AES/EBU SPDIF and ADAT MFX3

[techristian]

What a headache trying to send my MFX3 audio to my PC DIGITALLY ! It sends out AES/EBU or SPDIF depending on what I select. I tried first using coax cable spdif at first. NO THE FOCURITE DOESN'T SEE IT. Then I bought a HOSA ODL-312 AES/EBU to OPTICAL SPDIF OUT and still the FOCUSRITE SCARLET ....no go !!!!!!!

 

 

HELP !

 

DAN

[Anderton]

I'm not sure what you mean by MFX3. I assume you're referring to the Fairlight MFX3, and not the TV wall mounts or Brazilian fetish sites that jump to the top when you do a search on MFX3?

[Mike Rivers]

Is MFX3 a file format that comes out of something? Or the something with the digital output? Do you have anything that it works with? Maybe the digital output isn't working. Do you have an oscilloscope? You could look for a signal coming out of the digital outputs to at least see if there's something there. Or, on the other end of the cable, do you have anything else around that generates an AES or S/PDIF output so you can verify that the Focusrite interface is set up correctly and working?

 

And in case it really is a Fairlight, got a good stock of 8" floppy disks?

[techristian]

I have has some luck sending SPDIF from my Fairlight MFX3 directly to my AKAI S3000XL sampler...(my pseudo Fairlight CMI) using a RCA cable, but it is not the industry standard 75 ohm , but rather a high quality RCA cable. Someone suggested placing a 75 ohm resistor from the live to ground. I never tried it because it works for my AKAI. I bought this HOSA adapter instead. From what I have been reading , the Focusrite may be looking for ADAT optical instead, BUT SPDIF 75ohm SHOULD BE SPDIF ! So if that is the case, the HOSA specs only send SPDIF optical. However my SONY DAT DTC-670 also has OPTICAL inputs and can't see the HOSA ? I may need to play with the master clock though?

 

There also may still be use for the HOSA. If I can get the SONY DAT DTC-670 to read 75ohm cable SPDIF from the Fairlight, I may be able to send a regenerated cable signal to the laptop. (as long as the Sony is SPDIF and not ADAT.

 

Or I can just stop all of this foolishness and send it over audio !!

 

Dan

[Anderton]

I haven't had good luck with hi-fi RCA cables. I bit the bullet and against my gut instincts paid the extra for a "works with digital" cable...and, well, it does.

[Mike Rivers]

The suggestion of the 75Ω resistor is to terminate the output properly so as to avoid standing waves. But there are some assumptions - first, that the RCA S/PDIF output is really 75Ω, and second, that the input impedance of the Focusrite's RCA S/PDIF input isn't already 75 ohms. Given that you're talking about devices that are 25 or more years apart, it may be that the output level from the Fairlight is just too low to drive the input of the Focusrite.

 

What's the Hosa adapter? Coax to optical? When you're sending data (or think you are) from the Fairlight to the adapter, does the optical output light up?

 

Have you checked to see if you have the Focusrite set to the same sample rate that the Fairlight is sending? They have to be pretty close in order to sync. If the Fairlight is set for 44.1 kHz and the Fairlight is sending 48 kHz, that might be your problem right there.

 

You're correct that the RCA S/PDIF jack should be 2-channel audio, but Focusrite makes a bunch of interfaces with an ADAT optical input so that you could connect an 8-channel mic preamp to it to expand the Focusrite's input capability. Only a few products that use ADAT optical for expansion have a switch that converts them to Toslink S/PDIF.

[techristian]

Thanks Craig and Mike !

 

Seems to me that I have made a 75 ohm cable years ago. I ported some old tracks over from my DAT to a computer with one of my old audio interfaces. It is a bit more tricky with the Fairlight, because the output is all handled with DB plugs with multiple pins. The original owner made up cables and set them up for AES/EBU by connecting only to the AES/EBU lines on the DB plugs. I took one of them , unsoldered it and connected it to the SPDIF pins. As I said, it worked fine for the AKAI sampler with the very tight gold RCA cables. I'm using one of the original AES/EBU cables for the HOSA interface.

 

To answer your question Mike, the HOSA is supposed to be AES/EBU SLR to SPDIF OPTICAL OR SPDIF OPTICAL to AES/EBU SLR.

 

dan