the Q was .707. Q of .5 closely matched the response of an infinite baffle, but the resultant box was ten cubic feet. If you say i should aim for a flat response i am going to have to have a ported box, because i cannot have a minus 3 at 37hz. hmmm, it is tough listening to the driver in free air and trying to anticipate what it will sound like in a box...
thanks for the help
thanks for the help
Here's an Idea Tade....
Make a Interchangeable box.
This is VERY easy to do. Simply get on WinISD and model a ported box with a response that you would like. For the ports use 3" or 4" PVC pipes(whichever size and however many you need to get a good port length and low windspeed) and the buy plugs for the pipes. They sell expandable rubber plugs at most hardware stores in the plumbing section. I dont know Exactly what they're called but attached below is a picture of what one looks like.
Then you build the enclosure as a ported box and try it out, if it is dissatisfactory simply slide in the plugs and tighten the wingnuts and then you have a sealed box
Make a Interchangeable box.
This is VERY easy to do. Simply get on WinISD and model a ported box with a response that you would like. For the ports use 3" or 4" PVC pipes(whichever size and however many you need to get a good port length and low windspeed) and the buy plugs for the pipes. They sell expandable rubber plugs at most hardware stores in the plumbing section. I dont know Exactly what they're called but attached below is a picture of what one looks like.
Then you build the enclosure as a ported box and try it out, if it is dissatisfactory simply slide in the plugs and tighten the wingnuts and then you have a sealed box
Attachments
ive done it!
I put it in a sealed box of three cubic feet. i decided i had a lot better ability to make a solid box than to mess with ports. To my ears i get extention to about 25hz. I can live with that. Now my problem is my little two ways are the limiting factor in terms of volume. I have the sub crossed at fifty hz by some active crossover simulators from parts express. My bookshlfes are rolled off at around fifty and below that is just wasted excursion, and sacrificed midrange clarity. I think it would require a pretty large cap to passively crossover the mids, but to get a pair of high pass crossover's will cost 25 bucks. IS this the cheapest route?
thanks for the help guys!
I put it in a sealed box of three cubic feet. i decided i had a lot better ability to make a solid box than to mess with ports. To my ears i get extention to about 25hz. I can live with that. Now my problem is my little two ways are the limiting factor in terms of volume. I have the sub crossed at fifty hz by some active crossover simulators from parts express. My bookshlfes are rolled off at around fifty and below that is just wasted excursion, and sacrificed midrange clarity. I think it would require a pretty large cap to passively crossover the mids, but to get a pair of high pass crossover's will cost 25 bucks. IS this the cheapest route?
thanks for the help guys!
this is what i am using for a low pass:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-250
I bought them because i didnt want to even think about electronics.
I could buy their high pass analog.
My mains are vented, but right now i have then sealed up because their F3 vented is about 49hz.
The system sounds sweet, i am noticing certain things about songs i never have, but now i would like a little more volume!
I guess it boils down to, can I build an active crossover for less than thirty bucks?
Thanks for the help.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-250
I bought them because i didnt want to even think about electronics.
I could buy their high pass analog.
My mains are vented, but right now i have then sealed up because their F3 vented is about 49hz.
The system sounds sweet, i am noticing certain things about songs i never have, but now i would like a little more volume!
I guess it boils down to, can I build an active crossover for less than thirty bucks?
Thanks for the help.
Looks like line level passive low pass filters. If it were a steeper slope then it would possibly be a reasonable match to the mains. If sealed your mains will probably have an F3 at 80 Hz or higher with 2nd order rolloff. Then all you need is a variable lowpass on the subs at around 80 Hz with 2nd order slope. The mains should not need any filters.
so i put .35 farads in series with the mains and it has reigned in the excursion significantly. The problem is i believe these are polarized caps. should running them with an ac signal only decrease their life, or will it also degrade the signal?
I think it would be pretty keen to make a career out of audio. Any advise? : )
I think it would be pretty keen to make a career out of audio. Any advise? : )
I had sealed my mains to give them lower distorion, and crossed the lot over at fifty hz, but i was still having much excursion. Then i realized, ill open up the ports and damp them, it works beautifully. i now have quite the rockin 2.5 way.
Here are pictures of the sub and mains unfinished. I doubt i will ever finish the sub, Ill just try and hide it, The mains are ongoing. i am going to biwire them, that should facilitate crossover tuning. Those are diy ribbon tweeters and HIVI B4N drivers. everything which is supposed to make sound in my system is aluminum.
www4.ncsu.edu/~tkwolick/subwoofer.jpg
www4.ncsu.edu/~tkwolick/mainleft.jpg
The sub is 15X15X24 inches, with one brace halfway through. I was very worried the thin 5/8 inch underlayment would resonate intolerably, but right now the worst thing is my concrete box of a room.
Here are pictures of the sub and mains unfinished. I doubt i will ever finish the sub, Ill just try and hide it, The mains are ongoing. i am going to biwire them, that should facilitate crossover tuning. Those are diy ribbon tweeters and HIVI B4N drivers. everything which is supposed to make sound in my system is aluminum.
www4.ncsu.edu/~tkwolick/subwoofer.jpg
www4.ncsu.edu/~tkwolick/mainleft.jpg
The sub is 15X15X24 inches, with one brace halfway through. I was very worried the thin 5/8 inch underlayment would resonate intolerably, but right now the worst thing is my concrete box of a room.
Tade,
I don't really know about in the US, but general consensus is that it's not easy to make much money out of audio! Most are best keeping it as a hobby, however if you find a way to make it a hobby which pays for itself, you are doing better than most. If you manage to at any point turn it from a hobby that pays for itself, to being a hobby business, then that's even better.
Your sub box looks a bit like mine at the moment! (except not hidden)
Is that ribbon tweeter installed BEHIND that baffle cutout? For that to work, it could be a waveguide if the edges were chamfered, then you would need compensation in the xo to allow for the acoustic gain at certain points. Easier than this is just to flush mount.
I don't really know about in the US, but general consensus is that it's not easy to make much money out of audio! Most are best keeping it as a hobby, however if you find a way to make it a hobby which pays for itself, you are doing better than most. If you manage to at any point turn it from a hobby that pays for itself, to being a hobby business, then that's even better.
Your sub box looks a bit like mine at the moment! (except not hidden)
Is that ribbon tweeter installed BEHIND that baffle cutout? For that to work, it could be a waveguide if the edges were chamfered, then you would need compensation in the xo to allow for the acoustic gain at certain points. Easier than this is just to flush mount.
yes, i agree completely except, i cannot hear the difference. Is this waveguide effect highly audible? what should i be listening for? Also, the construction would make that difficult. I think i will adress this if i ever build another ribbon tweeter. When i finish the front baffle i will rear mount both the tweeter and the woofer, and round over the edges. then i will cover the front with felt.
Yes, i decided there wasnt much to do with a big ole box!
I love audio!
Yes, i decided there wasnt much to do with a big ole box!
I love audio!
Tade, a waveguide will normally boost the low end by 6db and this will taper off at the top end, hence it should sound like it has missing top end. However, yours is not a waveguide, more like a resonant tube. You would be better to mount the ribbon on the front of the baffle. If you can't flush mount then you can use some foam, which could also be a cheats way of making it look finished! 
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=265-128
What do you think of that as a crossover. i will have to supply it with 12v dc?
What do you think of that as a crossover. i will have to supply it with 12v dc?
Member
Joined 2003
That will "work", but it will be of low quality and will require 12V supply. For home use, there are much better options, but the cost is also greater for these better products.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=245-880
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=245-862
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=248-664
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=245-880
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=245-862
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=248-664
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