Hello esteemed Forumers.
I know this question has been brought up before, and i did use the search function, but did not get much wiser from it. If that is due to the search function or myself, i'll refrain from ascertaining.
So, i'm trying to cobble together a preamp de luxe from various bits and pieces, to feed my Fetzilla. The heart of it is a DCB1 and a Subbu DAC v3(mounted internally). The plan now is to use one of those old russian silver-on-ceramic rotary selector switches to route the analog signal, and have one of the inputs select the Subbu. Then use a rotary encoder together with some kind of display(might go with a 7-segment led display as i have some nice early eighties vintage ones by TI). This means i could use a remote control to select between digital sources
The situation 'm facing is i have several(media streamer, logitech squeezebox, airport express, iptv box) digital sources, and no convenient way of switching between them. So the specification is:
Maximum of 8 digital inputs, either spdif over coax or toslink(toslink with the appropriate extra hardware of course).
I wish to avoid relays, and i'm looking at digital control(i2c or similar) for selecting which input gets routed to the Subbu.
I seem to recall someone doing something like that using a cmos mux, maybe something like the 74HC151, but i was unable to find it when i searched.
Anyone here know of something already done that i could take a look at and tweak? When connecting this many digital sources together, should i opt for isolation transformers a la aes/ebu on all the coax inputs to avoid possible issues with my sources? Any other caveats you digital folk know about that could be helpful for me before i start wiring something up?
Thanks in advance.
I know this question has been brought up before, and i did use the search function, but did not get much wiser from it. If that is due to the search function or myself, i'll refrain from ascertaining.
So, i'm trying to cobble together a preamp de luxe from various bits and pieces, to feed my Fetzilla. The heart of it is a DCB1 and a Subbu DAC v3(mounted internally). The plan now is to use one of those old russian silver-on-ceramic rotary selector switches to route the analog signal, and have one of the inputs select the Subbu. Then use a rotary encoder together with some kind of display(might go with a 7-segment led display as i have some nice early eighties vintage ones by TI). This means i could use a remote control to select between digital sources
The situation 'm facing is i have several(media streamer, logitech squeezebox, airport express, iptv box) digital sources, and no convenient way of switching between them. So the specification is:
Maximum of 8 digital inputs, either spdif over coax or toslink(toslink with the appropriate extra hardware of course).
I wish to avoid relays, and i'm looking at digital control(i2c or similar) for selecting which input gets routed to the Subbu.
I seem to recall someone doing something like that using a cmos mux, maybe something like the 74HC151, but i was unable to find it when i searched.
Anyone here know of something already done that i could take a look at and tweak? When connecting this many digital sources together, should i opt for isolation transformers a la aes/ebu on all the coax inputs to avoid possible issues with my sources? Any other caveats you digital folk know about that could be helpful for me before i start wiring something up?
Thanks in advance.
I think the simplest approach for you is to build something with N coax and M optical inputs with maybe input buffering on each. These are connected to some kind of MUX IC, then an output buffer. This given you electrical spdif output. If you want optical for some reason you will also need an spdif optical TX. It's up to you to research what ICs are needed for this or you can wait for someone else to post part numbers. There is no need for isolation transformers.
Note that optical inputs will connect to a toslink RX, which converts optical to an electrical signal. You will probably need to adjust levels depending on what the logic level of the MUX and buffer ICs are used. All in all this is not all that complicated unless you start to go about 96k or 192k. I have been able to build this kind of MUXing system for SPDIF and run it at 96k on a solderless breadboard without any special treatment of the circuit in any way.
For some hints on ICs and so on, check out the Appendix (last) section on this page:
S/PDIF Digital to Analogue Converter
Also check out:
S/PDIF 4:1 Receiver/MUX Module
Forum member Linuxworks has developed an SPDIF muxer project but I can't recall what his web site is at the moment. Maybe he can chime in here with more specifics.
Note that optical inputs will connect to a toslink RX, which converts optical to an electrical signal. You will probably need to adjust levels depending on what the logic level of the MUX and buffer ICs are used. All in all this is not all that complicated unless you start to go about 96k or 192k. I have been able to build this kind of MUXing system for SPDIF and run it at 96k on a solderless breadboard without any special treatment of the circuit in any way.
For some hints on ICs and so on, check out the Appendix (last) section on this page:
S/PDIF Digital to Analogue Converter
Also check out:
S/PDIF 4:1 Receiver/MUX Module
Forum member Linuxworks has developed an SPDIF muxer project but I can't recall what his web site is at the moment. Maybe he can chime in here with more specifics.
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Awesome Charlie, thanks for the input and links. So convert up from the rather low levels of coax spdif, mux it, and then convert back down for the receiver(I believe Wolfson in the Subbu DAC).
And with toslink i presumably get TTL from the toslink receiver, mux that directly and then down to coax spdif levels.
And with toslink i presumably get TTL from the toslink receiver, mux that directly and then down to coax spdif levels.
From what I could ascertain from the posts about the project, it's a little deficient on the switching aspect. You just lock to the first SPDIF signal found. What if the user wants to then choose another input but the first spdif feed is still happening? How do you force it to switch to another input?
A smart phone can force a channel change through bluetooth. The channel polling can be turned on and off at wish as well.
I probably should update the first post in that thread to have include all that have been implemented.
4:1 Mux/Demux Switching Module
I knew i had seen something like this. That board seems to do the trick, albeit with only 4 inputs, but it is worth investigating.
I knew i had seen something like this. That board seems to do the trick, albeit with only 4 inputs, but it is worth investigating.
After a great post in another thread i stumbled across the MAX455.
Here it is doing 15 input, but 1 of 8 mux is quite easy.
simple but reliable +/-5V PSU. A question, how would i go about trying to sense active inputs without actually decoding the spdif datastreams?
An externally hosted image should be here but it was not working when we last tested it.
Here it is doing 15 input, but 1 of 8 mux is quite easy.
simple but reliable +/-5V PSU. A question, how would i go about trying to sense active inputs without actually decoding the spdif datastreams?
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