5th speaker

[bryan750]

I asked this question before but I had an idea about building my own 5th speaker,I currently have a pair of cornwalls and a pair of heresys and I was thinking of buying raw drivers and a x-over for a cornwall, anyone tried this and would I need the 15inch woofer?

[michael hurd]

You could build your own center channel speaker, as many have done on this forum, but there are several points that you need to make clear.

Do you have wood working skills, and/or access to power tools? Do you have soldering skills, and a basic knowledge of circuits, both parallel and series? What type of television or display do you have, and will the speaker be close to it?

You wouldn't necessarily need a 15 inch woofer, two 8" or 10" shold be fine, but keep in mind that to match the sensitivity of the cornwalls, you need efficient drivers.

Check out the Eminence beta 8" woofer, parts express # 290-404. It sells for $ 47.06 usd and will work fine if you do NOT have a regular tube type television.

Just ran some numbers in the parts express box program. Looks like 2 beta 8" in a 4.06 cu ft ported enclosure would be quite nice.

Of course you could make a smaller enclosure, but this would be the maximally flat response. The numbers are as follows, 4.06 cu ft enclosure ( internal measurements are 30.97" x 19.14" x 11.83" ) with 4 2" diameter ports 1.83" long. Tuning frequency comes in at 52.17 hz with a theoretical f3 of 45.32 hz.

Sensitivity is 94 db, so two in parallel would give you 97 db/1 watt, very close, with the cornwall crossover that you proposed. Impedance is 8 ohms each, so the crossover would have to be changed to keep the crossover point at 600 hz.

Specs are as follows:

Specifications: * Power handling: 225 watts RMS * Voice coil diameter: 2" * Le: 0.58 mH * Impedance: 8 ohms * Re: 6.36 ohms * Frequency range: 55-4,000 Hz * Magnet weight: 34 oz. * Fs: 58 Hz * Vas: 1.25 cu. ft. * Qms: 6.54 * Qes: .36 * Qts: .34 * Xmax: 3.0 mm * Dimensions: Overall Diameter: 8.24", Cutout Diameter: 7.13", Mounting Depth: 3.5".

[michael hurd]

The easier way would be to buy a single heresy or a pair, and ose one for a center channel. If your televison is a rptv, then you will be fine. If you have a tube-type television, the magnetic field can affect the color of the display. It could be reduced by: turning the heresy upside down on top of the television, and also elevating the speaker a few inches above the television. You could also wall mount the speaker, if this is possible.