1 Topic by jj

  • jj
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Topic: Fireface UFX+ and Neumann KH 750

Hello everyone,

I would like to connect my Neumann KH 750 Subwoofer (https://de-de.neumann.com/kh-750-dsp) to the Fireface UFX+ on a digital connection. The KH 750 has its own DA converter and integrated DSP, and distributes the room-corrected analog audio to the monitors.

To be honest, I am a bit confused by the different standards, formats and connectors... sorry!
So here's what I found out:

Connection on the KH 750:
The KH 750 has a digital AES3 BNC input for AES3 or S/P-DIF-output signals. Neumann specifically asks for 75 ohms. I guess it's the "AES3id" standard?
Connection on the Fireface:
The Fireface has a digital AES3 XLR output. I assume, it's 110 ohms and the "AES3" standard?

So how does AES3id and AES3 go together?
The KH 750 manual states:
- "AES3 signal levels in XLR cables are much too high for the DIGITAL INPUT socket (BNC)".
- "Use a Neutrik NADITBNC-F impedance and level converter for XLR to BNC conversions of AES3-signals. This method brings impedance matching, level matching and source-receiver isolation. The Neutrik NADITBNC-F converter is guaranteed to work up to 48 kHz." Alternative they write regarding a DIY solution: "Use a resistor network to passively attenuate the XLR signal from 3.1 V down to 0.42 V and change the impedance from 110 Ω to 75 Ω".

So my questions are:
- What would be the best solution for the digital connection?
- Do I really need a converter? I am a bit confused by the "up to 48 kHz" statement by Neumann regarding the Neutrik converter, since the subwoofer itself can handle up to 192 kHz.
- Would the Fireface "Consumer" mode for the AES ouput help? Would that change the impedance and voltage level according to what Neumann is asking for?


Thanks for your help!

2 Reply by waedi (edited by waedi 2021-03-14 18:53:18)

  • waedi
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Re: Fireface UFX+ and Neumann KH 750

"AES3 signal levels in XLR cables are much too high for the DIGITAL INPUT socket (BNC)".

In my case I just would ignore that and plug in the adapter cable from the RME interface AES output (real working AES connection ) to the BNC input of the Subwoofer.
Neumann may write idiotic things in user manuals but the gear they sell is of very good quality and I am pretty sure they do not risk a damage from digital connection to professional equipment.

But don't take me wrong, this is not an advice or recommendation, it is only opinion.

M1-Sonoma, Madiface Pro, Digiface USB, Babyface silver and blue

3 Reply by MC

  • MC
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Re: Fireface UFX+ and Neumann KH 750

That Neutrik adapter works perfectly at 192 kHz. I have no clue why they don't spec it when it does work (I got and measured one myself).

Regards
Matthias Carstens
RME

MC's Website

4 Reply by jj

  • jj
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Re: Fireface UFX+ and Neumann KH 750

MC wrote:

That Neutrik adapter works perfectly at 192 kHz. I have no clue why they don't spec it when it does work (I got and measured one myself).

Thank you!

So that means:
- Do I really need a converter?
→ As I understand your answer: yes.

Regarding the other question:
- Would the Fireface "Consumer" mode change the impedance and voltage level according to what Neumann is asking for?
→ I assume the impedance is not changed to 75 ohms in "consumer" mode, correct?

  • ramses
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Re: Fireface UFX+ and Neumann KH 750

jj wrote:
MC wrote:

That Neutrik adapter works perfectly at 192 kHz. I have no clue why they don't spec it when it does work (I got and measured one myself).

Thank you!

So that means:
- Do I really need a converter?
→ As I understand your answer: yes.

Regarding the other question:
- Would the Fireface "Consumer" mode change the impedance and voltage level according to what Neumann is asking for?
→ I assume the impedance is not changed to 75 ohms in "consumer" mode, correct?

You need the Neutrik AES to BNC converter and the good news is, according to MC, it supports 192 kHz (so the info in the Neumann manual is wrong).

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13
  • FD10
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Re: Fireface UFX+ and Neumann KH 750

MC wrote:

That Neutrik adapter works perfectly at 192 kHz. I have no clue why they don't spec it when it does work (I got and measured one myself).

Hello,

I have a question if I have the Neutrik NADIT BNC-F adapter and the Neumann KH750 which cable do I need then the AES XLR 110 Ohm cable is clear to me but the BNC connection on the Neutrik adapter as well as on the KH750 which cable is additionally needed here?

Thank you in advance.