Topic: voltage to power a coresound 4061 pair

[bonghitwillie]

i have a the coresound 9v batt box and 2 dpa 4061 mics.  how far can i run the batteries down and not effect the freq response? at what voltage will this occur?  what goes first the low or high end?  thx in advance.

[SmokinJoe]

In the case of most electret condensers "what goes first" is not the frequency response, but rather the ability to tolerate loud music before distortion.  Loud is a relative term of course.  But with a full 9V you can tolerate xxx dB's before the mics brickwall.  When it gets down to 6V it will brickwall at a lower value.  If you are looking for some one to tell you "as long as it's about 6.0v you are good", I don't think anyone can say that for sure.

This is what I do (right, wrong, or otherwise).  If you put a voltmeter on a new 9V alkaline battery, it will probably read a bit above 9.0V, like maybe 9.5.  If you run it for a few shows it will probably be down to 9.0.  After a few more shows it's probably down around 8.5.  The mics probably have plenty of headroom at 8.5, but that's where I tend to replace them because at some point in the near future voltage will probably start to drop like a rock, and that's the show that will get distorted.

If you aren't into voltmeters, then just replace the battery before every "important" show to be safe.

[Gutbucket]

Joe is right on.. though the voltage numbers specific to the DPA 4061 is slightly off.  Regardless of the specific numbers, here's a very important catch- The open circuit Voltage of a battery will measure different than its Voltage in use.  In other words, the voltage you measure with the battery disconnected may be considerably higher than the voltage the battery produces while operating in the circuit.  So even if the battery meaures OK after a show when you take it out of the box, it may not be making enough voltage to correctly supply the mics in use.  Best way to meaure the voltage is with the battery conected in the box with the mics if possible.

The 4061 is designed to use a 5V supply.  It works fine with 9V or a bit more but I wouldn't give it a whole lot than that.  It seems to me to be a bit more current hungry than some other minitatures by my experience but I've never measured that.  By current hungry I mean that the battery will be depleted sooner than other mics with less current draw, and that the voltage will tend to drop a bit more in use.  I had some rechargable 9.6V NiMH which after a year of hard use measured OK after a show, but would drop low enough in use to cause problems.  I didn't figure out what the problem was until I measured the battery voltage at end of a show with the mics still powered up and found the battery Voltage very low, but if I took the battery out it measured OK in isolation.

Short an long of it is, like Joe, I change disposable alkaline 9V batteries when they drop below 8.5V, and re-charge the 9.6V NiMH if they are below 9V.