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Old Dec 21, 2007, 3:01 PM   #1
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So, I've owned an A-HD for about 2 weeks now. I received it with Firmware v 1.60, and like others, had severe sound issues. Everything else was better than I had expected for the price, but the sound was Noise-Gated somehow, where if the ambient sound was low, the camera would squelch the sound,. Until someone talked, or a loud sound "woke up" the recording. This just sounded retarded and was unusable.
So, being the MacGuyver kind of guy that I am, I built a tiny external, mono, 9v battery powered Microphone Preamp. It consists of simply a small Electret Condenser microphone element, a 2.2 microfarad Capacitor, and a 10k ohm, metal film 1% resistor, a 9v battery pigtail, mounted on a small PCB breadboard. All in all, about $15 in parts fromn radio shack. I also mounted a 3.5mm jack and a switch so I can run and power an external microphone instead of the internal one :


After a little tweaking, I mounted the 9v battery and Microphone/Preamp onto the camera with foam double-sided tape.:



I also used Fishy's idea of cutting a hole in the back lense cap of a Wide-Angle to fashion a slip-mount wide-angle lense. You can see I used Black Electrical tape eccessively It is just a Digital Optics wide angle lense I already had from a previous digital camera that I got on ebay a while back.



I have upgraded my firmare to v2.002, and so far, have not experienced the same audio clicking problems. Although, I updated after I installed the mic pre, so my results maybe aren't typical. I hadn't noticed a degradation in picture quality, but I also haven't done an A-B test yet.

All in all, I love this camera and take it anywhere. The 9volt battery actually helps me to grip and balance it, and it keeps my index finger on the record button, away from the flash. It does look a little strange and it draws a lot of questions/comments. But the audio quality is better than it could ever be on this camera with just a microphone alone. A powered microphone preamp lets you record much, much higher sound levels. Like loud environments, live recordings, etc.. It sounds much more natural, in spite of the A-HD's 128kbps audio bitrate and the mono electronics.

I'll post updates here. I'm hoping to cram the electronics back inside the camera, so I can put the Silver plastic cap back on, but there would still be a 9volt battery on the side.
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Old Dec 21, 2007, 4:36 PM   #2
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Have you seen this?

http://www.hackaday.com/2007/11/28/m...ock-connector/

it would definately be small enough to hide internally and it draws 3.3v from the connector. No PCB only device mounted, pretty impressive. I think you'd only have to 'maybe' change 1 resistor value for this to work with the 3.7 v aiptek battery.


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Old Dec 21, 2007, 5:19 PM   #3
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Win.........

Love the idea and the excellent review..

I would love even better a list of the exact parts, and a drawing of how to connect the parts. I am deffently going to try this ifI have the info.

Do you truely need 9 vlts to run the device or can one find a lower voltage, and would a lithium watch battery work?

tapping off the 3.7 vdc should be simple

Addt'l info asking:

1. do you need to have that preamp to work just that mic, or is it for the jack itself?




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Old Dec 22, 2007, 11:17 AM   #4
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This is what I came up with on thepreamp, went to the local radioshack and failed. walked out with not one item. they are not the best place for these parts for me. Your list was not in full detail, and leaving out the watts on the resistor, and volts on the capacetor., the mic was not even in the store. There were bundle pkgs but not worth a purchase with again left out info.

What I know is . the size is not a problem,- less the switch and jack- you placed on.

need that info as well, for a option to add on to this diagram.



All of this will and can be tucked in without a pc board. and if possable a less voltage used wiring to the lithium is a snap. if not a remote control battery is smaller and will also and can be tucked in.



Microphone : condensor Mic. 2.2 microfarad capacitor (XX vdc). 10k ohm, 1% metal film resistor (XX watts).


This diagram does not have the fulldetailed parts needed

preamp mod


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Old Dec 22, 2007, 1:45 PM   #5
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You are correct on the Diagram. Although, the mic will continue to draw power, so a switch could be used, or just make sure to unplug the battery when not in use.

3.7volts would just not be enough to effectively power the mic element. The higher the voltage, the higher the Sound Pressure Levels and better quality it will be. A smaller 9volt battery maybe. Note: the whole idea is to be able to record in any environment, quiet or noisy.

Here is a part number list for Radio Crack. Prices are approximate.:


270-090 - PC Board Condenser Microphone element $3
272-997 - 2.2mf Electrolytic Capacitor, 50v (anything 9v or higher is fine) $2
271-309 - Assorted Metal Film Resistors, pkg of 50 (you just need one 10kohm)$3
276-148 - General Purpose Dual PC Board $3
275-409 - SPDT Submini Slide Switch, or equivalent $3
274-246 - 1/8" Stereo Phone jack (bridge the tip and ring together) $3
plus a 9volt battery and a 9volt battery connector w/pigtail. $5-6


CAUTION: This is not really for the first timer or the squeamish. I have many years experience with a soldering iron and I have built/fixed many a electronic device, so take heed, young Skywalker. Don't forget, this will obviously void your warranty, blah blah..

I'll post more later.. Really busy with Christmas Ho hO! Plus, I'll post some more videos on Vimeo soon. :?

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Old Dec 22, 2007, 2:06 PM   #6
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Will correct the diagram.

switch goes from battery lead befor resistor +----switch-----resistor common sense.

external jack how would that go, you should be bypassing it if plugged in? that is where we need to correct? ifonewants to do so



And Like I said rather solder on the PCB board snip and use solder shrinks.



thanks All the parts are not by me andthe pkg assortment is 13.00 lol in the bin


Would the Ext go on before the mic and capaceter of(+) and gre (-) wire?
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Old Dec 23, 2007, 1:26 PM   #7
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Excellent work, windowkiller.

Could you set up a watch battery, or several to power the mic? There probably would be room for the batteries inside the case.
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Old Apr 19, 2008, 12:49 AM   #8
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Whatever happened with this, I'm really interested in buying an Aiptek A-HD for in-car video recording and to my knowledge the audio would suck. What's the current solution to the subpar audio?
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Old Apr 19, 2008, 6:38 AM   #9
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members come and go. the unit is not defective, it is the mic and its interior seliphane so possably just replacing it will improve the sound, you may try the Mod andwhat I gotout of it was a headset mic mod worked great but could not go further tahn 2 inchsfrom mouth
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