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Post by hifiaudio2 on Jun 12, 2017 15:40:17 GMT -5
I posted in the XMC sub forum but that seems to get way less traffic... re-posting here...
I have no ground loops, hiss, noise, etc when playing any content, or when playing pink noise for speaker level calibration, etc, but when Dirac calibration kicks in, I get a low level "humming and hiss" noise. Any ideas?
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Post by goozoo on Jun 12, 2017 16:00:11 GMT -5
Could be your connection from your computer to the XMC-1. Maybe some line noise or gain is traveling and being amplified by the speakers. Does the sound go away after the calibration is complete and you are unplugged from the unit?
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Post by hifiaudio2 on Jun 12, 2017 16:04:41 GMT -5
That's a good thought, and I figured that as well, but I DON'T get the noise when just telling REW to send test signals from the computer to the XMC-1. And... the connection from the controlling computer to the XMC-1 is wireless to the laptop otherwise... so I could just disconnect that HDMI cable from the computer. I will try that, but like I said, I don't get the noise just sending REW test signals to the XMC-1 from the computer.
...perhaps having that HDMI connection to the XMC-1 at the same time Dirac was being controlled from the network connection even though wireless threw it for a "loop" somehow... I will mess with it again and report back.
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Post by goozoo on Jun 12, 2017 16:09:55 GMT -5
Two different questions. 1) Have you tried an ethernet connection with Cat5? 2) How are you sending signals from your laptop wirelessly tot he XMC-1? All I ever get when I try is garbled.
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Post by hifiaudio2 on Jun 12, 2017 16:19:45 GMT -5
I just ran a quick test by turning on the system, firing up the laptop and starting Dirac. No noise at all, until I click "TEST" on the Dirac page for setting speaker output levels and mic gain. As soon as I click that, I get a decent pop, and then a constant sound, mainly from the subs, that sounds like low level hiss, or could be described as the sound you hear like a hose pipe is turned on outside of your house but you are inside, hearing the water run in the pipes in the wall. This sound will not go away until I shut down Dirac, whether or not I stop the test signal. This time when I shut down Dirac on the computer I got a bunch of static type pops in all the speakers. That did not happen before.
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Post by hifiaudio2 on Jun 12, 2017 16:20:47 GMT -5
Two different questions. 1) Have you tried an ethernet connection with Cat5? 2) How are you sending signals from your laptop wirelessly tot he XMC-1? All I ever get when I try is garbled. Sorry I meant that I am connected to the XMC-1 through my network from a central switch over cat 6. Only the connection to the laptop is wireless. I suppose there could be some junk getting into the signal over the cat 6, but I would think it would get there whether or not the XMC-1 was running Dirac at the time. Perhaps the signal from that connection is well shut off and even a ground loop is protected unless it is active.
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Post by goozoo on Jun 12, 2017 16:39:17 GMT -5
This sounds like a ground loop as well as electrical arching. The subs will usually get a ground loop as they are the longest runs in a system. Are you running XLR to the subs? If not, then do and that should solve the ground loop in the sub problem. For the electrical arching, I don't know what is causing it. You don't have this problem when listening to music or watching movies with DIRAC engaged....correct?
My XMC-1 has been acting weird as of late as well and I am rolling back the firmware in hopes of it being corrected. I know there was a DIRAC "fix" with the newest firmware release. Are you using version 4.1? Did you have this problem before or after the firmware upgrade?
Also, are you using the same mic for the DIRAC calibration as well as measuring in REW? I'm asking because it may be a USB issue to the connection between the USB and the XLR mic. Do you have another USB mic that you can use? If not and none of the above works, rent a USB mic from Guitar Center and try it out to see if you get the same problem.
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Post by hifiaudio2 on Jun 12, 2017 17:09:45 GMT -5
Im using the UMM-1 usb mic to the laptop.
My sub amp is the Behringer iNuke dsp6000, so the amps are in the rack, and they are running XLR from the XMC. Technically a single XLR to two XLR cable from each sub output (a total of four subs). The sub amps are plugged into the same outlet and breaker as the XMC as well.
This is a new system and I upgraded the XMC to 4.1 before doing anything, so no older scenario to compare to...
And correct, I do not have this issue when listening to any source with Dirac engaged (or not engaged).
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KeithL
Administrator
Posts: 9,966
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Post by KeithL on Jun 13, 2017 8:57:11 GMT -5
This seems confusing at first... but it really isn't. I can explain why you're HEARING the hum only when the Dirac calibration is running...... but not where it's actually coming from....... The overall GAIN on the XMC-1 is raised significantly when the Dirac calibration is running. So you've got some very low level hum, probably from a minor ground issue somewhere.... And the hiss could be from something up-stream, or simply the inevitable background noise level of the equipment..... But you only NOTICE them when the gain gets cranked up during the calibration procedure. (Our hearing is very level-dependent.) I posted in the XMC sub forum but that seems to get way less traffic... re-posting here... I have no ground loops, hiss, noise, etc when playing any content, or when playing pink noise for speaker level calibration, etc, but when Dirac calibration kicks in, I get a low level "humming and hiss" noise. Any ideas?
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Post by hifiaudio2 on Jun 13, 2017 9:02:55 GMT -5
Ah OK good to know. I will go under that assumption then and see if I can eliminate the ground loop while Dirac Calibration is engaged. May be hard to trace this down since I only have two circuits for the whole theater. They are new home runs to the same panel. One circuit drives the 7 powered Emotiva speakers and the other connects the subs amps , projector, and all electronics.
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Post by elfrodo on Jan 24, 2018 15:34:07 GMT -5
Sorry for pulling up at old thread but I have run into the same issue here.
As soon as Dirac connects to the XMC-1 there is a pop and incredible loud background noise (pink noise / digital jitter incl) but it is only restricted to the LFE output. If I lower the level slider in the software on my two sub channels the noise is completely gone.
I can only assume that this must have an impact on the performance when Dirac runs the measurement as the noise level is very prominent. Any fix for this?
-elfrodo
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Post by socketman on Jan 24, 2018 15:56:48 GMT -5
i would suggest unhooking anything but the necessary during the run since it sounds like a ground loop issue. Cable tv is notorious for casueing these noises and you may require a baluns in your cable line. shut everything off excetp the xmc and plug everything in to one power bar for the run and see if that helps.
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