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speaker design help needed

duder1982

duder1982

Active Member
hello everybody(using a voice like dr. nicks off of the Simpsons).

I was looking at building a "inwall" or in this case a in celling surround speaker. I know I could buy some decent ones that would work great.. But I would like to take a diy approach to it myself. I have tosed around a few ideas but the one I would like to stick with is based off of these drivers/horn components.

Horn

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=279-106

woofer

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=294-2060

Couple of reason for these parts, I have some Klipsch/tractrix in my system as is. Plus the woofer was recommended for that horn by the tech team at pe.

The areas I need help is figureing what cab volume is needed, and crossover design. These seem basic but as I start to look into it, it gets confussing.

If woofer list there recommended air space that makes it easy but when they don't how do you calculate what is needed for appropriate air space.

The dayton ones at pe for 2 way are 2nd order Linkwitz-Riley, but they don't offer a 4000 hz.
The recommended crossover is at 4000 hz, when I google 2 way crossover designs I get them for 1st order 2nd order and so on. Then they add Linkwitz-Riley, Butterworh, Bessel. What does all this order and names stand for.

What do you all think, I don't know how it will all sound but I would like to find out.:scratch2:

Thanks
Duder
 
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The recommended crossover is at 4000 hz, when I google 2 way crossover designs I get them for 1st order 2nd order and so on. Then they add Linkwitz-Riley, Butterworh, Bessel. What does all this order and names stand for.
Click to expand...

Let me suggest you this reading: Every concept explained there.
http://www.bcae1.com/xoorder.htm

About the box volume, there are several calculators on-line and free software to download. You need the manufacturer data for your woofer. Try different calculators to double check the value.
http://www.hometheatershack.com/forums/enclosure-volume-calculator/

If you want to do it the easiest way, I suggest you to get a kit, already designed and calculated. If you prefer to learn, a 2 ways is a very good starting point.
 
Hey thanks for the info, I think I have a idea on the crossover. I just need to figure out what quality components to use.

I have used the box calcutlations in the past for other projects, but on this one I don't know the needed volume. So I kind of cheated and emailed Celestion's tech support.

I have some time to do some more research, as I don't plan on really doing anything until after Christmas. Which gives me plenty of time for research on this project.

THanks
 
duder1982 said:
I was looking at building a "inwall" or in this case a in celling surround speaker. I know I could buy some decent ones that would work great.. But I would like to take a diy approach to it myself. I have tosed around a few ideas but the one I would like to stick with is based off of these drivers/horn components.
Click to expand...

First thing...the horn. If you're doing an in-ceiling surround speaker you want something with good dispersion. A horn isn't it. What you'll get is very strong sound directly under it and weak sound elsewhere. If your listening position isn't right under them then things will get weird.

The areas I need help is figureing what cab volume is needed, and crossover design. These seem basic but as I start to look into it, it gets confussing.
Click to expand...

That woofer really wants a ported box. Putting it in a small, sealed box will give you a very high F3 (bass roll off point). Bassbox6 says that optimum sealed is .28ft^3 which gives an F3 of about 180Hz. That's way too high. It will sound like an old AM radio.

A ported box of about .5ft^3 would get you down to around 90Hz. It'll be much more reasonable but still not much low bass. You'll be giving up low bass to gain sensitivity.

The dayton ones at pe for 2 way are 2nd order Linkwitz-Riley, but they don't offer a 4000 hz.
The recommended crossover is at 4000 hz, when I google 2 way crossover designs I get them for 1st order 2nd order and so on. Then they add Linkwitz-Riley, Butterworh, Bessel. What does all this order and names stand for.
Click to expand...

The order of a filter describes how fast it rolls off the response of that driver. A first order will be 6dB per octave. So every time the frequency doubles (or halves) the response will go down 6dB. A 2nd order will be 12dB/octave, and so on. In a real world filter the order will be represented by the number of capacitors and inductors in the circuit. A first order high pass filter would be a single capacitor. A second order high pass filter would be a capacitor in series and an inductor in parallel with the driver.

The names associated with filters describe the shape of the filter at the roll off point. Butterworth filters are maximally flat and the 2 parts of the crossover intersect so that each driver is down 3dB at the crossover point. A Linkwitz-Riley crossover will cross so that each driver is down 6dB so the summed amplitude response is flat.

That may be more technical mumbo jumbo than you were looking for but I hope it helps some.

FWIW, I don't think horns based, ceiling mounted surround speakers are a good idea. Of course that's just my opinion.
 
RayW said:
First thing...the horn. If you're doing an in-ceiling surround speaker you want something with good dispersion. A horn isn't it. What you'll get is very strong sound directly under it and weak sound elsewhere. If your listening position isn't right under them then things will get weird.



.
Click to expand...

So it would be better to have mounted on the back wall or side all if used a surround.
 
RayW said:
That woofer really wants a ported box. Putting it in a small, sealed box will give you a very high F3 (bass roll off point). Bassbox6 says that optimum sealed is .28ft^3 which gives an F3 of about 180Hz. That's way too high. It will sound like an old AM radio.

A ported box of about .5ft^3 would get you down to around 90Hz. It'll be much more reasonable but still not much low bass. You'll be giving up low bass to gain sensitivity.



.
Click to expand...

I emailed tech support at celestion and yes they recommended a box with a 12-20 litres which turns out to be about .42-.70 cubic feet with a port about 2 inches in dia, by 1-2 inches. So sounds like you hit that pretty close on the nose.

I will take your input on the ceiling mounted horns.

As for the crossover thats a lot of tech stuff I have been slightly understanding. Would it be possible to try a couple of different crossovers and take some readings to make sure they are crossing over correctly and some a/b comparison to see what I like best.
 
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