TDIF cables

need to make (new) cabels for connection of DAW TDIF. I already have made 9 of these cables running 4-5 meter. Now i need longer ones.
How long can i make TDIF cables without problems in data/clock?

I've ordered shielded ribboncable tru Farnell but that was outrageous priced, any better sources found?

what the influence of different brands of sub25-connectors?
Last ones where very pro with metal casing where i soldered an extra ground to, dunno if this is necesary?

All you need to remember is that TDIF is four pairs of AES (with clock/sample rate stripped) in each direction... each AES pair runs over a 75-ohm unbalanced line.

True TDIF for long runs needs to be run via 8 x 75Ω coax (4 sends, 4 returns) and of course, the pins need to be reversed at the opposing ends.

1+2 are on pin 1 (with the shield on pin 14)
3+4 are on pin 2 (with the shield on pin 15)
5+6 are on pin 2 (with the shield on pin 16)
7+8 are on pin 2 (with the shield on pin 17)

7+8 are on pin 10 (with the shield on pin 22)
5+6 are on pin 11 (with the shield on pin 23)
3+4 are on pin 12 (with the shield on pin 24)
1+2 are on pin 13 (with the shield on pin 25)

... forget which are the sends and which the returns... but run these 8 coaxes. The remaining nine pins are also wired according to the pattern that you should notice emerges: i.e. each pin at one end oes to it's mirror-image equivalent at the other end...

pin1 goes to 13, pin 14 goes to 25
pin2 goes to 12, pin 15 goes to 24
pin3 goes to 11, pin 16 goes to 23
pin4 goes to 10, pin 17 goes to 22
pin5 goes to 9, pin 18 goes to 21
pin6 goes to 8, pin 19 goes to 20
pin7 goes to 7
pin8 goes to 6, pin 20 goes to 19
pin9 goes to 5, pin 21 goes to 18
pin10 goes to 4, pin 22 goes to 17
pin11 goes to 3, pin 23 goes to 16
pin12 goes to 2, pin 24 goes to 15
pin13 goes to 1, pin 25 goes to 14

Notice that this list reads the same reading upwards as downwards...

You can make a TDIF extender by crimping a couple of D25s topgether, but swapping one so it's reversed.

The only time you hear a difference is when there's a big problem. -Forget about it.

Keith

never thought about running 8 times 75 ohm-wires together, thanks Keith!

saves the bank bigstyle :grin: :thumb:

yeah, the remaining lines are less sensitive... (LRCK out/in, CLOCK out/in, sample rate identifiers and grounds -from memory) and won't make a mess of the audio... -I can't remember if the clock would also benefit from a pair of 75-ohm coaxes or not... but whatever you do, you'll need to get that thin stuff... ten or so coaxes rinning into a D-sub 25... -Yikes!! :shock:

I've done it loads of times, and if you can get that VGA monitor cable and burst it open, you'll find 5x subminiature coaxes in there, (red, green blue, horizontal sunc & vertical sync) which will be perfect for the job. A pair of VGA cables will make a bidirectional cable.... you can save money if you're only ever sending signal one way and just use one run of cable, perhaps buy a 15-meter VGA extension cable and chop the connestors off and rewire to DB25's.... or buy a pair of cables if you need it to be bidirectional.

Keith