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President of the Imperial Galactic Government
President of the Imperial Galactic Government
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Originally Posted by One2Many
Does MMHR have technical advantage over SL ...
No, this discussion is more to do with using just one AES channel in MMHR in to a 2 channel controller that is equipped with an AES or SpeakerLink input (against using SPDIF).

Originally Posted by One2Many
I noticed in Duncan's Meridian Info section on HD621 there is document outlining how to configure HD621 for a 2 channel system? Does that assume you will be using one of the SL outputs not MMHR?/quote]There are no SL outputs only MMHR and 4x SPDIF.

[quote=One2Many]The Reason I ask is if you buy a G65 and HD621 and want to start out just 2 channel and grow into multichannel as toy budget allows, can you use MMHR
Yes, but it would probably be better to let the G65 down mix 5.1 to 2.0.

Regards,
Carl


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Ian Offline
President of the Imperial Galactic Government
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Does MMHR require shielded cable?

If MMHR is balanced, they will likely be configured as 4 sets of balanced twisted pairs.

What then would act as ground? I'm asking as I don't know.


Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).
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President of the Imperial Galactic Government
President of the Imperial Galactic Government
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Hi Ian,

As AES / EBU is differential it does not need a ground.

The cable's screening (when available) would be grounded to the equipment's chassis [not reference ground] via the screened RJ45 connection.

Regards,
Carl


861v6+ID40, HD621, 8000.2, 7200HC, 7200.2, SKYQ Silver, PS3, PDP-LX6090, QNAP TS870-Pro (8*6TB), Roon, iPadAir2.
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Ian Offline
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So you are saying the pin 1 (ground/shield) on AES/EBU XLR connectors are not needed?


Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).
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President of the Imperial Galactic Government
President of the Imperial Galactic Government
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Not needed for the audio signal. However, it is needed to ground the cable's screen to guard against RFI. The shield in a AES3 cable should be considered as an extension of the chassis.

Regards,
Carl


861v6+ID40, HD621, 8000.2, 7200HC, 7200.2, SKYQ Silver, PS3, PDP-LX6090, QNAP TS870-Pro (8*6TB), Roon, iPadAir2.
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Ian Offline
President of the Imperial Galactic Government
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Definitely?

I ask because the AES/EBU standard is 2 balanced and ground.

I understand that you can put audio, i phone cable, over 2 twisted balanced pair, but that's not AES/EBU.

With SpeakerLink, there is a direct 1:1 mapping of SL on to AES/EBU, i.e. I use a SpeakerLink to XLR dongle that plugs into an AES/EBU socket, but what's the situation with MMHR as there is no 1:1 mapping?


Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).
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President of the Imperial Galactic Government
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Hi Ian,

MMHR 4 twisted pairs and a common shield (chassis ground).

Picture this custom cable:

Shielded RJ45 at one end, four 3 pin XLR connectors at the other (with all the pin 1's connected to a common cable shield.

There is no audio signal on pin 1, it is only used for protection from RFI.


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Great Green Arkleseizure
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Re Carl
I can picture this but I would not like to produce it.
Hector


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Ian Offline
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Originally Posted by Carl
MMHR 4 twisted pairs and a common shield (chassis ground).
Which is why I asked if MMHR required a shielded cable. Does it?

I'm still not convinced that it's balanced and is nothing other than 4 unbalanced pairs, ie 4 x SPDIF running over cat5.

And lets not go there that AES/EBU can operate as unbalanced.

[EDIT]Just read the manual. Balanced over STP. So it sounds like the drain wire is the ground,


Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).
Joined: May 2008
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President of the Imperial Galactic Government
President of the Imperial Galactic Government
Joined: May 2008
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Originally Posted by Ian
Originally Posted by Carl
MMHR 4 twisted pairs and a common shield (chassis ground).
Which is why I asked if MMHR required a shielded cable. Does it?
Hi again Ian,

Yes, it yields sound even when using the cheapest of un-shielded cables (I've just tested to double check), but of course there is a greater risk from RFI.

The message I was trying to get over over is that with differential transmission the ground wire is irrelevant to the audio signal.

Regards,
Carl


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Meridian Partner
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Backtracking a little, I guess the reason why no-one has made an MMHR to SpeakerLink cable is why would one be required?

If you are only after a two-channel signal from a video source then you would be better taking the audio direct from that source, rather than having it send the audio down the HDMI cable to the HD621 as that route will add lots of jitter.

Unfortunately a necessary evil when you're after multichannel high-res digital audio.

Rick


Audio Images, 284 Glossop Road, Sheffield, England. Tel: 0114 273 7893
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