[tangent]

I have a source with only a Toslink output and I want to hook it up to an ART DI/O, which only has S/PDIF inputs. I searched the forums here and at Headwize and could only find projects for going the reverse direction. Does anyone have any plans for this, preferrably with parts lists? I don't want to mod the source, for what that's worth.

If this is too tricky to do as a one-day project, what about a recommendation for a commercial converter box? I've found a few cheap-looking things that I'm wary about. In the "big trustable name" department there's the Monarchy DIP ($250) and the M-Audio CO-3 ($200). The DIP also does reclocking, which is nice, I guess, and the CO-3 does simultaneous conversion to and from S/PDIF, TosLink and AES/EBU. I don't think I need these two features, but if I can't build it myself or find something trustable but inexpensive (under $80, say), I may spring for the DIP....

 

[aos]

It shouldn't be too hard. I've seen schematics somewhere at any rate, but I need to do the same thing myself as I just finished a DAC that doesn't have optical input. It might be as simple as connecting optical receiver output directly to coax in, but that would work only on some digital receiver chips (CS84xx family). I think SPD/IF is bipolar (uses both positive and negative voltage) while optical receiver gives TTL levels (0 to 5V). I can easily test it at home, and I really do need it immediately, I'll inform you of results.

 

[aos]

http://sound.westhost.com/project85.htm

Look at the bottom for TTL to COAX converter. It uses two '04 inverters and couple of resistors/caps. Add the TORX173 or any other optical receiver in front of it, and that should work. I can test it hopefully tonight.

 

[aos]

It works. I didn't have exact values of resistors and plus I hacked it on a breadboard without any bypass capacitors on optical receiver, that's probably why I got it to work with only one source and optical cable. It probably works with everything given proper values and routing.

 

[tangent]

Thanks aos, I'll give that a try. I don't have any of the parts required, so it'll be a week or so before I can try it.

 

[aos]

I added bypass capacitor to pins of TORX173 which is required per datasheet (didn't do it originally as I had done the whole thing point to point and it's probably obvious that you try to avoid soldering 5 wires to one pin if you can

). And now it works with my other source as well. In short, schematics does work.

 

[Dusty Chalk]

Ironically, there is also a project in the current audioXpress magazine (same one as has the EMP review).

Would also recommend the GW Labs DSP.

 

[tangent]

So, where does one get this magical TORX173? I've looked.... I can't even find anything similar by other manufacturers.

 

[aos]

:>>>>

Ah yes, TORX173. I have about 25 of them, for my PDAC. If my PDAC project fails, I intend to sell off the excess. In the meantime, it's a Toshiba part. I've seen it in a few places but some of them have minimum orders (avnet?) (coincidentally 25 because I didn't order from there). Sells for about $3-5 US. The place I ordered from (through my local sales rep) has $50 minimum order so don't expect to be able to buy just 1 piece anywhere. They also sell Crystal chips so I fill my order by getting those as well.

There is a few alternative modules like TORX176 or my own elusive favorite TORX141 (not in stock anywhere), plus a few more. I don't think any of them is available any more easily though.

 

[zoboomofo]

Hi tangent, I've found a commercial unit from zhtham's for sale post. He used one of these to hook up a toslink out to his DI/O and blimey its cheap!

 

[maczrool]

Digikey has the Sharp equivalent (roughly) of the TORX-173. They are under $2, if I remember correctly, and no minimum order.

Stu

 

[aos]

OH MY GOD!

After spending countless days trying to find these these bloody things and all the money I've spent, now suddenly Digikey has them?! Even the combined optical/electrical mini jacks? With very low power consumption? Aaaarrrrgggghhhh.

 

[tangent]

Thanks for the info, maczrool. There are several models to choose from, but for the hobbyist, the GP1FA551RZ looks like the one to get. It's among the lowest in terms of supply current, it's one of the cheapest, and it's got good performance. $2.38 apiece.

I already solved my actual problem with some other purchases, but I think I'll tack one of these onto an order in progress and play with it anyway. Should be fun.

 

[maczrool]

AOS,

I understand your frustration. I just bought 50 Sharp GP1FA511TZ at ~$1.75 a piece and then I see that Digikey could have sold me the same ones for $1.00 ea. Anyway, I love the new shuttered design, very clever.

Stu

 

[aos]

My favorite is GP1F595R. Expensive, but is a minijack and has also the ability to plug in standard 3.5" minijack. Used in PCDPs/MDs.

This one also has the lowest power consumption - 5mA! The one tangent has mentioned has 15mA, and the TORX173P has 23mA. Also, minijack uses 2.5V meaning the power dissipation is only 12.5mW. However, you need level shifter since the lowest voltage digital receiver chips I've seen use 3.3V and "high" on 2.5V will not be enough to register as "1" (and 5V receivers might be even worse). Actual MDs probably have specialized receiver chips running on 2.5V or less.

I can't believe Digikey is selling this. This must be a recent development, I bet they didn't have them last year.