1 Topic by avr90 (edited by avr90 2023-09-06 13:42:57)

  • avr90
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Topic: The optimal length for AES and Spdif cable?

Hello,
I'm interested in the RME's recommendation about a digital cable length, Spdif coaxial and AES. Speaking about connection of a Dac to my UCX II or an A/D converter or some other gear to it?

I've read some information about Jitter, transition times, reflections in the cable etc etc, and it the end, if I understand correctly, the optimal length depends on the devices I try to connect. There's a general rule about 1.5 meters, but if 2 hi quality fast devices are connected - it can be any length, and a short one cable may be preferable (3 feet, or 1 or even less than 1).

So, if my A/D and D/A sit in the same rack with my audio interface, should I go with 1 foot AES/Spdif cables to make it short as possible, or should I go with a medium length of 3 feet?
Speaking about the gear I will connect together: Two Notes Torpedo Studio Loadbox via spdif coax to my UCX II; UCX II via AES to the DAC Crane Song Solaris.

Thanks for any advice!

I refered to this topic:
https://forum.audiogon.com/discussions/ … for-either
And this article:
https://www.positive-feedback.com/Issue14/spdif.htm

  • ramses
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Re: The optimal length for AES and Spdif cable?

There are technical specs for digital cables.
Stay within the length of the specs and choose the length that you require.

Optical SPDIF normally 10m, but with RME TOSLINKS up to 16m work as a charm up to 192 kHz.
AES .. XLR based, up to 100m. Even longer is possible with other cables, but 100m should be fine for you, right?

I would use Coaxial SPDIF only in cases, where optical SPDIF. ADAT or AES is not possible (because of no galvanic isolation).
You do not necessary run into issues, if mass of two devices is connected with each other, but to be on the save side I prefer connections with galvanic isolation.

If a coaxial SPDIF cable is needed, I would try to make it as short as possible, but with a little reserve of perhaps 30cm to be able to mode devices. Up to 5m should be no issue. Devices like ADI-2 DAC/Pro with Bittest (or ADI-2/4 Pro SE) would tell you, whether there was some data loss. If the transmission was lossless, then all is fine.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • avr90
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Re: The optimal length for AES and Spdif cable?

Hi, thank you for the reply,
3m or 5m or 50m - it is too much! I'm speaking about close distance in a one rack.
Should I buy a 30cm coax spdif to connect 2 devices or, for example, 1.5m?
Should I buy a 30cm AES cable or 1.5m?

I'm just interested whether I need to take into my attention all these arguments about "an optimal minimum length" or just go with the shortest possible length of both types of cables for my rack.

Thanks.

  • From: Germany
  • Registered: 2007-04-10
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Re: The optimal length for AES and Spdif cable?

If it's within spec, it really doesn't make a difference...

Regards
Daniel Fuchs
RME

RME Support's Website

  • ramses
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Re: The optimal length for AES and Spdif cable?

Sorry, but didn't I clearly say that the length doesn't matter as long as you stay within the specs?
And that I would choose coaxial SPDIF as the last option for the reasons I mentioned?

I gave you the maximum cable lengths, with the intention that you can see that the lengths you mentioned are completely uncritical. Do you get it?

I never told you nowhere to really use such long cables .. please read it again and use online translation tools if needed.

To put one concrete example to you: whether you use 30 cm or 1.5 m AES cable (110 Ohm digital cable) is completely irrelevant, as the the cable can be up to 100m long without any issue.

Therefore, do you really think you have to pay attention on either 30cm or 1.5m?

Maybe we misunderstand each other but I have the impression you are looking for the wrong things and worry too much.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • avr90
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Re: The optimal length for AES and Spdif cable?

Ok, I understood you correctly, I just wanted to be sure that there is no minimum optimal length for a cable and all these people talking about it are wrong, including Steve Nugent.
I will go with a 20-30 cm cable length, thanks.
Arsen.