Scale this down to size
Here's the idea, but, just use the 2x 15" I mentioned, so Imagine 1/4 of what you see here. The drivers' forces cancel each other and the acoustic outputs load into the "manifold". The opening to the outside world must be at least 2 times the SD of one driver. Size it as you wish, but remember as the dimensions approach 1/4 wavelength of the highest frequency in the band pass, you'll start to get reflective resonances. The fact that this is essentially a 4 ohm load allows you to buy more inductor value for the buck, but a system like this is really much better served via an active crossover- but you established a budget.
Here's the idea, but, just use the 2x 15" I mentioned, so Imagine 1/4 of what you see here. The drivers' forces cancel each other and the acoustic outputs load into the "manifold". The opening to the outside world must be at least 2 times the SD of one driver. Size it as you wish, but remember as the dimensions approach 1/4 wavelength of the highest frequency in the band pass, you'll start to get reflective resonances. The fact that this is essentially a 4 ohm load allows you to buy more inductor value for the buck, but a system like this is really much better served via an active crossover- but you established a budget.
Attachments
very hard for me to understand that box from the photo?
all i see is some motors and a large sheet of mdf 🙂
all i see is some motors and a large sheet of mdf 🙂
thanks for your input *again* jim. (you've been asked not to)
no answer from you *again* (always math but no box)
just negativity *again* (you'd benefit from a beer and a fun listening session, put the calculator down for a couple hours, get your favorite 2 albums out and sit back and relax)
jbell is right and you'll be lucky if they dont pull your ability to post. Why don't you pick up a calculator and put down the beer, do some work yourself and stop being rude.
THERE IS NO PERFECT BOX. Everything has a compromise you just need to buy a decent driver and build a couple boxes until YOU find one that does what YOU want!
THERE IS NO PERFECT BOX. Everything has a compromise you just need to buy a decent driver and build a couple boxes until YOU find one that does what YOU want!
Please -- ask a question with specifics.... You are asking a question with an infinite number of possibilities. That's why the moderators consolidated your multiple posts, and why they should consolidate this one. Asking an unanswerable question might be considered 'trolling.'
Please specify:
What SPL
at what distance
at what low cut off frequency
at what efficiency
in what size box
That is a question that has at least a limited number of possibilities.
You eliminate any of them, and it is unanswerable
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edit I posted before the threads were merged.
No kidding.
Btw I think the mystery subwoofer mentioned above is similar to a slot tuned push pull.
I'm guessing we're not looking for sub 30hz output here for the most part, since it's outdoors. So I'd look to something like the Tuba 60 or one of the others shown here.
Plans to build these are available for $15 from the website owner.
http://billfitzmaurice.net/
No kidding.
Btw I think the mystery subwoofer mentioned above is similar to a slot tuned push pull.
I'm guessing we're not looking for sub 30hz output here for the most part, since it's outdoors. So I'd look to something like the Tuba 60 or one of the others shown here.
Plans to build these are available for $15 from the website owner.
http://billfitzmaurice.net/
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60ndown. We have merged your threads yet again after asking you not to start another one. Please check your PM box.
Not the best example
Sorry, that was not the best example. It's simple really, just fire the two drivers in a common cavity, just large enough to house the 2 woofers physically, BE SURE the opening to the outside world is 2x the effective cone area of one driver. Another option is turning one of the woofers around by 180 degrees, effectively "humping" the other driver, sometimes referred to as PPSL.
The rear wave volume is treated the same for any other design; in this case you get the best woof bang for the buck in a vented/ported enclosure.
From what I am reading of the other posters, I'm beginning to think you may not have much experience in building loudspeakers at all, especially since you didn't reckognize magnet-to-magnet mounting technique.
All I tiried to do was answer a budget challenge; the woofers I sited are a nice example of value for the dollar. Not a cheap driver at all, but not in the league of the super woofers, either. The Qts value of .32 fits in nicely on box size and relative performence thereof.
I started reading "how to" speaker building books back in 1972; it's still a great way to learn: reading, that is. Much to my dismay, however, it's all too easy to access info on the web.
Again, I apologize for the confusion... good luck on your endeavours.
Sorry, that was not the best example. It's simple really, just fire the two drivers in a common cavity, just large enough to house the 2 woofers physically, BE SURE the opening to the outside world is 2x the effective cone area of one driver. Another option is turning one of the woofers around by 180 degrees, effectively "humping" the other driver, sometimes referred to as PPSL.
The rear wave volume is treated the same for any other design; in this case you get the best woof bang for the buck in a vented/ported enclosure.
From what I am reading of the other posters, I'm beginning to think you may not have much experience in building loudspeakers at all, especially since you didn't reckognize magnet-to-magnet mounting technique.
All I tiried to do was answer a budget challenge; the woofers I sited are a nice example of value for the dollar. Not a cheap driver at all, but not in the league of the super woofers, either. The Qts value of .32 fits in nicely on box size and relative performence thereof.
I started reading "how to" speaker building books back in 1972; it's still a great way to learn: reading, that is. Much to my dismay, however, it's all too easy to access info on the web.
Again, I apologize for the confusion... good luck on your endeavours.
The rest of you have the option of steering clear of this thread or reporting a post if you see a rules violation.
Thank you.
OK I think I see the problem here.
60ndown seems to be asking what would *you* do, he doesn't want to provide specifics, perhaps he doesn't care and providing specifics will limit the possible outcomes.
I can completely understand where jbell is coming from though, as well, without any guidelines it is impossible to give advice specific to *60ndown's* requirements.
So I think and I could be wrong, that what 60ndown wants is for people to say what *they* personally would do with the parameters he gave in the $400 challenge. That will include any compromises that you personally would make, eg one person might make a 300L cabinet, and another might make a 75L cabinet.
60ndown, if this is the intent, then if someone does post what they would do and it does not fit with what you require then I expect you to thank them for their contribution even if it is not something you would ever contemplate doing yourself.
Note that this post has been made with my member cap on not my moderator cap 🙂
Tony.
60ndown seems to be asking what would *you* do, he doesn't want to provide specifics, perhaps he doesn't care and providing specifics will limit the possible outcomes.
I can completely understand where jbell is coming from though, as well, without any guidelines it is impossible to give advice specific to *60ndown's* requirements.
So I think and I could be wrong, that what 60ndown wants is for people to say what *they* personally would do with the parameters he gave in the $400 challenge. That will include any compromises that you personally would make, eg one person might make a 300L cabinet, and another might make a 75L cabinet.
60ndown, if this is the intent, then if someone does post what they would do and it does not fit with what you require then I expect you to thank them for their contribution even if it is not something you would ever contemplate doing yourself.
Note that this post has been made with my member cap on not my moderator cap 🙂
Tony.
Member 60ndown has got the SIn Bin after a personal attack post of his had been reported (and removed) a little before. 
He wants 125 dB at 30 Hz outside at 1 meter in a "large box". Since it is residential type use, the full system limit is 120V/15 amps from a single outlet. With a Class D digital, that puts the limit at 1,000 watts max.
I would learn Horn Response, screw around with it to see how close I could get. Since power compression is around, I'd shoot for 97 dB at 1 watt/1 meter at 30 Hz so a horn would work well with that. Assuming you'd gain "only" 6dB with a horn, shoot for 91 dB 1 watt/1 meter from a single speaker or 88 dB 1 watt/1 meter from a pair of woofers.
After the build, if it gives a boost of 8 dB VS 6 dB, consider it a bonus.
As far as plans go, there are some that use two Eminence LAB12 speakers--it will go to 30 Hz and give what he wants.
Plan 12PII BassHorn ( labhorn )
The woofers run $165 each or $330 per pair. (free shipping) Depending how inexpensively you can get the wood--it might make it to around $400. It would help if you had a sheet or two just "laying around" to make that price point.
Eminence LAB 12 Generation II 12" Subwoofer
You gotta pay to play though, speakers are not getting any cheaper and if you want a PA horn that will do 30 Hz at well over 125 dB--I consider it very inexpensive.
The LABhorn is my final answer! After all, Pro Audio uses PRO audio speakers that are designed to last for years. Follow the plans, don't cheese on any portion of the build and enjoy. If you don't follow the plans, scream, yell and point fingers is fine--but only in a mirror. As Led Zeppelin would say "It's nobody's fault but mine!"
I would learn Horn Response, screw around with it to see how close I could get. Since power compression is around, I'd shoot for 97 dB at 1 watt/1 meter at 30 Hz so a horn would work well with that. Assuming you'd gain "only" 6dB with a horn, shoot for 91 dB 1 watt/1 meter from a single speaker or 88 dB 1 watt/1 meter from a pair of woofers.
After the build, if it gives a boost of 8 dB VS 6 dB, consider it a bonus.
As far as plans go, there are some that use two Eminence LAB12 speakers--it will go to 30 Hz and give what he wants.
Plan 12PII BassHorn ( labhorn )
The woofers run $165 each or $330 per pair. (free shipping) Depending how inexpensively you can get the wood--it might make it to around $400. It would help if you had a sheet or two just "laying around" to make that price point.
Eminence LAB 12 Generation II 12" Subwoofer
You gotta pay to play though, speakers are not getting any cheaper and if you want a PA horn that will do 30 Hz at well over 125 dB--I consider it very inexpensive.
The LABhorn is my final answer! After all, Pro Audio uses PRO audio speakers that are designed to last for years. Follow the plans, don't cheese on any portion of the build and enjoy. If you don't follow the plans, scream, yell and point fingers is fine--but only in a mirror. As Led Zeppelin would say "It's nobody's fault but mine!"
no, that does not hold.
The maximum output level of an amplifier is a maximum not an average.
The transient peaks are fed from the smoothing capacitors and decoupling.
The transformer supplies the average current to re-charge the capacitors. The transformer is not sized to suit the transient peak currents drawn by the speaker.
You could easily fit a 1kVA transformer to a 110/120Vac 15A supply.
I would expect a 2kVA transformer to also run well when fed from a 110/120Vac 15A supply.
Those transformers could allow amps with a peak transient capability approaching or even exceeding 2kW.
Hi 18Hurts,
While the 12Pi does make it to 125dB @ 30Hz w/ 1000W into 3 Ohms, it also exceeds Xmax substantially (the simulation says: 24.3mm), and that is without losses or power compression in Hornresp. By throwing 125dB @ 30Hz into the equation you are specifying the Danley TH-115. Maybe Xoc1's version of the SS15 will get there, but at what driver cost? Or, maybe Art Welter's Keystone sub loaded with the 4015LF? If any of those are not enough, he can always double up (side-by-side cabinets, 2-in-1) on any of these and try whatever inexpensive drivers he can find?
Regards,
While the 12Pi does make it to 125dB @ 30Hz w/ 1000W into 3 Ohms, it also exceeds Xmax substantially (the simulation says: 24.3mm), and that is without losses or power compression in Hornresp. By throwing 125dB @ 30Hz into the equation you are specifying the Danley TH-115. Maybe Xoc1's version of the SS15 will get there, but at what driver cost? Or, maybe Art Welter's Keystone sub loaded with the 4015LF? If any of those are not enough, he can always double up (side-by-side cabinets, 2-in-1) on any of these and try whatever inexpensive drivers he can find?
Regards,
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Hi Djim,
Nice link. Well, that and some OSB for the fun box should almost do it. 🙂
Regards,
Nice link. Well, that and some OSB for the fun box should almost do it. 🙂
Regards,
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For roughly the cost of the 18LW2400 you can build a complete pair of OSB horns including the amp to meet the required 125dB@30Hz.
Sure does!
HOWEVER, I call it a rough cut measurement--in a residential outlet, it is connected to other outlets--other rooms. I never assume that I can get all the power available, it is not going to happen.
THEORY 1875 watts available of clean 120VAC and surge capacity exceeding 2400 watts (20 amps)
REALITY Jr. has a welder and has popped the breaker in the garage about 100 times and it has been weakened. Breaker now trips at 13 amps. Mr. Block Party has a fridge in the garage to keep his beer cold, don't forget the electric garage door opener motor. Mrs. Block Party has food warmers plugged in to keep the snacks hot plugged into the outside outlet of said garage.
This is why I spec 1000 watts max peak power to the subs for a reliable measurement for residential houses. After all, the difference between 1 KW and 2 KW is 3 dB, that is assuming you won't get massive power compression (you will) Never mind the distortion, the power compression, risking damaging your amps from voltage drops... it just sounds so much better to run multiple bass bins at lower wattage...
In reality, I'd never build a 30 Hz capable 125 dB single sub for playing outside. I'd build two bins when coupled together would perform that function. The actual output above that is free but my back would appreciate moving two subs around VS one giant one.
2 KW sub amps are for club use, home use is way too unknown to depend on such high power outputs. Oddly enough, if you blow a breaker it is "your fault" so I just avoid that potential mess by limiting output for the worst case scenario.
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