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[Dan Mortensen]

Results are in for phase 1. It's too bad this forum software does not allow intermingling of photos and comments.

What should be the first pic in sequence (DSC_0796) shows a table of the results.

Full charge is 5 bars, and with no audio passing through the mics at any time (quiet shop), it took over 4 hours for any of the mics to get to 4 bars, and 16-18 hours to get to full discharge.

The mic in the ferrous bread pan was consistently the first to reach the next lower level, and the aluminum foil one was consistently next, with the free air mic lasting longest at each level. It's interesting that the final shutoff time difference between the aluminum and free air ones were not as far apart at final discharge as they were at every step in between.

There's a few more pictures below showing pictures of the video camera monitors showing:

--0785: state of the screen at 9h 44m, with the battery levels of each mic, their frequencies, and where they were physically located;

--0790: at 15h 36m (the camera starts a new file after 12h recording) showing the low battery symbol on the Ferrous and Aluminum tray mics. It was surprising that there was still another hour or so of transmission on 0 bars.

--0792: the RF signal meters just before the Ferrous batteries die.

--0793 same just after they died.

I've decided not to post this on Youtube as it would rival Andy Warhol's 24 hour movie of the Empire State Building for boringness, and am going to delete the hard drives for the cameras to start the next phase.

That will be measuring life in each condition with sound going through each mic. I'll put two little speakers near the mic heads, one at the free standing mic and one just above and in front of the two adjacent ferrous/aluminum trays, and create a level that lights up the LED ladders on the displays. I'm thinking I'll swap the Free mic with the Ferrous mic to see if any of the life disparity is due to individual mic. I'll add a layer of aluminum foil to see if that makes any difference to the same mic.

And FYI rather than loading these files onto a computer at USB 2.0 speeds for editing and viewing, I just watched on the cameras' screens and fast forwarded using using their internal clocks to show time, which are visible in the pictures.

If anyone take me to court the only saved documents will be the photos posted here and the spreadsheet with further results.

So far, I think James, that guy, and RF Venue are right.

[Keith Broughton]

Nice work Dan! Nothing like real world testing to get to the truth.
Another test would be to see if ferrous or aluminum is better at reducing intermod activity.
I have found that the cheap  aluminum pans from the Dollar Store seem to work well

[TJ (Tom) Cornish]

Results are in for phase 1...
So far, I think James, that guy, and RF Venue are right.

Dan, thanks for taking the time to test this.  Just to keep the original question in view, "that guy"'s claim was that rechargeable batteries are unusable because the pans "kill them by the radiated RF".  You have demonstrated that there is some power consumption difference with the pans, which is surprising to me but there is a reasonable explanation.  If you or someone else are bored enough to repeat your experiment with rechargeables, that would be interesting. 

I wonder if "that guy" set his mics to the right battery type for accurate metering, or if he's confusing simply the operational differences of rechargeables and the pans.  Depending on the chemistry of the standard AAs, rechargeables may have more energy available (or not), but the mic needs to know what's in it to calibrate the battery meter.

[Keith Broughton]

Seems unlikely that rechargeable batteries would behave differently.
Tom's idea that the calibration is off sounds more plausible.
In the end, the slight degradation of the battery life pales in comparison to the advantage of using  the pans.

[Tim McCulloch]

Dan, thanks for taking the time to test this.  Just to keep the original question in view, "that guy"'s claim was that rechargeable batteries are unusable because the pans "kill them by the radiated RF".  You have demonstrated that there is some power consumption difference with the pans, which is surprising to me but there is a reasonable explanation.  If you or someone else are bored enough to repeat your experiment with rechargeables, that would be interesting. 

I wonder if "that guy" set his mics to the right battery type for accurate metering, or if he's confusing simply the operational differences of rechargeables and the pans.  Depending on the chemistry of the standard AAs, rechargeables may have more energy available (or not), but the mic needs to know what's in it to calibrate the battery meter.

I think he was repeating advice given him.  I posted this to see if he was given correct advice as I'd not heard of reflective RF containment affecting the battery life of rechargeable relative to alkaline, and if so, what the mechanism of this was.

He was a good A2, and well versed in keeping the video feeds running (a trickier task than the wireless mics), fixing problems with orchestra pit racks and several other duties that seemed to befall the audio dept.  I'm not throwing him under the bus at all; I was impressed with his work and work ethic.

The tour has been out for over a year so I'm fairly certain they have the right battery calibration selected...

[Dan Mortensen]

Another test would be to see if ferrous or aluminum is better at reducing intermod activity.
I have found that the cheap  aluminum pans from the Dollar Store seem to work well

Thanks, Keith.

That was going to be my next test after I post the results of swapping the two mics: showing what the intermods would be with the mics in exactly the same positions as they are now:

A) the Free Standing mic 4' from the nearest of the other two, and those two together, pans touching (one ferrous, one aluminum foil)

B) same but both Ferrous pans

C) same but both aluminum foil wrapped cardboard pans (I couldn't find all aluminum pans long enough to accommodate these mics - 12" but narrow)

D) same but no pans

My initial impression during the day was that battery life was not much affected by having signal go through them, but that's speculation at this point. I'll post the test conditions when posting the summary, which should be in a couple hours.

[Dan Mortensen]

Thanks, Keith.

That was going to be my next test after I post the results of swapping the two mics: showing what the intermods would be with the mics in exactly the same positions as they are now:

A) the Free Standing mic 4' from the nearest of the other two, and those two together, pans touching (one ferrous, one aluminum foil)

B) same but both Ferrous pans

C) same but both aluminum foil wrapped cardboard pans (I couldn't find all aluminum pans long enough to accommodate these mics - 12" but narrow)

D) same but no pans

Below are the conditions as above.

This post will have A and B, the following post will have C and D.

3 pics per condition to measure amplitude of each mic signal. All scans are average of 10 scans. The last pic in each post is the background RF in my shop for reference.

I decided to take screen pics with my camera handheld, but I maybe should have done screen grabs. But I didn't.

[Dan Mortensen]

Here are C and D as above.

Other conditions are the same as the last post.

[Dan Mortensen]

As a bonus, here are a couple more conditions:

The E series is all transmitters adjacent (like 2" apart) to each other. I forgot to say that the A,B,C, and D all have the free standing mic 4' from the nearest transmitter. All transmitters in all tests are about 11' from the antenna, and are at 10mW.

The last couple pics are a bad transmitter that I found but not before I used it in the other intermod test as the second mic. It is really nasty.

The first picture has it in the same stand as the freestanding mic from the earlier tests, and the picture is a 10 scan average.

The second picture is a 10 scan maximum of me waving it around.

Note that the spectrum segment is widened to 460-608MHz to show how fully awesome this mic is as a generator.

The last picture shows the shop RF background with no devices active.

[Dan Mortensen]

OK, back to the main topic, battery life in metal pans.

Here is the final chart, rearranged a little from yesterday.

The trend looks stable regarding free-standing vs. ferrous vs. non-ferrous, although the exact numbers are a little different. Today the aluminum foil pan was the worst even though it was the same mic as yesterday.

I realized that I moved the two pans together to get them under the speaker, which probably put the aluminum pan in the influence of the steel pan, so it got the worst of both worlds, maybe. (Second Picture)

The diminished life could be also due to the fact that they were all working harder doing audio processing, although that effect can't be very great with these mics since the overall battery life differences at each step for each condition between audio/no audio seem almost to be within margin of error.

I did what I felt I could to light them up without slamming too much (Third, Fourth, and Fifth Pictures)

The music that I chose, since I was going to be listening to it for a while off and on, was a 9.5 hour playlist of my favorite reggae band, Steel Pulse. Although I thought repeating the playlist twice would be sufficient, I'm afraid that a new variant of Mortensen's First Law (about 3/4 down an entertaining page put together by our AES Section's Webmaster, Rick Chinn) was discovered with this test.

Instead of running out before the test, the music ran out about a minute before the first transmitter died, so I can't tell audio behavior at the end of battery life. I also forgot to record the audio signals from the mics, so I don't know if they go bad as they go off, or for how long they sound bad before shutting off.

Regardless, the pans are good to reduce intermods despite a minor hit on battery life.

One other thing: Has anyone used metal mesh pans instead of solid? I'm kind of surprised at how heavy a bunch of steel pans are.

This was an interesting homework project for this student. I've learned a lot about these mics and about measurement.

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