Electret microphone

Hey all!

I want to make an Irving Microphone System for Grand Piano. Think of getting some panasonic WM-61a capsules (or does anyone have a better suggestion?) with the Linkwitz Mod. However, I am stuck on how to sum the outputs (I'm guessing just parallel), and how I can make it so it can run on phantom power. I dont wanna mess with batteries or external power sources. I've searched the internet and found the same question multiple times, but slightly different so I still haven't found a suitable solution.

Thanks in advance!

Chris
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
The primary problem so far is that you do not ask for individual control of each capsule. A piano is regulated to sound "balanced" in the room, it sounds quite different laying above the hammers.

I also have concerns about overload (even with Linkwitz) when close-miccing a piano.

However: you can put the capsules straight parallel (they work well into their triode regions) without gross conflict (lower impedance is often good), AND it looks like a $20 parts-list so no big disaster if it isn't ideal and you have to break it up for individual microphones. The current goes up but my *estimate* is that it is still inside the 8mA limit on most Phantom supplies. (1970s desks, and $97 USB boxes, may sag.)
 

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Thanks for the reply! Do you mean an overload per individual capsule, or combined? I read a 10 ohm resistor will take care of the combined overload possibility.

About the individual capsule control, I have no intent to use it in a studio environment. It’s 100% for live, to increase gain before feedback. I don’t want to end up with 12 channels for grand piano only, and the problems outweigh the solution to the heavy eq’ing to combat feedback I think. The stereo image is quite weird in this setup, but I don’t want stereo information at all on a PA where half the audience will only hear one side.

Thanks again for the reply! I’ll just go make it, and post the results here.
 
I just mentioned the attached file. I noticed you changed a few values. The capacitor that used to be 10uF is changed to 50uF, does that have anything to do with the fact that you have 5 capsules in that diagram? I am planning on using 6, so would that value rise to 60uF? And how about the other changed values?
 
Allright. So just over 50uF and just over 0.25uF capacitors, just under 1k and 5.6k resistors would be good? Im guessing you are talking about the impedance of the capsules. I am going to order too many capsules, so I can test then each and pick the ones that will fit the best, so measuring impedance will be one of those criteria I guess.
 
Last edited:

Dave Zan

Member
2010-11-21 7:12 am
...the remake, the JLI-61A. I've done some research, and as far as I could find, they are identical.

I recall there was a lot of frustration when the Panasonic version went obsolete because the intended replacements didn't have the same level of quality control and weren't as consistent.
Probably the JLI is ok, IIRC the consensus was that the Primo microphones were the best option for quality.
Not sure about the LInkwitz mod on the Primo.

Best wishes
avid
 
I recall there was a lot of frustration when the Panasonic version went obsolete because the intended replacements didn't have the same level of quality control and weren't as consistent.
Probably the JLI is ok, IIRC the consensus was that the Primo microphones were the best option for quality.
Not sure about the LInkwitz mod on the Primo.

Best wishes
avid

I bet, but those are a LOT more expensive. 66 euro's per 4 matched. I'd rather order 44 JLI ones, test 'em myself, pick the best 4, and use the other 40 for less critical purposes.