TOPIC: Digital link out - issue with single-ended input

Hello, I discovered something interesting with the digital pass through. When driving the digital input of amp A with a balanced (digital) signal and using the passthrough to drive the digital input of amp B, it works great. However, when driving the digital input of amp A with a single-ended input (as documented in the manual), amp A picks up the digital signal fine. However the passthrough doesn't seem to switch on so amp B gets no signal.

A quick clarification since I may need some of these, do you mean from "channel A to channel B" or from your "left plate amp to right plate amp"?

I guess I should call it digital link out, since that's what the manual uses. It goes from one amp to another. I'm wondering if I've done something wrong, that's all. It works fine when supplied with an AES/EBU signal. Hence question to miniDSP/devteam.

Don't you have to configure that one to be an output? In any case, that clears up my question. I think.

John Ashman wrote:
I don't think so... I'm not entirely sure though, I'll have another look.

Today I'm unable to reproduce the behaviour I noted in the first post... Now the amp and the link out behave the same. What I've found:

1. With an AES/EBU input connected it works fine (and sounds very good BTW) - tried with OpenDRC-DI and an Alesis AI-1 SRC, unfortunately my CD transport with AES/EBU output kicked the bucket a little while ago
2. One source connected via single-ended input, the OpenDRC-DI, works fine.
3. Other sources connected via single-ended input (DVD player, Ipod dock) aren't detected - silence

I was only expecting it to work with a balanced digital signal anyway but thought I would try a single ended SPDIF signal since it was mentioned in the manual.

The adapter cable I'm using has pins 1 and 3 connected to the RCA shield and pin 2 to the RCA hot.

If MiniDSP is paying attention, I'm a little disappointed by the pick of AES-EBU since there's really no advantage. The world runs on coax digital and AES-EBU is something most gear simply doesn't have or need in anyway. Buying expensive adaptors all the time is not fun.

@John.reekie,

Sorry for the delay in getting back to you. We were just trying to find some time to reproduce the issue.
It's a level issue (SPDIF for most consumer has low level of 0.5V or lower). That's real low and not very good for long distance. We use higher level for the openDRC-DI hence the reason why the SPDIF output works fine there. Two option for those looking for SPDIF.
1) Make a modification to the board (simple resistor pad)
2) Use a buffer to up the signal. (e.g. SPDIF to AES)

Hoping this info helps, we could see how we could add a jumper maybe to next rev?
DevTeam

You could also use such an adapter: NADITBNC-MX. Will be arround 40-50$ though...

It would be nice to have the output switchable between analog and digital since most things still work off analog still.

OR.....wireless.

devteam wrote:
Thanks devteam, that clarifies the issue. I expect a jumper would be helpful to many.

@curryman, thanks for the link, I couldn't find one of those quickly but did manage to get a Canare BCJ-XP-TRB (used) for $25 posted. I think it's the same thing... Anyway I'll try it and see.

@John Ashman, with digital link/passthrough there is no deterioration. Plus only one is needed. For analog I think Y-connectors would be better.

John, this is true, but the problem with AES/EBU is that it's the very LEAST used of all the connections.

Virtually very home product has RCA. Virtually every commercial product has analog XLR.
Sonos, at the very least, has variable digital coax and toslink.
AES/EBU is rare, and even more rare would be a unit with variable AES/EBU.

I wouldn't take it OFF, but I would at least make the XLR output switchable to analog as that makes daisy chaining in a pro situation far easier.

Also, the ethernet is to be commended, but not at the expense of USB, because there are many situations where you might want to make a settings change on the fly and, darn, no router, no network. I assume you might be able to direct connect if you fix the IP on the speakers and the computer, but that's also a chore and not everyone knows how to do that.

Hi John, you're clearly envisaging scenarios that I haven't thought of.

devteam wrote:
Update. I've tried a Canare BCJ-XP-TRB SPDIF->AES/EBU convertor, with no success. I've verified that the convertor is at least passing something through by using it at the input of the OpenDRC, but when used at the input of the PWR-ICE125 driven by a consumer SPDIF device, no luck.

I read that the "minimum eye-level height" of AES/EBU is 200 mV. So I think some changes may be needed on the detection level. Could you post the details of option 1 (resistor pad) and I'll give it a try?

Sure, we could send you the modification for the resistor. Easiest that you get in touch with us by email. We can email you the steps. It's best for us knowing it's an SMD modification (require a value of SMD that you most likely won't have). All boards now shipping have that modification done in house.

DevTeam