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Author Topic: Right channel suddenly drops mid-recording  (Read 1439 times)

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Offline bucsab12

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Right channel suddenly drops mid-recording
« on: May 24, 2018, 05:58:44 PM »
I have been recording for the last year with the following setup:

Schoeps MK-4V > nbob active cable > nbox platinum > RCA to stereo cable > Sony PCM-M10 (line-in input)

The entire rig other than the Sony PCM-M10 were purchased a year ago (purchased new).
In the last two concerts that I went to, at the middle of the show, the right channel drops to very low levels and there is some noise that is suddenly added to the channel.
I am taking very good care of my equipment and I have made sure that the batteries in the M10 and in the nbox are charged.

I have tried to replicate this behavior while not in concert and I haven't been able to.
I only record stealth. My Schoeps mics are stationary and I never remove them from their holder.
I didn't want to start tinkering with the equipment mid-concert (settled for a mono recording), so once the concert ended, I unplugged the mics from the line-in input and plugged them into the mic-in input.
Both channels worked as expected. I then plugged the mics to the line-in input again and suddenly everything worked great.

I have attached the sound file where the channel suddenly drops. I would love to hear any suggestions since I am really baffled by this behavior.
Thank you in advance.

Offline Gutbucket

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Re: Right channel suddenly drops mid-recording
« Reply #1 on: May 24, 2018, 06:21:35 PM »
Clean all connections thoroughly, particularly the TRS stereo mini plug > M10 line-in jack.  Also consider gaff-taping the miniplug securely to the M10 so it cannot be accidentally pulled out ever so slightly, which can make one of the signal paths go intermittent/noisy or drop out entirely.
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Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #2 on: May 24, 2018, 06:39:21 PM »
Thank Gutbucket for the quick reply.
Can you please advise on what is the best way to clean the M10 line-in jack without damaging the electronics?
Mid-show, when I saw the channel dropped, I did try to twist the mini stereo connector and push it in deeper to see if it could reconnect but it didn't work.

Offline Gutbucket

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Re: Right channel suddenly drops mid-recording
« Reply #3 on: May 24, 2018, 07:04:32 PM »
99% Isopropyl alcohol (95% works too, just contains a bit more water) or electronics connection cleaner like Caig Deoxit.  You can use a tiny brush (like a mascara brush) to clean the jack, or simply clean the plug well, then re-wet it with alcohol or cleaner and plug/unplug/rotate it in the jack to clean the internal jack contacts.

What I posted earlier is the first thing which comes to mind, a common problem, and will be good practice to do anyway..
..but I just listened to your sample and it doesn't sound like a dirty or intermittent connection because it seems to manifest as a quick clean fade, not as an immediate cut-out and has no apparent scratchiness or noise during the fade.  That suggests an alternate issue such as a change of gain or loss of power to the mic capsule.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
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Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #4 on: May 24, 2018, 07:20:50 PM »
Do you have any guesses to what may be the culprit for the power drop in the right mic capsule?
The strange thing is that it happens mid recording. In the first show it happened after 34 minutes and in the second after 20.
The only thing that comes to mind is maybe some issue with the batteries in the nbox in case the batteries are separated for the different channels.
I switched now between the capsules to rule out an issue with the mics but I think it must be something else.
I am also attaching the right channel drop from the first concert. Maybe it can provide some additional information.
« Last Edit: May 24, 2018, 07:24:03 PM by bucsab12 »

Offline nulldogmas

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Re: Right channel suddenly drops mid-recording
« Reply #5 on: May 24, 2018, 07:48:22 PM »
I've had similar things happen with my M10 on occasion — one channel will gradually fade to a lower level, then sometimes the other will follow. Changing batteries in the battery box seems to have fixed it, but honestly I'm not entirely sure if that was coincidental or not.

Offline rippleish20

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Re: Right channel suddenly drops mid-recording
« Reply #6 on: May 24, 2018, 08:10:29 PM »
What kind of batteries are using in the nbox?

Schoeps CMC6 (MK22's, MK41's) / AKG C480B (ck61, ck63, ck8) / Telefunken M60 (TK61, TK63) - for sale / DPA (4061)
KCY 250/5 and 250/0 > naiant PFA or IPA or Nbox 
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Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #7 on: May 24, 2018, 08:32:15 PM »
I own the nbox platinum that requires four 9v batteries.
I use the latest version of the low self discharge Powerex 9.6v batteries.
I will try to change the battery order in the nbox.
By the way, while charging the batteries, I have noticed that 2 of the 4 have lost much more power than the other 2.
I try to change the order after every charge but I never ubderstood why there is such a substential  difference in power consumption between the batteries.

Offline rippleish20

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Re: Right channel suddenly drops mid-recording
« Reply #8 on: May 24, 2018, 08:46:01 PM »
If you have a meter I would test their voltage after charging. I have had issues with a couple of them not fully charging.
Schoeps CMC6 (MK22's, MK41's) / AKG C480B (ck61, ck63, ck8) / Telefunken M60 (TK61, TK63) - for sale / DPA (4061)
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Offline gewwang

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Re: Right channel suddenly drops mid-recording
« Reply #9 on: May 24, 2018, 09:00:21 PM »
I own the nbox platinum that requires four 9v batteries.
I use the latest version of the low self discharge Powerex 9.6v batteries.
I will try to change the battery order in the nbox.
By the way, while charging the batteries, I have noticed that 2 of the 4 have lost much more power than the other 2.
I try to change the order after every charge but I never ubderstood why there is such a substential  difference in power consumption between the batteries.

If it's the batteries causing the issue, that should be easy to re-create at home.

Offline perks

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Re: Right channel suddenly drops mid-recording
« Reply #10 on: May 24, 2018, 09:58:44 PM »
The ‘vintage’ nbox draws down each pair at a different rate. The instruction are to change 1 set every show and the other set every other show. Not sure if the platinum version operates the same way.

Here's an explanation why....

https://taperssection.com/index.php?topic=150820.msg2002227#msg2002227
« Last Edit: May 25, 2018, 12:18:07 AM by perks »
Mics: Schoeps MK5, Schoeps MK41, AT853u (C,SC,H,O)
Preamps/converters: Schoeps VMS52UB (x2), Nbox (x2), E.A.A. PSP-2 (x2) Grace Lunatec V2 (for sale), Sound Devices MP-2 (for sale), DPA MMA6000, Naiant Tinybox v1.5, Naiant PiPsqueak, Church Ugly, Apogee Mini-Me, Benchmark AD2k+
Recorders: Tascam DR-680, Korg MR-1, Edirol R-05, Sony PCM-M10 (x2), Tascam DR-07, Marantz PMD-661

Offline swordfish

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Re: Right channel suddenly drops mid-recording
« Reply #11 on: May 25, 2018, 01:04:48 AM »
I own the nbox platinum that requires four 9v batteries.
I use the latest version of the low self discharge Powerex 9.6v batteries.
I will try to change the battery order in the nbox.
By the way, while charging the batteries, I have noticed that 2 of the 4 have lost much more power than the other 2.
I try to change the order after every charge but I never ubderstood why there is such a substential  difference in power consumption between the batteries.

If it's the batteries causing the issue, that should be easy to re-create at home.

I would use regular alkaline batteries for the next 2-3 shows, fresh set for each show.  Just to see if the problem reoccurs..just m $0.02

Offline tim in jersey

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Re: Right channel suddenly drops mid-recording
« Reply #12 on: May 25, 2018, 01:32:00 AM »
I own the nbox platinum that requires four 9v batteries.
I use the latest version of the low self discharge Powerex 9.6v batteries.
I will try to change the battery order in the nbox.
By the way, while charging the batteries, I have noticed that 2 of the 4 have lost much more power than the other 2.
I try to change the order after every charge but I never ubderstood why there is such a substential  difference in power consumption between the batteries.

Beat me to it.

If it's the batteries causing the issue, that should be easy to re-create at home.

I would use regular alkaline batteries for the next 2-3 shows, fresh set for each show.  Just to see if the problem reoccurs..just m $0.02

Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #13 on: May 25, 2018, 08:17:39 AM »
Thanks guys for the answers.
I have tried to replicate the issue at home today.
I have placed my mics in front of my stereo while playing some heavy rock music with a lot of bass.
I can't get the levels really high because of my neighbors so I set the levels on the M10 to 10.

At first I used the exact same setup as I had in the last two concerts.
After some time, the issue happened again, and the levels on the right channel dropped.
At that point, while the M10 is recording, I moved the stereo connector from the line-in to the mic-in input and back and the levels were fine again.
After that I switched between the caps to make sure that the issue is not caps-related.
Sure enough after some time, the levels on the right channel dropped again so at least I know it is not the caps.
I have a voltmeter and I will check the battery levels later this weekend when I get a chance.
I will try to disconnect them directly after recording to get the voltage level before they get a chance to recover.
I will also try to use alkaline batteries as you have suggested to see if this is really a battery issue.

Offline Gutbucket

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Re: Right channel suddenly drops mid-recording
« Reply #14 on: May 25, 2018, 09:12:49 AM »
I suspect the batteries.

If at all possible, measure them while still under load in the device after the problem occurs to get an accurate reading.  If not, take them out and measure them with a battery tester, or under some other load with a voltmeter.  They partially recover to near nominal voltage quickly, which can hide a failing battery when tested directly with a voltmeter. 

Took me a while to figure that out when I had some Powerex 9.6Vs reaching the end of life causing similar issues.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
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Offline goodcooker

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Re: Right channel suddenly drops mid-recording
« Reply #15 on: May 25, 2018, 09:15:15 AM »

Take a headphone out of your stereo and record that for a while to isolate the M10 or not. If the problem is with the M10 and not the rest of the setup you will experience the same problem and will have completely eliminated the nBox/cables/mics from the equation....
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Offline gewwang

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Re: Right channel suddenly drops mid-recording
« Reply #16 on: May 25, 2018, 09:41:40 AM »
Thanks guys for the answers.
I have tried to replicate the issue at home today.
I have placed my mics in front of my stereo while playing some heavy rock music with a lot of bass.
I can't get the levels really high because of my neighbors so I set the levels on the M10 to 10.

At first I used the exact same setup as I had in the last two concerts.
After some time, the issue happened again, and the levels on the right channel dropped.
At that point, while the M10 is recording, I moved the stereo connector from the line-in to the mic-in input and back and the levels were fine again.

This statement adds the interconnect as a potential point of failure. Do you have another interconnect to test with?

Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #17 on: May 25, 2018, 11:29:30 AM »
Thanks again guys for your suggestions.
My voltmeter has  those pins at the end if the probes so I think I will be able to check the batteries voltage while under load.
I did try to connect the M10 directly to my computer headphone out connection and it worked normally but it was just a quick test.
I will try to leave it connected for a longer period to see if the problem is caused by the M10.
I also suspected that the interconnect may be at fault. When I record, I place the M10 on top of the nbox in a small side bag.
The M10 and the nbox are placed on their side inside the bag and the interconnect, which is 1 foot long, makes a loop inside the bag and part of it is located on the bottom of the bag under the M10 and the nbox.
During the show I take the M10 and the nbox in and out of the bag a for a few times to check the levels and that may have caused some connection issues in the cable.
It is a very sturdy cable so I didn't expect it to be the cause if the problem.
I don't have another interconnect cable but I will get a simple one just to check. I will first try to eliminate the M10 and the batteries.

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Re: Right channel suddenly drops mid-recording
« Reply #18 on: May 25, 2018, 05:49:16 PM »
I think its batteries too.  I stick to Duracell Pro-cells these days.  As Dr. Nick for his thoughts.

Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #19 on: May 26, 2018, 07:56:23 PM »
So today I connected my M10 directly to my computer using a stereo 3.5 to stereo 3.5 cable.
I recorded for approximately 5 hours and didn't notice any drops on the right channel.
Since that eliminated the M10 line-in input, I went back and connected the original rig to try and replicate the problem.
I have tried to recreate the problem for a few hours but without luck.
The only differences I have made to the rig since it failed mid-concert was to change between the capsules and then going back to the original setup and I also changed the order of the 9v batteries in the nbox.
I thought that this may mean that I had some connection issue and one of the batteries in the nbox wasn't connected properly.
On the other hand, this doesn't really fit with the fact that when the issue occurred, moving the interconnect cable from the line-in input to the mic-in and then back to the line-in solved the problem.
I wrote Nick and he also suggested that this sounds like an interconnect problem.
I will try to cause the failure again, but in case I am unable to replicate it, I guess I will have to wait until the next concert and see how it behaves in a concert environment (in terms of high sound levels and handling of the rig during a concert).

Offline gewwang

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Re: Right channel suddenly drops mid-recording
« Reply #20 on: May 27, 2018, 09:11:27 AM »
So today I connected my M10 directly to my computer using a stereo 3.5 to stereo 3.5 cable.
I recorded for approximately 5 hours and didn't notice any drops on the right channel.
Since that eliminated the M10 line-in input, I went back and connected the original rig to try and replicate the problem.
I have tried to recreate the problem for a few hours but without luck.
The only differences I have made to the rig since it failed mid-concert was to change between the capsules and then going back to the original setup and I also changed the order of the 9v batteries in the nbox.
I thought that this may mean that I had some connection issue and one of the batteries in the nbox wasn't connected properly.
On the other hand, this doesn't really fit with the fact that when the issue occurred, moving the interconnect cable from the line-in input to the mic-in and then back to the line-in solved the problem.
I wrote Nick and he also suggested that this sounds like an interconnect problem.
I will try to cause the failure again, but in case I am unable to replicate it, I guess I will have to wait until the next concert and see how it behaves in a concert environment (in terms of high sound levels and handling of the rig during a concert).

Have you tried moving the interconnect or picking the m10 up and moving it around while trying to recreate the issue?

Offline bucsab12

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Re: Right channel suddenly drops mid-recording
« Reply #21 on: May 27, 2018, 11:48:31 PM »
Yes, I have done both.
When I connected the m10 directly to my computer I trued to twist and turn it while recording.
When I connected the entire rig, I left the mics in place and tried to handle the m10 along with the nbox the same way that I always do during a show (taking them in and out of the side bag that I put them in while recording).
I will try to replicate it again until I cause it to fail and hopefully I can find out where the problem lies.

 

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