GR-33 "dirty" audio out

Started by cooltouch, November 16, 2020, 06:33:55 PM

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cooltouch

I don't really know how else to explain what I'm hearing. By the way, I hear it in a track after I've recorded it -- not while I'm playing or anything. It sounds like your typical 60 cycle hum, but distorted, hence "dirty."


This is what I did. I have a track that I've already laid down with my GR-33, but I wanted an audio track of the same thing. In Cakewalk (which is the only DAW software I use), the GR-33 comes in through my audio interface and I've indicated it is my GR-33 via its .ins file. But for audio, I'm running a TRS cable from the GR-33's mono audio out, connecting it to the audio interface. It's this audio connection that's creating this dirty hum.


So, in Cakewalk, I open a track for this audio channel, and then record the sound of the MIDI track onto this audio track (I solo the MIDI track and Record with the audio track). It's the only way I've figured out how to create an audio track for the GR-33, since it doesn't have any sort of .dll that would provide me with options. If the GR-33 showed up in Cakewalk's Synth Rack, like all the other synths I use, it would then have an audio track laid out, that I could then use to adjust the MIDI signal with audio plug-ins and adjustments.


Anyway, the way I'm doing it works fine, but I have that dirty hum when the GR-33 isn't being played. Once it is, however, this hum is no longer detectable. I dunno if it's still there but buried, or if it actually stops once playing commences. Nonetheless, I cannot detect the hum once the GR-33 has something to do. In the Cakewalk software, after recording the track, I go in and cut out all the bits where the GR-33 is inactive and I can detect the dirty hum. This works, but it's inconvenient and seems to be a bodge that I shouldn't have to do if everything is working as it should. And yes, I did clean the GR-33's 1/4" phono connections -- all of them -- just to be sure it wasn't dirt or corrosion or crud buildup causing this problem.


So, I guess I'm wondering this: what do I have to do to fix this hum condition? Is it something I can do or should I find a pro to do the "repair." I can solder and read a schematic, but I'm no electrical expert, by any stretch. I guess if I were to try and do the repair, I'd start with that audio out connector and work my way up the chain, but I don't really know what to look for.
Best,
Michael

gumtown

"TRS cable from the GR-33 mono audio out"
Your problem might be there, I am not aware the GR-33 has balanced outputs.
Also the GR-33 is not grounded on its own, try plugging into mains connected device with one of the audio In or Out jacks from the GR-33.
The device (guitar amp or such) doesn't need to be switched on, just plugged into an earthed mains outlet.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

mooncaine

I have a PDF of its manual downloaded years ago. On page 12, it says "You can use the L (PHONES) jack as a headphone jack for stereo headphones that have a standard 1/4" stereo plug--leave the R (Mono) jack unplugged."
Now that I think about it, I used to connect mine to my JVC stereo amp's CD input, using a 1/8" (stereo) extension cable and an adapter plug. Seemed OK to me. Gosh, that was about 15 years ago. I don't recall noise being a problem, and I did make some clean recordings on the PC I had back then. MySpace ate them. I'm sure they didn't taste all that great.

Anyway, I'd expect this to work, but what do I know (except what I just wrote above)?

Also, speaking of my own ignorance: could this be a ground loop issue? I had a terrible time plugging a guitar into a USB audio interface and eventually learned (from our fellow players here) that it was a ground loop.

cooltouch

Thanks for the responses, guys. Gumtown, actually I did try it with just  standard 1/4" phono (aka guitar) cable first, but I mentioned the TRS because I was assuming that the GR-33 accepted them. Either way made no difference. Thanks for the grounding tip. I'll give that a try and report back.


Mooncaine, in the almost 20 years I've owned my GR-33, I've never once thought of using its stereo out, just didn't see the need. And since I'm recording guitar, which is a mono instrument, I always try to record in mono. Sometimes I'll forget and leave things set up in Cakewalk where it records in stereo, which results in one channel that's flat, so I end up converting the track to mono anyway.


If trying the ground doesn't fix the problem, I dunno. As I dimly recall, when I first set up my DAW, I was running the GR-33's audio outs into my Mackie 12-channel mixer, which is grounded. Probably running TRS too, although I don't recall anymore. Perhaps this is why I never heard any dirty humming back then?


Best,
Michael

gumtown

I had a similar experience yesterday with Cakewalk when mixing down a recording, as I shift my laptop to various places and use different audio devices.
At work I use a cheap USB 2 channel out 16 bit audio adapter (as the docking cradle audio sounds bad), and had this distorted sound, spiking twice every second.
The problem ended up selecting the correct driver type (WASAPI, WMD, ASIO, MMC) and matching the correct bit rate.
I have ASIO4ALL installed and ended up having to use that, and selecting the device in the ASIO control panel.
All worked great after that, nice clean audio.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

cooltouch

The audio interface I'm currently using supports ASIO only, so I don't have conflict problems like that. I wish it were more flexible, though. I have a guitar amp with a USB out that I'd like to use for recording in this mode (currently I have to mic it), and when I plug it into my computer with the audio interface up, Cakewalk sees the amp as a midi instrument. If I change driver formats to something other than ASIO, Cakewalk recognizes it as an audio input device. But the interface will no longer work. I've recently heard that the MOTU M2 and M4 don't have this problem, but I haven't yet been able to confirm it. If this is true, I'll be switching audio interfaces. The MOTU appears to be a better unit (better specs, features) than what I'm using currently.
Best,
Michael

cooltouch

Plugging the GR-33 into an amp I had just sitting around -- but plugged in -- worked great. Dead quiet for recording now. That's a relief.

Best,
Michael

gumtown

Awesome !!
So it just needed to be grounded to the "Earth".

It should also fix any prickly tingles too.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

mooncaine

Yay! Credit moonie with an assist, refs! Glad you found the underlying cause.