Open Baffle Sub

[inrank]

i want to add some cheap agumentation to my Hawthorne Audio 10" Silver Iris's, and i would like to go OB....

so are cheapish car subs any good?

found this...
http://www.partsexpress.com/pe/showd...number=297-284

with QTS-0.72, 91dB, Fs-28Hz and 10mm xmax looks great for open baffle and at $50 very cheap.

then partnered with a sub amp like this....
http://www.partsexpress.com/pe/showd...number=300-805

for $150 in total, is this a good idea?

(would go for the Auggies, but dont want to spend so much at the moment )

[mashaffer]

Are you wanting to do a true subwoofer or just an augmenting woofer. If the later there is some advantage I think in going with something like the Eminence Alpha 15. It has larger cone area and higher Qts which will help keep the baffle size under control.

The Fs on the Alpha is higher and the Xmax lower (mitigated by the larger cone) but the pioneer will not go any lower really on a reasonable sized baffle. If you are doing a seperate subwoofer than a really large baffle might give the pioneer an advantage.

I had pretty good luck with a suboptimal driver in an N-frame box. My limitation was the low Xmax of the organ speaker I used. I would expect the pioneer to do quite well in that arrangement, plus in the N frame no one would see the silly blue paint job.

See the attached picture of the N frame layout. There is a top and bottom plate on it to make a box. It is about 21" deep 18" wide and 17" tall as I recall.

Hope this helps.

mike

[inrank]

hi thanks, i am not looking for 'lots' of bass, had looked at the Alpha 15, didnt really want somthing that big, only got a smallish room of 11ft square, that 'n' baffle looks interesting, does it rob some efficiency? and could it be made a little shallower

[mashaffer]

The N is pretty easy to build so no reason not to play with it. I made sure to give the driver plenty of room to breath so I don't think it hurt efficiency at all.

I never did get around to measuring the params on that organ speaker but it seemed to have a fairly low Q based on its perfomance on a plain baffle and the fact that the organ it came from was ported. With a higher Q speaker you should be able to make the box a bit smaller. Smaller box will give more baffle rolloff but the higher Q would compensate to some extent. Try something about 18" deep and see how it works. My version was solid down to 40Hz and had usable output down to 30 if I recall.

That pioneer is about ideal for IB and pretty good for OB by the looks of it. I say get one and try it out.

A pair of these in a W frame is another possibility for a fairly compact OB. The cost is similar to the pioneer and the combined xmax is close. The much larger Q would allow for less baffle.

And a pair of these would move a lot more air me thinks.

mike

[Riche Lemuey]

hi mashaffer,

you mentioned about the W-frame.... was that the W-type baffle?
if it is... i was actually searching information about that....

i have an 18" 600watts speaker.... iwant to Diy a W-type baffle...
can you give me details on this? the dimentions, how would it look like....

i am planning to drive this with "brother of Quasi- Bip350
or the Leach SuperAmp.
Thanx..

Riche

[RobWells]

Just remember to add postage, vat and import duty to anything you buy from partsexpress - their postage costs have always ruled them out as a supplier for me.

Rob.

[mashaffer]

Riche, what I am talking about is an pen baffle system rather than a W bin horn which many envision. If you take two of my Ns above and remove the panel behind the driver and then stick them together with the woofers back to back you have the general idea.

Dimensions would not be super critical I think just be sure woofers can breath. Also longer chambers lower overall system f3 but eventually would become a noticable resonator ala transmission line.

mike

[AndrewT]

Hi,
the cost of big drivers in the US is very attractive.
Transport more than doubles (or is it triples?) the cost by the time they land in the UK.
A box big enough to hold a couple of 15/18inchers will surely attract the attention of customs (=duty).

[inrank]

thanks for the reply's, been thinking and looking at my bank balance, i cant really afford that idea, so i am going to add a pair of Eminence Alpha 12's onto the baffles of my existing speakers, with a simple passive low pass, cost about £50 and then i can save up for some HA Auggies and Plate amps

[tinitus]

The Alpha 12" might actually be a good choise, but a bit high Fs and small Xmax

May I suggest you take a look at this very cheap 12" Monacor with nice "dipole-specs", designed fore "Free-air"

http://www.monacor.dk/produkter/bils...er/vnr/102820/

The bigger 15" has very low Fs=20hz, but Qts is "low" at 0.44, and more "expencive"

http://www.monacor.dk/produkter/bils...er/vnr/102830/

You should be able to find them in UK

http://www.monacor.com/int/en/produk...pr=EN&brand=CP

BTW .... 4ohm drivers means you will need smaller inductor