Taperssection.com
Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: Scuzzi on April 25, 2009, 01:19:27 PM
-
A while back I finally ditched DAT and got a MicroTrack II. The setup works great most of the time but on the odd and seemingly random occasion the MicroTrack will lose the right channel input and it won't return until stopping recording and restarting. The problem sometimes won't happen for several hours of use, and then all of the sudden it might happen 3 or 4 times during one show. Obviously it's a major pain. Has anyone seen this or by chance have a solution? I've tried and experienced it with two different MicroTrack II's both with the latest firmware available so I don't believe it's an issue with that.
I've also tried to run the Apogee AD1000 into an Edirol R-4 and it doesn't even pick up a signal at all.
Any suggestions?
-
I remember that Grace had to do a hardware update when the microtrack came out.
Our team has contacted Grace Designs and it appears that the Lunatec does not send the 'status bit' information required by the MTII in order to write the file at a higher sample rate. This simply means that Grace Designs chosen for whatever reason, not to send the status bit and as a result it is writing the file as 44.1kHz.
Maybe this is what is happening
-
I remember that Grace had to do a hardware update when the microtrack came out.
Our team has contacted Grace Designs and it appears that the Lunatec does not send the 'status bit' information required by the MTII in order to write the file at a higher sample rate. This simply means that Grace Designs chosen for whatever reason, not to send the status bit and as a result it is writing the file as 44.1kHz.
So a stock V3 will pump out 24/44.1 to an MT2 without this issue while it might/will have an issue at 24/96 (without the update)?
-
The chip update is free. I think most have been fixed already and the new ones already have the updated chip. Changing the chip is very easy to do and it is free.
http://www.gracedesign.com/support/V3/V3_firmware.htm
-
IIRC, the AD1000 was developed when the consumer/professional status information wasn't yet fully agreed upon for assigning bits in the data stream for the AES professional digital audio standard or the spdif consumer digital standard. So the AD1000 was implemented with the best information they had at the time, which ended up being different from what the relevant AES and spdif standards settled upon.
As a result, the newer recorders depending on how they are handling pro vs consumer digital signals and how strictly they conform to the standards may not work with the AD1000. It probably could be fixed with a firmware update, but I'm not sure how motivated recorder mfg's will be to re-write their firmware to allow their recorders to remain compatible with such old AD equipment. My guess is if you want to keep using the AD1000, you'll have to find a recorder that works well with it.
This is somewhat similar to the problem Grace had with the V3. I got the MT when it first came out, and it worked fine with the V3. I'm not sure about the MTII though. I've now got a Sony D50, and it didn't work with the V3 until I got the V3's firmware updated (which required a hardware-based firmware update--ie, the new chip). The original V3 firmware was based on a 24 bit digital implementation that didn't end up being the 24 bit implementation that was eventually written into the digital standards. So same kind of thing as the AD1000.
I think though that the issues are very similar but different. The V3 wasn't conforming to the 24 bit digital standard once it was formalized, but the AD1000 is not conforming to the professional vs consumer status portion of the digital standard.
-
Thinking a bit more about it, you might want to try the MTII and the R44 using both the AES output on the AD1000 (XLR out) and the spdif digital output, which is part of Apogee's 14pin DIN connector (or whatever that thing is -- long time since I ran my AD500's).
Again, IIRC, the 14pin DIN connector's digital output is a consumer spdif output and the XLR digi out is the AES professional digital output (again, more or less, since I don't believe they conform exactly to the relevant standards).
It might be that one or other of these digital outputs might work with your recorders. So you might try the opposite of what you've been using.
-
Trying to figure out your suggestion... Right now I use the output from one of two coaxial plugs that come from the 15-pin HD plug. You are suggesting I use the AES output instead of or in addition to this? Any idea what piece of equipment I need to go from that AES plug to coaxial? Thanks for the assistance.
-
Sorry, I wasn't clear. Yes, try using that XLR AES output instead of the digi out from the 15pin HD. I don't know if it'll work, but it's worth a shot.
You should be able to use it with just an XLR to RCA cable (depending on the cable, not the best, but should work for testing purposes). Or just use something like this plus your regular RCA-RCA coax cable:
http://www.bhphotovideo.com/c/product/408137-REG/Hosa_Technology_GXF_132_GXF132_RCA_to_XLR.html
I'm guessing you should be able to pick something like that up at a local Guitar Center rather than needing to order one online and have it shipped.
-
Sorry, I wasn't clear. Yes, try using that XLR AES output instead of the digi out from the 15pin HD. I don't know if it'll work, but it's worth a shot.
You should be able to use it with just an XLR to RCA cable (depending on the cable, not the best, but should work for testing purposes).
I don't know what sort of hitches you'll run into, but it might be worth brushing up on the AES/SPDIF standards to see what problems might occur.
http://www.rane.com/note149.html (first or second google result).
-
I only scanned that Rane article, but it looks like it's got some good information. I didn't want to muddy things that much, so I just said it will probably work.
There are two main differences between the AES professional standard and the spdif consumer standard. One is that the different standards use different electrical standards for transmitting the data. This is all the Rane article gets into. The other big difference is the data requirements of the standards -- each standard has slightly different requirements as to what the data word that characterizes the audio must have. Among other things, this includes how to set the professional vs consumer bit of the data word. It is this latter difference I think might be causing the problem, so that is what I'd like the OP to test by using the AES output.
In terms of the electrical difference, the main difference I think is the 110 ohm impedence of the AES standard vs 75 ohm for spdif, and that the AES signal is about 5v, while the spdif signal is 0.5v. The Rane article gets into how to properly convert the electrical side of these two digital outputs.
To do it right, you should at least use a 110>75 ohm impedence transformer that will change the impedence of the AES signal and drop its voltage. Something like this:
http://www.canare.com/index.cfm?objectid=DCBD1A35-3048-7098-AFF302A4C46790F8
The Rane article describes other ways to get to the same result, rather than a storebought transformer.
When I had my Lunatec V3, I used a Canare transformer, and it worked great.
I also used a simple XLR>RCA cable I built using Canare 110 ohm digital (http://www.canare.com/index.cfm?objectid=ED839FCB-3048-7098-AFECCDD67DCC2B4C). It was just 110 ohm, with no impedence transformation, and it also worked great. Many people on ts.com have used this type of set up to use their AES output.
The only reason I said it "should work for testing purposes" is that the cable I used was a true 110 ohm digi cable. If you built a cable using random microphone cable, it probably wouldn't be the best for use in your actual rig, but I'm pretty confident it would at least work to see if using the AES output (and getting the AES data stream instead of the spdif data stream) would solve the problem. If it does, it'd be best to rig up things right, get an impedence transformer, etc. If it doesn't, well, back to the drawing board.....
-
I had a similar issue with my Apogee AD500e (rev c)
I ran my AD500e > MTII this past weekend for a friends band rehersal and had issues with the spdif out, it would drop out occasionally. I finally hooked up the AES xlr cable and got a "Invalid Spdif" message on the MTII at first. I stopped and restarted the MTII and it ran without issue for the rest for the weekend
-
Thanks for all of the advice everyone. I picked up the XLR to RCA adapter at my local guitar shop and it seems to be working. Time will tell if the issue where the right channel drops on the MTII pops up again, as I mentioned it happens sporadically. At 10 bucks this is certainly worth a try.
Todd, regarding the Canare Transformer... the technical details are a bit over my head. If the converter I have now works won't that be sufficient?
-
Thanks for all of the advice everyone. I picked up the XLR to RCA adapter at my local guitar shop and it seems to be working. Time will tell if the issue where the right channel drops on the MTII pops up again, as I mentioned it happens sporadically. At 10 bucks this is certainly worth a try.
Todd, regarding the Canare Transformer... the technical details are a bit over my head. If the converter I have now works won't that be sufficient?
I'd just keep using that adapter you have and a typical RCA coax cable. Does it work now with the R4 as well, or just the MT?
-
The R-4 seems to be a whole different issue. I once again got no signal when plugging in the AD1000 using the AES -> RCA output. So I decided to dig the DA-20 out of the closest and that too could not get a signal to the R-4, so at this point I'm assuming the digital in on the R-4 is busted unless someone else has an idea. I think it's kind of strange the unit will record even with no signal present. I'm used to most recorders not even running without a SPDIF signal, but this R-4 is new to me and it's actually on loan.
I'll report back later on how the new output to the MTII holds up. Like I mentioned before I could sometimes go for 10+ hours of use without having the right channel drop, and other times it could happen 3 or 4 times during one show. I don't think I can count it as safe until I use this setup without problem for about a month.
-
I also ran the MTII with DMA in the off position
I had a similar issue with my Apogee AD500e (rev c)
I ran my AD500e > MTII this past weekend for a friends band rehersal and had issues with the spdif out, it would drop out occasionally. I finally hooked up the AES xlr cable and got a "Invalid Spdif" message on the MTII at first. I stopped and restarted the MTII and it ran without issue for the rest for the weekend
-
I've used the AES output several times now without experiencing the channel dropping out, so I think this has been a success. Thanks everyone for your suggestions.