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-   -   4:1 or 4:2 mux.... (http://www.diyaudio.com/forums/twisted-pear/226822-4-1-4-2-mux.html)

Russ White 1st January 2013 07:43 PM

4:1 or 4:2 mux....
 
Hey Folks,

So - Today Brian and I have been discussing the 4:1/4:2 mux that I have been working on getting designed. I know a few of you have been anxious to get it.

I had it done, and nixed it at the last minute because I didn't like it. I was not comfortable that it was what you people really wanted.

Since Brian and I need to get a good feel for what you folks really want out of the design we are doing the logical thing -asking. :)

The chip I want to use is a high quality 4:2 bus mux/demux. It will work with TTL and lower signals (like SPDIF).

First - what sort of signals do you plan on MUXing/DEMUXing?

1) PCM/DSD (TTL)
2) SPDIF (TTL or CONSUMER)

Two approaches I am currently thinking of are these (in no particular order):

Approach #1

- Create a 4:2 PCB where inputs and output can be paralleled to create a 4:1
- Allow for stacking so that PCM/DSD (which requires at least 3 signals) can also be used.
- Create a second PCB for SPDIF input - it would possibly include spots for jacks (RCA/BNC or XLR) as well as a trafo for isolation and spots for resistors to setup termination and voltage division as necessary.

Approach #2

If it turns out that most people only wish to use SPDIF - then I would put the trafos and termination parts on the MUX/DEMUX PCb itself and already parallel the channels so that it does 4:1.

We already have the OTTO-II for switching between 2 PCM sources. And most people will not have more than 2. yet it is fairly common to have up to four (or even more) SPDF/AES sources.

So this is your chance to tell us which approach you like better! before I order the boards. :D

Happy new year!

Cheers!
Russ

RollE2k 1st January 2013 09:43 PM

Well, at least for me (and i think many more) i will use one or two I2S sources, where at least one is PCM/DSD combo, and the other will probably be PCM. And then i will have at least 2 inputs which is SPDIF, one optical and one coax.

So for me Approach #1 will be the best one.
But looking at Approach #2 then i guess it would allow me to have one PCM/DSD input through the normal DSD-input on B3-SE, and put the SPDIF-mux on the SPDIF input port, so i would then have possibility of one I2S and up to four SPDIF, right?

If this secondary alternative is true, then it would work fine for me, but Approach 1 seems more usable for more people.

Sean Henderson 1st January 2013 10:10 PM

Russ,

My input needs are SPDIF and USB2/3.

Russ White 1st January 2013 10:12 PM

Quote:

Originally Posted by RollE2k (Post 3307090)
Well, at least for me (and i think many more) i will use one or two I2S sources, where at least one is PCM/DSD combo, and the other will probably be PCM. And then i will have at least 2 inputs which is SPDIF, one optical and one coax.

So for me Approach #1 will be the best one.
But looking at Approach #2 then i guess it would allow me to have one PCM/DSD input through the normal DSD-input on B3-SE, and put the SPDIF-mux on the SPDIF input port, so i would then have possibility of one I2S and up to four SPDIF, right?

If this secondary alternative is true, then it would work fine for me, but Approach 1 seems more usable for more people.

Your setup sounds best served by approach #2 plus an OTTO-II.

You would connect the OTTO-II to the PCM/DSD input pf B3SE and the 4:1 SPDIF mux to the SPDIF input.

Then you would use IP_S to switch between PCM/SPDIF and the OTTO-II and 4:1 mux to switch their sources.

Zero Cool 1st January 2013 10:38 PM

I guess I am not understanding what you want to get from a new product? You already have the 4:1 SPDIF to I2S mux board and now you have the Otto-II 2:1 I2S switch board. so you pretty much have all the bases covered?

I think like you said. most people will have multiple SPDIF sources and one USB type source. Now You may want to combine an the 4:1SPDIF Mux board and the Otto-II boards together into one product creating a 5:1mux where the 5th input is an I2S input for connection to a USB board.

The only instance I can see for a 4:1 or 4:2 I2S switch board is if in some rare instance where someone needed more then 4 SPDIF inputs and wanted to connect 2x 4:1 SPDIF boards and a USB to I2S board. But even then it would only be 3:1

and even rarer yet would be someone that wanted to have 2x I2S output's for switching between 2 different types of DAC chips but I can't imagine you would sell more then a few of such boards. hardly making it worth while.

So am I missing some parameter? Otherwise i think you got it already?

Zc

Jeffrey Davison 2nd January 2013 06:24 AM

approach 2 :)

RollE2k 2nd January 2013 01:58 PM

Russ: But would there be some east way to switch all inputs with just one stepped switch then? i mean like on the old B3-dac with the 4:1 spdif board?
Also, for this - would i just need to buy OTTO-II + the older 4:1 board from B2-era, or the newer one that was made for B3(non-SE)?

Russ White 2nd January 2013 02:28 PM

I think it's time for me to draw a diagram. :)

BrianDonegan 2nd January 2013 02:32 PM

Quote:

i mean like on the old B3-dac with the 4:1 spdif board?
There is no 4:1 board for the B3 (8-channel). There is only a four-channel level converter. All mux'ing takes place on the B3.

RollE2k 2nd January 2013 02:58 PM

Brian: But it's THAT board we are talking about in combo with the OTTO-II right? :-)


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