Re: B.A.F. equals...
I read that the way a fibrous material kills sound waves is like this:
First, recall the gas law: PV=nrT; Pressure times volume equals temperature times a couple of constants. Just because the pressure in a sound wave is changing very rapidly doesn't mean there isn't some localized heating and cooling. The fibers have a lot of surface area in contact with the air, and as the air heats (positive pressure), the fibers are heated up and take some of the energy out of the air. As the air is cooled by the negative pressure, the fibers give up some of that heat.
I wish I had a link for where I read about this....
Anyway- I'd suggest getting some cheap fiberglass batting to line the cabinet. If that's too nasty to work with, then you could get a horribly unloved quilt from the local thrift shop (but make sure to wash it first) and staple that to the inside walls. You're looking to kill reflected high frequency sounds throughout most of the enclosure. The pointy top end down to some short distance below the driver could use some poly-fill (the fluffy stuff they sell to make your own pillows). It's fairly cheap at Walmart in big bags. There's no need to go with exotic audio stuff for this project.
moray james said:
I read that the way a fibrous material kills sound waves is like this:
First, recall the gas law: PV=nrT; Pressure times volume equals temperature times a couple of constants. Just because the pressure in a sound wave is changing very rapidly doesn't mean there isn't some localized heating and cooling. The fibers have a lot of surface area in contact with the air, and as the air heats (positive pressure), the fibers are heated up and take some of the energy out of the air. As the air is cooled by the negative pressure, the fibers give up some of that heat.
I wish I had a link for where I read about this....
Anyway- I'd suggest getting some cheap fiberglass batting to line the cabinet. If that's too nasty to work with, then you could get a horribly unloved quilt from the local thrift shop (but make sure to wash it first) and staple that to the inside walls. You're looking to kill reflected high frequency sounds throughout most of the enclosure. The pointy top end down to some short distance below the driver could use some poly-fill (the fluffy stuff they sell to make your own pillows). It's fairly cheap at Walmart in big bags. There's no need to go with exotic audio stuff for this project.
OK , so 1" polyester batting from a cloth store will work it seems..
Thanks Moray and others..
deiksac,
Nice to have a crossover for the Selenium tweeter. I don't think the 15" wouldn't work in this box anyway, and 12" is already outrageous! Clearly the box design doesn't correspond to our box here.
panomaniac:
Good idea with the poles, either would work, I think you are right, a few more couldn't hurt. Funny about the dimensions on my drawing. I gave myself away as an architect!, BUT as you suggested, the box is so big, the feet and inches worked great! Funny! I will post plans that are easier to read soon.
Punkrockr:
I would suggest glueing decent pieces of 2x4 around the top of the horn on the outside to stiffen it up. Will add to final drawings
Blumenco:
For full on DJ work, a more pro type tweeter such as deiksac mentions, might be better. It won't have the highest frequencies, but a lot tougher. For Punkrocker, with the speakers in his room, I think the FT17 will give him better sound. If the FT 17 is crossed over really high, as we are planning for Punkrockr , it migh be tough enough for hard use- I just don't know!!
Heavy as the birch is, it is lighter than MDF, and a lot tougher, as you point out. I have mentioned some "imported birch" that is not as high quality as the 5'x5' stuff, but cheaper and comes in 4x8 sheets.
For DJ use, the concentric 12/tweet would be worth looking into for sure... I think that if you are going to cross the thing over lower like you would with a pro tweeter, that concentric is the way to go.
Obviously if your friend is using a receiver, then he is in the same boat as Punkr, the cost matters. And the 12 LTA is a lot of driver for the money!
Let me suggest that the Eminence 12LTA is in keeping with the standard, smaller BIB speakers that are built with whizzer cone drivers, and the driver is known to sound good, so I am intrigued by this choice. There is no doubt other drivers will work, but the calcs should be reviewed. I'll bett the same crew here will calculate for other big drivers if someone is truly planning to make the thing!
All and all , this is a really fun thread! I hope we see some pics soon!
Thanks Moray and others..
deiksac,
Nice to have a crossover for the Selenium tweeter. I don't think the 15" wouldn't work in this box anyway, and 12" is already outrageous! Clearly the box design doesn't correspond to our box here.
panomaniac:
Good idea with the poles, either would work, I think you are right, a few more couldn't hurt. Funny about the dimensions on my drawing. I gave myself away as an architect!, BUT as you suggested, the box is so big, the feet and inches worked great! Funny! I will post plans that are easier to read soon.
Punkrockr:
I would suggest glueing decent pieces of 2x4 around the top of the horn on the outside to stiffen it up. Will add to final drawings
Blumenco:
For full on DJ work, a more pro type tweeter such as deiksac mentions, might be better. It won't have the highest frequencies, but a lot tougher. For Punkrocker, with the speakers in his room, I think the FT17 will give him better sound. If the FT 17 is crossed over really high, as we are planning for Punkrockr , it migh be tough enough for hard use- I just don't know!!
Heavy as the birch is, it is lighter than MDF, and a lot tougher, as you point out. I have mentioned some "imported birch" that is not as high quality as the 5'x5' stuff, but cheaper and comes in 4x8 sheets.
For DJ use, the concentric 12/tweet would be worth looking into for sure... I think that if you are going to cross the thing over lower like you would with a pro tweeter, that concentric is the way to go.
Obviously if your friend is using a receiver, then he is in the same boat as Punkr, the cost matters. And the 12 LTA is a lot of driver for the money!
Let me suggest that the Eminence 12LTA is in keeping with the standard, smaller BIB speakers that are built with whizzer cone drivers, and the driver is known to sound good, so I am intrigued by this choice. There is no doubt other drivers will work, but the calcs should be reviewed. I'll bett the same crew here will calculate for other big drivers if someone is truly planning to make the thing!
All and all , this is a really fun thread! I hope we see some pics soon!
Variac said:
I got the last two of the 15" coax from PE at 99 USD ea. during the clear-out. Yes, the last two.
I don't know if they are even made anymore, can't find anything from Selenium.
Those along with a 15" powered woofer make sweet music at party time.
EDIT: They still show it as being made but it doesn't seem available anywhere. Under Pro gear at the bottom right.
http://www.seleniumloudspeakers.com/
EDIT 2: These guys show it:
http://www.martinsoundpro.com/item.asp?id=369
I tried adding it to the cart at Martin, and it lists it, so I guess they have some. For DJ use this would be a good choice, and after figuring in the cost of a crossover and the tweeter, a great deal. BUT, more money than the Eminence... and sometimes $100 is a lot...
Also, it isn't established that the Selenium would sound better than the Eminence. Even though I'm a Selenium fan, for home use I suspect the opposite..
Also, it isn't established that the Selenium would sound better than the Eminence. Even though I'm a Selenium fan, for home use I suspect the opposite..
Another Beyma budget option...
is the 10AG/N. This is a 10 inch full range driver in their public address series which takes 100 watts and is 97 db efficient with a posted frequency response of 60-1700 Hz. No specific data is listed in the catalog but they would probably provide it if you asked. The driver has a whizzer cone and the response graph looks smooth. Would guess that this is in the same kind of price range as the eminence LTA perhaps less expensive. Probably a very good candidate for those on the euro side of the world. The usual driver modifications would also probably help and it looks to be well enough extended to get you up and running without a tweeter to start. Regards Moray James.
is the 10AG/N. This is a 10 inch full range driver in their public address series which takes 100 watts and is 97 db efficient with a posted frequency response of 60-1700 Hz. No specific data is listed in the catalog but they would probably provide it if you asked. The driver has a whizzer cone and the response graph looks smooth. Would guess that this is in the same kind of price range as the eminence LTA perhaps less expensive. Probably a very good candidate for those on the euro side of the world. The usual driver modifications would also probably help and it looks to be well enough extended to get you up and running without a tweeter to start. Regards Moray James.
jamikl said:
Everything is back to normal, thanks! We got quite a shaking Sunday morning. Magnitude 6.6 I'm rarely awake at 7 AM, but just happened to be. A wild ride.
Earthquakes always start to same way for me, the low rumble- "must be a big truck". Then the bigger rumble "wow, must be a big bulldozer". Then things start to shake "Oh my God! They dropped the big one!" (Child of the Cold War, you know).
Then when things are really tossing back and forth "Ohhhh.. it an earthquake." I kinda like them. =)
Let me tell you, I can point right to where to sound was coming from - and that direction is the Big Island. The epicenter was about 6 miles off the Big Island in our direction. Who says low bass is non-directional? I sure knew where it was coming from.
Only trouble we had was power out for about 5 hours. The power plants have seismic sensors and shut down when there is too much shaking. Takes a long time to spin the plants back up.
OK, now back to real bass, like the BBBIB!
I know you are moving up to 12+....but
..how about these 10" eminence -- no bidders on eBay as yet...
http://cgi.ebay.com/1-Pair-Eminence...4QQihZ005QQcategoryZ47095QQrdZ1QQcmdZViewItem
BP102 Emenince , 95dB, 200W, 40Hz - 9KHz, etc
..how about these 10" eminence -- no bidders on eBay as yet...
http://cgi.ebay.com/1-Pair-Eminence...4QQihZ005QQcategoryZ47095QQrdZ1QQcmdZViewItem
BP102 Emenince , 95dB, 200W, 40Hz - 9KHz, etc
Bass guitar speakers are usually a bit more neutral than guitar speakers. http://www.eminence.com/pdf/legend-b102.pdf
FR is fairly flat +/- 1.5 db to 2K, but there are impedance bobbles indicating some cone floppies from 400 Hz on up.
Would probably do nicely for a system where loud is more important than absolute sound quality.
FR is fairly flat +/- 1.5 db to 2K, but there are impedance bobbles indicating some cone floppies from 400 Hz on up.
Would probably do nicely for a system where loud is more important than absolute sound quality.
I don't know if it as been mentioned, but here is the "Master " thread about BIB speakers:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66173&perpage=10&pagenumber=1
I agree that Bass speaker might well be OK , maybe more than OK with a decent tweeter on top!
Whoops! They went for $125 the pr on e-bay That's probably close to mail order price!
I sure hope someone makes one of these monsters soon!!
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66173&perpage=10&pagenumber=1
I agree that Bass speaker might well be OK , maybe more than OK with a decent tweeter on top!
Whoops! They went for $125 the pr on e-bay That's probably close to mail order price!
I sure hope someone makes one of these monsters soon!!
VARIAC - I would just say this selenium is the minimum and cheapest compression driver worth buying; its sound is say a bit metallic but comparable driver from competition (B&C, Fane ...) cost min 50% more
Going for 12" is good in terms of xover freq/directionality but the size of the box somehow limits its use. But perhaps I am biased - since here in cz it is not that big problem to take sound out and make a private loud party where an extra bass output of a 15" comes pretty handy
Going for 12" is good in terms of xover freq/directionality but the size of the box somehow limits its use. But perhaps I am biased - since here in cz it is not that big problem to take sound out and make a private loud party where an extra bass output of a 15" comes pretty handy
looking at the specs of the Eminence 12 LTA, it is a pretty lousy driver, sensitivity in the bass spectrum below 95dB (yep the horn makes for this)
The worst thing about this speaker is its size which limits its use, involves a lot of material and work and makes the speaker pretty hard to get rid off - Punkrockr, don't you think you will use these speakers for ever?
I can see those LTAs are very cheap but still I would suggest not to stick to the cheapest option available. I would go to invest more $ into drivers than into the box, say Eminence Delta 15 LF costs (listed) 110$, the selenium goes for 45$ which would make 350 USD inclusive xover. Also much less material to be used, perhaps one or two MDF sheets will be okay. Add some carpetting, protective grilles and handles and you end up with a pair of nice sensitive speakers, which in a room will still blow your ears and will be much more useful (and possible to sell in case your requirements grow).
The worst thing about this speaker is its size which limits its use, involves a lot of material and work and makes the speaker pretty hard to get rid off - Punkrockr, don't you think you will use these speakers for ever?
I can see those LTAs are very cheap but still I would suggest not to stick to the cheapest option available. I would go to invest more $ into drivers than into the box, say Eminence Delta 15 LF costs (listed) 110$, the selenium goes for 45$ which would make 350 USD inclusive xover. Also much less material to be used, perhaps one or two MDF sheets will be okay. Add some carpetting, protective grilles and handles and you end up with a pair of nice sensitive speakers, which in a room will still blow your ears and will be much more useful (and possible to sell in case your requirements grow).
and another reason to go for selenium is the price of the replacement diaphragm - which is close to zero, I thin kfostex will be rather more expensive in this respect
perhaps it seems like I am denouncing this humble project but usually those who go for the cheapest things become disappointed or spend a lot for replacement parts afterwards
perhaps it seems like I am denouncing this humble project but usually those who go for the cheapest things become disappointed or spend a lot for replacement parts afterwards
Dieksac,
Specs don't say everything about a driver
IF you want to discuss options to the BIB please go here:
http://www.diyaudio.com/forums/showthread.php?s=&postid=1034147#post1034147
You are repeating things we have discussed there.
I own a pair of those Selenium drivers and we have discussed them.
Specs don't say everything about a driver
IF you want to discuss options to the BIB please go here:
http://www.diyaudio.com/forums/showthread.php?s=&postid=1034147#post1034147
You are repeating things we have discussed there.
I own a pair of those Selenium drivers and we have discussed them.
Re: Mounting Fostex Tweeter on BIB Speaker
No, it will not. This horn's output will all be in the bass range; most rear-loaded horns are that way, so protrusions and small discontiuties (geez I shouldn't have tried to spell that word before my first cup of coffee
) won't have any effect due to the small size of the feature in relation to the wavelength of the sound in question- AND due to the relatively small reduction in cross sectional area at that part of the horn.
Oh, and because I still need to brew that first cup- I forgot to think of it this way.... The tweeter (this fosex is a bullet tweeter, so it really doesn't sitck into the cabinet that far) is going to look WAY smaller inside the cabinet than the motor structure of the woofer. Think about it like that, eh?
A big 2khz horn might take up enough volume for this to be an issue. A coaxial horn like many of the drivers discussed should not be an issue. Perhaps MJK or someone with experience in horn design will care to comment on how a more significant protrusion of this type is dealt with.
donwb said:
No, it will not. This horn's output will all be in the bass range; most rear-loaded horns are that way, so protrusions and small discontiuties (geez I shouldn't have tried to spell that word before my first cup of coffee
) won't have any effect due to the small size of the feature in relation to the wavelength of the sound in question- AND due to the relatively small reduction in cross sectional area at that part of the horn.Oh, and because I still need to brew that first cup- I forgot to think of it this way.... The tweeter (this fosex is a bullet tweeter, so it really doesn't sitck into the cabinet that far) is going to look WAY smaller inside the cabinet than the motor structure of the woofer. Think about it like that, eh?
A big 2khz horn might take up enough volume for this to be an issue. A coaxial horn like many of the drivers discussed should not be an issue. Perhaps MJK or someone with experience in horn design will care to comment on how a more significant protrusion of this type is dealt with.
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