Issue w/ Multiport SPDIF Switch and Bit Depth

[Connor1a]

Hi All

I have 2 optical connections going into a WiiM Ultra via a cheap (25$) 4 port toslink switch I bought on Amazon.

Audiolabs 6000CDT —> Toslink (1) —> WiiM Optical-In

Technics SL-100C —> Waxwing —> Toslink (2) —> WiiM Ultra Optical-In

The Wiim is correctly sensing the Audiolabs as LPCM at 1411 kbps @ 16/44.1. However, on the Waxwing, when it should be sensing LPCM at 3027 kbps @ 24/96, it’s only picking up 16/96.

The Waxwing is definitely set to 24/96. The WiiM is set to definitely set to the same.

I just installed the toslink switch so am “pretty sure” that its the switch causing the problem. It’s not intuitive to me why a “passive” switch would be knocking down the bit depth though. Perhaps one of you rocket scientists could educate me? Otherwise, I’m looking at the Inday DA4X-R (with the fetching blue display) as a possible replacement. But before I pulled the trigger, (1) I wanted to make sure that it’d resolve the issue and (2) it’s a bit large (I can make it work if necessary though).

I’d really appreciate your thinking…. Thanks much.

 

[staticV3]

Your switch likely has some circuitry inside and it's not unimaginable that it'll truncate signals to 16bit.

If you're feeling adventurous, give the cooidea toslink switcher a try. Its cheap, compact, automatic, and has good reviews.

 

[kyuu]

I'm not sure an entirely passive TOSLINK switch is possible. As Static said, there's almost certainly some circuitry inside. Do you have a link for the switch in question?

 

[DVDdoug]

Did you try bypassing the switch?

Even if there's active circuitry it would be a LOT easier to make a 24/96 circuit than a converter.



...It's also questionable if you need 24/96 for anything, but certainly you don't need it for vinyl records. (But I don't blame you for wanting to use the capability you're supposed to have.)

 

[Connor1a]

I'm not sure an entirely passive TOSLINK switch is possible. As Static said, there's almost certainly some circuitry inside. Do you have a link for the switch in question?

Sorry for the delay. Life has been “eventful”… Here’s the switch I bought:

Amazon.com

 

[Connor1a]

Did you try bypassing the switch?

Even if there's active circuitry it would be a LOT easier to make a 24/96 circuit than a converter.



...It's also questionable if you need 24/96 for anything, but certainly you don't need it for vinyl records. (But I don't blame you for wanting to use the capability you're supposed to have.)

Fair enough lol… But you know, it bugs me.

 

[kyuu]

Sorry for the delay. Life has been “eventful”… Here’s the switch I bought:

Amazon.com

As I suspected, it's certainly not a passive device. Unsurprisingly for a cheapie Amazon-special, there's no specifications for what it does support beyond codecs. If it will work 24 bits without the switch in the circuit but you're getting downsampled to 16 bits when the switch is present, it's safe so assume that the switch itself is doing the resampling and there likely isn't anything you can do about it. Besides not use it, of course.

After a brief search, I haven't found any cheaper units that specify anything except codecs, sample rates, and baud rates... which all happen to be identical so I suspect they are all using the same chipset. I did find one that specifies that it supports up to 24 bits at 192kHz, but it's not cheap. You could also try using a passive splitter like this one. While technically those are designed to connect one source to two receivers, I believe they should work in the reverse as long as both devices are not on at the same time.

 

[Connor1a]

So I went out and bought an Inday 4 port optical/coax switch. 100$. Expensive, but had a handsome blue light which color coordinated w/ my other gear. Buhahaha. I’m not joking.

However, it didn’t solve the problem. Or rather, it solved the 16bit limitation of the prior switch, but did not solve the issue with the Waxwing. I’m still limited to 16bit (albeit now at 3072kbps vs 1411kbps so there’s some progress).

I removed the switch from the equation just to be sure - I ran the Waxwing directly into the optical in on the WiiM. It’s not a limitation of the switch. I also ran my Sonos Port, through the switch, into the WiiM and picked up 24bit so I don’t think it’s the WiiM either. I think it’s the Waxwing. I’ve reset it several times. Rebooted it yet more times. Etc.

I sent a note off to Shannon, but has anyone successfully paired a Waxwing with a WiiM Ultra at 24bit?

Looking for some of your rock star thinking guys. Thanks much!

 

[phofman]

The Waxwing user guide says the output format is just 24/48(96):

19. OUTPUT

The Output menu option switches between the usual analog RCA outputs and digital ones: a coax and optical output. Useful for those wanting to bypass the internal DAC and use their own DAC, but also extremely useful for decoupling the turntable from the systems leakage currents when using the optical connection (recommended).

Possible Settings:
Analog (default)
24/48
24/96

SPDIF always uses 24 bits for the audio sample. It's up to the transmitter to set bits in the SPDIF preamble to specify how many of those 24 bits are actually effective:

IMO the Waxwing just sets the the SPDIF preamble incorrectly. I would be surprised if the SPDIF receiver in Wiim intentionally truncated the received 24 bits to produce the sample length announced in the preamble - IMO it just takes 24 bits anyway. All further processing will most likely be in 32bits or float for any input format.

 

[Connor1a]

I’m not a technologist, but if the WiiM is correctly picking up my Sonos Port at 24-bit, logic would suggest that it should be picking up the Waxwing at 24-bit … unless the Waxwing isn’t presenting 24-bit at the connection… No?

The Waxwing is configured correctly:

From the WiiM screen:

 

[phofman]

That's what I am saying - if Waxwing sets the spdif preamble incorrectly, wiim would detect 16 bits format. But it may still be receiving (and using) all 24 bits since SPDIF always has 24 bit positions in the stream (with the lower bits set to zero by the transmitter, if it really transmits 16bit format).