, I could go digital out on the Wiim and have the subs deal with the conversion and volume control?
 
7040/7050 don't have digital input or remote volume. F One has a wired remote volume control that probably works via the DSP, and has digital input, so should be usable that way. It has RCA outputs.
 
We discussed this recently—again for the millionth time. Follow Bill Whitlock's recommendation as illustrated below:

View attachment 366769

If you make them yourself, use a 'regular' XLR connector and a good Shielded-Twisted Pair (STP) cable that does not have a drain wire. If you're so inclined, you can even use a star-quad cable like Mogami W2534. Additionally, it is imperative to maintain the twist of the inner conductors right up to the solder cups in the connector—at both ends. Using an adapter and a two wire cable gives you no rejection. If you use a STP unbalanced cable to the adapter, the 'untwisting' of the pairs in the adapter will defeat the purpose of using an STP cable.

If you buy pre-made cables, you should open them up and examine the layout and the build quality on both ends of the cable. Bad solder joints, stray wires, or untwisted pairs in the cable? Send them back and find another vendor.
First, thanks for posting this. Even though I'd seen these diagrams many times, this was the first time I noticed a reference to using 2 conductor Shield-Twisted Pair. For completeness, Mogami W2549 is also a commonly recommended STP wire for such interconnects. The Star-Quad (W2534) vs STP (W2549) debate is a different conversation.

But a question:
Why does Bill Whitlock show the RCA shield being connected to both the "Lo" (Pin 3) wire and the shield wire; while the RaneNote 101 recommended wiring (Rane 17) shows the RCA plug only being connected to the "Lo" (Pin 3) wire and not the shield wire? These seem to be contradictory — so is one right and one wrong? Or are there cases where Whitlock's connecting the shield wire is preferred, and other cases where Rane 17's leaving shield disconnected is preferred?

Rane 17.png
 
Leaving the shield floating at the RCA End will generally reduce ground loops. The RCA Ground gets terminated through the (relatively high-z) inverting side of the differential input - and is not shunted to the XLR Pin-1 Shield/Chassis Ground.
 
Both Whitlock's and Rane's suggestions should work. I would say Whitlock's should be preferred for safety, but may have ground-related noise issues (ground loops, 'USB noise' etc.) in some systems. Rane's avoids the ground-related noise, but if the 'ground' floats to a significantly different voltage there's a possibility of damaging a poorly protected input. In balanced connections if the shield needs to be disconnected at one end because of ground-related noise (because of a 'Pin 1 problem' for example), it is better to disconnect at the receiving end to avoid degrading the CMRR. I don't know if this holds with RCA to XLR as the cold doesn't have a matched impedance. If you know the output impedance of the source you can put a matching resistor between RCA shield and the black of the pair to improve this.
 
Both Whitlock's and Rane's suggestions should work. I would say Whitlock's should be preferred for safety, but may have ground-related noise issues (ground loops, 'USB noise' etc.) in some systems. Rane's avoids the ground-related noise, but if the 'ground' floats to a significantly different voltage there's a possibility of damaging a poorly protected input.

In balanced connections if the shield needs to be disconnected at one end because of ground-related noise (because of a 'Pin 1 problem' for example), it is better to disconnect at the receiving end to avoid degrading the CMRR. I don't know if this holds with RCA to XLR as the cold doesn't have a matched impedance. If you know the output impedance of the source you can put a matching resistor between RCA shield and the black of the pair to improve this.
Thanks. And of course, this raises a few additional questions that I am also wrestling with how to properly integrate consumer-level devices and professional-level audio equipment. Especially since many of the articles I find on this topic are written from the perspective of live performance venues or professional studios. That is, cases where grounding safety, RFI/EMI issues, and cable lengths are all potentially significant factors to consider when wiring interconnects between SE & Balanced connections.

One of my goals is to understand the normative wiring design(s) that are the most optimal and/or the most pragmatic within the the context of a home studio / home stereo. That is, where all equipment is well designed with proper health safety certifications (i.e., CE, FCC, UL marks), the cable runs are reasonably short (within same room), and the RFI/EMI is typical for a home setting.

Note:
  • The following questions are from such a home studio / home stereo perspective
  • The context is only for interconnects from Unbalanced output to Balanced input (not the other direction)

On whether to connect the ground (Whitlock vs. Rane):
[Q] In what cases would or should someone like myself (home office stereo) or a musician (home studio) want to follow Whitlock for the increased safety over Rane for the lower ground-noise? Given that all equipment is properly certified, undamaged, unmodified, using correct cables (i.e., no cheater plugs), and indoors.

On maintaining CMRR benefit:
One of the benefits (as mentioned by both Whitlock and Rane) for using 2-conductor rather than coax is that it will allow the input device to use CMRR to cancel out any noise introduced into the interconnect cable. In some posts, there is no mention of adding a resistor (at the RCA side between sleeve and the Pin 3 wire). Other posts say that such a resistor must be added to have the CMRR benefit.
[Q] Is there no CMRR benefit at all if an impendence resistor is not added, or is there some benefit without it and even greater benefit when adding it?

On when RCA-side impedance matching could be pragmatically (i.e., potentially noticeably) beneficial:
[Q] In what cases is adding the resistor even worthwhile, especially for those of us who are making our own cables (i.e., trivial to solder in a resistor) or are perfectly happy to pay extra for a custom-made cable? And does that answer change based on whether the usage is for a home studio context (i.e., recording, mixing, mastering) vs. a home stereo context (i.e., just listening to music on speakers or headphones in our home office, living room, etc.):
  • Home studio: <01m, i.e., from closely placed devices, synths, etc.
  • Home studio: <10m, i.e., from devices, synths, etc. further away, or out to speakers / subs
  • Home stereo: <01m, i.e., from closely placed inputs (e.g., DACs, CD/DVDs, etc.)
  • Home stereo: <10m, i.e., from devices, turntables, etc. further away, or out to speakers / subs
  • Home stereo: <30m, i.e., out to speakers / subs in a very large living room
 
For reference see Jensen Transformers' AN007 covering the causes of noise pickup and practical ways to address them in detail.

Ground related noise (loops, USB noise etc.) is a system problem that depends on the details of all the connected equipment, the mains wiring and how everything is connected. It's an inherent risk with single ended connections, but not a certainty. Properly implemented balanced connections are immune, but not all are properly implemented (not following AES-48, leading to 'Pin 1 problems').

In a home setting the biggest potential problem is ground related noise (loops, USB etc.) although it's far from a certainty. It's uncommon enough that balanced interconnects haven't become standard in hifi, but common enough that we keep having people ask how to solve it. The more parts to the system, and the more spread out it is, the greater the risk. If you keep on connecting different things you're also more likely to run into a problem. In a home studio this is an irritation, but in pro settings fixing it costs time and hence money, making balanced a no brainer.

In the home you probably don't have too much risk of noise pickup from electrical or magnetic sources. The most likely is probably magnetic field leakage from an amp with a big transformer, but you might also have something with a noisy power supply, or a noisy light dimmer. Moving the cable further away from the interference source is usually enough to make it inaudible, even with single ended interconnects. For this reason I wouldn't get too worried about the CMRR part. A mess of kit in a home studio makes this a bit harder to control. In pro settings there are often more sources of noise, and longer cable runs make it more of a problem, so again the noise rejection of balanced becomes a no brainer.

I'd go with Whitlock first, and mod the cable only if I encountered a ground related noise issue. In a hifi setting ground related noise issues are rare enough that the industry has stuck with RCAs but common enough that we keep getting threads from people asking how to solve them. Hifi systems change relatively rarely, so you aren't constantly having to sort such problems and it's harder to justify the small extra expense for balanced. In the studio things are changed more often,
 
For reference see Jensen Transformers' AN007 ["covering the causes of noise pickup and practical ways to address them in detail.
Huge thanks for your response and the a great reference document from Bill Whitlock!!![/INDENT]

In additional to the AN007 document (aka "Understanding, Finding, & Eliminating Ground Loops in Audio & Video Systems", Bill Whitlock, 2005), I also came across a slide deck that he presented at an AES conference in 2021: The Myth and Mystery of Analog Signal Interfaces

That presentation helped me more fully understanding the whitepaper. That said, the whitepaper (AN007) on its own is pure gold.
Ground related noise (loops, USB noise etc.) is a system problem that depends on the details of all the connected equipment, the mains wiring and how everything is connected.

In a home setting the biggest potential problem is ground related noise (loops, USB etc.) although it's far from a certainty. [...]
In the home you probably don't have too much risk of noise pickup from electrical or magnetic sources. [...]. Moving the cable further away from the interference source is usually enough to make it inaudible, even with single ended interconnects. For this reason I wouldn't get too worried about the CMRR part.

I'd go with Whitlock first, and mod the cable only if I encountered a ground related noise issue.
Putting your response (combined with what I understood from reading Whitlock's paper) into my original framing context.

On whether to connect the ground (Whitlock vs. Rane):
Whitlock—who has done extensive research on ground noise and is a leading audio industry Fellow—recommends always connecting the output device's chassis ground with the interconnect shield, regardless of whether the chassis ground on input device is also connected to the shield wire. Further, though Whitlock is well aware of Rane Notes, he does not cite any situations where the RCA sleeve on the unbalanced output device should not be connected to the shield wire.

Thus:
  • Whitlock's wiring (i.e., connecting RCA sleeve & interconnect shield) should be recommended for home studio / home stereo.
  • That connection should only be removed after (a) following the outlined diagnostic steps to determine the real source of the issue, and (b) there is no other effective way to solve the ground noise issue.
  • Only at that point would the Rane wiring be recommended.
  • Whitlock would recommend using an input transformer (with no gain increase) as a better solution to adding a resistor. But that is more expensive (and out of scope of my focus here). Also, if the issue is only CMRR and not ground noise, it is not clear to me whether use of a transformer is any better than using resistors to achieve impedance matching between the Pin 2 and Pin 3 conductors... I'd love comments from others on this aspect!
On maintaining CMRR benefit:
The most common type of RCA to XLR cable (i.e., using a 1-conductor Coax) will work to connect an Unbalanced device to a Balanced device. However, it will provide 0 dB CMRR benefit, which may (or many not) affect how well this interconnect works in your specific context. For many people, that will be a non-issue.

Using a 2-conductor STP cable (as described by Bill Whitlock or Rane Notes) will automatically provide a CMRR (common mode rejection ratio) of 30 dB; and perhaps even more depending on how the balanced input circuit (i.e., IC chip or transformer) is implemented within the Balanced device.

Achieving the maximum potential CMRR available from the Balanced device's input circuit requires precisely matching the impedance (Z) between the two balanced wires at the Unbalanced device's side. As such, adding a resistor between the RCA Sleeve and the interconnect wire (Pin 3) to more closely match the driver's output impedance (i.e., on the RCA Tip side) will incrementally increase the CMRR. However the actual CMRR increase will depend on a number of factors, including the design of the input balanced circuit to start with, how closely the resistor matched the impedance, the input device's impedance, output device's impedance, etc.

Whitlock does not directly mention adding a resistor to the RCA-end of the interconnect cable to match the impedances. However, he does imply the potential value based on (a) commentary on the benefit of exactly matching impedances, and (b) reference to the value of the Jensen input transformer or their special designed IC chip for balanced input circuits.

Thus:
  • If you aren't having any issue with common mode noise being injected into the interconnect in the first place, any properly wired Coax or STP is fine
  • That said, using a 2-conductor STP interconnect is always preferred since it provides an automatic 30 dB CMRR (and perhaps even more). In most home audio situations, this should be sufficient assuming proper management and isolation of signal lines vs. AC power lines.
  • If common mode noise is still a problem in the 2-conductor interconnect, then adding a resistor to more closely match impedances would increase the CMRR. E.g., cases where the interconnect is much longer (e.g., out to subwoofers) or a shorter interconnect can't be moved away from very noisy RF/EM sources
  • Finally, consider use of an input transformer if you are facing significant common mode noise issues (or replace your Unbalanced device with a Balanced device)
On when RCA-side impedance matching could be pragmatically (i.e., potentially noticeably) beneficial:
Probably not for most people, but definitely for some people:
  • Start with 2-condcutor STP (per Whitlock or Rane) as best practice
  • Add resistors only after determining there is a common noise problem that can't addressed by isolating from the EM/RF source
  • Or, go ahead and include a resistor proactively if you have resistors lying around, you like doing such soldering, you know the impedance of the Unbalanced output driver, and you have nothing better to do with your time)
In a hifi setting ground related noise issues are rare enough that the industry has stuck with RCAs but common enough that we keep getting threads from people asking how to solve them.
From what I read, Bill Whitlock considers that a serious failure on the part of the HiFi industry. From his view, CMRR is an increasingly pressing issue as we have moved from AM Radio and 78 RPM records to modern audio equipment that is now pushing >120 dB SINAD across all components in the audio chain (excluding the speaker itself).
Hifi systems change relatively rarely, so you aren't constantly having to sort such problems and it's harder to justify the small extra expense for balanced.
Fully agree that in a professional setting, there are huge benefits in using balanced audio. That is why it has been the professional standard for a very long time. And more recently, also within a home studio now that the cost of balanced equipment has dropped to very affordable prices.

BUT... (IMHO) I don't believe the lack of frequent audio component changes is a reason not to use balanced audio in a home stereo setting. Especially in view of the increasingly high SINAD ratings of the even the cheapest audio components. And even more so, now that modern DAC and DSP chips themselves are being internally based on balanced audio architectures.

Of course, as always, I would greatly appreciate any additional insights and corrections that others can add. My end goal is to have a good understanding of how the various options (and their trade-offs) apply within the context of a home stereo / home studio setting.
 
That seems to cover it fairly well.

Adding the resistor to the cold probably isn't mentioned because it needs information that's not usually available. Either you need schematics which aren't common any more, or you need to make some measurements or reverse engineer the output to determine the resistor value. It's essentially adding the resistor externally instead of internally - see for example the output stage in The G word or Self's explanation of balanced options. Some people regard this as somehow not being 'proper' as the cold isn't driven, but I don't understand the reasoning.

I'm in the camp that thinks hifi should have gone balanced ages ago, if only to avoid ground ground loops and USB noise, as it needn't be expensive. Others here disagree because unbalanced usually works well enough - I'll leave them to make their case if they want.

Transformers have their pros and cons too. The cons mostly relate to price and/or distortion. Search thread titles for transformer review to see some measured examples.
 
Enoaudio makes correct wired ones:

More expensive indeed but seems doing things right.

I am in a similar position as you as I need a new pair and don't want to go to DIY route.

I already have these ones in 0.5m but I need to replace them to a longer version (1m).

I was hoping to find cheaper ones but I cannot find alternatives to these enoaudio ones.

To come back on the original topic, as I needed 3 RCA/XLR cables and the einaudio ones I mentioned (good quality mogami/neutrik) are quite expensive (2 pairs of 1m for 150€ and sold by pair) for just correctly wired ones (XLR Pin 1 and Pin 3 separate all the way to the RCA plug), I ended up with these ghentaudio ones, advertised as correct wiring.
They are based on canari with neutrik connectors clones (but seems good quality) and cost 10$ vat excl. per cable.

Had to wait for 1 month for delivery and paid for 2 pairs 50€ all included (got a 4th one to optionally dismantle it and verify wiring).
 
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To provide a small update - I've gotten the adaptors and XLR cables, but haven't bothered installing them. The original setup that was supposedly wrongly wired just works. Haven't had any issues. Make of that what you will.
 
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