XLR phase inversion. Purpose?

Chris Cables

Chris Cables

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Got an Etsy customer asking me to build some XLR cables for his nice-looking Esoteric N05-XD streamer/dac to his Accuphase E-650.

He asked me to swap pins 2 and 3 at the Accuphase ends (input) but I advised him to just go for a conventional pinout for the cables (pin1 = ground, pin2 = hot, pin3 = cold) so he can use the cables with other equipment later if desired. The Accuphase has a phase-inverter switch which swaps polarity for pin2/pin3.
(Why did Accuphase and other Japanese domestic market manufacturers do this?)

Anyway, now I'm not so sure about my advice to him after reading more into it here.
Is there any advantage to having an asymmetrical pinout arrangement for these cables, using the conventional XLR pinout at the output side and the Accuphase proprietary pinout at the input side?
I doubt there would be any audible difference would there?

Rear panel of his Accuphase E-650
accuphase-e-650.jpg
 
I'm with you and wouldn't deviate from current AES convention.

Early days there wasn't a "standard" and XLR connectors were pinned both ways. Since the Accuphase accommodates either pin out, (sort-of) I for sure say stay with current standard convention.

I do see the pre outs are the old way, and maybe for those cables you get jiggy with it. Maybe.

3-Pin XLR Audio Pinout
Three-pin XLR connectors are by far the most common style, and are an industry standard for balanced audio signals. The pinout listed below is the Audio Engineering Society (AES) industry standard for balanced audio XLR wiring.

1 ground
2 positive
3 negative

(case/shell floating)


1718658764206.png
 
Well, if he's sensible and interested in future-proofing the cables to sell on or use with other equipment then he'll opt for the AES 'standard'.
He hasn't responded and I feel I may have just confuzzled him even more. lol

I go through this process with Naim owners to an even worse degree. Naim are probably the manufacturer with the least consistent conventions and choices for connector types and pinout arrangements. DIN5/180, DIN5/240, DIN4, signal only, signal&power, etc.
I have to go through a 10-step check procedure to establish that they're correctly requesting what they think they need. A good half of all customers actually ask for the wrong thing!
 
I would suggest correct cables and then a pair of “pin changer” pigtails to attach to one end of the standard cables.

More money for connectors, but a better answer I think. (They might even exis already)
 
No, he actually doesn't need converters etc. It's either one or the other. He has a switch on the rear panel of his Accuphase to use depending on which option he goes for. See photo above.

Reading that stevehoffman thread it's actually debateable whether he would notice any audible difference even if he opts for cables with AES standard pin config and forgets to set that option from the Accuphase config by flipping the switch.

I think Accuphase def managed to confuzzle a lot of owners by offering the switch to invert phase as well as not clearly indicating which of the rest of the XLR I/O's are which in terms of pin 2/3 phase. I assume they're all pin2=cold, pin3 = hot (?)
 
The Accuphase flips the polarity of both channels, not individually, so they are both either standard or flipped polarity.

Just speculating...
If your customer desires to bridge his balanced input stereo amplifier for higher power mono output purposes, it would generally require a normal phased cable on one channel and an out of phase cable on the second channel to achieve this.

The Model ONE amp that I designed allows the user to do this without the use of out of phase cables on a channel by channel selectable basis. If the amp your customer owns does not offer a similar feature, the way to achieve this is with a cable inversion flip. Again, just speculation.
 
I’d want to consult the manual on that.

And we should know the entire chain of that system. Balanced connections are great, when used correctly.
 
Or just make what he asks for, label each end with what pin is hot and collect your money.

“the customer is always right”

(just get everything in writing for when something goes wrong because of “your” cables)

I had XLR to twin RCA cables made up to go from preamp to power amps and they were made exactly as I specified. But those aren’t going to get mixed up with a standard XLR cable…
 
#3 is hot on the Coherence so any cable terminated in it will be like this. All the other XLR gear I have is #2 hot, so bastard cables it is....
 
Customer saw sense and decided to go for the conventional 2=hot, 3=cold AES pinout.
(When you have that option on your Accuphase why wouldn't you?)
a920f1cd21208abe0a93b64184b1ffa1.png

I'd still be keen to learn why the Japanese market went for an inverted phase pin config though.

@J!m I always go through a check-procedure with clients re. pinouts, especially for when it's anything 'balanced' or for Naim equipment. I learned that the hard way, lol.
@laatsch55 can you describe what you hear comparatively?
@Gepetto that's way beyond the scope of supply in this case. Any amp-bridging he does using my cables would be his call. He's gone for AES so as long as he configures his gear accordingly there shouldn't be any phase issues.

thx @all for considered responses. ;)
 
I believe Accuphase simply predated the universal adaptation of the AES standard. And there are others still using something other than AES. Always RTFM (read the f’n manual).

They want to support their legacy customers and attract new ones so they added the switch.

That’s my take on it anyway.
 
"Cold" can be coupled to ground inside some components... This is partly why AES does not ground the outer shell- you might create a ground loop if it is.
 
J!m said:
"Cold" can be coupled to ground inside some components... This is partly why AES does not ground the outer shell- you might create a ground loop if it is.
Click to expand...
That would defeat the balanced nature of XLR connections if cold was grounded, it would turn it effectively into a single ended connection.
 
A lot of “Balanced” components actually are single ended…
 
Here's an Ashly XR 2001 crossover schematic with a balanced in and out interface setup. Based on my experience Aragon schematics are difficult to come by.

ashly_xr2001.pdf_safe.jpg
 
Fully-balanced too by the look of it.
One of the reasons that for all of its' 'noise and distortion' as decreed by those ass-hats over at ASR, I still love my Audio-GD dac/amps.
It's the only way to go afaiac.

IMG_20180514_182357.jpg
 
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