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[jarleifv]

Has anyone ever implemented BVC using a mixer and wired microphones, and wired speakers? 
I'm planning on installing small speakers in the air ducts right below the floor registers to avoid having to hide a speaker in a corner behind the couch..or out in plain view where there's no furniture to hide behind...

I'm also planning to install microphones slightly poking up through the floor register, with some sort of wind deflector below the microphone for when the heat is on.
Has this been done before? if so I'd be curious to know how the microphones functioned at floor level. i'm using a Radio shack mixer so that I can use the line-in instead of the mic input on the pc.

Thanks

[HA Dave]

Has anyone ever implemented BVC using a mixer and wired microphones, and wired speakers? 

Yep. Knightrider has (he has an awesome top-of-the-line setup). I am sure he will respond here also.

I'm planning on installing small speakers in the air ducts right below the floor registers to avoid having to hide a speaker in a corner behind the couch..or out in plain view where there's no furniture to hide behind...... Has this been done before?

I haven't heard or read of a furnace duct-work install. But I do know they make special higher temperature CAT5 for duct-work.

i'm using a Radio shack mixer so that I can use the line-in instead of the mic input on the pc.

The "line in" is what always has to be used. The autogain on the microphone jack makes continual use on it... impossible.

[jarleifv]

The air duct seemed like a logical place to me, since there's at least one air duct in every room. I'm planning to drill a small hole for a small speaker (something I'd harvest out of old computer speakers), then mount this on the outside of the duct playing into the duct and up the floor register. To limit the sound traveling into the basement i'll cover up the speaker with some duct tape, the reflective kind for ducts. 
I wouldn't need any special wire since the only thing touching the duct would be the speaker (it's not like the duct gets all that hot by the floor register anyway). 
I'll mount the speaker on one side of the 2"x12" opening, and the microphone on top of the grate with the wire poking through the sheetmetal below the floor.

in theory ..this should work...the only thing i'm worrying about is how the mic's will respond at floor level. Anyone have any experience with cheap sub $10 omni mic's?

[-Bill- (of wgjohns.com)]

... Anyone have any experience with cheap sub $10 omni mic's?

I would guess that the built-in mic in my old Pentium III laptop was similar, and it worked well from half-way across the house.   
 

[HA Dave]

.... I'll mount the speaker on one side of the 2"x12" opening, and the microphone on top of the grate with the wire poking through the sheetmetal below the floor.
........ the only thing i'm worrying about is how the mic's will respond at floor level.

I just put my [baby monitor] microphone on the floor to test it for you... and it worked fine. I originally setup using babymonitors (as seen in this YouTube video). I had always planned on using intercoms [both microphone and speakers... and wireless]. But the Monitors have worked great or four years now and I never bothered to switch.

[Knightrider]

i have whole house audio with a gated mic system and speakers mounted in-wall.  Used un506's to switch.  had an amp to handle the various loading. posted it all here somewhere.

one concern:

I'm very careful with my mics and corrosion/ moisture.  I always cringe when I hand a mic to a best man and he blows air on it to check to see if it's on.  This is bad.

I'd worry that an hvac system might do the same.

I'm heading to western Indiana, and will post more or answer questions when I get back (hopefully Sunday)

[dave w]

I'm heading to western Indiana, and will post more or answer questions when I get back (hopefully Sunday)

Hey, Wave as you drive by!   

[HA Dave]

..... will post more or answer questions when I get back (hopefully Sunday)

So glad your here to provide info Knightrider. My setup is a result of NOT having the audio knowledge required to create a suitable setup. But I did several tests and experiments and found something that worked for me. I.. of course... want to encourage jarleifv [and any new BVC user] to also try out their ideas. But... I just don't have the knowledge base to offer advice or direction.

[jarleifv]

picked this Mic up today. Waiting on the mixer to arrive so I can test this thing.. My plan is to flush mount the mic in the baseboard surrounding the built-in shelf in the TV wall...hopefully that'll pick up the Living room and Dining room.

http://www.radioshack.com/product/index.jsp?productId=2062215

Next on the list is mounting speakers in the floor register duct..just below the floor. I'm using some old PC speakers that I took apart. i'll wire the speakers in a variety of series and parallell depending on impedance. Can't imagine this PC speaker set is stable real low..although, I'm not playing constant music through these speakers, just the occasional voice confirmation from BVC..

stay tuned! 

[jarleifv]

The first speaker was mounted last night, on the side of the cold air return duct. This speaker is 2"x3" out of an old computer speaker pair. It covers our living room and kitchen easily.




The speaker was mounted at #1.

I used sheet metal screws to hold the speaker to the duct, and to transfer the sound into the duct I used a nail and made 5 small holes in the duct. The speaker was simply placed on top of the holes. It sounds just like the speaker is laying right below the grate!  I'll cover the speaker up with some sheet metal and insulation. This should prevent most of the sound from entering the basement, as it's currently just as loud in the basement as upstairs! 

[HA Dave]

I certainly appreciate your posting the pictures and updates!!! This is something that has no text books to learn from. We only have each others experiences on which we build our knowledge base. Posting this kind of information helps everyone! Thank you for keeping us in the loop.

[aussie mate]

I installed wired speakers and microphones in my setup. I use a multi zone amplifier to provide switching for the output to the speakers in different rooms which is turned on by motion sensors. For the microphones I used Beyerdynamic MPC22-EQ3-WS microphones with phantom power and a 12 channel microphone mixer with automatic gating. This is voice activated to switch between the ceiling mounted microphone in each room. The output from the mic’s go into the PC via a line level input using an external sound card.

I can see some potential issues with your proposed setup.

Speakers: - these should be ok but you don’t say how you plan to switch between them or will they all be on at the same time? If you plan to switch then on & off then you need to make sure you match the impedance so it doesn’t become unbalanced which can not only cause problems but ruin the amplifier.

Mic's: I think you will struggle to get more than 1 mic working unless the mixer can automatically switch them on & off. I also think that as the mic you list is not powered the gain from them will be low and/or distorted to work effectively.
You also need to look at the room acoustics and such things as echo. If you have carpet then it will work better than a hard surface.

Note that getting the mic's to work reliably is the biggest challenge.

[Brian H]

aussie mate. Made a good point. The microphone from Radio Shack needs a DC power supply of 2-10 volts and then a few electronic parts to get the sound and DC separated.

It may come with a diagram on the package but here is some generic data on the condenser type microphone.
http://en.wikipedia.org/wiki/Electret_microphone

[HA Dave]

...This is something that has no text books to learn from. We only have each others experiences on which we build our knowledge base.

I was mistaken! The electronics and audio knowledge that people like Brian H, aussie mate, Knightrider, -Bill- (of wgjohns.com) and others could fill VOLUMES of books (none of which.. I have read).

..... make sure you match the impedance so it doesn’t become unbalanced which can not only cause problems but ruin the amplifier.

When aussie mate mentioned ruining an amplifer... I was reminded that on the other end sound cards can also be ruined with too heavy a burden [of PC speakers] as well. Likely the only reason my poormans setup actually worked and didn't damage my PC was because I listend to these people or people like them.

It can be a fine line between trying something new and innovative... and making a costly [or even dangerous] mistake. These guys make a very helpful sounding board for new ideas.

[jarleifv]

all good thoughts and things to think about.. I'm not sure that a gated setup is required since my home is pretty quiet..my wife and I are almost never in different rooms, and no kids so I'm thinking i'll be ok without the gated option..

as far as speakers go, I'm pretty much all covered there. I don't power speakers off the sound card, and I'll wire speakers while observing effective impedance after serial/parallel connections..

my next little mini hurdle is a Line-in on the tablet i'm using..it only has a mic input, so I just picked up an external USB sound card with a line-in.. now all that remains is playing with microphones to find an optimal solution..should be the most difficult and most frustrating i'm sure.. lol

If i have to build some small PCB's with 9 volt batteries to power mic's I'm ok with that, since I'm sure the batteries will last a while even if they're left connected at all times..can't imagine the drain current would be all that high..

I'm on a diy el-cheapo budget, so I'm not planning to buy $300 microphones..