Creating a subwoofer cabinet and coaxial connection

[lsutiger]

Hey peeps! I am trying to be as frugal as possible. I have two 15" woofers that are in a set of Yamaha speakers. I am building a home theater and in the process came up with a thought. I am builing a cabinet for my lcd tv to sit upon. The room underneath this cabinet would be perfect for a sub, which I would take the woofers and crossover from the speaker set. The question I have is how hard is it to connect the speakers via coaxial ( That's what my amp has as a sub output)? And would any of you suggest this idea? (I do have experience in sub cabinet building, sound reflection - from building for cars...but never did it through coax).
Thanx in advance!
Da Tiger

 

[markw]

Just feed that coaxial output into an amplifier.

and take the amp's output, which are speaker connections, and run them to the speakers.

 

[lsutiger]

Ok

OK..just never did the coax thing...seems simple enough....will go look at some tomorrow

 

[bmccord]

wow, now that is crazy...just last night I had that idea. I am picking up a new DLP and rather than buy a new base cab, i thought I would build a sub enclosure to set the TV on as my current stant is only 50" wide. Then I was going to point support a sheet of perferated stainless steel on the front face of it and paint the enclosure like a deep burgandy. This is what happens when an architect thinks about sub boxes . Anywho, the only thing I have left workin on is how to build the box rigid enough so that the sheet metal does not turn into a giant resonance plate....sorry for the thread hijack, just thought that would be a good use for a couple big subs....

 

[JennAir]

I would take the woofers and crossover from the speaker set.

I'm assuming you have a pair of Yamaha speakers that each have one 15" woofer in them, correct?

The crossover for woofers in a 2-way or 3-way speaker is a low pass filter designed to cross to the mid or tweet. The crossover frequency is most likely going to be well above 200 Hz. If you're building a "subwoofer" chances are that is going to be far too high a crossover point to go to satellites.

If you have a "Sub-out" RCA jack on your receiver it's a line level signal that will require an amplifier to drive speakers with. Your receiver may have a built in crossover. There are many plate amps available that also contain a variable electronic crossover.

Calculate the volume of the cabinets that the woofers came out of. Say, for example, one of the boxes is 1.5 cu. ft. you should build a box that's 3 cu. ft. if you want to use both woofers. If the cabinets are vented you'll need to calculate the volume of the vent tube and double that as well.

Hopefully there's an impedance stamped on the back of the drivers. If it's 8 ohms, wire the woofers in parallel for a "nominal" 4 ohm load. The typical plate amp will be fine with that.

 

[bmccord]

One thing to take into consideration is, though not sure about the effects on LCD, is how big are the magnets on the yami's. I was bored last night and approached my dayton 10 with a compass and it pointed at it when i was 3 feet away so I dont know what that magnetic field will do to an LCD, but I am pretty sure it would kill a CRT. Just a side not, does anyone else know what the effects of magnitism is on other video production units is, such as LCD, DLP, etc...

Brett