1 Topic by RensG (edited by RensG 2024-10-12 19:39:57)

  • RensG
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Topic: Fireface UC or ADI-8 PRO as clock source?

Hello fellow RME-enthousiasts,
I recently purchased an old ADI-8 PRO (Nuendo 8 i/o, the original 44.1/48 kHz version) to expand my old Fireface UC via ADAT for live preformance.
I read that it would be wise to set the ADI as master and the Fireface UC as slave because the ADI would be of superior quality. This feels counterintuitive to me since the UC is the main audio-interface, but in all honesty, I'm not that tech savvy. I'm using the clock i/o with a BNC cable.

Could anybody enlighten me on what would be the wisest?

Thank you!

  • vinark
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Re: Fireface UC or ADI-8 PRO as clock source?

The idea is that the UC has the better jitter reduction, steady clock. But if you use the UC inputs and outputs more or for the more important stuff, you could set the UC as master. When I use my adi 8ae I set it as master.

Vincent, Amsterdam
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  • waedi
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Re: Fireface UC or ADI-8 PRO as clock source?

I can't say if it's wise or better, it's just how I learned it.
I would connect two Adat toslink cables and set the UC clock-mode external optical.
The ADI-8 clock-mode internal.

No BNC cable it's one thing less to carry with.

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Re: Fireface UC or ADI-8 PRO as clock source?

vinark wrote:

The idea is that the UC has the better jitter reduction, steady clock.



@ RensG with these two, it really doesn't matter. If you want the converter to follow the interface when switching between 44 and 48 without having to push any buttons, set the UC as master.

Regards
Daniel Fuchs
RME

RME Support's Website

5 Reply by ramses (edited by ramses 2024-10-13 10:21:28)

  • ramses
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Re: Fireface UC or ADI-8 PRO as clock source?

Although the ADI-8 Pro has been released 10 years before the UC (1999 vs 2009) the technical data of the ADI-8 Pro are better. By this, I make no claim regarding better sound, I only want to mention it.

ADI-8 Pro has no SteadyClock. SteadyClock was introduced with FF800 in 2004 if I am not mistaken.

ADI-8 Pro's manual mentions "Bitclock PLL". From the description, it seems to perform a few tasks of SteadyClock, but it sounds to me as if SteadyClock would do a bit more, e.g. jitter suppression (of > 30 dB).

So it ** might ** be better to use ADI-8 Pro as clock master to use its internal clock to reach the documented specs and to configure the UC as the clock slave, where SteadyClock can additionally perform jitter dampening.

Both devices have Low Jitter Design where the UC seems to be slightly better in terms of Word Clock (maybe due to SteadyClock design).

ADI-8 Pro:
- Super Low Jitter Design: < 4 ns word clock PLL, < 1 ns ADAT PLL, < 1 ns internal
- Internal sample rates: 44.1 kHz, 48 kHz
- Supported sample rates through word clock in: 27 kHz - 57 kHz
- Internal resolution: 24 bit
- Outputs: ADAT optical (24 bit), TDIF-1 (24 bit), word clock
- Inputs: ADAT optical (24 bit), TDIF-1 (24 bit), word clock
- Supported sample rates through ADAT In: 33 kHz - 57 kHz

UC
- Clocks: Internal, ADAT In, SPDIF In, word clock in
- Low Jitter Design: < 1 ns in PLL mode, all inputs
- Internal clock: 800 ps Jitter, Random Spread Spectrum
- Jitter suppression of external clocks: > 30 dB (2.4 kHz)
- Effective clock jitter influence on AD and DA conversion: near zero
- PLL ensures zero dropout, even at more than 100 ns jitter
- Digital Bitclock PLL for trouble-free varispeed ADAT operation
- Supported sample rates: 28 kHz up to 200 kHz

On the other hand, it could be an advantage to let the UC be the clock master from a handling perspective.

If you should often work with different sample rates (44.1, 48 kHz) then you only need to set the sample rate in the DAW
project. The UC as clock master would learn it from the driver, and the ADI-8 Pro could learn it automatically as slave from its ADAT input.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • ramses
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Re: Fireface UC or ADI-8 PRO as clock source?

RME Support wrote:
vinark wrote:

The idea is that the UC has the better jitter reduction, steady clock.

No Steadyclock on the UC..

No? According to the manual, the UC has SteadyClock.
https://www.dropbox.com/scl/fi/vv0dmu3j … 4&dl=1

Therefore, I thought the UC might be a little better suited to act as clock slave.

RME Support wrote:

@ RensG with these two, it really doesn't matter. If you want the converter to follow the interface when switching between 44 and 48 without having to push any buttons, set the UC as master.

I have now made many assumptions in my post without being able to say whats really better (e.g. in terms of sound, less jitter).

The whole thing is based on the assumption that you configure the UC as a clock slave and utilize "SteadyClock" there.

On the other hand, the UC also has a very good clock and I assume that the good low-jitter values would then also be transmitted via ADAT to the ADI-8 Pro as a slave, so that the lack of SteadyClock on the ADI-8 Pro would not be tragic at this point and you could just as well make the UC the clock master.

Should I then delete my post if it ultimately doesn't matter, as you say, who is the clock master in the setup and that it is better to use the UC as the master so that you don't always have to change the sample rate on the ADI-8 Pro?

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
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Re: Fireface UC or ADI-8 PRO as clock source?

ramses wrote:

No? According to the manual, the UC has SteadyClock.
https://www.dropbox.com/scl/fi/vv0dmu3j … 4&dl=1

Therefore, I thought the UC might be a little better suited to act as clock slave.

True, but it also means that the outgoing clock is just fine and the ADI will sync to it perfectly with no need to clean up anything. And of course the internal clock of the ADI is also of excellent quality and doesn't really need any Steadyclock treatment...

Regards
Daniel Fuchs
RME

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