Taperssection.com

Gear / Technical Help => Ask The Tapers => Topic started by: Cheesecadet on August 26, 2017, 12:42:02 PM

Title: Pops in recording - Now With Sample Link
Post by: Cheesecadet on August 26, 2017, 12:42:02 PM
Does anyone know if a low battery in preamp could cause a popping sound?

The first two hours of recording last night went great, the last two hours had intermittent pops throughout.

Mics and cables are essentially new.

Preamp is a Tinybox v1.5  (Mid 2011) with original lithium battery from several years back. I already sent an email to Naiant asking Jon his thoughts but also thought I would inquire here.

Thanks for any feedback!

Ryan
Title: Re: Pops in recording
Post by: Cheesecadet on August 26, 2017, 01:29:44 PM
Jon at naiant said it would not be a battery issue so I guess I get to check all my cables...yeah fun
Title: Re: Pops in recording
Post by: splumer on August 28, 2017, 03:09:10 PM
Best thing to do (besides checking your cables) is to upload a sample so we can hear the popping of which you speak.
Title: Re: Pops in recording
Post by: Cheesecadet on August 28, 2017, 05:19:10 PM
Best thing to do (besides checking your cables) is to upload a sample so we can hear the popping of which you speak.

I intend too shortly.  I had this happen once before a year ago.  It is a slight almost inaudbile white noise that builds to a pop and resets.  DPA found nothing wrong with my mics and even replaced them with new ones under warranty.  Only other thing in the chain is a Tinybox with an 1/8 inch cable out into an M10 line in.  It happened last year at the same venue (Nedfest) using a PIPsqueak last year (instead of a Tinybox) ...into an M10.  So I know it's not the mics.

Standby...
Title: Re: Pops in recording
Post by: nak700s on August 28, 2017, 06:22:22 PM
Could be the line connection.  The mini plugs can be temperamental if not secure, and that would produce a noise or possibly a popping.  Try a different cable.  Do this at home, and do it like you're at the show.  If you wear your equipment (stealth), do the same and move a bit like you would at the show.  Any movement would most likely create noise if there is any tapping on the cable or the connection isn't completely secure and not spinning/moving in the plug.  Please report back so we know.
Title: Re: Pops in recording - Now With Sample Link
Post by: Cheesecadet on August 28, 2017, 06:55:05 PM
Here is the sample of raw recording.  The recorder was just sitting in my gear bag so it was not being jostled around FWIW.

https://we.tl/z19NCzjEQv

Would love feedback or suggestions.  Thanks to those that already responded a bit.
Title: Re: Pops in recording - Now With Sample Link
Post by: thatjackelliott on August 28, 2017, 09:25:42 PM
The pop is common to both channels . . . presuming that there were two mics with their own cables, then this kind of rules out a faulty mic or mic cable. If one channel is inverted in polarity and summed with the other then the pop is completely cancelled out, leaving a L-R signal with no dropouts. So the audio was riding atop the pop waveform. The audio isn't lost, just slammed by the pop. This suggests to me that it isn't a phantom power supply glitch (if one was being used) which would result in pops and no audio.

A glitchy ADC or reference voltage supply in the unit might cause this.

My two cents.
Title: Re: Pops in recording - Now With Sample Link
Post by: Cheesecadet on August 28, 2017, 10:13:16 PM
Thanks for the responses.  Keep them coming please.  Has anyone else experienced this?

The crazy part is that the first 2 hours of the show had no issues then these pops showed up for about 40 minutes or so, then the recording is fine again.

There was no phantom power being used.  DPA4061's > Naint tinybox v1.5 > 1/8" > pcm-m10 was the chain. 
Title: Re: Pops in recording - Now With Sample Link
Post by: admkrk on August 28, 2017, 11:27:32 PM
The pop is common to both channels . . . presuming that there were two mics with their own cables, then this kind of rules out a faulty mic or mic cable.

Quote from: Cheesecadet
> 1/8" >

Quote from: nak700s
The mini plugs can be temperamental if not secure, and that would produce a noise or possibly a popping.

I did not listen, but nak hit on the first place I would look. If both channels are equal, then it should be down stream of when they get combined. Worn sockets or failing solder connections, along with failing wire in the cable are the most likely places to look.
Title: Re: Pops in recording - Now With Sample Link
Post by: splumer on August 29, 2017, 08:15:31 AM
I did not listen, but nak hit on the first place I would look. If both channels are equal, then it should be down stream of when they get combined. Worn sockets or failing solder connections, along with failing wire in the cable are the most likely places to look.

That would be my first guess too. Over time, mini jacks get a little looser, so if the connection isn't perfect in there, even sitting in a bag it could cause noise. That would be the first thing to check. Try to reproduce the noise at home.

Also, did you have your phone or some other electronic device in the bag with your recorder? Cell phones these days don't cause the interference they used to, but every once in a while at work (I do AV at a university) I get a doc with a pager or cell that causes interference to mics.
Title: Re: Pops in recording - Now With Sample Link
Post by: opsopcopolis on August 29, 2017, 08:24:17 AM
I can't download the file at work, but the build up > pop > repeat type of noise is usually a connection based issue in my experience. If you've had the mics checked already it could be cable or recorder side. Had a similar issue with one of my telefunkens last year and it turned out that the solder on the ground pin had come loose
Title: Re: Pops in recording - Now With Sample Link
Post by: lsd2525 on August 29, 2017, 08:27:16 AM
Could this have something to do with the SD card possibly?
Title: Re: Pops in recording - Now With Sample Link
Post by: thatjackelliott on August 29, 2017, 12:21:04 PM
None of the other ideas (bad mic cable, bad mic, bad SD card) fit the symptoms of the pops being common-mode but no audio loss during the pops. Do the test I did: invert the polarity of one channel and then sum the two channels and listen. You'll hear only L-R sound -- the pops will be canceled out entirely as well as everything else in the center. (This is how the karaoke "vocal remover" trick works -- common-mode signals are nulled out). Whatever is causing the problem is common to both channels but isn't a bad connection or you'd lose audio, too. This has the earmarks of a voltage glitch being injected into the signal.

"The crazy part is that the first 2 hours of the show had no issues then these pops showed up for about 40 minutes or so, then the recording is fine again."

Not at all crazy. Resistors and other parts can go noisy or intermittent depending on the phase of the moon and how they feel about things. You ever take a car to the mechanic only to find that it has stopped making that funny noise?

Send the builder the track and suggest they try the out-of-"phase" summing trick I did.