I mean. It depends on your woodworking skills (gaps between panels, angle cuts spot on? Or slightly off? Do you care how it looks when finished from the outside?)
On my last box http://www.diyaudio.com/forums/subwoofers/221660-new-ht-subwoofer-dayton-ref-18-a.html
I didn't use a single screw. Fitment on enery panel was pretty spot on thou.....
On my last box http://www.diyaudio.com/forums/subwoofers/221660-new-ht-subwoofer-dayton-ref-18-a.html
I didn't use a single screw. Fitment on enery panel was pretty spot on thou.....
no wood skills at all, so i think i will need to get scrap cheap wood at the lumber shops and start doing cuts
and make some boxes, or at least practice to make the "box" with the 4 outside panels
nahh i dont think i can make spot on stuff, so super slight off, lol
i dont care how the outside looks, i can use that filler thing to "make up" a bit and tons of duratex
Yes screws are a mechanical fastener.
If you want to bang the box out in a few hours there's no other way to do it without using screws. The way I did that box, glue, position, clamp And let it dry overnight Then move on to the next panel etc.
I deff. Suggest making some practice measurements, markings, cuts, and figments before diving right in to a horn build. There's angle cuts, exact measurements etc etc.
And you can never have enough clamps squares etc so stock up at harbor freight to save a few $$!!
If you want to bang the box out in a few hours there's no other way to do it without using screws. The way I did that box, glue, position, clamp And let it dry overnight Then move on to the next panel etc.
I deff. Suggest making some practice measurements, markings, cuts, and figments before diving right in to a horn build. There's angle cuts, exact measurements etc etc.
And you can never have enough clamps squares etc so stock up at harbor freight to save a few $$!!
ic,
harbor freight is second hand right ?
there is not much of wood working stuff around here on my town
so maybe ebay ?
No it's all (mostly) Chinese made stuff. Hit or miss really, but for clamps squares etc its great. You're in the US right? You can order online
Harbor Freight Tools ? Quality Tools at Discount Prices Since 1977
Harbor Freight Tools ? Quality Tools at Discount Prices Since 1977
Wg_Ski,
On Mr Doom's PRV driver, a BL of 20-ish is not too abnormal for a 15" i think ..... It looks to me like they used a light cone and a VERY tight suspension which is what drove the FS so darn high ..... The tight suspension also drove the QTS up quite a bit ...
It doesn't simulate well at all in an SS15 so that combination wont work, but the PRV driver could work well in other even simpler designs such as a straight tapped pipe, or a partially stuffed QWP with the driver one third of the way down the pipe...Single fold.... Pipe area would need to be almost the same as driver SD (i used 850 in this case)... Pipe needs to be long enough to create a fundamental resonance of 40hz ... Total internal airspace ends up being only about 155 liters which is smaller than the SS15 and could easily be made from one sheet but you are also sacrificing about 3 or 4dbs (at 55hz+) compared to the classic SS15 with 3015lf, but thats just the nature of the beast right? there are always compromises ...
There is a cool feature of the QWP version though, which is the fact that the front of the cone can face forward, and is on the outside of the box like an old scoop cabinet, however since the driver is offset in the pipe and the pipe is partially stuffed there is no issue with the nasty suckout dip in the midbass which the old scoops suffered from, so you can essentially run this design from 40hz all the way to 1khz if the driver has a smooth midrange response....... The midrange would be just "direct radiating" though, so not nearly as efficient as some of the other midrange solutions but it surely is simple, quick and cheap and knocks the socks off of a simple bass reflex/ported box (but larger , but then there's those darn compromises again
) .... By the way , the same QWP should also be possible with 2 Dayton PA-310 12" drivers, giving you a little more cone area and a few more DBs in the midrange ....
209 liter "SS-18PS76" contender!
Ok, I think i might have come up with a competitive design for JBELL's single sheet challenge! This box may be a good alternative for those who wanted something that has a little more bass extension ..... It has an internal airspace of 209 liters just like Jbell's amazing SS15 but the throat to mouth ratio is much less, allowing me to have a path length which is also less yet still meets the target tuning ... You can squeeze a B&C 18PS76 into this box and with this design's low compression ratio there is little risk of shredding the large diameter cone ...
*The 18PS76 has a low VAS and a low QTS which makes it function well in such a small TH, and with some added series inductance (3 or 4mh total in hornresponse which includes the driver inductance) you can get a pretty smooth response, but the inductor may not actually be necessary in real life with this box ...
*The B&C handles more power, sweeps just as much air (due to it's larger cone area) and retails for less than the 3015LF....
*The bass response "knee" (point at which response falls off like a rock) is more than 10hz lower in frequency compared to an SS15+3015lf which is pretty significant!...
*At the same power level this PS76 design is 4db more sensitive at 40hz and also 2.5db louder at 50hz but sacrifices a little bit of sensitivity to the SS15 around 60-80hz.....
*At 40hz with 600 watts (the rms rating of the PS76) , this box is 5db louder than the SS15 ....
*Overall this PS76 box is flatter according to simulation and has more bass extension ....
*If you want even more extension you can add a Brian Steele styled "DFD" constriction which should flatten the little response bump at 50hz and shift the fundamental resonance down by roughly 5 hertz, fill in the dip at 185hz , and give you a small amount of gain at 80hz and above based on Brian's charts... In theory it should work since this box is basically a scaled up version of Brian's POC#2 (with a slightly shorter path and a tuning/impedance minimum that is identical to the ss15 combined with a throat-to-mouth ratio and compression ratio that matches Brian's POC#2), but of course we wont know for sure if it works until someone builds one .. I am hoping to have access to a cabinet shop here again in the near future and i think i might give it a whirl
BY THE WAY , for a higher powered version you can drop in an 18LW2400 , or an 18TBX100 but they seem to need a little more series inductance ...
Ok, I think i might have come up with a competitive design for JBELL's single sheet challenge! This box may be a good alternative for those who wanted something that has a little more bass extension ..... It has an internal airspace of 209 liters just like Jbell's amazing SS15 but the throat to mouth ratio is much less, allowing me to have a path length which is also less yet still meets the target tuning ... You can squeeze a B&C 18PS76 into this box and with this design's low compression ratio there is little risk of shredding the large diameter cone ...
*The 18PS76 has a low VAS and a low QTS which makes it function well in such a small TH, and with some added series inductance (3 or 4mh total in hornresponse which includes the driver inductance) you can get a pretty smooth response, but the inductor may not actually be necessary in real life with this box ...
*The B&C handles more power, sweeps just as much air (due to it's larger cone area) and retails for less than the 3015LF....
*The bass response "knee" (point at which response falls off like a rock) is more than 10hz lower in frequency compared to an SS15+3015lf which is pretty significant!...
*At the same power level this PS76 design is 4db more sensitive at 40hz and also 2.5db louder at 50hz but sacrifices a little bit of sensitivity to the SS15 around 60-80hz.....
*At 40hz with 600 watts (the rms rating of the PS76) , this box is 5db louder than the SS15 ....
*Overall this PS76 box is flatter according to simulation and has more bass extension ....
*If you want even more extension you can add a Brian Steele styled "DFD" constriction which should flatten the little response bump at 50hz and shift the fundamental resonance down by roughly 5 hertz, fill in the dip at 185hz , and give you a small amount of gain at 80hz and above based on Brian's charts... In theory it should work since this box is basically a scaled up version of Brian's POC#2 (with a slightly shorter path and a tuning/impedance minimum that is identical to the ss15 combined with a throat-to-mouth ratio and compression ratio that matches Brian's POC#2), but of course we wont know for sure if it works until someone builds one .. I am hoping to have access to a cabinet shop here again in the near future and i think i might give it a whirl
BY THE WAY , for a higher powered version you can drop in an 18LW2400 , or an 18TBX100 but they seem to need a little more series inductance ...
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im not asking if someone bild it,
im asking is there some sort of plan(fold)
Hey there Epa,
Just a sim so far, and it was a sim to sim comparison that i was making.. I know that actual measured results can be different ...
I think i will try to draw up some plans but i haven't yet developed the keen folding and sketching skills that many more seasoned folks on here possess, so it will probably be simple .... Just a single fold version to start..
Neo Dan ,
Keep in mind that the 18PS76 and 3015LF both have an RE of 5.3 ohms ... At 2.83 volts the comparison looks like the screen shot i took of hornresponse which is attached to this message ... You can see the increased output at 40 & 50 hertz .... I wish it had more output at 60 but you always have to compromise somewhere right?
Brian Steele's "DFD" style constriction should improve the extension further and fill in the big dip at 180 hertz but i don't imagine it will give me any gains at 60..
Keep in mind that the 18PS76 and 3015LF both have an RE of 5.3 ohms ... At 2.83 volts the comparison looks like the screen shot i took of hornresponse which is attached to this message ... You can see the increased output at 40 & 50 hertz .... I wish it had more output at 60 but you always have to compromise somewhere right?
Brian Steele's "DFD" style constriction should improve the extension further and fill in the big dip at 180 hertz but i don't imagine it will give me any gains at 60..
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Its cool Neo Dan ,
I know that B&C does make some 4 ohm 18" drivers so its an understandable mistake ....
To answer your and EPA's questions about plans & measurements I think i will just cook up some cheesy sketch with the basic dimensions and then i will cobble together a single fold version out of cheap OSB just to make sure that this TH works well in real life ... If i'm happy with the way it performs I will then build something out of a good plywood, cube shaped ideally as EPA suggested If i can figure out how to manage the folding bit ..
I think i almost have the dimensions for the single fold version worked out , I know these are rough and will probably revise them a few times but accounting for the airspace taken up inside by the single internal panel i ended up with something like 43.3"x20"x18.5" ....
If i can get away with reducing the width by another half inch then it could have a nearly square footprint with 43.3"x19.5"x19" but it will be a pretty tight fit for the woofer..... The DFD constriction will probably end up around 1/3rd of the way up the pipe from the mouth, but that will have to be measured and adjusted to find the exact spot ..
I know that B&C does make some 4 ohm 18" drivers so its an understandable mistake ....
To answer your and EPA's questions about plans & measurements I think i will just cook up some cheesy sketch with the basic dimensions and then i will cobble together a single fold version out of cheap OSB just to make sure that this TH works well in real life ... If i'm happy with the way it performs I will then build something out of a good plywood, cube shaped ideally as EPA suggested If i can figure out how to manage the folding bit ..
I think i almost have the dimensions for the single fold version worked out , I know these are rough and will probably revise them a few times but accounting for the airspace taken up inside by the single internal panel i ended up with something like 43.3"x20"x18.5" ....
If i can get away with reducing the width by another half inch then it could have a nearly square footprint with 43.3"x19.5"x19" but it will be a pretty tight fit for the woofer..... The DFD constriction will probably end up around 1/3rd of the way up the pipe from the mouth, but that will have to be measured and adjusted to find the exact spot ..