ECM-MS907 Has Gone Really Quiet

[Jonny Morris]

I purchased a Sony ECM-MS907 Stereo microphone some years ago and back then it worked brilliantly, however it went into storage for several years as I didn't do any audio recording (partly due to my minidisc recorder packing up).  Now I have a working minidisc recorder again I brought out the old Sony mic only to find it's apparently not working, it doesn't even register on the minidisc recordings I try to make.  I plugged the mic into my Bose Aux socket, still nothing, I plugged the mic into a PC and saw a tiny amount of level in Audacity, not enough to be audible though.

I took the covers off the mic, all looks like new inside, no dust or loose wires, everything where it should be.  I tried several different AA batteries (including Duracel, and a freshly charged Eneloop AA), I get the small red battery check when turning the mic on so that should indicate that the battery is fine.  Tried the mic in 90 or 120, no joy.

I'd really like to be able to make recordings to minidisc again, the MD recorder is a Sony MZ-R500, I've found nothing to indicate that a mic would not work with this model.  When I plug the mic into the Line In socket (white) and press record it says Line on the display, I have record level set to Auto.

Any advice please?

[KJ_Palmer]

Sounds like the microphone is still working, if Audacity is getting a signal, however low. 

The ECM-MS907 is designed to be used with a microphone input (on MD recorders this is called 'plug-in power') rather than a line or aux input. It simply doesn't give a strong enough output to drive a line level input properly. You could set your line input level to maximum and that might give better results, but you 'd be better off using a recorder with a mic input, which the MZ-R500 lacks. Or a powered microphone, or use a  microphone pre-amp ('battery box') with your ECM-MS907.

[sfbp]

Yeah, the output from most normal microphones (without a so-called "battery box") will never drive Line-In, which requires of the order of 0.5-2.0 volts. Your mike will generate at most about 50mV, which explains the results you see. Try searching on these forums for "battery box" and this will help, if you can build one. Unless there's a RED socket on your MD recorder that says "plug-in power", you are, as K says, out of luck for the moment.

 

[Jonny Morris]

Thank you for your responses, that makes sense as my previous MD recorder had a red input and it worked fine with that, strange and annoying that the Sony MD recorder does not have it (is there a recommended portable MD recorder model that does?)

I'll definitely have a look into that battery box project.

[kgallen]

All those referenced articles on the Forum are fantastic. If you want a bit more background, this Instructables article is quite accessible:

https://www.instructables.com/id/Electret-Microphone-Preamplifier/#step2

(Note the above is a single channel design. The Forum threads are covering a stereo (two channel) design.)