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Are you you using rechargeable AA or 9 V DC cells? Got problems? Please read this.

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Ty Ford
Are you you using rechargeable AA or 9 V DC cells? Got problems? Please read this.
on May 28, 2017 at 4:29:45 pm

I answered a recent email with a question about powering devices with rechargeable batteries. I thought you might find the solution helpful.

I purchased a pair of Berhinger C2 condenser microphones, just because I needed something, anything, for the moment. The sounds is better than the old, and now damaged from battery corrosion, vidpro xm-55 shotgun that I had at school. However, I am encountering a couple of problems.

I tested the mics when I got them and they seemed fine. Today, when I used the microphones, I encountered a strange issue. As usual, they were plugged into my Tascam DR-40, which was providing 48v of phantom power, from 3 full charged AA batteries.

>>>>>>>bzzt! Rechargeable batteries will, over time, not charge to their full level. This can cause big problems. Try fresh non-chargeables or new recheargebales. Try plugging in just one mic to see if the phantom current drain is too much and is bogging down the system, causing artifacts.

When I began recording there was a little bztz sound every second. This was only audible when I was recording, not while I was in the level-checking mode. And it appears in the final file. When I plugged the Tascam into the wall for external power, the sound went away.

>>>>>>>a clue about lack of power from the battery.

But then the strange thing was, when I took out the plug and reverted back to phantom power from the batteries, the sound did not come back.

>>>>>>>>possible temporary rebound from rechargeables, then they fail again.

However, it did return once again when I turned the phantom power to the microphone off and on again.

>>>>>>>>see above

After doing this many times to see what the problem could be, it stopped having an issue even when I turned the phantom power off and on. However, the sound returned once again when I turned the Tascam off and on.


In addition to this, there was always 3 seconds of helicopter sound when the phantom power was turned on, but I never worried about this because it always went away after 3 seconds.

>>>>>>>>yeah, that usually happens with condenser mics, although the sound may be different due to different circuits in different mics.

Do you know what the issue could possible be? Is it with the power from the Tascam, or with the microphone?

>>>>>>>>Batteries proving the right voltage, but not enough current. If you wan to go rechargeable (I suggest you do, because the Tascams do chew batteries quickly) Get a rechargeable USB power supply like the RavPower RP PB16.

(I have one)


Ty Ford
Cow Audio Forum Leader

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Eric Toline
Re: Are you you using rechargeable AA or 9 V DC cells? Got problems? Please read this.
on May 28, 2017 at 7:56:13 pm

As an FYI: AA batteries are rated at 1.5vdc. Brand new Alkaline or Lithium AA non-rechargeable will test out at about 1.62vdc unloaded and go down from there as you use them. Rechargeable batteries never recharge back up to the rated voltage, they always top out at about 1/2 to 1 volt less than the rated voltage and their discharge rate is somewhat faster than non-rechargeables.

"I push the RECORD button and hope for the best"

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Bouke Vahl
Re: Are you you using rechargeable AA or 9 V DC cells? Got problems? Please read this.
on May 30, 2017 at 2:40:59 pm

From memory (haven't done any measuring lately), rechargables have 1.2 volt per cel (for an AA that's just one cell)
So a typical 9 volt battery has 6 cells, times 1.2 = just 7.2 volt.
In Ty's example, he starts out with just 3.6 volt, not the expected 4.5.


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