SPDIF router

[[email protected]]

I'm looking for a low cost SPDIF router or DA, maybe 1 in to 5 out. Don't
need anything elaborate

Recommendations?
--
Joe Salerno
Video Works! Is it working for you?
PO Box 273405 - Houston TX 77277-3405
http://joe.salerno.com

[Arny Krueger]

" > wrote in message
nk.net
> I'm looking for a low cost SPDIF router or DA, maybe 1 in to 5 out.
> Don't need anything elaborate
>
> Recommendations?

You can fan-out SP/DIF with a regular off-the-shelf video amp. A SP/DIF
signal is in my recollection about 1 volt p-p, and needs 6-12 MHz bandpass
depending on the audio format being transmitted.

[Scott Dorsey]

> wrote:
>I'm looking for a low cost SPDIF router or DA, maybe 1 in to 5 out. Don't
>need anything elaborate
>
>Recommendations?

You can use an old video synch DA. You can also use a good 75 ohm patchbay
too. Ask the engineer at your local TV station what is in the junk pile.
Old Dynair synch DAs should be free for the asking pretty much.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Sugarite]

> You can fan-out SP/DIF with a regular off-the-shelf video amp. A SP/DIF
> signal is in my recollection about 1 volt p-p, and needs 6-12 MHz bandpass
> depending on the audio format being transmitted.

Your frequencies are 2x too high. S/PDIF is 2.82MHz @ 44.1kHz and 6.14MHz @
96kHz. I've never tried a video splitter, but I bet it would work. Should
be able to get by without an amp, and it's not a bad idea to use heavy gauge
TV cable for S/PDIF cables anyway, unless the gear is moved often, might
damage the plugs.

[Preben Friis]

"Sugarite" > wrote in message
...
> > You can fan-out SP/DIF with a regular off-the-shelf video amp. A SP/DIF
> > signal is in my recollection about 1 volt p-p, and needs 6-12 MHz
bandpass
> > depending on the audio format being transmitted.
>
> Your frequencies are 2x too high. S/PDIF is 2.82MHz @ 44.1kHz and 6.14MHz
@
> 96kHz. I've never tried a video splitter, but I bet it would work.
Should
> be able to get by without an amp, and it's not a bad idea to use heavy
gauge
> TV cable for S/PDIF cables anyway, unless the gear is moved often, might
> damage the plugs.

2.82 MHz bitrate... but unless you want the digital signal to look like
sines, you want a bandwidth at least twice that.

Check out: http://www.epanorama.net/documents/audio/spdif.html

/Preben Friis

[Len Moskowitz]

Sugarite > wrote:

>> You can fan-out SP/DIF with a regular off-the-shelf video amp. A SP/DIF
>> signal is in my recollection about 1 volt p-p, and needs 6-12 MHz bandpass
>> depending on the audio format being transmitted.
>
>Your frequencies are 2x too high. S/PDIF is 2.82MHz @ 44.1kHz and 6.14MHz @
>96kHz. I've never tried a video splitter, but I bet it would work.

I've used a two-way video splitter: Radio Shack #3415-2582 with F to RCA
adapters on all three ports. Strict per-standard S/PDIF is only .5V so
you can't split it too many times until it doesn't work and you need an
amp to make it work.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

[Sugarite]

"Preben Friis" > wrote in message
...
>
> "Sugarite" > wrote in message
> ...
> > > You can fan-out SP/DIF with a regular off-the-shelf video amp. A
SP/DIF
> > > signal is in my recollection about 1 volt p-p, and needs 6-12 MHz
> bandpass
> > > depending on the audio format being transmitted.
> >
> > Your frequencies are 2x too high. S/PDIF is 2.82MHz @ 44.1kHz and
6.14MHz
> @
> > 96kHz. I've never tried a video splitter, but I bet it would work.
> Should
> > be able to get by without an amp, and it's not a bad idea to use heavy
> gauge
> > TV cable for S/PDIF cables anyway, unless the gear is moved often, might
> > damage the plugs.
>
> 2.82 MHz bitrate... but unless you want the digital signal to look like
> sines, you want a bandwidth at least twice that.

Since when does a digital interface care if the pulses come in sine or
square? I also don't see much help in leaving higher frequencies unfiltered
while filtering out the bitrate frequencies... (he said 6-12MHz *bandpass*)

[Arny Krueger]

"Sugarite" > wrote in message


>> You can fan-out SP/DIF with a regular off-the-shelf video amp. A
>> SP/DIF signal is in my recollection about 1 volt p-p, and needs 6-12
>> MHz bandpass depending on the audio format being transmitted.
>
> Your frequencies are 2x too high. S/PDIF is 2.82MHz @ 44.1kHz and
> 6.14MHz @ 96kHz.

Those are the data rates. Since we're talking a modulated signal, additional
bandwidth is required to transmit the data. SP/DIF is biphase modulated. The
frequency of the clock is twice the bit rate. Reference:

http://www.epanorama.net/documents/audio/spdif.html

The bandpass numbers I cite come from Crystal Semiconductor literature, and
I think they know a little something about SP/DIF.

> I've never tried a video splitter, but I bet it would work.

Yup.

> Should be able to get by without an amp,

Been there done that for a fan-out of 2. It's not uncommon for SP/DIF line
drivers to vigorously overdrive their outputs.

> and it's not a
> bad idea to use heavy gauge TV cable for S/PDIF cables anyway, unless
> the gear is moved often, might damage the plugs.

[Arny Krueger]

"Sugarite" > wrote in message

> "Preben Friis" > wrote in message
> ...
>>
>> "Sugarite" > wrote in message
>> ...
>>>> You can fan-out SP/DIF with a regular off-the-shelf video amp. A
> SP/DIF
>>>> signal is in my recollection about 1 volt p-p, and needs 6-12 MHz
>>>> bandpass depending on the audio format being transmitted.
>>>
>>> Your frequencies are 2x too high. S/PDIF is 2.82MHz @ 44.1kHz and
>>> 6.14MHz @ 96kHz. I've never tried a video splitter, but I bet it
>>> would work.
>> Should
>>> be able to get by without an amp, and it's not a bad idea to use
>>> heavy gauge TV cable for S/PDIF cables anyway, unless the gear is
>>> moved often, might damage the plugs.
>>
>> 2.82 MHz bitrate... but unless you want the digital signal to look
>> like sines, you want a bandwidth at least twice that.

> Since when does a digital interface care if the pulses come in sine or
> square?

It's biphase modulated. You need more bandwidth than the basic bit rate.

> I also don't see much help in leaving higher frequencies
> unfiltered while filtering out the bitrate frequencies... (he said
> 6-12MHz *bandpass*)


Bad choice of words. I meant band pass through 6 to 12 MHz. We're talking
baseband video here, right? In my book that always presumes response down to
DC or very close to it.