Can any one tell me why the aux returns(1/2) are only 20 bit?When I purchased this board I was under the assumption that this was STRICTLY a 24 bit mixer!!Don't get me wrong,beside some minor setbacks(and $4,500)I am pretty content.(or so i think so.......)Is there a possibility coaxial will be able to transmit 24 bit in the near future???

It's 24 bit. What has given you the impression that it's 20 bit?

On another note... just to clear stuff up:

75 Ohm Coaxial, 110 Ohm balanced, or optical cable can carry the same signal identically (in result, not the physics). There is currently no data limitation based on the cable type.

The limitation of optical is length. Add a repeater/amplifier and length isn't an issue. The benefit of optical is 'no' line noise - it's impossible unless the insulation is damaged. [ADAT]

The limitation of 75 Ohm coax is length. Line noise can become a problem - depending on the environment. [S/PDIF]

The limitation of balanced 110 Ohm cable is that it has to be wired properly. Something I'm finding many manufactures don't agree on. Otherwise, balanced lines are great for long runs. [AES/EBU]


[This message has been edited by marcn (edited 05-04-2000).]

Hey Marcn,I just purchased a T.C Electronics Fireworx(which has 24bit ad/da)but in the manual it states that the coaxial(s/pdif)is only 20 bit.I was under the impression that 20bit is the highest that coaxial can send.Maybe you can clear this up for me.Should I dither my signal coming into the Da7 at 20bits?

There's contradictory information in the tc electronics manuals. I'm looking at the Fireworx, M3000 and Finalizer manuals and they all say the same thing:

In the Fireworx manual, on page 9, it shows a diagram where all digital outputs are routed from the same path. Then on page 78 the stats reference 20 bit whenever S/PDIF is mentioned.

... I'm looking at the moment for information on the S/PDIF spec. It might simply be 'out of spec' to send more than 20 bits S/PDIF and tc electronics decided to stay to spec.

Many devices use 24 bit AD DA but these are CONVERSIONS and is not necessarily the word length transmitted in a direct digital connection. Sometimes higher bit length is employed for internal processing as well...like the DA7. I am not familiar with the devices you are using but something to keep in mind.

Although it's not stated in the User Guide, the convertors for AUX 1/2 are 24 bit the internal processing in the DA7 is 32 bit.

As far as the TC Electronic device I'm unaware of it's bit depth. However AUX 1/2 on the DA7 can be dithered down to match the device that's connected to it.

Responding to myself: 20 bits is not a limitation of S/PDIF.

http://www.cl.cam.ac.uk/Research/SRG/HAN/docs/sp-dif.txt http://www.hut.fi/Misc/Electronics/docs/audio/spdif.html

It's my opinion that you're seeing a limitation of the tc electronic equipment. Apparently, it's entirely up to the manufacture of a product what the last 4 bits over 20 are used for.

maric, exactly what kind of "converters" are you refering to for aux 1/2? ---this is a digital send and return! it does send a 24 bit word length, to confirm the original post question.

It sends 24 bit as a default. It can be dithered from 24 to 16 bit and anything in"bit"ween.

I use an TC M2000 hooked to the Aux 1 and 2 @ 24 bits that I set in the TC unit. So far it works great.

Randy

Okay,quite simply should I dither the aux 1/2 to 20bits while using the fireworx or should I leave it in its default position.

yes, since the tc unit's spdif in is only 20 bit.

I'm not sure... I'm not sure the book is right. I mean, why would tc electronic truncate 4 bits for the S/PDIF input/output? It doesn't make any sense.

Well, if the manual is right... then I'd get two AES/EBU - S/PDIF converters and get my 4 bits back, damn it!

[This message has been edited by marcn (edited 05-06-2000).]

I got ahold of a T.C. tech and he told me that the s/pdif out is 24 bit.

ammjjc,

The 20 bit auxiliaries you've heard about are the ANALOG Aux 3-6 ins. They get converted using 20 bit A-Ds.

Kind of curious that Ramsa would make everything 24 bit EXCEPT these Aux ins!! Who knows; maybe it was a cost cutting decision!?



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richard clingman
songseeds.com

Marcn -

According to information I received from Belden, typical AES/EBU transmission length limitation is 1640 feet. Not sure about S/PDIF. Anyone have the figures off hand?