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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: aberg on July 25, 2005, 01:37:04 PM
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For about a year now, I've been dealing with a recurring issue with my rig [Mics (superluxes upgraded to akg 463s) > DIY digimod UA-5 (optical) > JB3]
I performed the digimod myself back in July 2004 and it seemed to work fine. I can always get a signal, but sometimes on some recordings there are little clicks (these can be removed with software but it's long and tedious) scattered throughout the recordings. I thought it could be a problem with bad optical cables, so I tried a whole bunch of configurations, with and without right angle adapters, beefy cables, etc. I still get the clicks. I taped moe in Buffalo on Friday and decided to bypass the ADC of the UA-5 and just go RCA out to 1/8" line in on the JB3, and while going analog in picked up some HD noise (that's another story altogether), there was no clicking. I'm convinced at this point that the problem is not an optical cable issue or a JB3 issue. My guess is that I didn't perform the digimod properly (I followed the instructions correctly -- cut the trace, and then soldered the jumper) however my solder points are really sloppy. There is a chance that something is sorta messed up which still allows a signal to be passed to the optical out but it sometimes gets "clicky".
Since I know there are a lot of UA-5 experts on this board, I was wondering if:
a) Somebody could suggest to me a course of action to resolve this problem
or
b) Somebody could take a look at my digimod and see what's going on and possibly fix it for me (I will pay for this service if necessary)
I'm hoping to get this done fairly quickly since there's some stuff coming up that I'd like to be able to tape. Thanks!
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did you shave down the input jack on the JB3?
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did you shave down the input jack on the JB3?
Or, along similar lines, have you checked that the optical jack isnt going bad. It's a common problem. If you know someone with a JB3, or even a portable DAT, you could use their recorder to test your UA5. record using their unit and then check for clicks.
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did you shave down the input jack on the JB3?
check that first.
Some other things:
Could also possibly be a bad input on the JB3
bad output on the UA5.
If you feel it is something bad w/ the mod the same symptoms would showup on a coax > dat recording since technically the Digital signal would revert to USB only. I doubt this is the case and would continue to further investigate the RX/TX optical connections.
Probably at the stage you should start borrowing some gear to further isolate the issue.
1.) Try a different JB3
2.) Try a different UA5
3.) Try recording to a Dat via Coax
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decided to bypass the ADC of the UA-5 and just go RCA out to 1/8" line in on the JB3
FWIW, it's not possible to bypass the UA5s ADC, i.e. there is no analog passthrough. You actually ran analog signal IN > ADC > DAC > analog signal OUT. This leads me to believe the problem does not lie in your self digi-mod. As I understand it, the self digi-mod cuts the trace that outputs to USB and then bridges the USB-out and USB-in paths (see attachment). All of which happens *before* the DAC. So it seems if the problem lied with the self digi-mod it would appear whether you're running analog-out or digital-out. But maybe I don't fully understand the self-digi-mod.
Some good suggestions already on other potential causes and troubleshooting, so I'll just leave it at that.
Edit to change attachment...I think I had the USB trace cut wrong on the first one.
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did you shave down the input jack on the JB3?
Or, along similar lines, have you checked that the optical jack isnt going bad. It's a common problem. If you know someone with a JB3, or even a portable DAT, you could use their recorder to test your UA5. record using their unit and then check for clicks.
Also, if you have a soundcard with optical-in you could just record some music from the stereo. That would work if you didn't know somebody near with a DAT.
Good idea
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DKlein (or anyone else) - two questions for you:
[1] Is my trace-cut / jumper on the block diagram noted correctly?
[2] If so, why is it necessary to cut the USB trace at all? Why not just make the jump without cutting the trace? The only time I can see it would cause a problem: if trying to run signal in from both analog and USB - there'd be two signals inputting to the DAC, then. But as long as one uses only a single input, I'm not sure why this wouldn't work.
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DKlein (or anyone else) - two questions for you:
[1] Is my trace-cut / jumper on the block diagram noted correctly?
[2] If so, why is it necessary to cut the USB trace at all? Why not just make the jump without cutting the trace? The only time I can see it would cause a problem: if trying to run signal in from both analog and USB - there'd be two signals inputting to the DAC, then. But as long as one uses only a single input, I'm not sure why this wouldn't work.
not sure if the diagram is right, but i believe if you don not cut the trace and just have the jumper the digital output is active(red light on for optical) but no signal is actually passed.
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decided to bypass the ADC of the UA-5 and just go RCA out to 1/8" line in on the JB3
FWIW, it's not possible to bypass the UA5s ADC, i.e. there is no analog passthrough. You actually ran analog signal IN > ADC > DAC > analog signal OUT. This leads me to believe the problem does not lie in your self digi-mod. As I understand it, the self digi-mod cuts the trace that outputs to USB and then bridges the USB-out and USB-in paths (see attachment). All of which happens *before* the DAC. So it seems if the problem lied with the self digi-mod it would appear whether you're running analog-out or digital-out. But maybe I don't fully understand the self-digi-mod.
Some good suggestions already on other potential causes and troubleshooting, so I'll just leave it at that.
Edit to change attachment...I think I had the USB trace cut wrong on the first one.
Wow, that's really good to know. So it's possible that my JB3 input jack is messed up. I haven't filed it down cuz it seems that my plugs fit in nice and snug... however, maybe it's deceiving.
If either the toslink out on my ua-5 or mini-toslink in is messed up, what can be done for that?
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next show you go to run a 2nd source... the optical > jb3 and the coax > dat and if the clicking doesnt show up on the dat then you can possibly narrow down your problem. if its on both sources then you wil have to expand your search.
also, fwiw, sometimes a ciggy lighter can sound like a click on your tape if the person is sparkin' a butt/dube right under or next to your mics.
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next show you go to run a 2nd source... the optical > jb3 and the coax > dat and if the clicking doesnt show up on the dat then you can possibly narrow down your problem. if its on both sources then you wil have to expand your search.
also, fwiw, sometimes a ciggy lighter can sound like a click on your tape if the person is sparkin' a butt/dube right under or next to your mics.
Up here in Canada, there's rarely more than one taper at each show so finding a DAT to run would be tricky... but thanks for the idea.
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did you shave down the input jack on the JB3?
this is unneeded if running optical in. this prob is only with certain analog cables
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DKlein (or anyone else) - two questions for you:
[1] Is my trace-cut / jumper on the block diagram noted correctly?
[2] If so, why is it necessary to cut the USB trace at all? Why not just make the jump without cutting the trace? The only time I can see it would cause a problem: if trying to run signal in from both analog and USB - there'd be two signals inputting to the DAC, then. But as long as one uses only a single input, I'm not sure why this wouldn't work.
hmmm...been a while since I thought about this. Going by memory (I'm not opening any boxes today!)
[1] the jumper actually runs from the a/d (24/96 output) to the SRC (which isn't shown on the block diagram), which then feeds the digital outs. The difference is that the connection will not pass a digital signal from input to output as you would expect from the diagram above. It might however, if you didn't do the trace cut.
[2] I can't remember if this is a preventive measure in case the UA-5 does get connected to a computer (so you don't end up 'doubling' the digital signal) or if it was required. The block diagram is a very simplified view, not entirely accurate.