My ADA8000 has gone belly up, and it's broke too! (Subject of another post) and I have been trying other options. I have an olde Roland Stereo Interface which has Optional SPDIF and the RCA (Coax?) phono plug type digital in/outs and this will do the job.

But when I use the RCA output to the input of my interface, the timecode 'slips' every few seconds.

I have a DM24 also which I have tried as both Master and Slave for the clock.

I have tried Word CLock(using BNC connectors), ADAT, etc to try and fix the 'slip' which causes a little pop.

The Roland has neither word clock not any other visible means of setting as master/slave as regards clock source. SO I have tried it as slave both to the DM24 and the interface in my PC.

The interface has always seemed quite happy with the ADAT for the sync. But when I try the SPDIF optical out of the Roland to the input of my interface I get no signal, though I can if I use the RCA connections between the same two devices.

Now the burning question - will a stereo optical signal be passed to an 8 channel i/o ADAT, which is what my PC interface (soundcard) uses. Or even though the both share the same connectors one cannot be recognised be the other.

I had this notion that the Stereo SPDIF output will be picked up by channels 1+2 of the ADAT?

ANother quick question - do the BNC connectors have to be terminated using one of the T-shaped connectors with the resistor on both devices. I have a single cable running between the DM24 and soundcard.

Can anyone tell me why I bothered going digital - hardest question of the lot!

Quote OneWorld:

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Or even though the both share the same connectors one cannot be recognised be the other.

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That.

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I had this notion that the Stereo SPDIF output will be picked up by channels 1+2 of the ADAT?

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No. They are 2 different protocols that happen to use the same connector.

That said, some devices are capable of handling both protocols. No idea if that applies to yours (I assume not).

Right, that explains a lot. Have managed ot get it working direct from the mixer now and there's no slip or breakfast cereal type snap crackle and pop noises. THanks

Quote OneWorld:

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But when I use the RCA output to the input of my interface, the timecode 'slips' every few seconds.

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What timecode? Do you mean you get a glitch? If so the problem is probably that the interface is not configured to derive its clock from the S/PDIF input. There must only be one clock source in any system, so if you are sending digits from a preamp etc, the interface has to become a clock slave to those digits.

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The Roland has neither word clock not any other visible means of setting as master/slave as regards clock source. SO I have tried it as slave both to the DM24 and the interface in my PC.

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If it doesn't have a wordclock input or any means to select a digital input as a reference clock, it can only serve as a master, and everything else will have to slave to it.

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The interface has always seemed quite happy with the ADAT for the sync. But when I try the SPDIF optical out of the Roland to the input of my interface I get no signal, though I can if I use the RCA connections between the same two devices.

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Although ADAT optical and S/PDIF optical use the same physical connectors and lightpipe, the data they carry is totally non-compatible. That's why you get no signal. Some devices have a mode switch somewhere (hardware or software) to configure the optical port for either ADAT or S/PDIF data formats.

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Now the burning question - will a stereo optical signal be passed to an 8 channel i/o ADAT, which is what my PC interface (soundcard) uses.

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No.

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even though the both share the same connectors one cannot be recognised be the other.

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Correct.

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I had this notion that the Stereo SPDIF output will be picked up by channels 1+2 of the ADAT?

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No, I'm afraid not. Completely different data structures means they are wholly incompatible.

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do the BNC connectors have to be terminated using one of the T-shaped connectors with the resistor on both devices.

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Not necessarily -- it depends on the equipment and the configuration of the cables.

Word Clock is distributed as a constant impednace interface, which means that there has to be a 75 ohm source at the clock output terminal, and the end of the cable has to be terminated with 75 ohms.

If you are connecting one clock output to one clock input, then the input should be terminated with 75 ohms. Most devices have that built in and sometimes switchable to a high-impednace bridging mode.

If you are 'daisy-chaining' a clock around several devices, then you can use the T-piece to link the clock across the back of one device and on to the next. Each device along the chain should present a high-impednace (bridging) load -- so if the product has a 75 ohm termination switch it should be set to hi-Z mode. Only the very last device in the chain should be set to terminate that line with 75 ohms, or the last T-piece can be fitted with a 75 ohm resistor.

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I have a single cable running between the DM24 and soundcard.

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Simply switch the device receiving the clock input signal to terminate with 75 ohms. Check the handbook -- it might be fixed that way anyway.

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Can anyone tell me why I bothered going digital - hardest question of the lot!

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Because you are a slave to fashion?

Hugh

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Technical Editor, Sound On Sound

Thanks a lot Hugh, that clears a lot up. Have managed to get it working now.

What started al this off was that my ADA8000 went pop and had to find a way round the system without that piece of equipment. Have managed to set up using just the desk and DAW without the Roland or spare 2408 as an external AD converter.

Why did I go digital? Because of you lot at SOS, I read a review of the desk and it was given a good review so I bought one!

And the old analogue desk, with the meter bridge etc blocked my view out of the window, which gives a brilliant view of the Etherow Valley, facing East, good for inspiration, doesn't affect the sound much, but nice anyway!

And most of all, wanted recall on the desk, a smaller footprint, a more compact setup. In an ideal world though, I would have more space, an analogue desk, with some ability to recall. The digital result is more 'brittle' sounding, but am sure if I really gen up on the desk and production techniques I can use one of those 'analogue feel' type VSTs

Thanks again for such a detailed answer - SOS comes to the rescue yet again!