Q12 System

Just posted pics of these in the other place so thought I would also share with FSP.

Bass cab is a tiny 35L nett box tuned to 45hz with a suitable 12" long throw driver with a very low Fs and the tops are 3" Faital Neo drivers. Usable 35-20000 with remarkably little EQ to get flat.

The 4 x 3" are actually mounted on a 3mm mild steel baffle that has been Laser cut and then powder coated.

very nice little PA system - any idea of power ratings for these cabs...

I am looking to build a compact system, although this is a little more compact even for me...

The top boxes are 4 x 20 watt and should be capable of around 112db cont above 250hz and the 12" are 600w and are capable of around 118db cont.

Not meant for ear pounding bass heavy music although in a medium sized domestic room they can certainly do that and more

Tony

looking good, would be very nice as infill speakers or seating areas etc in larger venues, for back ground music.

very cool. the big man of little speakers

i bet that sounds nice in the top end, no metalic parts in any of the cones, diaframs. is it rear ported, judging by the 200hz rolloff it sounds like a sealed box. nice example of simplicity. id like to hear some of your stuff.

what i was wondering is if it behaves like a line source, im sure that at least acros some of the bandwidth it must, its kinda hard to judge the spacing well between drivers from only the pick. was this one of your aims in the design, and if so how does it behave with vertical dispersion/throw?

cheers
dave

Dave, The spacing between drivers is just to get them as close as possible to each other, this box is not meant as a line array in any other way other than the drivers form a vertical line.

You can hear some interaction of the drivers at high frequencies if you change your height whilst listening however it is very small and you have to listen very carefully to hear it.

The boxes are ported on the rear to around 95hz but basically will act as a sealed box when crossed at 200hz. For use on their own when used near a boundary , wall etc then with a bit of boost around 100hz they sound surprisingly good and could certainly be used on their own on a TV etc.

I am doing more testing at the moment to see what the limitations are regarding absolute sound levels and it looks like the twin 4x3" arrangement with one Q12 sub is ideal but need to do more work. I suspect that the 4x3" will come under a lot more pressure for its intended use for live work.

Tony

thepersonunknown wrote: very cool. the big man of little speakers

i bet that sounds nice in the top end, no metalic parts in any of the cones, diaframs. is it rear ported, judging by the 200hz rolloff it sounds like a sealed box. nice example of simplicity. id like to hear some of your stuff.

what i was wondering is if it behaves like a line source, im sure that at least acros some of the bandwidth it must, its kinda hard to judge the spacing well between drivers from only the pick. was this one of your aims in the design, and if so how does it behave with vertical dispersion/throw?

cheers
dave

hay tony.

is that twin one on top of the other, or side by side? from my earlier post u can probably see what im thinking when i ask.

anyway i was hoping you might give me you opinion on somethng. you said the cab behaves as a sealed cab above 200 (and lower i imagine). when porting a cab, does the driver lose tightness in the upper mid from the lack of preasure/vacume behind it through its cycle. i must say in my experience with reflex, ive never noted this, but with the resistance of a horn in front do you think it would sound different.

i know that question may sound weird, but im trying to get my head arround an observastion made by another forum member, and work out the cause of a posible slip up.

cheers
dave

They would be side by side angled at approx 45 deg to each other, this helps with the lower mids, bottom end response by increasing the width of the array as well as obviously giving greater output,

With regards the sealed/ported cab, basically above a certain frequency the method of cab loading becomes immaterial and you could just as well have them mounted on a flat plate. The drivers own suspension and the amplifier control dominate the cones behaviour.

Done even more tests and have now got the bass driver fed from an 800w amp (Matrix XT800 in bridged mode) and the tops keep up with that until it gives in

The combination of the speakers and 2 off XT800,s is proving to be a very nice match.

Tony

I just posted a min ago, but it dont seem to have loaded, so sorry if this is a double.

anyway, the post went a little someting like this

thanks for the swift reply tony. i was told by doober that he had found the top end in his ported bass horns undefined when compared to a similar horn with a sealed back chamber. im kinda stumped as to why. what you told be just confirmed what i originaly thought. at a high enough frequency a driver could even be hung in free air and be unaffected. i must say though, its a dead end with regards to my diagnosis of the problem. back to the drawing board. at least the problem may not be chronic of this method, so to speak. im not in a position to be building prototypes with falures that a bit of reading and brain work could have avoided, so ill keep at it.

i understand (quite obvious realy :blush:) why you stack and splay the cabs horizontaly. i overlooked the narrowing dispersion of the cones a higher frequencies , lets call it linearray blindness . i guess thats a drawback of eliminating all metalic parts from the cones/diaframs (i imagine this was one of your objectives right?). djk recently told me about slot loading cone drivers to widen high frequency dispersion, but with the extremely high frequencies which are coming of thoes 3 inchers, i can imagine that the rolloff would be detrimental to your design.

its suprising to see that they soak up power so well, but then again, logic dictates that 4 voice coils will disipate head much more efficiently that one larger one, all be it of a higher power rating. how are they wired, seires pairs in paralel?

just an after thought, would you agree that 6 by 9 inch speakers (like thoes used in car audio) but smaller (2 by 3 ish for example), and of decent quality would be great for these aplications? line source characteristics could be pushed right up, while still holding some lower frequency ability. as far as i know no such driver exists, im just speakeing hypotheticaly

anyway, thanks again, and top work.

cheers
dave

quick PS. sorry for all the questions, but i think this layout has great potencial for some hardcore home hifi (nice warm hadcore though, if u get me, loud.... but not loud)

whats the motiation for the metal baffle? its much more difcult than just making a wooden one. leads me to believe theirs some idea behind it

cheers