[Brucemck]

I purchased a pair of Feastrex d5 Alinco units used.

Considering a design with the d5s covering the high end and a sealed box covering the low end.  Will actively amp and use DEQX or similar as crossover.

For aesthetic reasons would prefer a narrower over a wider baffle.  If I want to cross the d5s around 150hz or 200hz do I need the wider baffles I see in so many designs, or, would a baffle just slightly wider than the d5s themselves work ok?

Put differently, if I don't need bass below 150hz or so, what are the tradeoffs with narrower/wider baffles?

[dewar]

Hi Brucemck

I wont try answer your question, though I have a suspicion that slightly wider than 5" will put roll off a fair way above 150-200hz.

What I'm wondering about is whether DEQX has the ability to flatten 300-200hz if say roll off started at 300hz? Should cost much headroom to bump up these frequencies a few db.

Do you also think the insertion cost of the ADC-DAC step (as transparent as the DEQX is) is worth it if you have active XO on the subs and are not going to use a tweeter, i.e just highpass the Feastrex? I was thinking of going your exact route a with the Feastrex and DEQX a while back.

Would be really interested to hear how it turns out.

Cheers
B.

[Magnetar]

In my experience a .2 QTS 5" is more like an upper midrange or low treble driver on an open baffle. With a narrow baffle to reach 200 cycles (it will require a lot of eq) you will be giving up a lot of dynamic headroom and output as well as driving the little driver into major excursions and distortion. A wider baffle will only be a little bit better.

The best way to extend the response of a 5" low QTS driver is with a good horn.

I purchased a pair of Feastrex d5 Alinco units used.

Considering a design with the d5s covering the high end and a sealed box covering the low end.  Will actively amp and use DEQX or similar as crossover.

For aesthetic reasons would prefer a narrower over a wider baffle.  If I want to cross the d5s around 150hz or 200hz do I need the wider baffles I see in so many designs, or, would a baffle just slightly wider than the d5s themselves work ok?

Put differently, if I don't need bass below 150hz or so, what are the tradeoffs with narrower/wider baffles?

[Angaria]

Based on my experience I'd agree with magnetar.  There are a number of programs/worksheets to calculate dipole rolloff. 

[Christopher Witmer]

You may want to experiment with fold-back wings on a  piano hinge, or some other way of getting a larger baffle without getting a broad frontal area.

-- Chris

[scorpion]

Brucemck,

I also agree with Magnetar. But of course you can and shall go OB but bafflewidth is essential. Have a look at Dick Olsher's Feastrex baffle here: http://www.enjoythemusic.com/magazine/equipment/0107/diy_loudspeaker_project.htm . The NoBox construction is here: http://www.visaton.de/en/bauvorschlaege/breitband/noboxbb/bauanleitung.html . This width or about 18" should fix 200 - 300 Hz crossover and if you don't already have the subs I definitely  also would recommend the Augies for a formidable combination. 

/Erling

[Brucemck]

Erling, thanks for the links ... A "dumb" question I suppose ....

I tried using Edge to model the speakers (and now understand why a very narrow baffle won't work), but, why do people put the midrange or full range driver on the horizontal middle line?  Edge suggests that offsetting the driver to either the left or right side gives a far better frequency response in an open baffle?

[scorpion]

Well, there are more consideration to this question. Offsetting the driver will benefit the on axis response by equalizing diffraction performance just in that direction. The argument is however that this is just on axis as soon as you go outward dispersion performance will be degraded. This is another compromise you will have to live with. Myself I offset a bit because for yourself you usually listen on axis. But I do not think that that the differences are that determining, so if you will choose a more balanced dispersion pattern I think you will live happily placing the speaker midway also when listening on axis.

/Erling