FullThrottleRic said:Matt, don't bother with any of the drivers from Maplin (I work there btw LOL), they are all PA, ie VERY efficient and don't go as low as most 6.5's.
Goto BK Electronics and get yourself a couple of BSB 10-500's, awesome woofers, only 10" but they have a P-P excursion of almost 50mm and they're only £130.
I built a sub for a friend recently, using 2 BSB 10-500's in a sealed box, with each woofer on an opposite side of the enclosure (cancel each others vibrations) in push-push with a Linkwitz transform and 1000w amp.
They can reach into the mid 20's happily, but their fotre' is making the place shake
i dont have that much money to spend, and the speakers from maplin are cheap, and maplin is the nearest place to buy speakers for me.
OMNIFEX said:
I find this to be very inaccurate. To say that an 18" driver moves slower than a 15" driver is just wrong. If that was the case, that would mean that if you had both a 15" and 18" driver play the same frequency at the same amplitude, say 40Hz, the 18" would really be producing a 35Hz tone and the 15" would still be playing at 40Hz?
See, 40Hz is 40Hz no matter what size driver is reproducing it. In order to produce 40Hz, that means the driver has to move back and forth 40 times a second. And the reason why an 18" driver might sound heavier than a 15" or 12" is not because it moves slower, but because of its T/S parameters, motor structure size, type of enclosure it is in, and what kind of power you are pushing into it.
My DIY subwoofer is a 6 cubic ft sealed enclosure that is heavily braced and damped throughout. I used to run an 18" Klipsch driver in it and it was extremely transient. Very accurate, tight, clean, and musical, and yes, it could play very loud. However, I was never really too thrilled with its low end extention. The 18" rolled off at 30Hz or so and could not hit those 16Hz pedal notes that make listening to organ music exciting. So one day I pulled out of my closet one of my 15" drivers that came out of an old cheap dbx subwoofer my brother used to have, built a baffle adapter plate to mount the 15 in the 18" hole, and to my amazement, this cheap little dbx 15 incher extends much lower than the Klipsch ever could. Now my subwoofer extends all the way down to 12Hz measured with an AudioControl SA-3055 Analyzer at my listening position. So it just goes to show that bigger is not always better. As for transients, it is very tight and musical just like the 18 was, but I'm sure that also has a lot to do with the high damping factor of my Carver PM700 amp that I'm pushing it with and the 700 watts of clean power.
""I find this to be very inaccurate. To say that an 18" driver moves slower than a 15" driver is just wrong. If that was the case, that would mean that if you had both a 15" and 18" driver play the same frequency at the same amplitude, say 40Hz, the 18" would really be producing a 35Hz tone and the 15" would still be playing at 40Hz?""
If the 15's playing at the same spl as the 18, it will have to move backwards and forwards more than the 18 to compensate for the smaller surface area. Therefore the 15 will have to cover more distance per cycle than the 18, and has to move faster to do so.
Cheers
Rob
If the 15's playing at the same spl as the 18, it will have to move backwards and forwards more than the 18 to compensate for the smaller surface area. Therefore the 15 will have to cover more distance per cycle than the 18, and has to move faster to do so.
Cheers
Rob
I find it interesting that no one really mentioned the importance of linear excursion capability. Especially at the really low frequencies, the PA drivers just can't keep up low distortion ... this is why if you want low bass (<30Hz), you should consider a hi-fi driver (examples include Adire Tempest, Stryke AV15, etc) with less ultimate output capability at higher frequencies, but lower distortion at low frequencies because of their higher linear displacement.
you type in all the specs for the chosen driver, and model the size for you required application - sealed (what Q you want) , vented (with port sizes). When you're happy with the response,the pc works out the correct size, and also will give you dimensions of calculated box..
Best way is to download it and play with it...( type in a few diff. drivers to compare etc etc...
Rob
Best way is to download it and play with it...( type in a few diff. drivers to compare etc etc...
Rob
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