Scottmoose said:
OK, got it. But how much is "Swamp?"
In this case you've got a box, a really big box, with a volume of about 16.4 ft^3 (464L) Or 3.33 x driver Vas. That's a big box! No wonder these things don't get built much.
Interesting... So if you turned it over the driver could be placed better, right?
Yikes!
I've never heard a TQWT with really good bass, but never heard the BIB or anything like this crazy BBBIB. If it really is powerfull to 30Hz, it will be a monster.
Let me put it this way. My BIB cabinets with the 6 1/2in Fostex FF165K (which, for your interest, are 70in tall x 9in wide x 14in deep) are flat to 30Hz in-room & have a final cut off at about 20Hz, give or take. They're about 99db efficient for 1w at 1m. My friend Dan Mason has a pair of similar proportions using the FE168ESigma, which go almost as low. And no, I'm not romancing. These things thunder. So yup, this big thing really will give a lot of bass.
This cabinet is a little exceptional -it's much larger than most of the BIBs that are built in terms of footprint, but the driver has a high Vas, so it needs it. GM & I did one for the Visaton B200 which has a 102 litre Vas and a high 0.7 Qt, so that too needed to be considerable. Terminus area was 350in^2. And I had a mad moment, threw the usual conical expansion aside and did this for the Hemp FR8: http://www.zillaspeak.com/bib-hemp.asp See 2nd cabinet & you get the idea... 1x4x9 anyone?
The swamping bit (that's technical language you know ;-) varies according to the driver's Vas, it's Q, the tuning frequency etc. About 3 times Vas is the minimum needed. More is good.
Best
Scott
This cabinet is a little exceptional -it's much larger than most of the BIBs that are built in terms of footprint, but the driver has a high Vas, so it needs it. GM & I did one for the Visaton B200 which has a 102 litre Vas and a high 0.7 Qt, so that too needed to be considerable. Terminus area was 350in^2. And I had a mad moment, threw the usual conical expansion aside and did this for the Hemp FR8: http://www.zillaspeak.com/bib-hemp.asp See 2nd cabinet & you get the idea... 1x4x9 anyone?
The swamping bit (that's technical language you know ;-) varies according to the driver's Vas, it's Q, the tuning frequency etc. About 3 times Vas is the minimum needed. More is good.
Best
Scott
I trust the way (in general) that these enclosures are modeled in Martin King's worksheets. There will be some difference based on room placement, and this may be a big help for evening out the response. Even if the response isn't exactly the same, I believe that you'll be able to get some big bass out of this driver in this enclosure.
I was able to build a huge ported box (you might call it a mass loaded transmission line) for a single Eminence Beta 8, and after extensive equalization I was able to get really loud and solid bass down to about 35 hz. It dropped like a stone below that, and I couldn't get any audible output below 35 hz. Above 50 hz, the speaker was quite solid. Above 200 hz (with an active highpass), it could get as loud as we were talking about for the original "wire my 1500 watt" project.
One thing I would recommend- EQ! It's sort of uncertain how even the bass response will be because nobody is able to really simulate what it will be like in your room. Since the Behringer stuff is in short supply right now, please check out parametric equalizer that run on your PC.
The equalizer I used was this one: http://winamp.com/plugins/details.php?id=4591
I was using my PC to play all of my music. Also, I noticed a big improvement in sound after I upgraded my sound card. Sine wave sweeps had audible distortion with the default motherboard sound output, but were clean and clear with the sound card. At first it sounds like onboard sound is good enough, but when you get real speakers you realize that it's not!
I was able to build a huge ported box (you might call it a mass loaded transmission line) for a single Eminence Beta 8, and after extensive equalization I was able to get really loud and solid bass down to about 35 hz. It dropped like a stone below that, and I couldn't get any audible output below 35 hz. Above 50 hz, the speaker was quite solid. Above 200 hz (with an active highpass), it could get as loud as we were talking about for the original "wire my 1500 watt" project.
One thing I would recommend- EQ! It's sort of uncertain how even the bass response will be because nobody is able to really simulate what it will be like in your room. Since the Behringer stuff is in short supply right now, please check out parametric equalizer that run on your PC.
The equalizer I used was this one: http://winamp.com/plugins/details.php?id=4591
I was using my PC to play all of my music. Also, I noticed a big improvement in sound after I upgraded my sound card. Sine wave sweeps had audible distortion with the default motherboard sound output, but were clean and clear with the sound card. At first it sounds like onboard sound is good enough, but when you get real speakers you realize that it's not!
Hmmmm- flatter but mucho bigger!
These dims are more as I feared
yow!
I guess one can choose any size in- between and get a compromise..
I think that getting the least waste out of cutting the ply might help us decide
Basically a front and side should add up to 48" if we are using 4'x8' x 3/4" thick material.
internal 30 1/2" x16" is perfect
ie 32" side panels and a ( front or rear or divider) of 16" between the side panels
That way you can get a side panel and a (front or back or divider) panel from a sheet, AND three front or back or divider panels from a sheet.
So the 8 sides of 2 speakers will take 4 sheets of ply,
two 16"dividers and a third 16" wide strip for the 2 bottoms from a 5th sheet.
So that's 5 sheets total. (didn't account for kerfs in this quick calc)
These dims are more as I feared
yow!I guess one can choose any size in- between and get a compromise..
I think that getting the least waste out of cutting the ply might help us decide
Basically a front and side should add up to 48" if we are using 4'x8' x 3/4" thick material.
internal 30 1/2" x16" is perfect
ie 32" side panels and a ( front or rear or divider) of 16" between the side panels
That way you can get a side panel and a (front or back or divider) panel from a sheet, AND three front or back or divider panels from a sheet.
So the 8 sides of 2 speakers will take 4 sheets of ply,
two 16"dividers and a third 16" wide strip for the 2 bottoms from a 5th sheet.
So that's 5 sheets total. (didn't account for kerfs in this quick calc)
Well I did warn you... That's why I did the 'smaller' (ha!) one. But, as I said, & Greg has demonstrated, Bigger Is Better. Oh yes indeed. Big = good. Massive sound. Potential to blow your doors out of their frames. Decent control from even a small amplifier (within reason). Plus, you could paint them up to look like the Tardis, which could only be a good thing.
That's why I did the 'smaller' (ha!) one. But, as I said, & Greg has demonstrated, Bigger Is Better. Oh yes indeed. Big = good. Massive sound. Potential to blow your doors out of their frames. Decent control from even a small amplifier (within reason). Plus, you could paint them up to look like the Tardis, which could only be a good thing.
I don't see the size as a problem, it is the amount of wood. I also saw the "monolith " which has wildly different proportions yet apparently works adaquately , right?. So I'm pretty fixed on changing the proportions slightly , but much less than the Monoliths. For Punkrockr's speakers saving a couple of sheets of ply is important. Other builders will now be aware of the optimal proportions.. So, could you review the 30 1/2" x 16" internal and do a plot of its response? Does the height of the driver change? I suppose not... How about my question of the optimal spacing from the top of the cabinet to the ceiling? After all, we could make them up to 8' high. I guess we should assume his ceiling is 8' though..
Punkrockr : could you measure the height of your ceiling?
Punkrockr : could you measure the height of your ceiling?
Re the ceiling height, as I say, it'd take someone with more math ability to figure it out than I posess. I think that's something even Greg's stuggled with, though I speak under correction. Martin's working on 1/8 space modelling for future upgrade to the sheet.
We can theoretically tune a little lower (though as Greg pointed out to me some time ago, it's a bad idea to tune lower than 0.707Fs) but that might put the driver too high, which is why I think both GM & I have restricted height somewhat. Driver height won't change with alterations to WxD.
Scott
We can theoretically tune a little lower (though as Greg pointed out to me some time ago, it's a bad idea to tune lower than 0.707Fs) but that might put the driver too high, which is why I think both GM & I have restricted height somewhat. Driver height won't change with alterations to WxD.
Scott
I assume that this one is "upside down" and vents to the bottom.
Doesn't seem to help the driver height that much.
So, ideally in a "conventional" BIB NOT like the photo should the driver be a bit higher or lower? ie should the closed end be longer or shorter than the number you gave me?
Top venting is actually pretty clever- In addition to being slightly easier to build, there are generally a lot less things in the way when you are that far above the floor, which probably makes for a better corner flare.
It would be interesting to know the excursion of the woofer at 30 hz. and various power inputs.... We only have 3mm xmax to work with I believe. I realize it's horn loaded, but still....
Doesn't seem to help the driver height that much.
So, ideally in a "conventional" BIB NOT like the photo should the driver be a bit higher or lower? ie should the closed end be longer or shorter than the number you gave me?
Top venting is actually pretty clever- In addition to being slightly easier to build, there are generally a lot less things in the way when you are that far above the floor, which probably makes for a better corner flare.
It would be interesting to know the excursion of the woofer at 30 hz. and various power inputs.... We only have 3mm xmax to work with I believe. I realize it's horn loaded, but still....
Attachments
Scottmoose and GM,
I was thinking about doing the same thing with an EV12trxb, and also with an EV15trx. I have Martin King's worksheets. Would you supply a screenshot of the input screen for the worksheet? I will modify appropriately for my dirver's parameters. Just need a starting point.
Thanks,
Paul
I was thinking about doing the same thing with an EV12trxb, and also with an EV15trx. I have Martin King's worksheets. Would you supply a screenshot of the input screen for the worksheet? I will modify appropriately for my dirver's parameters. Just need a starting point.
Thanks,
Paul
ML TQWT sheet. Use line length as per usual, set port position at 0.0001 less than length, 0.0001 lbs ft^3 stuffing. Vent radii is WxD /pi ^0.5
The reason Terry did the floor venting one is that particular cabinet is using the FE108ESigma. Fs for the 108 is a highish 77Hz, so the cabinet is rather short -too short, if venting upward, to couple properly into a corner. So he inverted it to couple to the floor instead. Upward-firing is the best option though -as you mention, & TC has in the past too, not much furniture to get in the way on ceilings!
I forgot to do an excursion graph, but if memory serves it doesn't go much beyond 2mm before cut off. I'll double check in the morning though.
The reason Terry did the floor venting one is that particular cabinet is using the FE108ESigma. Fs for the 108 is a highish 77Hz, so the cabinet is rather short -too short, if venting upward, to couple properly into a corner. So he inverted it to couple to the floor instead. Upward-firing is the best option though -as you mention, & TC has in the past too, not much furniture to get in the way on ceilings!
I forgot to do an excursion graph, but if memory serves it doesn't go much beyond 2mm before cut off. I'll double check in the morning though.
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