ERC-1 to XDA-1 & Jitter (coax or opt?)

[Erwin.BE]

Folks,

There has been some debate regarding the choice of the digital connection between ERC-1 to the XDA-1. You have the choice between coaxial or optical (Toslink).
I even asked Lonnie and he replied to me that all standard digital inputs (AES/EBU too) are by the same specifications and there would be no difference.

But I have read the review from Home Theater & HiFi of the Oppo BDP-83SE/NuForce player and on page 2 the reviewer comments to the graphic of the Jitter:
"Notice the difference between the jitter from the coaxial output and the Toslink output. This should put to rest any question about which output you should use if you have the choice. I have seen this same difference between coax and Toslink in another player of a different brand, the review of which will appear shortly, so it is not something specific to OPPO." Ouch!

Here's the link, it's the three bottom graphics:
www.hometheaterhifi.com/blu-ray-players/756-oppo-bdp-83se-special-edition-universal-blu-ray-player.html?start=1
When playing via coax, Jitter was between 7 and 10 picoseconds but via Toslink, it's 10 times more! Ofcourse, there's no real way of knowing if the same would be true with the ERC-1 until this is tested.

I will connect the ERC-1 via coax to the XDA-1. The Apple AE is optical Toslink only, so I am curious if I would hear a difference between ERC-1 and streaming via AE (with same CD ripped to the iMac ALAC)

If someone out there is not sure what Jitter is: it's errors in timing. Even if all the bits and bites themselves are 100% correct and accounted for, there's always the matter of the exact bit on the exact time. All digital sources are prone to Jitter, but the best perform far better ofcourse.

[rockguitar]

Jul 5, 2010 7:58:52 GMT -5 Erwin.BE said:

When playing via coax, Jitter was between 7 and 10 picoseconds but via Toslink, it's 10 times more! Ofcourse, there's no real way of knowing if the same would be true with the ERC-1 until this is tested.

I will connect the ERC-1 via coax to the XDA-1. The Apple AE is optical Toslink only, so I am curious if I would hear a difference between ERC-1 and streaming via AE (with same CD ripped to the iMac ALAC)

If someone out there is not sure what Jitter is: it's errors in timing. Even if all the bits and bites themselves are 100% correct and accounted for, there's always the matter of the exact bit on the exact time. All digital sources are prone to Jitter, but the best perform far better ofcourse.

The fact that in most cases the coax output performs better than optical with jitter is not surprising. Keep in mind that the digital output for coax and optical are both under the SPDIF standard where the coax keeps the digital signal as electrical. On the other hand, the optical output has to use an additional conversion of the electrical signal to light pulses. Since there is an additional conversion involved with optical, jitter performance and other performance of the optical output will be usually be worse. Also keep in mind that the differences between the digital outputs are also reliant on parts choices. If a better quality circuit/component were used, I would imagine the optical output would be better, but still not as good as coax, for jitter alone.

However, note that most DAC's usually have jitter surpressing inputs so the incoming jitter from the CD/transport will be minimized. How audible the differences between optical and coax cables will be have a lot to do with the DAC itself. I have heard little difference between optical and coax inputs on the Benchmark DAC-1 when using glass toslink fiber optical cable.

Here's some good info from Benchmark on jitter and even on converting an optical output into a coax one if you want to use coax.

www.benchmarkmedia.com/appnotes-d/

[rockguitar]

Last note, the main reason most manufacturers use optical instead of coax is due to cost. It costs a alot more to do the coax output right whereas the optical outputs are relatively cheap in comparison. Seems a bit counterintuitive doesn't it?

[Erwin.BE]

Jul 5, 2010 9:09:52 GMT -5 rockguitar said:

Last note, the main reason most manufacturers use optical instead of coax is due to cost. It costs a alot more to do the coax output right whereas the optical outputs are relatively cheap in comparison. Seems a bit counterintuitive doesn't it?

Yep! The optical only AE is only 90€, which is cheap for anything Apple. Are optical inputs more expensive than electrical coax?

But like you said, audible differences are not certain. I have read articles that minimize the audible effect of Jitter.