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Right channel slowly losing volume

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nulldogmas:

--- Quote from: admkrk on September 11, 2021, 03:03:11 PM ---Just swap channels. If it stays on the right - deck, if it moves to the left - mics.

--- End quote ---

Single 1/8" stereo plug, so that's not happening.

jefflester:

--- Quote from: nulldogmas on September 11, 2021, 05:45:00 PM ---
--- Quote from: admkrk on September 11, 2021, 03:03:11 PM ---Just swap channels. If it stays on the right - deck, if it moves to the left - mics.

--- End quote ---

Single 1/8" stereo plug, so that's not happening.

--- End quote ---
You could use a pair of 1/8" to RCA adapters back-to-back to facilitate the troubleshooting.

nulldogmas:

--- Quote from: jefflester on September 11, 2021, 06:22:09 PM ---
--- Quote from: nulldogmas on September 11, 2021, 05:45:00 PM ---
--- Quote from: admkrk on September 11, 2021, 03:03:11 PM ---Just swap channels. If it stays on the right - deck, if it moves to the left - mics.

--- End quote ---

Single 1/8" stereo plug, so that's not happening.

--- End quote ---
You could use a pair of 1/8" to RCA adapters back-to-back to facilitate the troubleshooting.

--- End quote ---

Hmm, that's an idea.

Or I can just swap out different mics, battery boxes, and recorders and see where the problem recurs.

Gutbucket:

--- Quote from: dunebug81 on September 10, 2021, 12:35:58 PM ---I think it has something to do with the MMA. No reason for that one channel to drop over the course of 30 min. A mic wouldn’t just lose sensitivity after working fine for an hour.

--- End quote ---


--- Quote from: nulldogmas on September 11, 2021, 01:06:25 AM ---This exact thing happened to me tonight, with an M10 and a Church Ugly battery box, and new batteries. Weirdly, if I unplugged the cable from the M10 mic in and replugged it, it seemed to fix itself, but then would fade again.

(That's all from monitoring it live; I haven't checked the waveform yet, as it's 1 am and I just got home.)

This has happened to me a couple of times before, and I blamed a dying battery at the time. But this one is just weird.

--- End quote ---

A sensitivity drop like this IS a somewhat common problem phenomena with these mics after many years of use, but when that happens the change in sensitivity does not continue to vary up and down over time.  I think that failure mode is related to the loss of the quasi-permanent charge of the dielectric material that provides polarisation in these back electret type microphones.  In this case the sensitivity drop is permanent and will not vary.  The mic should perform the same when swapped from one side to the other, if batteries are changed or if used in another rig.

My first suspicion in these cases is the state of charge of the 9V battery in the preamps.  Easiest way to check this with certainty is to measure voltage across the battery before and after the recording session with the battery remaining in circuit and powering the preamp.  The thin test leads of a voltmeter will reach the battery terminals without first disconnecting the battery from the battery clip of the MMA6000 or CA preamp.  With the load removed, a spent battery will tend to quickly return to a higher nominal static voltage, yet cannot and will not continue to hold that voltage if placed under load again.  However, the initial recovery may be sufficient to temporarily bring the sensitivity back up for a brief time.

I've experienced both these things over the years.  Check batteries first.

Cedric:
Hi,

I had the same problem this year with my Sony M10 on long run sessions (typically 24 hours unattended nature recordings), can't remember if it was the left or the right side.
The sound would vanish completely, and then come back again
The problem is internal as I don't use external mics with my M10:
- Fisrt because the internal mics are good enough (read: excellent!) for my needs.
- Second because the mic jack input is dead on this unit.
I turned the limiter off, the problem didn't happen again since then.
In my case, the issue might have been excess of humidity as well...

Cedric

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