Connect AES3 to SPDIF (Roland SRV-3030D)

Archived from groups: rec.audio.pro (More info?)

Hi.
I have a Roland SRV-3030D that has RCA type SPDIF connections for in and
out. I also have a MOTU 1224 with AES/EBU XLR In/Out.

I would like to connect the two digitally using these connections.

The Roland manual states that the 3030D can accept AES/EBU connections (does
that mean without modification). It also says that (paraphrasing) "Some
digital audio devices using AES/EBU make use of XLR connectors (as the Motu
does). Connections to such devices require use of a third party adapter."
Additionally I saw that is says the digital input and output are 75 Ohms
unbalanced with Electrical Characteristics RS-422A.

Now, I am confused. Does this mean I can make a straight connection as long
as the connector types match the device on each end, or does this mean I
need some sort of adapter for impedance matching? I would try a direct
connection but I don't currently have any compatible cables.

I found this document (http://www.rane.com/note149.html), but I am not an
electrical engineer and I am not sure if I need to do this kind of thing. At
the bottom there is a figure illustrating AES3 to SPDIF and visa versa.

So, Does the Roland really accept a direct AES/EBU signal, unmodified, or am
I misunderstanding. What do I need to do to connect these two units
digitally?

Thanks for the assistance.
Clay

Archived from groups: rec.audio.pro (More info?)

In article <damg74$7a7$1@nntp.usace.army.mil> lahatte@vicksburg.com writes:

> The Roland manual states that the 3030D can accept AES/EBU connections (does
> that mean without modification). It also says that (paraphrasing) "Some
> digital audio devices using AES/EBU make use of XLR connectors (as the Motu
> does). Connections to such devices require use of a third party adapter."
> Additionally I saw that is says the digital input and output are 75 Ohms
> unbalanced with Electrical Characteristics RS-422A.
>
> Now, I am confused. Does this mean I can make a straight connection as long
> as the connector types match the device on each end, or does this mean I
> need some sort of adapter for impedance matching? I would try a direct
> connection but I don't currently have any compatible cables.

Maybe, to both. What the Roland manual is saying is that the digital
inputs and outputs are unbalanced, 75 ohms. AES/EBU is balanced, and
110 ohms. But what's true and what they don't say is that the audio
data format is the same for both, and that the Roland 3030 doesn't
care about the status bits that differentiate the professional and
consumer formats.

There is a difference in the voltage level of the two signals which
may be a problem or maybe not. The impedance makes a difference with
long cables but doesn't matter much with short cables.

So, as Lorin says, just try it with physical adapters first, but make
sure that they're wired so that you actually get signal where it's
supposed to be. The RCA plugs should be connected so that the center
conductor goes to Pin 2 of the XLR, and the shield goes to pin 3 and
(optionally) to pin 1.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

By the way, I found these items. So, I guess if a direct cable connection
won't do it, I can try these things...

http://www.westlake-electronic.com [...] BCJ-XP-TRB

https://www.digitalconnection.com/s [...] de=BNCXRCA

Now, I just need to find a couple of decent 16ft digital cables.

Clay

"Clay LaHatte" <lahatte@vicksburg.com> wrote in message
newsamg74$7a7$1@nntp.usace.army.mil...
> Hi.
> I have a Roland SRV-3030D that has RCA type SPDIF connections for in and
> out. I also have a MOTU 1224 with AES/EBU XLR In/Out.
>
> I would like to connect the two digitally using these connections.
>

Archived from groups: rec.audio.pro (More info?)

"Mike Rivers" wrote ...
> You might do better, since this is your first time, by cutting up a
> good audio cable with RCA connectors rather than a good video cable.
> Some video cable is built with a foam dialectric and very thin wires
> (for low capacitance, hence low loss) and it may be difficult to
> solder.
>
> But don't use too good of an audio cable or it might be built in a
> similar manner. You can't tell until you cut it.
>
> Alternately, you can buy a pre-made adapter. You want a Switchcraft
> 322 (XLR female) or 324 (XLR male) which adapts the XLR to an RCA
> jack. Plug that into the unit with the XLR, and then connect the two
> units with an RCA-RCA cable. You can use a video cable for this if you
> want to be nice to your signal.

Are we recommending interconnecting coaxial (assumed 75
ohms unbalanced) with XLR (110-ohm balanced) without
a balun transformer, etc? In addition to the impedance and
bal/unbal aren't there signal voltage differences as well?

Archived from groups: rec.audio.pro (More info?)

In article <Mq-dnQ1QJsXoYFLfRVn-ug@comcast.com> arnyk@hotpop.com writes:

> Mike you didn't mention the real possibility of video cable
> with aluminum shield and/or center conductors, with
> attendant acute problems with soldering.

That's what I was thinking of when I mentioned the foam dialectric.
Though I know there's foam cable with braided shield and reasonable
diameter inner conductors, most RF video cable that's easy to buy is
the foam/bonded foil stuff suitable only for crimping on Type F
connectors (which rank very close to mini phone jacks on my least
favorite connector list).

> AES3 to SP/DIF via ordinary XLR-RCA cable adaptors can be
> problematic. The AES3 side is balanced, often with both
> signal wires floating.

This is why you can usually get away with connecting it to an
unbalanced device. Not always, but most of the time. Both AES/EBU and
S/PDIF coax are supposed to have transformer isolated outputs, but
sometimes manufacturers cheat.

> Ordinary XLR-RCA adaptors connect one hot to the center pin
> of the RCA, and connect pin 1 to the shield side of the RCA.
> This works a lot of the time with analog audio. However,
> when connected to a floating balanced source which might be
> what the AES3 source is, it results in an open circuit.

This is why I suggested opening up the adapter to see how it's wired,
and modify it if necessary. I think it was here (or maybe it was
somewhere else where this very same question came up recently) where I
made it clear that the RCA cable needs to go between pins 2 and 3 of
the XLR, with pin 1 being optional.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

"Mike Rivers" wrote ...
>
> Richard Crowley writes:
>> Are we recommending interconnecting coaxial (assumed 75
>> ohms unbalanced) with XLR (110-ohm balanced) without
>> a balun transformer, etc? In addition to the impedance and
>> bal/unbal aren't there signal voltage differences as well?
>
> I'm recommending TRYING it before spending money on a
> transformer. It almost always works, and if it doesn't, it didn't
> cost much to try.

I like it. Its something I would do myself.

But perhaps it would be better to identify it as a cheap/kludge
alternative rather than an "official" methodology? You never
know who is reading these postings and assuming they are gospel?

Archived from groups: rec.audio.pro (More info?)

"Mike Rivers" <mrivers@d-and-d.com> wrote:
>
> This is why I suggested opening up the adapter to see how it's wired,
> and modify it if necessary. I think it was here (or maybe it was
> somewhere else where this very same question came up recently) where
> I made it clear that the RCA cable needs to go between pins 2 and 3
> of the XLR, with pin 1 being optional.



It was here, in response to my instructions to use pins 2 and 1. I
hadn't thought about the floating output possibility.

Of course, much like your comment about the difficulty of soldering
prefab video cables, sometimes Arny just uses different specifics to
make exactly the same point.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)

Archived from groups: rec.audio.pro (More info?)

Thanks for all the good advise. I'll try to post the results once I get some
cables and adapters.

By the way for those that may not have seen it, I am trying to digitally
connect a Roland SRV-3030D (S/P-DIF) Digital Reverb to a MOTU 1224
(AES/EBU).

Thanks.
Clay

"Mike Rivers" <mrivers@d-and-d.com> wrote in message
news:znr1120909116k@trad...
>
> In article <U_SdnVcuiarh6lLfRVn-1A@canufly.net> lahatte@vicksburg.com
writes:
>
> > Are there any special type of connectors I need to for digital, or can I
use
> > standard audio connectors and make do.
>
> For your purposes, any connectors that fit will work just fine.
>
> > I assume I can just cut a good video cable with RCA connectors and
attach an
> > XLR to one end.
>
> You might do better, since this is your first time, by cutting up a
> good audio cable with RCA connectors rather than a good video cable.
> Some video cable is built with a foam dialectric and very thin wires
> (for low capacitance, hence low loss) and it may be difficult to
> solder.
>
> But don't use too good of an audio cable or it might be built in a
> similar manner. You can't tell until you cut it.
>
> Alternately, you can buy a pre-made adapter. You want a Switchcraft
> 322 (XLR female) or 324 (XLR male) which adapts the XLR to an RCA
> jack. Plug that into the unit with the XLR, and then connect the two
> units with an RCA-RCA cable. You can use a video cable for this if you
> want to be nice to your signal.
>
> Those adapters are constructed so you can take it apart by loosening
> just one screw and you can see how it's wired, and modify it if by
> some chance they're wired with pin 2 or pin 3 not connected. Some
> older gear used XLRs for unbalanced connections and wired only two
> pins, sometimes the wrong two pins.
>
> Don't use adapters that go the other way so you'd have to plug the RCA
> end of the adapter into a chassis mounted RCA jack. The adapter and
> cable are too heavy and the plug will fall out.
>
>
> You can order the adapters ($10.49) from Markertek:
>
> http://www.markertek.com/SearchPro [...] &sort=prod
>
>
>
> --
> I'm really Mike Rivers (mrivers@d-and-d.com)
> However, until the spam goes away or Hell freezes over,
> lots of IP addresses are blocked from this system. If
> you e-mail me and it bounces, use your secret decoder ring
> and reach me here: double-m-eleven-double-zero at yahoo