Sample rate and QED 'Graphite' optical cable

[camtwister]

Hello.

Has anyone encountered problems with QED optical cable in the 'graphite' range - not carrying data at 96kHz?
I have toslink to mini-toslink termination.

Thanks.

[Landloper]

Hello.

Has anyone encountered problems with QED optical cable in the 'graphite' range - not carrying data at 96kHz?
I have toslink to mini-toslink termination.

Thanks.
I used a Graphite few years back with no problems at all. I was under the impression all optical cables were fine with 96kHz. Like you I have used mini to toslink cables. I don't think the mini termination has the effect of reducing the bandwidth the cable can carry.

[camtwister]

That's my understanding also, Joanna.
However, when I send 96kHz files to my DAC via this cable, I'm getting nothing but distortion. It's working correctly at sample rates below this, at both 16 and 24 bit resolution.
Odd.

[Landloper]

That's my understanding also, Joanna.
However, when I send 96kHz files to my DAC via this cable, I'm getting nothing but distortion. It's working correctly at sample rates below this, at both 16 and 24 bit resolution.
Odd.

You've probably already checked this, but have you got your source device settings to allow 96kHz?

[CageyH]

What is the set up you are using this in?

[camtwister]

This is in my workshop system.


Qobuz Hi-Res > Wireless 2.4GHz > Chromecast Audio dongle > QED 'Graphite' optical cable > Rega DAC


i) I've ordered a cheap optical cable to test against the QED and determine if it's the interconnect.


ii) I thought Chromecast Audio was capable of acting as a transport for 24/96 PCM wav files. Perhaps it can only transport the FLAC codec at this resolution.
Does anyone know?
The internal DAC of the Chromecast can translate these streams - but I don't want to use the Chromecast convertor.

Perhaps I'll post in the digital section about that, if I don't get a response in this part of the forum.


I'm fairly confident my
Chromecast Audio > Beresford Bushmaster
didn't have this problem, and I know the Rega is happy with 24/96, hence I suspected the cable (or damage to it).

[struth]

have you selected hi rez in the system options for chromecast... im sure you used to have to select hi quality...

[camtwister]

There is no option to change audio settings other than dynamic range or equalisation, using Google Home.
I have the second generation of CCA.

[CageyH]

You have turned on full dynamic range?
Other options are to try a different cable, and if that does not change anything, send it back for replacement.

[camtwister]

Yep, full dynamic range is on.
I've been using it for years. This problem is new, which is why I thought the cable was prime suspect.

[struth]

im not sure re pcm wav.. i think it is flac at 96khz

[CageyH]

These are the formats supported:

FLAC (up to 96kHz/24-bit)
HE-AAC
LC-AAC
MP3
Opus
Vorbis
WAV (LPCM)
WebM

Taken from here - https://developers.google.com/cast/docs/media#audio_codecs

[camtwister]

Thanks Kevin.
I've seen that. I suppose, because they don't explicitly state that wave files are supported at 96KHz, it means they are not.
But if the internal DAC can convert them, why can't it transport them also?
I just don't recall having the problem before the weekend and I've been using the thing for years.

[CageyH]

What changed at the weekend?

[CageyH]

It seems you are not the first to experience this. https://pinkfishmedia.net/forum/threads/chromecast-audio-through-beresford-bushmaster-2.248565/

[camtwister]

I changed many things at the weekend; power amp, DAC and cables.
You can see why I thought that the cable is the most likely culprit.

It may still be part of the problem. However...

I've have just put my Bushmaster TC-7530 DAC alongside my Rega unit and compared them.
The Bushmaster will play the 96kHz files via optical. The Rega will not play them via either of its two toslink inputs.

The Rega is specified to convert such files.
I'll try it with another cable when the postman delivers.
Otherwise, any ideas what is upsetting the Rega DAC?

Thank you.

[CageyH]

What Rega DAC is it?

[camtwister]

It's the original. Launched in 2011, if I remember accurately.

[CageyH]

Do you have a different source that you can feed the Rega DAC at the sample rate you want?
It may be an incompatibility between the CCA and the REGA DAC. There seems to be a few reports of that happening on the Web.

[camtwister]

Good idea.
I have a Squeezebox Touch in the workshop. I'll fire up the Logitech Server for the first time in years and feed the Rega from that at 96kHz, as a comparison.
I'll report back.

[camtwister]

Rightio, here are the scores on the board.

Chromecast Audio @ 96kHz and above > QED Graphite or Fisual Pearl toslink> Beresford Bushmaster TC-7530 = correct operation, no audible distortion, personable and handsome

Chromecast Audio @ 96kHz and above > Graphite > Rega DAC = harrowing distorted mess, macabre and sickening

Chromecast Audio @ 96kHz and above > Pearl > Rega DAC = discommoding distorted dirtiness but source material is identifiable

Squeezebox Touch @ 96kHz and above > Graphite or Pearl > Rega DAC = correct operation, no audible distortion, bewitching and lovesome

My conclusions are:
i) the Rega and CcA partnership is doomed,
ii) the cable choice has some impact on the Rega and CcA combination but it's not the fundamental cause of the problem,
iii) the Bushmaster acquits itself very well and is one hell of a competent DAC for the money. I happen to prefer the sonics of the Rega but that's a subjective opinion,
iv) the convenience of Chromecasting aside, this occurrence has reminded me of how rewarding the Squeezebox is as a transport.

I factory reset all of my Logitech settings, updated firmware and software, and set-up the Touch and LMS from scratch.
I configured all of the settings for optimal sound quality. You know, the EDO, etc.

I plumbed in:
Squeezer > Squeezebox Touch > Mark Grant/Van Damme 75ohm coaxial > Rega DAC

Hooray! I'm enjoying the music.