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STORMTROOPER VOICE AMP QUESTIONS
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TK 109
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Joined: 11 May 2007
Posts: 712
Location: Galena, Ohio

PostPosted: Thu Jun 21, 2007 12:23 pm    Post subject: Reply with quote

that's what the potentiometer is, a volume control (also known as a "variable resistor").
by following the instructions, i did that circiut in... 3 minutes?
i also found that the "gain" resistor (the actual amplifier) can be set to the highest restor for this aplication (white blck brown, or about... big number coming up.. 1 BILLION ohms of resistance!).
I want to find a very small project encloser box that will house the volume control (with a built-in switch, so i don't need to worry about a seperate switch).
i can make this circuit about 2"x2" square (or less), so if i can find a box that small (that will house my volume control), i HOPE can mount this thing in the back of my helmet, because i have foam and such to work around ( Mad stupid foam...)
i'll post some pics of it in the works, and it in the helmet as soon as i get the materials (which will be friday, or this weekend! Very Happy )
all i gotta say is, i hope this works! Very Happy
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jegner
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Joined: 30 May 2003
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Location: Texas, USA

PostPosted: Thu Jun 21, 2007 12:33 pm    Post subject: Reply with quote

I too am interested in this project. My past two voice amp systems have been big disappointments. Either too much feedback, or lack of volume, and always a headache to wire up once in the armor.

Fans, I have, and are life savers. A tiny option regarding the amp box, mounting it in the helmet, and a mic, then wiring that to some speakers hidden in the suit will be a great project. I am working on the belt, to house the speakers, hidden in the hip boxes.

It's just a matter of making the voice amp!

Keep us posted.

Jim
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TK 109
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Joined: 11 May 2007
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Location: Galena, Ohio

PostPosted: Thu Jun 21, 2007 12:53 pm    Post subject: Reply with quote

whoa!!
that was a fast reply!
Very Happy
one thing i have discovered with feedback is if you seal connections with hot melt glue (or whatever), then make a small cap to cover the black of the speakers behind the helmet (PVC?), and seal that, then you will have almost NO FEEDBACK ( Very Happy )
i need those supplies though...
here's my price list for material:
1. resistor $0.99
2. 1 M ohm (more or less) potentoimeter $2.89?
3. 2 small speakers (not on website) $4.00?
4. small circiut board $3.00
5. project enclosure box $3.00?
TOTAL $15
just an update!
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drcrash
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Joined: 04 Sep 2006
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Location: Austin, Texas

PostPosted: Thu Jun 21, 2007 12:56 pm    Post subject: Reply with quote

jegner wrote:
I too am interested in this project. My past two voice amp systems have been big disappointments. Either too much feedback, or lack of volume, and always a headache to wire up once in the armor.


A parametric equalizer would probably help with the feedback/volume problems. There's probably a kit out there to make one for a few dollars.

A parametric EQ has a selectable center frequency that it boosts or cuts, and can be used as a "notch" filter to cut frequencies within a narrow band around that center frequency.

Sound engineers use them to prevent feedback all the time. You just set the center frequency to the problematic frequency, and turn it down. That lets you raise the overall level substantially higher without feedback.

This is most likely to work if your feedback is generally at the same frequency, which is usually true due to some resonance.

(That might not be as true with something where the distance between the mic and the speaker changes---the resonant wavelength is usually a multiple of that distance. But I suspect it would help.)

A parametric EQ could probably be really small (and cheap) if you use trimpots instead of full-sized potentiometers to set the center frequency and the boost/cut level.
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Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com
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TK 109
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Joined: 11 May 2007
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Location: Galena, Ohio

PostPosted: Thu Jun 21, 2007 1:03 pm    Post subject: Reply with quote

so, i should go for a trimmer, rather than a full blown potentiometer for my volume control, then, or what?
just wondering!
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jegner
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PostPosted: Thu Jun 21, 2007 1:50 pm    Post subject: Reply with quote

Good points, Doc. I think one of my issues is my mic. I need a lower gain pickup, or to put it in other words, something less sensitive. My current one is a lapel mic. Too sensitive.

Jim
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TK 109
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PostPosted: Sun Jun 24, 2007 3:42 pm    Post subject: I'M DONE!! Reply with quote

I'm finally done with this thing! Very Happy
It works PERFECTLY for this application! I need to solve some issues on feedback, though.
here are some pics:

this is my helmet. the only thing different on the outside is real mesh for the areators. it's a rubies helmet, good enough for me!


here's the actual amplifier ciciut board. not much, really. its simply hot-melt glued in place. what does the underside look like? a mess! just imagine colorful spaghetti... the capacitor (the blueish tube-thing protruding for the board) doesn't really give me troubles for putting on the helmet. notice there is no volume control. just a 10 M ohm resistor. (the control simply would not fit) Sad what a cob-job, eh? I sealed connections with hot-melt glue.


here is a shot of the speakers, fan and other stuff. the helmet is blow-molded PVC, with the areators, so all i did was dril out the plastic, replaced with mesh, and hot-glued the speakers on. i'm thinking of sealing these up to prvent feedback (or SOMETHING). notice how the batteries are mounted... the mic is mounted on foam, to prvent feedback and vibrations.


the whole inside of the helmet. that green foam didn't interfere with mounting the project, really.


yeah. it works. it works well. Very Happy

the volume (and gain) is just enough to cover up my regular voice. my only issue is feedback. solution? seal up the backs of the speakers. i have a feeling this will work. i did test with the family, and they could not hear my regular voice, even up close. you can sorta see the wiring under the helmet, which is no big deal, i can probably paint it, or something.
so yeah, now you guys know this stuff works! I'm happy with it!
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jzawacki
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Joined: 12 Jan 2007
Posts: 70
Location: Illinois

PostPosted: Mon Jun 25, 2007 1:22 pm    Post subject: Reply with quote

can you post an .mp3 of you talking with it?
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thebluecanary
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Joined: 02 Feb 2006
Posts: 123
Location: St. Louis, MO

PostPosted: Mon Jun 25, 2007 2:15 pm    Post subject: Reply with quote

You could always uses a set of black wite gard things. They look like small coragated tubing that is split all down one side. You can find them in any auto place. They come in many colors. Just tell them you are trying to hide some wire. Easy as pie.
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TK 109
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Joined: 11 May 2007
Posts: 712
Location: Galena, Ohio

PostPosted: Mon Jun 25, 2007 2:44 pm    Post subject: Reply with quote

hmmm...
guess what, i do have feedback issues! you know what else? i tried to fix this issue by sealing away the speakers from everything else. it made the feedback MUCH worse. and then i tried to remove the little containers i glued in there, and broke BOTH speakers. Mad
back to radio shack i guess, and a question:
WHAT'S THE BEST WAY TO PREVENT IF NOT TOTALLY ELIMINATE THE ISSUES OF FEEDBACK? I tried google, and they gave me nothing.
i cant believe i broke it already! more money down the drain. I HATE THAT! Mad
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jegner
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PostPosted: Mon Jun 25, 2007 9:35 pm    Post subject: Reply with quote

Feedback are some of my issues with my current set-up. The ExtremeFX rig is looking better all the time. Try a different mic maybe? I think a lot of my issues are mic related.

Jim
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TK 109
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Location: Galena, Ohio

PostPosted: Wed Jun 27, 2007 1:21 pm    Post subject: Reply with quote

well...

i installed the new speakers, arranged the microphone, and tested.

at first, nothing happened. then, i added a restor in place of the missing variable resistor (volume control). i tested again. nothing again.

then, i just toggled the switch, and it fired up. seconds later feedback MUCH worse than ever before. I tried rearranging the mic again, and i got nothing different.

now its to the point where the instant you turn it on, you get VERY LOUD feedback ( Crying or Very sad )

I give up. I'm buying something online that's cheap, and something that works. i'm going to buy the xtremegadget amp. if this doesn't work, i surrender completely. oh well.... i guess that's how it goes, eh?

unless someone has a better, cheaper idea, i'm buying the xtremegadget amp.

man, what a dissapointment....
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TK 109
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PostPosted: Thu Jun 28, 2007 10:52 am    Post subject: Reply with quote

i'm going to buy a headset mic at radio shack, just to see if that does it.

if not, im going to scrap the whole thing before i spend more money on it!
i have a feeling a new mic will do it! i may try to buy a project enclosure box for it, and put it behind my chest plate (maybe)
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drcrash
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PostPosted: Thu Jun 28, 2007 12:09 pm    Post subject: Reply with quote

A couple of things that often help, besides a parametric EQ, are:

1. A directional microphone, with a cardiod or supercardiod pickup pattern, pointed directly at the sound source.

2. A directional speaker/enclosure, which projects sound forward more than to the sides. Specifically, you want one that doesn't radiate sound as effectively toward the microphone as it does toward whereever the sound is supposed to go.

Putting something in between the speaker drivers and the mic is a good first step. You want to block the major sound path(s) from the speaker to the microphone.

Depending on the frequency or frequencies that are feeding back, you may need a barrier with some mass to it. A lot of frequencies go right through lightweight stuff. (Lower frequencies go through more massive stuff better than higher frequencies.)
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Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com
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jzawacki
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Joined: 12 Jan 2007
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PostPosted: Thu Jun 28, 2007 3:50 pm    Post subject: Reply with quote

Maybe try some Dynomat to help deaden the sound around the bakc of the speaker.
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