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Trying to solve dynamic mic interference/noise/hum/ground problem
Old 6 days ago
  #1
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Trying to solve dynamic mic interference/noise/hum/ground problem

I'm at a new location and I've been having interference problems with my Electro Voice RE-20. Some of the noise turned out to be mechanical and some electrical interference, so I moved those devices to another room. However there is still noise and hum being recorded. My shotgun mic picked up some of this, but it's not as audible.

It appears to be around the 50-60hz range + harmonics, so it could be a ground problem, but idk. The 50-60hz also seems to change in intensity at times but the harmonics (or what appear to be, though broken up and not straight lines), are always there, so it might be unrelated. The overall background noise also seems to be high to me. It isn't the worst noise imaginable, however once tracks are layered in a mix, compression etc, it's unusable unless I filter the vocals, which isn't ideal and doesn't sound great. My sound modules connected via analog outs to the interface do not have this hum, even the unbalanced ones are clean compared to the mic.

I tried using or removing the cloudlifter I use, but there was no change. I tried using different XLR cables, with cloudlifter or direct into the interface, but no change. The cloudlifter keeps the noise a bit lower so I'm sticking to that setup.

I also tried recording through the same input/preamp and level with the mic cable disconnected. As expected, there is no sound at all, so the input appears to be fine.

I just tested the pins on the RE-20 output and pins 2 and 3 have continuity. Seems wrong to me, but I don't know much about dynamic mics. Perhaps there is a short inside the mic and the wires are touching so there is no phase cancellation of the noise? I bought it used, so maybe it has a problem.

Almost everything I use has 3 prong cables, but there are some exceptions: I have 2 dbx 163x compressors that are linked together with a TRS—they have 2 prong cables and live toward the bottom of the rack that my interface is in and plug into PSU (interface is at very top, sound modules in between). Lowest part of rack has MIDI interface and the very bottom is the PSU/backup battery. The gear isn't isolated, so I'm thinking of getting some rubber washers or something to decouple them from the metal rails. I also have a Furman Pluglock for my video gear which plugs into the PSU but it sits about 1.5-2 feet from the rack. I have seen no difference with or without that connected. There is an AC-DC power supply for a USB hub that plugs into the PSU, but I think I checked that disconnected and there was no difference in the noise. Interface connects with thunderbolt to the Mac.

My computer and a few peripherals plug into a separate upright PSU/backup battery on the other side of the room/desk (both made by Cyberpower). I currently have both PSUs connected to the same outlet. They previously were in separate outlets on the same breaker, however no change in the audio recorded in the mic wether they share the same outlet or a different one.

I also tested my outlets with a multimeter and the ground is normal, though I haven't had the cash to get an electrician out to check if there is any voltage difference between ground and common, etc.

I'm at the point where I'm going to start unhooking everything to try and troubleshoot, and kill all the breakers but my room and start turning on/connecting devices one at a time, but figured I'd post this first due to the pins having continuity.

Attached is a screenshot in iZotope RX showing the noise. This is through the cloudlifter with 25 dB of gain added at the interface preamp.
Attached Thumbnails
Trying to solve dynamic mic interference/noise/hum/ground problem-re-20_noise.jpg  
Old 5 days ago
  #2
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It's probably your pre-amp picking up a power supply.



-tINY

Old 5 days ago
  #3
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Continuity between pins 2 and 3 of the RE-20 is normal. It has an output transformer, and will measure quite low resistance, depending a bit on which output impedance is selected.

One problem I've seen with RE-20s that have been around for a while is that in the process of being handled, the lower portion of the body gets twisted, and it's possible for the ground wire to break. Likewise the screw for the XLR insert (caution: left hand threads!) may loosen also impairing the ground connection. You should have a good low resistance between pin 1 and the case, although measuring through the paint would be tricky.

If you carefully disassemble the back of the mic, you can check on the ground wire, circled in the attached photo. If it is broken, the mic capsule, which is surrounded in foam, will be ungrounded and potentially pick up noise.

Geoff
Attached Thumbnails
Trying to solve dynamic mic interference/noise/hum/ground problem-re20-1.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-re20-2.jpg  
Old 5 days ago | Show parent
  #4
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Quote:
Originally Posted by cbc6403 ➡️
Continuity between pins 2 and 3 of the RE-20 is normal. It has an output transformer, and will measure quite low resistance, depending a bit on which output impedance is selected.

One problem I've seen with RE-20s that have been around for a while is that in the process of being handled, the lower portion of the body gets twisted, and it's possible for the ground wire to break. Likewise the screw for the XLR insert (caution: left hand threads!) may loosen also impairing the ground connection. You should have a good low resistance between pin 1 and the case, although measuring through the paint would be tricky.

If you carefully disassemble the back of the mic, you can check on the ground wire, circled in the attached photo. If it is broken, the mic capsule, which is surrounded in foam, will be ungrounded and potentially pick up noise.

Geoff
Thanks man.

I checked and the ground wire is in place (breaking that glue around the XLR was fun). The screw for the XLR was tight. There were some "bits" on the screen so I carefully cleaned those off with some IPA. Can't test continuity through the paint though, as you said—be it the body or grill. Whoever owned this mic previously almost completely stripped the little screw holding the grill in place, so that's probably never going to screw back in.

The mic smells though, almost like weird perfume. The case smelled like that and the windscreen, but I'm wondering now if they spilled something on it.

I think I'm going to buy replacements for all the foam and the plastic thing in the top of the grill and then disassemble the mic and clean it out good. I need to also replace the rubber on the shockmount as it's all cracked and one of them already snapped. I found some some new rubber that apparently doesn't do this from some broadcast supply place.
Old 5 days ago | Show parent
  #5
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Quote:
Originally Posted by tINY ➡️

It's probably your pre-amp picking up a power supply.



-tINY

Would this happen if the other device with the power supply is off (but plugged in to mains) or does it need to be turned on for the interference to happen?

I also boosted the gain of the noise and I can hear really scraggly interference (I think what you guys refer to as "hash"). Sounds like screechy random sounds. This was more pronounced before I moved the other devices out of the room but it persists when they are not plugged in and gone.

I suppose I'll be unhooking everything today to try and find what the hell is doing this.
Old 5 days ago | Show parent
  #6
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Quote:
Originally Posted by gradivus ➡️
Thanks man.

I checked and the ground wire is in place (breaking that glue around the XLR was fun). The screw for the XLR was tight. There were some "bits" on the screen so I carefully cleaned those off with some IPA. Can't test continuity through the paint though, as you said—be it the body or grill. Whoever owned this mic previously almost completely stripped the little screw holding the grill in place, so that's probably never going to screw back in.

The mic smells though, almost like weird perfume. The case smelled like that and the windscreen, but I'm wondering now if they spilled something on it.

I think I'm going to buy replacements for all the foam and the plastic thing in the top of the grill and then disassemble the mic and clean it out good. I need to also replace the rubber on the shockmount as it's all cracked and one of them already snapped. I found some some new rubber that apparently doesn't do this from some broadcast supply place.
Somebody might have tried to clean it with a solvent that has reacted badly with the foam. There are two pieces of foam that need replacing after 20 years or so: the "bag" that the whole capsule sits in, and another disc of open cell foam on the top. I don't recall a plastic thing on the top, besides the capsule itself.

The set screw on the side of the screw-on cap is a .035" hex key.

Geoff
Old 5 days ago | Show parent
  #7
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Quote:
Originally Posted by cbc6403 ➡️
Somebody might have tried to clean it with a solvent that has reacted badly with the foam. There are two pieces of foam that need replacing after 20 years or so: the "bag" that the whole capsule sits in, and another disc of open cell foam on the top. I don't recall a plastic thing on the top, besides the capsule itself.

The set screw on the side of the screw-on cap is a .035" hex key.

Geoff
Yeah, I have the proper bit for it. But it was almost stripped (and now basically is) before I even touched it.

This is the piece in the grill I mentioned. Must be an internal pop filter.
Attached Thumbnails
Trying to solve dynamic mic interference/noise/hum/ground problem-screen-shot-2021-05-05-5.02.02-pm.png  
Old 5 days ago | Show parent
  #8
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Yes, that's the part I described in my post as "open cell".

The set screw isn't really critical, particularly if you're the only one using the mic. I think it's just there to keep idle hands from twisting the top off the mic. A friction fit ought to be sufficient.

Geoff
Old 5 days ago
  #9
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There are older threads about this:
EV re20 - Noise?
Old 5 days ago | Show parent
  #10
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Quote:
Originally Posted by edva ➡️
There are older threads about this:
EV re20 - Noise?
Thanks. I just took a look. I wonder if one of the following is what I'm dealing with:

Quote:
Originally Posted by MicDaddy ➡️
There was an issue for a few years where humbuckers were wired in phase with voice coils. There's quite a few thousand mics out there where humbuckers are AMPLIFYING interferences that were meant to be attenuated.
Quote:
Originally Posted by MicDaddy ➡️
The new passive filter inside the RE20 is an SMT layout. The output transformer had been redesigned in an SMD package.

The secondaries of this surface mount transformer are installed opposite polarity. This must've been a mistake at the board house or in design. I'm told that production caught it after the REV was implemented but don't know how many mics made it to the field pin3 hot.
I'm starting to unplug everything to see what might be interfering, but I'm probably going to open up this mic anyway and see if the polarity of that SMD is flipped. Not sure if anything can be done if the humbucking coil is wired incorrectly.

I also am getting some distortion effects that another poster mentioned if my mouth is too close to the mic—particularly it accentuates sibilance, which seems the opposite of what this mic is made to do. For now, I will try and refrain from smashing it with a hammer.
Old 5 days ago | Show parent
  #11
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Quote:
Originally Posted by cbc6403 ➡️
Yes, that's the part I described in my post as "open cell".

The set screw isn't really critical, particularly if you're the only one using the mic. I think it's just there to keep idle hands from twisting the top off the mic. A friction fit ought to be sufficient.

Geoff
Gotcha.

I figured that screw wasn't a big deal after I screwed the grill back on and saw how tight the fit was. It's just my personal mic, so unless my cat decides to grow opposable thumbs, it should be fine.

After reading that other post, I'm more concerned about how this thing was wired to begin with. It might not have been damaged by the original owner after all.
Old 5 days ago
  #12
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I'm gonna open up this mic and inspect it. I'll report back with photos so maybe you guys can help me figure out if it's wired wrong.
Old 5 days ago | Show parent
  #13
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Quote:
Originally Posted by cbc6403 ➡️
If you carefully disassemble the back of the mic, you can check on the ground wire, circled in the attached photo. If it is broken, the mic capsule, which is surrounded in foam, will be ungrounded and potentially pick up noise.

Geoff
I didn't remember this at first (because I opened it the day before you posted this), but there is no ground "coil" or whatever that is on this mic. There isn't even a hole for it in that metal piece. Instead, there is a yellow ground wire coming out of the pcb where the other 2 wires are connected. Not sure if that makes the one I have older or newer, but it's not there.

Also, the yellow and red wires are frayed! Not sure if this is the cause, but jfc! The green wire isn't the sexiest either. Luckily I have plenty of 22 gauge wire so I can replace this garbage in here. The wires came off the connector when I removed it this time, so I have to work out which is which. The yellow is ground, I assume the red is hot and the green cold. If not, please let me know.

Only good news is that the foam hasn't disintegrated, but it still smells weird, so I'll need to order replacements.

Here's some initial photos of the guts:
Attached Thumbnails
Trying to solve dynamic mic interference/noise/hum/ground problem-img_3619.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-img_3621.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-img_3623.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-img_3625.jpg  
Old 5 days ago
  #14
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Oh, you have one of the new ones with the PC board mounted transformer.

Sorry, I have no experience with them all. It does look like that yellow wire was pinched in something, although I can't see it causing hum. At least they labeled the colours on the PCB. I suspect red will be pin 2 on the connector if they were consistent with the old wiring.

I suppose there is a chance that you have one of the mics that has the hum bucking coil wired in phase with the voice coil, so it doesn't actually do anything. I don't think the coil is brought out separately to the outside of the capsule, so I'm not sure how you could fix that. Are there just two wires (blue and black?) coming off the capsule to the PCB?

Geoff
Old 5 days ago | Show parent
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Quote:
Originally Posted by cbc6403 ➡️
Oh, you have one of the new ones with the PC board mounted transformer.

Sorry, I have no experience with them all. It does look like that yellow wire was pinched in something, although I can't see it causing hum. At least they labeled the colours on the PCB. I suspect red will be pin 2 on the connector if they were consistent with the old wiring.

I suppose there is a chance that you have one of the mics that has the hum bucking coil wired in phase with the voice coil, so it doesn't actually do anything. I don't think the coil is brought out separately to the outside of the capsule, so I'm not sure how you could fix that. Are there just two wires (blue and black?) coming off the capsule to the PCB?

Geoff
The red one is pretty bad too.

No, on the back there's the blue and black plus another yellow ground wire coming from the capsule.
Old 5 days ago | Show parent
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Quote:
Originally Posted by tINY ➡️

It's probably your pre-amp picking up a power supply.



-tINY

I was thinking ground loop on the interface, or a crappy power supply in a mac, but a bad power cord or extension cord does that too.

The Mad SCientist returns from weaponized medicine land.... HaHaHa!
Old 5 days ago | Show parent
  #17
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Quote:
Originally Posted by audiospecific ➡️
I was thinking ground loop on the interface, or a crappy power supply in a mac, but a bad power cord or extension cord does that too.

The Mad Scientist returns from weaponized medicine land.... HaHaHa!
One thing I did try was to put the mic out in the hallway and close the door to get way from the Mac. I noticed if the mic itself is very close (like within a foot of the Mac) there is some nasty hash it picks up. However, the hum still remained out in the hallway, so it may be at the interface like you said, which is about 4-5 feet from the Mac because it uses 2 meter thunderbolt cable.

I'm not using any cheap extension cords and sprung for more expensive ones that were (I think) 16 AWG or so with higher shielding ratings, more expensive power supplies with extra thick cords for external AC-DC supplies. At least visual inspection and doing continuity tests and unplugging some gear has turned up nothing so far. DBX has 2 prong cord and 1 sound module has a wall wart. The only extra $%&^$ thin ones would be like power supply for USB hub that use those flimsy wires which is going to be tested by morning and I'm going to check the the sound modules one by one.

Also, sound modules aren't picking up the hum and they're plugged in to the same interface., but not sure if that matters or not. As others have said, it might be a fault in the mic itself. Still hunting for the culprit. At this point, the mystery is becoming more annoying than the problem.
Old 5 days ago
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Have you tried just your gear by disconnecting the firewire cable and turning off the mac? If the hum is still there, then it something else.
Old 4 days ago | Show parent
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Quote:
Originally Posted by audiospecific ➡️
Have you tried just your gear by disconnecting the firewire cable and turning off the mac? If the hum is still there, then it something else.
I did a while back but I didn't have the time to be thorough because I was busy with other work so I'm checking everything now.

While my RE-20 is out of commission for thge time being, I started doing tests with my AT8035 shotgun mic, since it was picking up some interference as well. Interestingly, it was picking up some higher freq stuff that the RE-20 did not.

I'll post some spectral data in a bit after I test the rest, but the USB hub was creating HF interference that the RE-20 did not pickup but the shotgun did—moving the power supply to the other side of the room and plugging it into another power strip solved it.

My Korg sound module wall wart was also creating some interference around 120hz-240hz.

There's still garbage coming in from very low up to around 2k.
Old 4 days ago
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try turning off the lights, as some of those alternatives to incandescent lamps give off noise.
Old 4 days ago | Show parent
  #21
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Quote:
Originally Posted by audiospecific ➡️
try turning off the lights, as some of those alternatives to incandescent lamps give off noise.
Thanks, I tested the lights already. I'm using tungsten bulbs, so no problems wether they are on or off that I could see in the spectral or when listening.
Old 4 days ago
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TESTS

Okay, so after my testing tonight I found a few sources that are causing interference. I did this with my shotgun mic AT8035. The shotgun picked up high frequency interference that the RE-20 was rejecting, so maybe its humbucking coil is functioning properly after all. The AT also picked up more crap in the low frequencies than it did previously, so idk wtf is going on.

Some named images are attached to show the baseline recording with shotgun mic and then subsequent recordings as I removed things.

USB Hub / AC-DC power supply
This was creating high frequency noise in defined lines: 4.5k, 9k, 13k, 18k, 21-22k. RE-20 did not pick this up at all. I solved it (for the most part) by moving the hub to the other side of the room and plugging it into the PSU the computer connects to. For all intents and purposes, the interference from it is now gone.

Korg sound module w/ Wall Wart
This was plugged into one of my Furman pluglocks and then into my rack PSU. It was creating noise between 120-240hz that I also saw in the RE-20. I don't know how to get rid of this. Maybe I need to buy a quality linear AC-DC supply with 3 prong cord and throw the Korg brick in the trash.

Roland sound module
This has a 2 prong cord but surprisingly no noise/interference seems to be coming from it. I only mention it because it is 2 prong but apparently not a culprit.

Pair of dbx 163x compressors
These units have thin, 2 prong, unpolarized cords and are "stereo strapped" as the manual says (linked with a TRS). They connect to interface via TRS also. However, they are creating interference noise between 800hz and about 1k. It's not extreme, but it's there. Not sure if it's normal or not. I had these modded by Jim Williams (and forgot to ask him for a power cord replacement). No offense to him as they sound great. I never noticed any interference from them until now. In fact, he dropped the noise floor over 10dB from factory spec.
Quote:
Originally Posted by Jim Williams
...
Jim, if you see this, would replacing the power cords on the dbx 163x with 3 prong cords alleviate this noise (at least in theory)? If so, I can do the mod here if you can advise where to connect the ground and if anything else needs to be changed. Hopefully an easy fix and I can just order 2 power cords and the correct-sized grommets.


This is as far as I've gotten tonight. Will test more tomorrow. As you can see in the images below, there is still a lot of crap in the low end that stretches up a ways.

Thanks for your suggestions.
Attached Thumbnails
Trying to solve dynamic mic interference/noise/hum/ground problem-shotgun_mic_noise_baseline.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-shotgun_highpass_engaged.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-shotgun_nousb.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-shotgun_usbhub_moved.jpg   Trying to solve dynamic mic interference/noise/hum/ground problem-shotgun_nokorg.jpg  

Trying to solve dynamic mic interference/noise/hum/ground problem-shotgun_nokorg_nodbx.jpg  
Old 4 days ago
  #23
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since the 163X is an unbalanced circuit, Defeating its double insulation will cause more problems than it solves. Because every unbalanced connection is a place for a potential ground loop because of the signal grounds strapped to earth ground in parallel. You see, the 163X will accept noise and push it through if the feedback circuit didn't suppress it. I would try flipping one of the power cords of the 163X and make sure their chassis are not grounding out on anything but them.

Grounding sometimes will cause issues especially when there is a lot of unbalanced connections because of paralleling signal commons (ground).

Other things that come to mind about ground loops is xlr cords grounding out on bare floor/concrete. Over the years, I've instructed audio engineers about this and to always keep a roll of gaff tape for just this occasion especially if they are doing things live outside.

Last edited by audiospecific; 4 days ago at 06:54 PM.. Reason: side comment removed
Old 4 days ago | Show parent
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Quote:
Originally Posted by audiospecific ➡️
since the 163X is an unbalanced circuit, Defeating its double insulation will cause more problems than it solves. Because every unbalanced connection is a place for a potential ground loop because of the signal grounds strapped to earth ground in parallel. You see, the 163X will accept noise and push it through if the feedback circuit didn't suppress it. I would try flipping one of the power cords of the 163X and make sure their chassis are not grounding out on anything but them.

Grounding sometimes will cause issues especially when there is a lot of unbalanced connections because of paralleling signal commons (ground).

Other things that come to mind about ground loops is xlr cords grounding out on bare floor/concrete. Over the years, I've instructed audio engineers about this and to always keep a roll of gaff tape for just this occasion especially if they are doing things live outside.
Thanks (I also love gaff tape).

I have a wood floor. All the wires in my rack I had made to length so they don't touch the floor. I think most are Mogami 2549 cable with neutrik connectors. Mic cables are Asterope. I also made a mic cable with Mogami 2549 to test and the noise is there with either. Some of the power cords lay on the floor and some are coiled because they're so long, however I don't seem to be getting noise from those and they are grounded. I'm going to monitor controller with SPDIF so that shouldn't matter. I also don't pick this noise up in monitors or monitor controller. Monitors have Asterope XLR cables (those do sit on the wood floor). I can test if taking those cables out or off the floor helps, even though monitors are clear of noise.

The DBX I have sitting in a metal rack shelf because the guy I bought them from didn't have the factory mounting bracket that joins them in the middle I'm putting the screws through that shelf and the dbx rack ears (which I do have). As soon as I find a proper mounting kit I will buy it (one on Reverb now looks too chewed up). The DBX manual said I can use TRS, so I figured it would be cancelling the noise the same way a mic does. Perhaps it is the unpolarized cords being flipped. Maybe I'll buy some polarized cords and install those if grounded power cords are likely to cause problems instead of fix them.

Being in a mild coma, I forgot to mention something about the Korg. The Korg outputs unbalanced RCA. I had cables made for it few years ago RCA->TRS. I think the ground is floated on one side. So it might be that and not the wall wart. I'll plug it back in but leave the outputs disconnected and see if the wart is causing interference or if it's the cables. I really need a DI box for it and other unbalanced gear. The noise it's creating is not on tracks I record from it, only in mics apparently. I really want a Radial DI-8 since it's 8 channel and has ground lift if needed. I suppose I could go with something like a Henry Matchbox HD in the meantime just to get the Korg outputting balanced +4dBU.

Roland is D-110. Have to look at what the cabling is (TS->TRS with floated ground or TRS->TRS). It's not making noise and it's not recording the noise the mics pick up. It could badly use a DI box though and maybe a dedicated preamp. Signals coming out of it sound even lower than -10dBV. My other Roland is digital and going through SPDIF. I tested it anyway, has 3 prong cord and not causing noise when unhooked.

One thing I can try that I mentioned above, is isolating the gear in the rack. I only have one gear rack. Perhaps the DBX living in the same rack is the problem and not the I/O or the power cords (chassis ground loop caused with the sound modules, dbx and interface). The Korg has a plastic chassis and since I lack the factory mounting kit, I just have it sitting on a rack shelf.

Anyone know a good source for rubber or plastic washers I could use to properly decouple each piece of gear from the rails and prevent the screw from hitting the rails? The rack screws I use have a plastic washer that decouples screw head from chassis but they didn't come with a second one for back, so they are just to avoid rash. They aren't great so I'd gladly replace them. That would probably be a cheaper way to try before buying a second rack. I can also get polarized cords for the DBXs.
Old 4 days ago
  #25
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I used to use plumbing faucet washers when I didn't have those plastic rack washers.

Edit: Running unbalanced on pin2&3 is a good practice I help introduced to some about 30 years ago. I'm glad it stuck somewhere. In cases where you need to break the dc coupling effect, sometimes you have to use a DI with a ground lift. Back when I had a lot of rca based equipment I used to have some signal transformers mounted on a rail on the back of the rack to bring everything up to proper signal operation.
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Quote:
Originally Posted by audiospecific ➡️
I used to use plumbing faucet washers when I didn't have those plastic rack washers.

Edit: Running unbalanced on pin2&3 is a good practice I help introduced to some about 30 years ago. I'm glad it stuck somewhere. In cases where you need to break the dc coupling effect, sometimes you have to use a DI with a ground lift. Back when I had a lot of rca based equipment I used to have some signal transformers mounted on a rail on the back of the rack to bring everything up to proper signal operation.
Cool. Would be fun to try and build a DI. I'm still learning, mostly doing repairs, recapping and cables. I need to look up some DI schematics and see what else is needed besides transformer and how to make a ground lift and keep everything noise free.

I just ordered 2 polarized cords. I'll start with those on the dbx and see if it gets rid of the noise. Will search for some washers tonight.

Do you happen to know the grommet size for the DBX? The cords I found were round 18awg.
Old 3 days ago | Show parent
  #27
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Quote:
Originally Posted by gradivus ➡️
Cool. Would be fun to try and build a DI. I'm still learning, mostly doing repairs, recapping and cables. I need to look up some DI schematics and see what else is needed besides transformer and how to make a ground lift and keep everything noise free.

I just ordered 2 polarized cords. I'll start with those on the dbx and see if it gets rid of the noise. Will search for some washers tonight.

Do you happen to know the grommet size for the DBX? The cords I found were round 18awg.
Polarized cords are not going to solve anything, and I wouldn't recommend it. Inserting transformers in the signal path does. Now these days there is many choices, I would set up a din rail in the back and use Jensen's din rail transformers: https://www.jensen-transformers.com/...o/din-modules/

Polarized cords are for devices that ground the chassis to the neutral or common wire and usually through a Y type safety capacitor. The DBX is ground isolated and double insulated so putting a polarized cord on it will not do anything to it but limit your phase choices of power based noise rejection. Which is why they chose to build it that way in the first place.
Old 3 days ago | Show parent
  #28
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gradivus's Avatar
 
🎧 5 years
Quote:
Originally Posted by audiospecific ➡️
Polarized cords are not going to solve anything, and I wouldn't recommend it. Inserting transformers in the signal path does. Now these days there is many choices, I would set up a din rail in the back and use Jensen's din rail transformers: https://www.jensen-transformers.com/...o/din-modules/

Polarized cords are for devices that ground the chassis to the neutral or common wire and usually through a Y type safety capacitor. The DBX is ground isolated and double insulated so putting a polarized cord on it will not do anything to it but limit your phase choices of power based noise rejection. Which is why they chose to build it that way in the first place.
Thanks, I'll check them out.
Old 3 days ago
  #29
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gradivus's Avatar
 
🎧 5 years
So, @ audiospecific , for a DIN rail setup, I would use modules like DIN-2LI for the DBX pair outputs (as it's 2 channel), would inputs from the interface need anything? Then use one of their 2-channel DI boxes for each of the unbalanced sound modules, or are you suggested using 2 DIN-DB modules for stereo sound modules/synths?

Also, is a DIN rail setup like this passive or does it require a power supply?
Old 3 days ago | Show parent
  #30
Gear Addict
 
audiospecific's Avatar
 
Quote:
Originally Posted by gradivus ➡️
So, @ audiospecific , for a DIN rail setup, I would use modules like DIN-2LI for the DBX pair outputs (as it's 2 channel), would inputs from the interface need anything? Then use one of their 2-channel DI boxes for each of the unbalanced sound modules, or are you suggested using 2 DIN-DB modules for stereo sound modules/synths?

Also, is a DIN rail setup like this passive or does it require a power supply?
I would use 1 DIN-2LI per dbx compressor for its ins and out. and one per stereo sound module (if they are rack mounted) But any passive stereo di with a pad will work for ones not in the rack. All of these things are passive no power supply required. You could probably get away with cheaper transformers but this would be a quick and professional way with dealing with it.
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