Hey AdamZuf
do you like psytrance?
a friend and myself had the same idea here in Australia, to build a fairly portable PA setup for parties in the bush.
after a great deal of research and testing, we decided to go with Bill Fitzmaurice's DR12s. let me tell you now, you will not be dissapointed, the only drawback, if you could call it that, is the extra time and patience required to build them. which was ok by us. im not sure on the DR250s but the DR12s require some nifty equalisation, which we used a Behringer DEQ2496 for, but you could build a standalone eq circuit with about 10 opamps. we decided to go all out and use EVM12Ls, awesome driver, expensive, but discontinued. but with all Bills horns you can always substitute fairly similarly spec'd driver with no major deviation. plus they only need around 300watts per side to really punish.
on the top end we couldnt stand the sound of piezos so we splashed out on some BMS 4540-ND compression drivers. from what i remember around 110dB with the horn so very less than 50watts are needed. awesome sound., and cheap too!
now bass. this is where my friend and i disagreed. i wanted to build some large bass horns that would fit onto a small towable trailer, the DRs are tops are just small enough to fit into a wagon. we ran the DRs full range and he liked the sound, and said it was good enough for now, but i wanted extra deep bass, eg sub 40hz. so the Tubas would be a definite go if you like ground rumbling bass.
we also had the crazy idea to forgo the genset and use batteries!
eg many 12V 200Ah that we could get access to, and... car amps.
but that idea, whilst laughable, was never really fully explored.
many other problems arose and we parted ways for now, and the moneys dried up so we have had to shelve the project for now.
heres some pics:
http://members.iinet.net.au/~jacen/DR/
and heres what others use here:
http://img.photobucket.com/albums/v67/psytye/Earthdance2004027_s.jpg
expensive mackie tops and subs with inbuilt compressors :/
good luck!
do you like psytrance?
a friend and myself had the same idea here in Australia, to build a fairly portable PA setup for parties in the bush.
after a great deal of research and testing, we decided to go with Bill Fitzmaurice's DR12s. let me tell you now, you will not be dissapointed, the only drawback, if you could call it that, is the extra time and patience required to build them. which was ok by us. im not sure on the DR250s but the DR12s require some nifty equalisation, which we used a Behringer DEQ2496 for, but you could build a standalone eq circuit with about 10 opamps. we decided to go all out and use EVM12Ls, awesome driver, expensive, but discontinued. but with all Bills horns you can always substitute fairly similarly spec'd driver with no major deviation. plus they only need around 300watts per side to really punish.
on the top end we couldnt stand the sound of piezos so we splashed out on some BMS 4540-ND compression drivers. from what i remember around 110dB with the horn so very less than 50watts are needed. awesome sound., and cheap too!
now bass. this is where my friend and i disagreed. i wanted to build some large bass horns that would fit onto a small towable trailer, the DRs are tops are just small enough to fit into a wagon. we ran the DRs full range and he liked the sound, and said it was good enough for now, but i wanted extra deep bass, eg sub 40hz. so the Tubas would be a definite go if you like ground rumbling bass.
we also had the crazy idea to forgo the genset and use batteries!
eg many 12V 200Ah that we could get access to, and... car amps.
but that idea, whilst laughable, was never really fully explored.
many other problems arose and we parted ways for now, and the moneys dried up so we have had to shelve the project for now.
heres some pics:
http://members.iinet.net.au/~jacen/DR/
and heres what others use here:
http://img.photobucket.com/albums/v67/psytye/Earthdance2004027_s.jpg
expensive mackie tops and subs with inbuilt compressors :/
good luck!
Thanx MikeE,
Trouble is they are on the opposite side of the planet from where I am. I see PartsExpress now carries Radian and that line offers a diaphragm for the Altec 802, but it is about $100.00 US. I don't know how the Ozzy dollar compares but the site you gave me has a replacement for the 802 for $50.00 AU.
I've got a pair of 2" VC Selenium compression drivers in my Selenium coaxial 12"ers and they sound quite good for titanium domes. I know Selenium makes some really large format compression drivers too and the prices are pretty reasonable. I think the compression drivers I have were recently on sale at PartsExpress for about $48.00 US.
The Altec drivers I have are alnico and have probably lost field strength. The newer Seleniums with their ceramic mnagnets will be fresh and won't have this problem.
I'm not in desperate need I am just examining my options. My system works as it is.
Trouble is they are on the opposite side of the planet from where I am. I see PartsExpress now carries Radian and that line offers a diaphragm for the Altec 802, but it is about $100.00 US. I don't know how the Ozzy dollar compares but the site you gave me has a replacement for the 802 for $50.00 AU.
I've got a pair of 2" VC Selenium compression drivers in my Selenium coaxial 12"ers and they sound quite good for titanium domes. I know Selenium makes some really large format compression drivers too and the prices are pretty reasonable. I think the compression drivers I have were recently on sale at PartsExpress for about $48.00 US.
The Altec drivers I have are alnico and have probably lost field strength. The newer Seleniums with their ceramic mnagnets will be fresh and won't have this problem.
I'm not in desperate need I am just examining my options. My system works as it is.
Oh yeah (-: I'm more of a Nick Taylor and Haltya guy then GMS, Scazy and all of the monotonic, heavy stuffphs said:
Maybe you had to EQ the system because of the EVM driver? Did Bil recommend it? I'm going for the DR250a probably, not the DR 12.
Sounds good! What's the Impedance and sensitivity of the driver?
Did they reproduced awesome sound without EQ'ing theyr range too much as well?
What's so cheap about them? They go for about $85 each!
Hey what do you think I'll play on these speakers, "Boyzone?"
Thanks for the tips!
Adam
Hey Adam
im into alot of different styles, listening atm to Sub 6 and Suria.
due to the horns shape there is some radical frequency response anomolies, which must be corrected with eq. the first time we powered them up with no eq and Fleetwood Mac i could have cried. not good! easy with Behringers one button push auto eq. i think the DR250a will also require eq.
i dont have any diagrams apart from whats in books and ready made circuits. we built 2&3way active crossover boards and were planning to build a stand alone eq circuit for the DR only, but never got around to it. look around for configurable notch&eq opamp filters.
the EVM12L is a great driver. 8 ohm, 300w, Qts 0.25 Fs 55hz. but discontinued and expensive for a recone i hear. but thats ok the DR250 uses a current item: P-Audio SN10-MB.
BMS compression drivers were fine, just dont overpower them! apparently you can cross them over at 2k! but thats asking for trouble in a PA application i believe.
we ran the DRs from 40hz to 4khz and the compression driver 4k to 20khz. the best thing about the huge bandwith of the DR was the imaging. you should hear panning psy, awesome!
haha @ Boyzone
no no! think of the piezos and DR12 as two different speakers.
originally i think Bill designed them for bass guitar applications, so that the piezos provided top air for the bass. try playing delicate psy through piezos and *cringe* my eardrums begin to split. so we never installed the piezos, just ran them on top of the DR itself.
the piezos are mounted on the front of the DR. they are not part of the horn itself! they are externally mounted.
im into alot of different styles, listening atm to Sub 6 and Suria.
due to the horns shape there is some radical frequency response anomolies, which must be corrected with eq. the first time we powered them up with no eq and Fleetwood Mac i could have cried. not good! easy with Behringers one button push auto eq. i think the DR250a will also require eq.
i dont have any diagrams apart from whats in books and ready made circuits. we built 2&3way active crossover boards and were planning to build a stand alone eq circuit for the DR only, but never got around to it. look around for configurable notch&eq opamp filters.
the EVM12L is a great driver. 8 ohm, 300w, Qts 0.25 Fs 55hz. but discontinued and expensive for a recone i hear. but thats ok the DR250 uses a current item: P-Audio SN10-MB.
BMS compression drivers were fine, just dont overpower them! apparently you can cross them over at 2k! but thats asking for trouble in a PA application i believe.
we ran the DRs from 40hz to 4khz and the compression driver 4k to 20khz. the best thing about the huge bandwith of the DR was the imaging. you should hear panning psy, awesome!
haha @ Boyzone
no no! think of the piezos and DR12 as two different speakers.
originally i think Bill designed them for bass guitar applications, so that the piezos provided top air for the bass. try playing delicate psy through piezos and *cringe* my eardrums begin to split. so we never installed the piezos, just ran them on top of the DR itself.
the piezos are mounted on the front of the DR. they are not part of the horn itself! they are externally mounted.
rcavictim said:
Woofer
Tweeter
Since that was discontinued, here is it's apparent replacementOther tweeter
Cal
Cal Weldon said:
Cal,
Those are the HF compression drivers I have in my Selenium 12" coaxial speakers 12CO1P that I built into large 50Hz front horns for my home theater setup. I cannot understand why they would have discontinued such a fine and very affordable compression driver.
That woofer looks like it is capable of exposing the cabinet weaknesses of any A-7 box. Nice!
Attachments
AdamZuf,
Just a few points before you dismiss the line array idea and I drop the subject:
In the nearfield, line arrays decrease in SPL by 3db for each doubling of distance. Point source speakers (pro or otherwise) decrease by 6db for each doubling of distance. This difference is huge, especially in terms of the size of the prime listening area
and the amount of power you need.
For example, let's assume you want 100db at 16 meters which seems about right for a group of 100 people outdoors. At 1 meter you need 124db from a point source speaker and 112db for the line array. The point source will be too loud up front and the line array will give you an area 8-10 times as large with comfortable but loud prime listening.
Also, 124db in the 30-60hz range, which I think is crucial for the music you want to play, is difficult and expensive, especially outdoors where there is no room gain from 50hz down like in a club. While I'm sure Bill has good speaker designs, the Tuba for example would need 1000 watts to play 124db in the 30-60hz range. The driver is only rated for 250 and I'm sure it sounds stressed long before that. Plus 1000 watts is expensive.
112db is easy to acheive with a line array. It just needs to be quite long and even longer for the bass frequencies. Plus the mids and up need very close spacing, so lots of drivers are needed. For bass, the array needs to be longer but drivers can be spaced further apart. The 16ft vertical arrays and 32ft bass arrays I outlined should get you at least close to a 16 meter near field/ far field transition distance.
Why can cheap drivers work? Because you are asking each to do only a little work. The 4" $1.50 drivers I use have a sensitivity of about 89db. 32 on one channel gets you up to 103db on 1 watt. 8 watts total to get you to 112db. You could use one of Target's $30 Tamps and play it all night on a small rechargeable battery pack. Each driver only needs 1/4 watt to get there, so there's no stress at all. Cheap 4" wide range drivers are plentiful because they are used in cars, radios, TV's etc. and many are designed for free air use in cars and TV's. They just can't handle much power and sound stressed when pushed too hard. The woofers would need more power. The ones I use are only 85db, so 16 gets you up to 97db at 1 w/m , so you need 32 watts to get up to 112db. Still easy though and only 2 watts per driver, so no stress at all. Even in free air dipole use you could probably go to 118db with no stress, 1 watt/driver on the vertical array and 8 watts/driver on the woofers. They're rated for 20 and 235 watts respectively, but in free air that would be significantly reduced.
Why dipole? 1. I prefer the natural dipole sound, but alot of the openess is likely to be lost with no back wall to reflect the back wave. The natural tone will be retained though. 2. It's very easy to get right. 3. With foldable and detachable baffles would make it relatively efficient to transport. There's no way you could tranport boxed bass arrays with what you have.
The alternative for relatively compact transport would be to use aperiodic membranes on the back of the drivers. The baffle wings would go away, making transport and setup easier, but getting the right tuning consistent accross the arrays would take alot of trial and error. The increase in output and power handling might make it worth the effort.
The more I think about it, the more I believe that arrays are the only way to go for outdoor use with anything more than a small group as long as transportation isn't an issue. The money saved on amps and power source alone could go toward one of the pro sound crossover/equalizer units to fine tune the sound to your liking.
While I realize it sounds a bit off the wall, there's real science behind what I'm recommending. Please, if there's a hole in the idea, someone shoot me down because I already have almost enough drivers to give it a whirl. Too bad I don't have the need, but building it would be reason enough to throw a party. All those driver holes though, yuck.
Just a few points before you dismiss the line array idea and I drop the subject:
In the nearfield, line arrays decrease in SPL by 3db for each doubling of distance. Point source speakers (pro or otherwise) decrease by 6db for each doubling of distance. This difference is huge, especially in terms of the size of the prime listening area
and the amount of power you need.
For example, let's assume you want 100db at 16 meters which seems about right for a group of 100 people outdoors. At 1 meter you need 124db from a point source speaker and 112db for the line array. The point source will be too loud up front and the line array will give you an area 8-10 times as large with comfortable but loud prime listening.
Also, 124db in the 30-60hz range, which I think is crucial for the music you want to play, is difficult and expensive, especially outdoors where there is no room gain from 50hz down like in a club. While I'm sure Bill has good speaker designs, the Tuba for example would need 1000 watts to play 124db in the 30-60hz range. The driver is only rated for 250 and I'm sure it sounds stressed long before that. Plus 1000 watts is expensive.
112db is easy to acheive with a line array. It just needs to be quite long and even longer for the bass frequencies. Plus the mids and up need very close spacing, so lots of drivers are needed. For bass, the array needs to be longer but drivers can be spaced further apart. The 16ft vertical arrays and 32ft bass arrays I outlined should get you at least close to a 16 meter near field/ far field transition distance.
Why can cheap drivers work? Because you are asking each to do only a little work. The 4" $1.50 drivers I use have a sensitivity of about 89db. 32 on one channel gets you up to 103db on 1 watt. 8 watts total to get you to 112db. You could use one of Target's $30 Tamps and play it all night on a small rechargeable battery pack. Each driver only needs 1/4 watt to get there, so there's no stress at all. Cheap 4" wide range drivers are plentiful because they are used in cars, radios, TV's etc. and many are designed for free air use in cars and TV's. They just can't handle much power and sound stressed when pushed too hard. The woofers would need more power. The ones I use are only 85db, so 16 gets you up to 97db at 1 w/m , so you need 32 watts to get up to 112db. Still easy though and only 2 watts per driver, so no stress at all. Even in free air dipole use you could probably go to 118db with no stress, 1 watt/driver on the vertical array and 8 watts/driver on the woofers. They're rated for 20 and 235 watts respectively, but in free air that would be significantly reduced.
Why dipole? 1. I prefer the natural dipole sound, but alot of the openess is likely to be lost with no back wall to reflect the back wave. The natural tone will be retained though. 2. It's very easy to get right. 3. With foldable and detachable baffles would make it relatively efficient to transport. There's no way you could tranport boxed bass arrays with what you have.
The alternative for relatively compact transport would be to use aperiodic membranes on the back of the drivers. The baffle wings would go away, making transport and setup easier, but getting the right tuning consistent accross the arrays would take alot of trial and error. The increase in output and power handling might make it worth the effort.
The more I think about it, the more I believe that arrays are the only way to go for outdoor use with anything more than a small group as long as transportation isn't an issue. The money saved on amps and power source alone could go toward one of the pro sound crossover/equalizer units to fine tune the sound to your liking.
While I realize it sounds a bit off the wall, there's real science behind what I'm recommending. Please, if there's a hole in the idea, someone shoot me down because I already have almost enough drivers to give it a whirl. Too bad I don't have the need, but building it would be reason enough to throw a party. All those driver holes though, yuck.
I really appreciate your advice, but it's huge!!!!! 16 and 32 foot for one side amplification ?!!??!!
Where will I store them? I'll soon have a small flat.
I really want it to be transportable. "let's take the setup here, let's take the setup there" kind of thing.
I'm just a guy that wants to have some fun..
Are you absolutly sure you got the calculation for the Tuba24 right?
Where will I store them? I'll soon have a small flat.
I really want it to be transportable. "let's take the setup here, let's take the setup there" kind of thing.
I'm just a guy that wants to have some fun..
Are you absolutly sure you got the calculation for the Tuba24 right?
It looked like 92db of sensitivity in that range which makes sense because it's a very small horn and most of that range is below Fs of the driver.
I understand the just for fun aspect, but 100 people sound more like a big party. The 4 8ft units for the vertical arrays would be nothing to strap on top of the roof rack. 16 of the 4 ft 2 driver base units is alot to move around, but you could cut that to 4 units per side a 4 drivers on each. Just put 4-5ft between each unit and still preserve the line array affect. But then tripping over wires etc. would become a problem. The bass arrays would form
a partial border for the party.
I can see that the big wings would be problematic for the woofers in dipole, so aperiodic is probably the answer spacewise and for looks too. After more thought the easiest way to do that is to build a small box that just covers the backs of the woofers sets. For the prototype, make the back removeable and drill small holes in the back plate until you find the correct amount of airflow resistance. Then just put the same number and size holes on each unit.
I think what I would do is put 4 drivers in each aperiodic unit. With 3/4' ply they would be just over 4ft wide 13" tall and 5.5"deep. Put a grill cover on each driver and if necessary use stakes in the ground so people don't knock them over. Space these units 4-5ft apart. Just bring a shovel along to make a small slice in the ground to run the wires so no one trips over them. You should have help anyway for a 100 person party. I think the 8 bass units and the 4 vertical units would fit easily in and on top of your little wagon. Setup time would be quick as well, plus the bass units would be strong enough for people to sit or stand on without you worrying.
For the vertical arrays make a detachable extension that would go into the ground. Use a post hole digging tool to make just the right size hole to stick the bottom of the array into. Get it in the correct position and fill in the gaps with dirt. Then you don't need guide wires that someone is sure to trip over. Yeah it's a little manual work but it's only 2 holes that would take a couple of minutes each. Just make a freeloading helper do it, you bought and built the rig.
I'm liking this idea more and more. I think it's close to being something marketable.
I understand the just for fun aspect, but 100 people sound more like a big party. The 4 8ft units for the vertical arrays would be nothing to strap on top of the roof rack. 16 of the 4 ft 2 driver base units is alot to move around, but you could cut that to 4 units per side a 4 drivers on each. Just put 4-5ft between each unit and still preserve the line array affect. But then tripping over wires etc. would become a problem. The bass arrays would form
a partial border for the party.
I can see that the big wings would be problematic for the woofers in dipole, so aperiodic is probably the answer spacewise and for looks too. After more thought the easiest way to do that is to build a small box that just covers the backs of the woofers sets. For the prototype, make the back removeable and drill small holes in the back plate until you find the correct amount of airflow resistance. Then just put the same number and size holes on each unit.
I think what I would do is put 4 drivers in each aperiodic unit. With 3/4' ply they would be just over 4ft wide 13" tall and 5.5"deep. Put a grill cover on each driver and if necessary use stakes in the ground so people don't knock them over. Space these units 4-5ft apart. Just bring a shovel along to make a small slice in the ground to run the wires so no one trips over them. You should have help anyway for a 100 person party. I think the 8 bass units and the 4 vertical units would fit easily in and on top of your little wagon. Setup time would be quick as well, plus the bass units would be strong enough for people to sit or stand on without you worrying.
For the vertical arrays make a detachable extension that would go into the ground. Use a post hole digging tool to make just the right size hole to stick the bottom of the array into. Get it in the correct position and fill in the gaps with dirt. Then you don't need guide wires that someone is sure to trip over. Yeah it's a little manual work but it's only 2 holes that would take a couple of minutes each. Just make a freeloading helper do it, you bought and built the rig.
I'm liking this idea more and more. I think it's close to being something marketable.
It's about the quality that I care about ; How can I know it will sound good?
Each driver sounds different, I can see the trouble of balancing coming, big time... Correct me if I'm wrong..
Also, we are talking about a total of 8 bass woofers, right? What diameter? How much of expense should I expect from this?
Talking about cost, I will DIY my amps, so the difference is not huge for more powerful amplifiers.
Another thing is that I'm a bassist and it seems like the Tuba24/DR250a will work as an excellent bass rig, I don't have an amp right now.. Although I don't know if it will sound good in a reasonable volume in the house
Each driver sounds different, I can see the trouble of balancing coming, big time... Correct me if I'm wrong..
Also, we are talking about a total of 8 bass woofers, right? What diameter? How much of expense should I expect from this?
Talking about cost, I will DIY my amps, so the difference is not huge for more powerful amplifiers.
Another thing is that I'm a bassist and it seems like the Tuba24/DR250a will work as an excellent bass rig, I don't have an amp right now.. Although I don't know if it will sound good in a reasonable volume in the house
rcavictim said:I cannot understand why they would have discontinued such a fine and very affordable compression driver.
That woofer looks like it is capable of exposing the cabinet weaknesses of any A-7 box. Nice!
I think it is just the evolution of a product. The 205 was old the 210 is new, and costs more, gee.
Those woofers have a way of making the cabinet into it's own resonant chamber. It's like the walls are their own passive radiators when you turn it up. No those cabinets weren't quite made for the woofs but what the heck, they're only for partying.
And besides, the girls like them. They're forever leaning against them.
Cal
Is use some 12" woofers that I get locally for $12.50 ea. Just some cheap highish Q woofers. They were the best sounding cheap ones I could find. Nippon NWX-1277 235watt peak power handling is all the info I have.
Not 8 woofers, 16 woofers per side so 32 total. You might be able to get away with 8 or 12 per side, but you'd need to space them out to get the line array length of 10 meters or so. Dipole I think you'd need the full 16.
Don't by anything cheap unless you hear it first. Most of the super cheapies are real junk, especially with woofers. Bad cheap wide ranges sound harsh, so they are easy to identify. Spend some time shopping around and listening and once you find something you like, negotiate the price. I could do the full speaker setup (64 widerange drivers, 32 woofers, 4 super tweeters) for $550 in drivers plus $150-200 in wood, wire, connectors, etc. That's here is Costa Rica, where shipping, import duties and taxes essentially double the price of all audio stuff.
2 ways to go with the balancing aspect. One, use the savings to get something like a Behringer xover/eq unit . Then you could adjust it any way you wanted. or Two, just do a first order passive xover at say 100hz. Use an Lpad and a cap on the tweeter. Separate amps for the woofers and tweeters would be essential due to the difference in efficiency. If you are building amps then you may want to just do your own active xover. Keep in mind that this is alot easier than designing a typical 3 way speaker because you want to use a wide range driver from say 100hz to 10khz, so you aren't crossing anything over in any critical range. The bass units will provide the low end impact and the tweeters will add the "air" on top, but the wide range units will actually play most of the music.
Not 8 woofers, 16 woofers per side so 32 total. You might be able to get away with 8 or 12 per side, but you'd need to space them out to get the line array length of 10 meters or so. Dipole I think you'd need the full 16.
Don't by anything cheap unless you hear it first. Most of the super cheapies are real junk, especially with woofers. Bad cheap wide ranges sound harsh, so they are easy to identify. Spend some time shopping around and listening and once you find something you like, negotiate the price. I could do the full speaker setup (64 widerange drivers, 32 woofers, 4 super tweeters) for $550 in drivers plus $150-200 in wood, wire, connectors, etc. That's here is Costa Rica, where shipping, import duties and taxes essentially double the price of all audio stuff.
2 ways to go with the balancing aspect. One, use the savings to get something like a Behringer xover/eq unit . Then you could adjust it any way you wanted. or Two, just do a first order passive xover at say 100hz. Use an Lpad and a cap on the tweeter. Separate amps for the woofers and tweeters would be essential due to the difference in efficiency. If you are building amps then you may want to just do your own active xover. Keep in mind that this is alot easier than designing a typical 3 way speaker because you want to use a wide range driver from say 100hz to 10khz, so you aren't crossing anything over in any critical range. The bass units will provide the low end impact and the tweeters will add the "air" on top, but the wide range units will actually play most of the music.
AdamZuf said:
The best sources I've found are electronics parts shops here that also carry some audio stuff, mostly raw drivers for car audio but also replacement speakers for TV, radios, etc. At least here, they always have a way to clip a speaker wire to it and here it play. Most of them have a big box and different baffles with different sized driver holes for auditioning. For the small drivers you really want to hold them in your hand so you can listen on and off axis and how much detail they have on the top end (ie can you hear the cymbals?)
That's a good one. Low price and good sound are what you want. The only specs on these types of drivers is the max power and ohms. For the small ones 4"-5" the Fs is usually between 90hz and 110hz, but it doesn't really matter too much. You want to know how high they go and do they sound good. Harsh cone breakups, poor sound, lack of extension, etc. are readily apparent when you listen to them. Stick with paper cones.
With woofers you want to listen for low end extension. Have them turn the treble all the way down because you don't want that to muck up what you are listening for. Bring your own tunes with low bass content and for high end extension on the small drivers for that matter. Have them crank up the volume to see what the woofer will do. Bring a ruler with you to estimate the xmax by pressing the cone inward (more xmax is better because SPL in low bass is about moving air). Compress the cone with your hand (if it goes in too easily, the Vas and Qts are too high) Press on the edge of the cone from the front and back to get an idea of the cone's stiffness (stronger is better).
Judging the Fs of woofers: Hold the woofer in one hand by the magnet, lean your ear over the cone and tap the cone with your finger. I've been told that tone is the resonant frequency (the Fs) of the driver. You won't know what that frequency is but you'll know which ones are lower than others. The lower the better because you want low bass.
A good way to tune your ears for what is good and what's not is to go to a store that sells high quality drivers, with known specs and do the above listening and feel tests with good expensive stuff first. A pro sound repair shop is a good place to start. Of course, they'll look at you like you are crazy when you're pushing and tapping on woofer cones. When they ask, explain it to them and they'll be impressed.
Go and listen to whatever you can find and buy one each of a few different small drivers. Don't buy any woofers until you are sold on the line array idea. Buy a tone generator for your computer if you don't already have one. Listen to music and and tone sweeps to pick the best one, both in free air and on a cardboard baffle. Listen at a distance as well, since some (especially those with whizzer cones) often sound much better at a distance than extremely close up. Once you have a favorite based on sound and price, buy 7 or 9 more and make a pair of 4 or 5 driver arrays with the drivers as close together as possible. Give them a listen on a table top. Then while they are playing stand up and hear the dramatic decrease in volume as your ears move outside of the plane of the arrays. Then you will understand what the line array effect is and why it is so beneficial.
My favorite is also one of the cheapest I have found at $1.50 . It's rated for 20 watts and is 4 ohms (ohms don't matter by the way since you'll do a parallel/series comination to get whatever impedance you want.) with a foam surround. It's a 4" and has B/K Quality Electronics #74BSP4420 on the back. They have a smooth open sound and are reasonably flat up to 10.6khz .
If found some off brand car audio 4's (if forget the name) that sounded almost as good for $4/pr with speaker grills and had a 200 watt power rating. They were slightly less sensitive and I didn't like what they did at the top end using a tone sweep. I did build an array using them for a friend because he wanted to use speaker grills. They also had some kind of treat cloth rolled surround that didn't compress consistently, which worried me, so I haven't used them since.
Another sweet sounding 4" for $3/ea . Is a shielded one that has the Mitsubishi logo on it. 8 ohms 20 watts and says Singapore on the back pt# 480P037A10 . With it the top end is a little lower, so it needs more help from the tweeter.
I've never been able to find any additional information online about any of these drivers.
In the past 9 months I've built 7 different arrays, most using the B/K's . 6 of those where dipole and the other was sealed using a piece of 8" pvc pipe and a wooden baffle.
The tallest was right at 10ft with 24 4's and 1 super tweeter. That one was for a bar to use as speakers for the projector setup I sold them. They already had plenty of bass, but the vocals were unintelligble and they needed clear voice for soccer games. They have really nice sound now in a big area 30m wide by 12m deep. I wanted to go with a taller array but the sloping metal roof would have caused reflection problems. The array is just drivers mounted on 12mm plywood hung from the ceiling 2 ft from the wall with a 1" layer of foam rubber needed over the back of the drivers due to the close proximaty with the wall. It was a nice little project for $100 in drivers, 2 caps, 1.5 sheets of plywood, and some thin black material to stretch over the front for looks and driver protection. They were more than happy when I charged them $525 after they heard how good it sounded, especially compared to the sound from thousands they previously invested. All of the other dipoles had a bass unit at the bottom and were quickly sold to friends and business aquaintances who heard them.
My next array will be for me, using everything I have learned. It will have an adjustable curvature concave baffle with 16 drivers plus a bullet tweeter and dipole bass units on the top and bottom, so I'll have the line array effect all the way up to over 10khz and an adjustable super tweeter to fill in the "air" at the top end. Plus, I should have much better imaging than with a traditional flat baffle array.
I've never built a subwoofer array and have never even heard one, since any concert I ever went to had the typical pro sound line array units that roll off below 50hz or so, but the theory is good. I've done some looking around and haven't run across anything to indicate a problem with the use of a horizontal bass array for your application. Pro sound setups would never use horizontal because their goal is wide dispersion. You don't want or need dispersion outside of the ends of those bass arrays and some focusing toward the group should make it even better.
I'm begining to like your idea
I'll go and search for 4->5" drivers.
Please tell me, knowlegable man, throughout this thread you talk in many terms that I yet to really understand (although I get the picture, just not some of the detail). Do you know a good site that explains all of these and how to put these terms into practice and calculation, like you do?
A simple example, I would like to calculate how much Watts each of them will have to play while within the array, if I got a certain number of them, required amp power and so on.
I wonder how good can a 5 drivers per side array sound in a small room, if a bit more money is spent for good drivers, woofers and tweeter.
Thanks for the help
Adam
I'll go and search for 4->5" drivers.
We're talking about the bass woofers only, right?
Please tell me, knowlegable man, throughout this thread you talk in many terms that I yet to really understand (although I get the picture, just not some of the detail). Do you know a good site that explains all of these and how to put these terms into practice and calculation, like you do?
A simple example, I would like to calculate how much Watts each of them will have to play while within the array, if I got a certain number of them, required amp power and so on.
I wonder how good can a 5 drivers per side array sound in a small room, if a bit more money is spent for good drivers, woofers and tweeter.
Thanks for the help
Adam
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