Making Two Speakers Work Together

[MuaDibb]

I intended to build some computer speakers using the fullrange 3" TB 871S. Breaking them in on the baffle I decided to scrap the cabinets and have a mini open baffle design. I would like to add a speaker below to help with bass like many normal sized OB's.

Top speaker: TB W3-871S 110-20,000 HZ
Bottom speaker: TB W4-9925 55-2500 Hz

On another thread with a similar design somone suggested connecting the speakers in series and putting a ~100uf cap across the +,- of the woofer speaker.

What crossover point does this yeild, and is there a way to figure what value cap will yeild a specific crossover point?

Does this just cut off the higher frequencies from the woofer and allow the top speaker to operate as a fullrange?

[owdi]

The xover frequency would be about 200hz. IMO, use a 50 uf cap on the w4 and a 2.5 mh coil on the w3. The coil will reduce distortion and increase power handling. With those two components your crossover frequency is around 450 hz, which is about where output from the w3 drops off on a small baffle.

Dan

[lndm]

Just how did they suggest you connect this cap? Did they say connect the two woofers in series and put the cap on the terminals of just one of the woofers?

This would give rise to a boost of 6dB or so at the frequency of interest, as above this frequency one woofer is shorted out of circuit. I would first guess the frequency to be 200Hz but your mileage may vary.

This effect would be desirable in compensating for baffle rolloff.

Do not connect the cap across both woofers or your amp will complain loudly.

[Andy G]

Originally posted by owdi
The xover frequency would be about 200hz. IMO, use a 50 uf cap on the w4 and a 2.5 mh coil on the w3. The coil will reduce distortion and increase power handling. With those two components your crossover frequency is around 450 hz, which is about where output from the w3 drops off on a small baffle.

Dan

Well looky at that, you just built yourself a series x-o !!

[MuaDibb]

Thanks guys thats what I was looking for. Since I know nothing about x-o's, could somebody post some suggestions for researching this topic?

I have also seen posts where they have suggested adding a wire
to connect the negative terminal on the speaker to the frame. Would either the 4" or 3" benefit from this and what does it actually do for the sound?

[rabbitz]

Have a look at these.

http://www.rzaudio.com/rz52/Crossover.htm

http://www.bcae1.com/passxovr.htm