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Post by jeromemason on Jan 24, 2019 13:07:14 GMT -6
I've bought the Motu 8 D to be a digital interface for running AES/EBU from my Dangerous Convert AD+ and also running Spidf out to my DAC. I'm doing AVB with my 16a so the Motu 8 D is going AVB to the 16a like this, 8 D >AVB16a>To Computer. So basically the 16a is handing all the information to the computer, it basically looks like one big interface to the computer and all the routing is completely done over AVB between the two Motu units.
I want to have a thread on this while it gets figured out because others could run into this.
So first off the Convert AD+ has a feature called Peak Guard and it basically tricks the interface into thinking that there is no clipping where there actually is. I'm not sure how they do it, but it's something to do with not relaying 0dbfs no matter how hard you're hitting it. The Convert AD+s' digital outs are all active at the same time and all are spitting out the exact same information, the same 1's and 0's. With all that said, if I tell my DAW to take the Optical In from the 16a (which the Convert AD+ is feeding simultaneously) I can absolutely crush the converter and not one peak warning goes off in the DAW, but, if I switch over to the Motu 8 D, bam there is the peak overs going off. This also happens if I make a new session, select the 8 D as the interface and feed it the same crushed signal, so I know it's nothing to do with the AVB or 16a, it's all in the Motu 8 D. So my question is; is it possible the Motu 8 D has some extremely small buffer that is like .0001db over 0dbfs? I would understand why they would do this, to keep people from clipping before they even clip. And this could be in the software because it's so important now days that there are absolutely no peak overs for the MFiT iTunes rules. But, Motu shouldn't be taking it upon themselves to just do that because they don't know what other pieces of gear is out there etc.
So, this definitely negates me even having the Motu 8 D because I can't clip my Convert AD+, which is when it starts to impart some really nice mojo. And, I don't feel like I should have to be doing workarounds either to use it. I'd really love to stay with the AES and Spidf and not be doing Optical, and mainly because Optical has always made me nervous. So does anyone happen to know what could be going on here? Has anyone ran into anything like this before and is this something Motu, possibly, should address with a fix. I have a very strong feeling other companies will start doing this kind of thing with mastering type A to D converters, it's quite genius.
I also am trying to get to Motu on this, but they're running skeleton crews over there because of NAMM, but if I find anything substantial out from them I will update this thread as a reference for the future.
Thanks!
-J
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Post by EmRR on Jan 26, 2019 21:51:31 GMT -6
No expert here, but I'd think this would have to be some sort of data flag, like Dangerous turns it off and the one MOTU turns it back on. 0 should be 0. A data stream should be a data stream, there's no conversion. I'd ask Dangerous also. If the one MOTU box does it, there have to be others out there that do also. Without an explanation of how dangerous makes 0 not report as an over, it's guesswork.
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Post by jeromemason on Jan 27, 2019 12:10:58 GMT -6
No expert here, but I'd think this would have to be some sort of data flag, like Dangerous turns it off and the one MOTU turns it back on. 0 should be 0. A data stream should be a data stream, there's no conversion. I'd ask Dangerous also. If the one MOTU box does it, there have to be others out there that do also. Without an explanation of how dangerous makes 0 not report as an over, it's guesswork. Thanks for responding.... Something is really not right here with this box and it's integration. Motu is supposed to be trying to replicate it right now, but they didn't rule out that my unit could be bad. I'm also getting some garbling every so often, and it's happening every time I playback a song, not in the same place. It doesn't tell Pro Tools either because I'm not getting any errors and I have the box unchecked to ignore pops and clicks. It's really really odd. It's almost to the point where I might have to just return this box and scrap this idea and go get some really good Light Pipe cables and stick with the 16a. Even still, I believe I heard the garbling even when bypassing the Motu 8 D, so I've got a problem there and I'd love to figure this out because I've got an EP, an LP and another LP to edit and right now I'm stranded in the Atlantic. I don't know if having the Motu 8 D and the Motu 16a running AVB is causing this or if I've somehow changed something, but I know it's not DAE or Disk errors, because, monitoring my memory and system usage it's running at half capacity. If anyone out there could help, that may of had the same problems, please do shout out your fixes or ideas on how to fix this. I need to be working and my system is shut down because all the shops are closed and it's pointless to work if my PRINT is going to have garbling. Any help, any ideas?? Really would be grateful to anyone that can help! Jerome |
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Post by EmRR on Jan 27, 2019 12:57:21 GMT -6
That is very odd. I've not had any AVB problems like that, only the rare occasion of the secondary AVB device not being seen at all. Could be worth reinstalling the firmware.
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Post by jeromemason on Jan 27, 2019 13:10:10 GMT -6
Ok, I'll give that a go. Thanks!
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Post by jeromemason on Jan 27, 2019 21:10:37 GMT -6
So I just went ahead and got some decent optical cables and decided to return the Motu 8 D. I'm not sure of what was going on and I genuinely hope they figure out all the issues I was having, but I've work to do and after sitting and listening I honestly don't hear any difference with the optical connections. So that saves me about $700 because I ordered Mogami AES and Mogami Spidf cables as well. Hopefully Sweetwater doesn't dock me for it being here a shade under a month, but geez I was fighting with it the whole time, and I was on the phone with Motu and Dangerous for hours on this. It'd be the last dollar they get from me if they do, all I'll say. Joel over at Westlake Pro here in town is the best I've ever dealt with and I'd be happy to give them all of my purchases this year.
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Post by svart on Jan 27, 2019 21:33:49 GMT -6
So I just went ahead and got some decent optical cables and decided to return the Motu 8 D. I'm not sure of what was going on and I genuinely hope they figure out all the issues I was having, but I've work to do and after sitting and listening I honestly don't hear any difference with the optical connections. So that saves me about $700 because I ordered Mogami AES and Mogami Spidf cables as well. Hopefully Sweetwater doesn't dock me for it being here a shade under a month, but geez I was fighting with it the whole time, and I was on the phone with Motu and Dangerous for hours on this. It'd be the last dollar they get from me if they do, all I'll say. Joel over at Westlake Pro here in town is the best I've ever dealt with and I'd be happy to give them all of my purchases this year. There's no reason to buy expensive coax cables either. Just regular BNC cables you buy for your A/V equipment are fine. The SPDIF/AES transceivers only trigger on edges, so amplitude doesn't matter, and neither does bandwidth since 75ohm terminations on coax generally has a bandwidth in the GHz. SPDIF/AES does not have an "over" bit. There is no intelligence built in for something like that. I don't know if you meant that you think it's somehow getting "over" status through SPDIF, but it can't. I don't think any hardware actually reports overs. I'm under the assumption that it's always the DAW software that monitors it's own input streams for metering. Optical SPDIF shouldn't sound different. It's digital for one, so you either receive a bit, or you don't. It's also self-clocking biphase encoded, so the data is also it's own clock, and therefor jitter in the signal is a non-issue across the conductors. However, a lot of the time the optical transceivers are kinda shitty, so a lot of the older SPDIF/AESid devices would only run at 48K or below on TOSLINK optical. |
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Post by jeromemason on Jan 27, 2019 21:45:40 GMT -6
So I just went ahead and got some decent optical cables and decided to return the Motu 8 D. I'm not sure of what was going on and I genuinely hope they figure out all the issues I was having, but I've work to do and after sitting and listening I honestly don't hear any difference with the optical connections. So that saves me about $700 because I ordered Mogami AES and Mogami Spidf cables as well. Hopefully Sweetwater doesn't dock me for it being here a shade under a month, but geez I was fighting with it the whole time, and I was on the phone with Motu and Dangerous for hours on this. It'd be the last dollar they get from me if they do, all I'll say. Joel over at Westlake Pro here in town is the best I've ever dealt with and I'd be happy to give them all of my purchases this year. There's no reason to buy expensive coax cables either. Just regular BNC cables you buy for your A/V equipment are fine. The SPDIF/AES transceivers only trigger on edges, so amplitude doesn't matter, and neither does bandwidth. SPDIF/AES does not have an "over" bit. There is no intelligence built in for something like that. I don't know if you meant that you think it's somehow getting "over" status through SPDIF, but it can't. I don't think any hardware actually reports overs. I'm under the assumption that it's always the DAW software that monitors it's own input streams for metering. Optical SPDIF shouldn't sound different. It's digital for one, so you either receive a bit, or you don't. It's also self-clocking biphase encoded, so the data is also it's own clock, and therefor jitter in the signal is a non-issue across the conductors. However, a lot of the time the optical transceivers are kinda shitty, so a lot of the older SPDIF/AESid devices would only run at 48K or below on TOSLINK optical. The whole "it blocks over's no matter how hot it hits your interface" just puzzles every person I've talked to. I have no clue how Chris Muth does this, but you can actually drive that converter so it's clipping so bad there is maybe 2db of headroom from RMS to Peak and it won't show not one over. There was something odd going on here and the way it was set up, either that or the Motu 8 D was defective and I'm starting to think more and more that it is. My system has never made a garble without triggering a DAE or Disk error and it was doing it 2 or 3 times on every playback of a track. My usage meters where all less than 50% and never spiked on the garbles, so it had to be something with that Motu 8 D. Now since I've got it out and back in the box and I'm running just the 16a, there's no clipping detected and not one garble. And, since it didn't make any perceivable sound difference to me now it seems like a dumb way to waste $700. I think when they credit my account I'm going to put that towards the Drawmer 1978 FET buss comp, I've heard some good things from guys about that box on the drum buss, and it's under $1k. |
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Post by svart on Jan 27, 2019 22:21:37 GMT -6
There's no reason to buy expensive coax cables either. Just regular BNC cables you buy for your A/V equipment are fine. The SPDIF/AES transceivers only trigger on edges, so amplitude doesn't matter, and neither does bandwidth. SPDIF/AES does not have an "over" bit. There is no intelligence built in for something like that. I don't know if you meant that you think it's somehow getting "over" status through SPDIF, but it can't. I don't think any hardware actually reports overs. I'm under the assumption that it's always the DAW software that monitors it's own input streams for metering. Optical SPDIF shouldn't sound different. It's digital for one, so you either receive a bit, or you don't. It's also self-clocking biphase encoded, so the data is also it's own clock, and therefor jitter in the signal is a non-issue across the conductors. However, a lot of the time the optical transceivers are kinda shitty, so a lot of the older SPDIF/AESid devices would only run at 48K or below on TOSLINK optical. The whole "it blocks over's no matter how hot it hits your interface" just puzzles every person I've talked to. I have no clue how Chris Muth does this, but you can actually drive that converter so it's clipping so bad there is maybe 2db of headroom from RMS to Peak and it won't show not one over. There was something odd going on here and the way it was set up, either that or the Motu 8 D was defective and I'm starting to think more and more that it is. My system has never made a garble without triggering a DAE or Disk error and it was doing it 2 or 3 times on every playback of a track. My usage meters where all less than 50% and never spiked on the garbles, so it had to be something with that Motu 8 D. Now since I've got it out and back in the box and I'm running just the 16a, there's no clipping detected and not one garble. And, since it didn't make any perceivable sound difference to me now it seems like a dumb way to waste $700. I think when they credit my account I'm going to put that towards the Drawmer 1978 FET buss comp, I've heard some good things from guys about that box on the drum buss, and it's under $1k. Makes me wonder if they're doing some shenanigans with the bit depth, as in when they get close to digital zero they shift it down a few bits so that it's never "zero". I guess it could be like a digital compression, but at the encoding level. |
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