• Registered: 2017-10-02
  • Posts: 17

Topic: Has VKWC got sample rate limit?

I wonder if VKWC, the internal word clock cable, has a sample rate limit? Does it support sample rate higher than 48kHz?

I have 5 RME products: 1x ADI-2 Pro, 1x ADI-2 Pro FS, and 3x HDSPe cards: AIO, RayDat, AES as an aggregate device. And a bunch of Apogee ADDA16Xs.

The clock flow: ADI-2 Pro FS is the Master clock, synced with RayDat via AES, then RayDat feeds the clock to AIO and AES through VKWC, then to ADI-2 Pro via AIO's AES out.

When I switch to ADI-2 Pro FS to INT 192kHz and put RayDat on AutoSync, it Syncs with no problem, showing AES sync 192kHz. But then I switch to AIO's page, the Sync in shows 48kHz. On the AES setup page, Int. also shows 48kHz. Despite of that, both the other ADI-2 Pro and my bunch of Apogee show 192kHz correctly.

Is it that the internal word clock via VKWC can only work on single-speed (although none of the 3 pages' "Single Speed" option is checked) or am I missing something?

2 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
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Re: Has VKWC got sample rate limit?

You need to activate QuadSpeed by starting a playback or recording on the AIO, then it should switch. The internal WC might also follow the 'Single Speed' option in the card's Settings dialog, so this option should be not set on any of these.

Regards
Matthias Carstens
RME

MC's Website

3 Reply by ywshuo (edited by ywshuo 2021-04-01 09:36:42)

  • Registered: 2017-10-02
  • Posts: 17

Re: Has VKWC got sample rate limit?

So my guess is true then, the VKWC can indeed only carry Single Speed word clock up to 48kHz. For higher than 48kHz, other cards can only sync using VKWC by double or quad speed.

Like I have stated, none of the "Single Speed" on either page is checked. Everything is working at 192kHz. All devices and DAWs. All three cards showing a Sample Rate of 192000Hz also.

Only the "Sync In" on the AIO setup page "Preferred Sync Ref / Input Status" section, and "Int." on the AES page same section says 48kHz. So my guess is that either VKWC can only work at Single Speed or there is a display error there.

4 Reply by MC

  • MC
  • MC
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Re: Has VKWC got sample rate limit?

The RayDAT uses ADAT I/Os and relies on SMUX. Therefore its internal WC will most probably stay on single speed. But as mentioned I don't see what the problem is. The following card can still sync on this signal when using double and quad speed.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2017-10-02
  • Posts: 17

Re: Has VKWC got sample rate limit?

Thank you MC.

Don’t get me wrong there’s no problem at all. Everything’s working properly. I was just curious. And also want to use this information to plan a better WC route.