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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: WiFiJeff on August 17, 2011, 01:09:58 PM
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I've had intermittant dropouts before, usually of right channel audio when making a poor connection or having a battery die, but last night I had something that's a new one on me.
Great recording DPA4060 > MMA6000 > Sony D50 until the final five minutes. Looking at the frequency spread in iZotope I see an intermittant dropout of the bass signal in both channels for a second or two, return of signal, dropout again, everything above say 200 Hz looks fine. The low-cut switch on the MMA6000 was pretty firmly off, and I was seated pretty quietly so I doubt I was accidentally toggling it. Anyone ever see something like this???
Jeff
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Maybe it happened to the bass and thats what the PA spewed out ???
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Symphony orchestra, no PA. Live it sounded fine, and the waveform didn't look obviously bad in the basic view in Wavelab, but you could hear a problem on playback and the frequency spread in iZotope showed that for a few minutes the low end was winking out and on, sometimes there were "holes" other times stuff was missing but just weak not gone entirely. A loud passage might bring it back for a moment, then it would go out again.
I cleaned all contacts, replaced the 9V cell in the MMA6000, then thought better of it and swapped out to a backup MMA6000, same mics and recorder last night and no problems. But of course that could be luck, it ran fine for over three hours with just four-five bad minutes the night before.
I just hate these random fails.
Jeff
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I find these are due to cord failures, or a bad battery connection that is giving power, just not tight enough for full power.
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I'm with Scooter on this one. I've had similar problems, and its usually been from bad contact in a connnector, failing solder joint to a connector or preamp battery related. It can be really frustrating sometimes chasing it down.
Random fails are always a bummer, but especially when the recording is otherwise great.
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replaced the 9V cell in the MMA6000,
How old was the battery?
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The 9V cell in the MMA6000 was a Duracell good to March 2014, it showed 3 green lights out of 5 on my Universal Battery Tester after the incident. This means about half down. The MMA light was still blinking green, and I've gotten up to three and a half hours after it starts blinking red. So it might have been defective in an annoyingly random way (had that happen once, but it turned off the MMA6000 entirely until a loud noise woke it up). The D50 batteries are Imedion 2400 mAh rechargeables, about a year old and no problem with them before or since, they were only about 1/3 down at that point, I've run them to about 3/4 down.
Jeff
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The 9V cell in the MMA6000 was a Duracell good to March 2014, it showed 3 green lights out of 5 on my Universal Battery Tester after the incident.
That's 3 lights out of 5 with no load, and I think it's not exactly clear what "3 out of 5" lights mean. It would be more interesting to know what a voltmeter reads under load.
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If you have this issue again, once you get home check voltage across the battery without disconnecting it from the preamp, with the preamp on. Then compare that voltage against a new battery in the preamp (or a known good and freshly charged if using NiMH), again connected and preamp on.
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Thanks for the suggestions. I ran 5 1/2 hours straight Friday with no issues, so I hope contact cleaning and a fresh 9V cell cleaned it up, I just wish it were a reproduceable thing I could test out as fixed. I'll run again tonight, if we are spared further earthquakes.
Jeff