AES48 , is there a test to determine?

Yes.


If you have an amplifier with a single-ended input, use an XLR adapter that connects only to pin2 and pin1 of the XLR output of the preamp. NOTE: pin 3 should **not** be connected for this test. Connect to the amplifier and listen to the result.


If it is free of buzz or hum, the preamp does not support the standard. If it does have hum or buzz, this is because the circuit is incomplete (pin 3 isn't connected).


A balanced source ignores ground and does not reference it- this is why you get the buzz with this hookup. In a balanced system the pin 2 signal is created with respect to pin 3 and vice versa. In the old days (and still today) this was/is done with an output transformer. That is why a lot of pro-audio studio gear has output transformers even though it might be solid state.


A quick and dirty, less accurate means of making this determination is if the output of the preamp has both RCAs and XLRs and there is no switch for going from one connection to the other, it likely doesn't support the standard. But if you have a DVM, you can measure for continuity between the center pin of the RCA and the pins of the XLR. If any have direct continuity and there is no switch as mentioned, then the standard is not supported.

@koestner Just as an FYI, I used the Benchmark StarQuad cables between the HPA4 and the AHB2 amp. Benchmark refers to these as professional grade cables because they carry a signal at 24dBU+. Whatever, the case I tried different XLR's between the components, including the Benchmark DAC3B and the StarQuads were just as good as anything I tried.

For my sources into the HPA4 (other than the DAC3B) I am using Audience AU24SE XLR and RCA. Those seemed to benefit from the more expensive Audience interconnets.

YYZ,

It was partially your high opinion of the HPA4 that lead me to try purchase one. Since the HPA4 is AES48 even though it has both balanced and single ended outputs without a switch (please comment Ralph) I was concerned about the Schiit Yiggy and the PS Audio M700's. I want to get 2 good XLR cables. I'm thinking of Audio Envy. They have 2 types of XLR cables. One the "GL" series seems to be for equipment that supports AES48 and their other line the "4:3" for those that do not. But, if my DAC and amp do support AES48 then it seems like the Benchmark XLRs will be just fine at less than 1/2 the price.

Ralph ... thank you for the "test" procedure, but I don't think I understand exactly what you mean. Does anyone know if the Yiggy DAC, or the M700 Ice Amps conform to the AES48 standard?

Thanks to all.

I hope you like it. There is nothing there in the HPA4 sound so you will hear your other gear.

You can always contact these 2 USA based companies and ask them directly. 

Let me say in advance I have never used XLR cables.  Also, that I may not be correct in what I believe Ralph was saying.  But I thought he wrote awhile ago that in a true AES48 standard balanced application one XLR cable will sound identical as another.

Ralph, please feel free to correct me if I have mischaracterized what you were saying.

@jetter ,
I recall Ralph saying that equipment using AES48 will result in cable artifacts being reduced. Whether differing cables will sound ’identical’ is probably more a matter of opinion.
FWIW, I bought a 10 meter set of XLR’s from Ralph years ago and didn’t think of upgrading until recently when I bought a set of AQ Mackensie XLR’s. To be honest, I didn’t perceive a marked difference in sound quality.- So, perhaps Ralph is correct.
YMMV.

Bob
PS- I should add that I am running Ayre and Atmasphere equipment. Both manufacturers utilize the AES standard.

@gdnrbob ,
Thanks for providing your experience using the XLR cables, very interesting and of course first hand knowledge is best. I’m still using all RCAs at this point.

It has always stuck in my brain that Ralph mentioned what we have been discussing.
George

@koestner You likely have seen this but I will post here anyways. It explains how your preamp is wired.

https://benchmarkmedia.com/blogs/application_notes/balanced-vs-unbalanced-analog-interfaces

Yyz, thanks for the link. I’m thinking my dac and amp are just the 4volt “balanced” type. So I will have to avoid the Benchmark xlr cables, and choose a more common type.

It was partially your high opinion of the HPA4 that lead me to try purchase one. Since the HPA4 is AES48 even though it has both balanced and single ended outputs without a switch (please comment Ralph)

Without a look under the hood I suspect that this preamp does not support the standard because it has RCA outputs that seem to be in parallel with the balanced outputs. A DVM would answer the question easily enough. Again, the balanced standard ignores ground- its literally not part of the audio circuit. Here is a nice primer about balanced connections:https://www.ranecommercial.com/kb_article.php?article=2107
As you can see, in a balanced connection the ground is chassis ground, not the audio ground. An RCA needs the sleeve connection to the same as the audio ground, not the chassis (which is why you usually see insulating washers with RCA connectors). Since the sleeve is audio ground and not the chassis, this would mean that the XLR ground (pin 1) is at audio ground. This is why AES48 is usually not supported if you see both types of outputs together. But it is possible to get around this by having additional circuitry driving the RCA output that is in parallel with that driving the XLR outputs. Then AES48 can be supported. That is why I say 'without a look under the hood', and why I've been careful to employ caveats.

OK thanks Ralph. The Benchmark website writes about this extensively, so I guess they are doing "something" to make it happen. I'm not technical enough to explain how, and I'm sure you're too busy to explore some other company's claims. It doesn't seem to be that important anymore as I have determined that my DAC and amp do not support the AES48 standard. So it seems I can not benefit from the special XLR cabling that does not use a ground.

I have determined that my DAC and amp do not support the AES48 standard.

If that is the case, you may not be able to run cables long distances and you might run into ground loop issues. But if there's no ground loop (which is entirely possible) than its not so much of a concern. I use Mogami Neglex in my home system. I've tried other cables but really don't hear a difference worth causing my hand to move other than to say this :)  Mogami Neglex cables are not expensive; you might pick up a pair and see what you think. If you don't hear a big difference than I'd say don't worry about it!

@yyzsantabarbara, does the benchmark conform to the AES48 standard in their design application, or does the unit merely support an AES48 input signal ?  Kinda like when a manufacture says that their unit supports xlr inputs, but they are merely single ended connection. 

@testpilot  You should email the designer of the BM gear.  I won't do that since I already bugged him with a few emails on compatibility of the AHB2 with my Thiel CS3.7's.

John Siau - JSiau@benchmarkmedia.com - designer

Rory@benchmarkmedia.com - is the email of the Sales guy.

@I have no dog in this fight, I was just curious. 

Maybe Mr Siau will see this thread and post a response. He is a member on A'gon.

Just saw this review on Sereophile. 

https://www.stereophile.com/content/benchmark-hpa4-headphone-amplifierline-preamplifier