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Old Feb 21, 2008, 6:53 AM   #31
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Welcome aboard. wow, great stuff. justwished the ino on what weneed to do would be shown i nadetailed vid

a screw on securuty lens, and a volume control wow.



88impact_blue88 wrote:
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It looks like someone has put examples of an the sound from an external mic port attached to the Aiptek A-HD

http://www.youtube.com/watch?v=ewrmIW-EP_4

http://www.youtube.com/watch?v=zpPMHx-sjCw
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Old Apr 18, 2008, 2:19 AM   #32
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It is likely that the microphone could have a separate preamp on the board, with the gain set by resistors. If so, changing the resistors will change the gain.

http://www.projectsunlimited.com/aud...ucts/index.htm has a lot of mics WITH exact specs, including sensitivity.

It is entirely possible that the Aiptek suffers from a hardware design problem that the software cannot compensate for. This would explain why they didn't address it in firmware upgrades. I'm confused as to what the problem is- I head on one side it's too quiet, and on the other side that it clips with modest sound levels. Is that right? The analog signal might be amplified too loud and clips the max voltage of the ADC, resulting in both clipped noise and a limit on how loud the audio can be. Software can't compensate for this.

A microphone must be properly biased of course, note that ProjectsUnlimited specifies voltages and impedances. What's the open-circuit voltage on those 2 wires with no mike hooked up?

I can't believe they faced that mike up. No wonder outside noise overwhelms the sound from what you're filming!
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Old Jun 5, 2008, 11:11 PM   #33
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Thanks for the ideas on adding the external mic. Here's my solution for an extra jack without having anything sticking out of the camera. Uses theoriginal mic unless and external mic is pluged in. Hot glue holds the jack in place.





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Old Jun 6, 2008, 6:11 AM   #34
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video sound sample is needed please lol



KurtC wrote:
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Thanks for the ideas on adding the external mic. Here's my solution for an extra jack without having anything sticking out of the camera. Uses theoriginal mic unless and external mic is pluged in. Hot glue holds the jack in place.




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Old Jun 6, 2008, 6:36 AM   #35
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Great work, I will implement this for sure, I will send audio samples when I have this ready, though I have never used hot glue before :-) I was thinking changing speaker location and installing mic port there, but this looks much better.

One question: what kind of jack you used? I can't find small enough jack with switch in any electronics store.

KurtC wrote:
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Thanks for the ideas on adding the external mic. Here's my solution for an extra jack without having anything sticking out of the camera. Uses theoriginal mic unless and external mic is pluged in. Hot glue holds the jack in place.




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Old Jun 6, 2008, 1:25 PM   #36
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I pulled the jack from an old mini tape recorder. It was a tight fit.



Audio is still the same unless I plug in the external mic. Don't really notice much change in sound quality with the remote mic. My main issue was wind noise as I have this mounted in my car for track video. I plan to put the external mic somewhere below the seat.
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Old Jun 6, 2008, 3:16 PM   #37
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what you're saying any type of filming like i do forexamplestanding outside 15 feet away trying to explain the scene, will get me the same exact sound with a mic?

"now imagine this. using a blue tooth mic or other type of wireless mic.

"I would like a drawing boar of how to hook up sorry if I am besing very descriptive

there are only two wires o nthe A_HD. and there seems to be a few moreto the mic.
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Old Jun 6, 2008, 4:42 PM   #38
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I just made external mic mod for AHD and no difference in sound. It really is low quality audio circuit in this camera which makes bad audio not bad microphone. I am trying new firmware which I got from Aiptek, I hope it will improve audio. I also bought external audio recorder, but it is so difficult to use, all editing and carrying lot of stuff isn't for me. I am going to use it only for rare occasions where top quality audio is needed like music performances.
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Old Jun 6, 2008, 8:40 PM   #39
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So, I still use my A-HD all the time. I've filmed my band live, I've filmed my family, indoors and out (indoor needs creative lighting).
I have changed my setup from the initial Bulky, battery pre taped to the side.
I used the same Radio Shack 1/8" plug from my first mod, but that's it.
Oh, I replaced the Aiptek Microphone element with a Radio Shack one. It is a little bigger, but for some reason, it sounds a hell of a lot better. Better frequency range, I think..

I wired the plug up pretty much the same as KurtC up above did, except without relocating the plug to the back, (and i used shorter wires).
So, it uses the built in mic normally, but if I want to use an external mic (with battery power or not) I can plug it in. Plugging into the jack effectively disconnects the internal mic.

Simple and highly effective mod. I have even been able to record live concerts with the internal mic without it crapping out. Maybe the jack adds just enough impedance to raise the headroom of the mic? I don't know.. But it works bitchin.
I did this mod back in February, and my camera has a few war scars, so it is tested and true.
Oh, and I bought a new toy that works and sounds much better than any mod to the Aiptek. Say hello to the Tascam DR-1:

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Old Jun 8, 2008, 2:19 AM   #40
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Hello all, I was wondering if any of you know what the output voltage is of the standard AHD electret mic? The reason I am asking is I have just bought an AHD (haven't received it yet) and I have started to design a preamp circuit for another electret mic and I am wondering what kind of gain I should have, although I have been thinking about using a trimpot to make it variable gain. I'll be tying it into the power supply of the AHD. Component count so far is 5, including microphone.

I also think I know why the mic gives off so much noise, Electret mic's usually have a built in FET based pre-amp, usually its pretty decent for mass production circuitry, but some of them are just shoddy and generate or pick up and amplify noise. So a 2nd preamp, with noise rejection should help.

I have seen another pre-amp circuit floating around, I can't remember who drew it, but sorry to say, it isn't a pre-amp. The circuit consisted of the mic, a resistor, a capacitor and a battery, this is just the proper way to power an electret microphone, but isn't a pre-amp. Any kind of amplifier needs at least 1 transistor.

Also, I have thought about possibly trying to move the microphone to the front, but I am unsure if there would be enough room to mount it there.

When I get my AHD and have built the circuit and tested it, I will post some before/after demo's of it. Hopefully it will work and make nice clean sound.
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