Correct; between me and a few others posting this on various forums, but mostly here, surprised you couldn't find it: Qts' = Qts + any added series resistance: mh-audio.nl - Home
All things considered though and assuming a nominal 8 ohm driver, then just use a 0.403 Qts where in a reflex, Vb = Vas, Fb = Fs, so 300L would be the absolute minimum in a BIB and ~900 L the point of diminishing returns with 125 dB/37 Hz transients/30 W/1pi per HR.
GM
Thanks GM, I promise that I did look for it. The BIB thread is one hell of a long thread now so things can get lost. Plus, it is me looking for it after all. 
Building a super efficient deluxe econowave into a BIB instead of the Jensen (Brociner) horns seems like such an amazing idea I'm surprised no one else has done it - 101 db efficient BIB's that should go DEEEEEEEP...
Should put my Sachikos in the shade in a few areas.
Components have arrived and I'm debating whether to build a test cabinet out of chip board or just dive in and build a plywood enclosure. I've gotta hear these!
Building a super efficient deluxe econowave into a BIB instead of the Jensen (Brociner) horns seems like such an amazing idea I'm surprised no one else has done it - 101 db efficient BIB's that should go DEEEEEEEP...
Should put my Sachikos in the shade in a few areas.
Components have arrived and I'm debating whether to build a test cabinet out of chip board or just dive in and build a plywood enclosure. I've gotta hear these!
You're welcome!
Well, admittedly one has the best luck finding stuff when just searching for the core 'theme', so I just did a search of the BIB thread for 'matching impedance' and the first 'hit' gave essentially what 'we' were looking for in post 130, so wouldn't have needed to even scan very far in this case: Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?
GM
Well, admittedly one has the best luck finding stuff when just searching for the core 'theme', so I just did a search of the BIB thread for 'matching impedance' and the first 'hit' gave essentially what 'we' were looking for in post 130, so wouldn't have needed to even scan very far in this case
: Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?GM
Actually....... the pipe horn variants I did way back when were almost all Econowave concepts using various cheap 12-15" wide range [mid] woofers and usually just a 1200 Hz wide range 40x90 horn capped off with a 2.2 uF, a popular combo used in floor standing and [stereo] consoles and always seemed to sound fine as long as they were coupled to the electronics they came with.
Did some smaller ones using 8" + 1" cheap Radio Shack drivers with the initial response that I was nuts to put an 8" into an 8 ft^3 cab until I cranked up Rick Wakeman's 'The Six Wives of Henry VIII'/'Jane Seymour' that is
.There was some folks 'threatening' to build some BIB versions, but don't recall it happening. 'Hope Springs Eternal' though............
I had occasion to get a little involved in a local system build using chip/flake board recently and found that its properties have changed quite a bit over the decades since I last used it and with the 3/4" having a MOE not that much less than BB, etc., ply that combined with the latter's price hikes in recent years I see no reason other than cosmetics to waste the $$$ on it and just add a little more bracing.
GM
I got the inspiration from Wilberforce's "What would you do with this cabinet" thread. I'd been wanting to build a the same cornerhorns he built but things got in the way - I kept trying to get cabinet makers interested, they'd say they'd do it until it came time to start and then they were "busy" or they'd "lost their woodworking space" etc.
The BIB calculator gives dimensions of 28 deep by 19.75 width 87.65 height and that's just perfect for efficient use of materials. I should be able to build a pair of them with five sheets, and I'm definitely going to build the first set out of OSB like the ones Variac did with the Pioneer BOFU 8" drivers back in the day. It should allow me to get an idea if the concept works and what it will sound like. I'll make a more ambitious build later or wrap the existing cabinet with 1/4" maple ply. Even though they're big they should be a lot easier to build than my Sachikos were.
JBL 2220A drivers have arrived intact and look like new.
The BIB calculator gives dimensions of 28 deep by 19.75 width 87.65 height and that's just perfect for efficient use of materials. I should be able to build a pair of them with five sheets, and I'm definitely going to build the first set out of OSB like the ones Variac did with the Pioneer BOFU 8" drivers back in the day. It should allow me to get an idea if the concept works and what it will sound like. I'll make a more ambitious build later or wrap the existing cabinet with 1/4" maple ply. Even though they're big they should be a lot easier to build than my Sachikos were.
JBL 2220A drivers have arrived intact and look like new.
Well, if they wind up sounding anything like mine did it will have most of the performance of an all compression horn system except bass 'attack' won't be quite as 'fast'/'sharp', but still better than standard cabs, so a small price to pay for a smaller cab that's much easier to build/move.
Sweet! :D
GM
Hi GM,
I looked at the posts from that link and didn't really get any closer to understanding "how close is too close" when it comes to the terminus and the ceiling. Maybe I'm just thick in the head
I think I'll just build the test cabinets, info on the driver says that the fs is 37hz, I put in 40hz because it was too long at 37. If I set the Qts as .17 and Vas as 300 and the Fs as 38 I get 92" height, width of 19.3 and depth of 27.4 which means the hypotenuse of the triangle becomes 94" so I'd have two inches to spare and the terminus will be four inches from the ceiling.
Too close?
A 40Hz Fs entered into the calculator gives me a couple more inches so basically six inches. Is that better than four?
I looked at the posts from that link and didn't really get any closer to understanding "how close is too close" when it comes to the terminus and the ceiling. Maybe I'm just thick in the head
I think I'll just build the test cabinets, info on the driver says that the fs is 37hz, I put in 40hz because it was too long at 37. If I set the Qts as .17 and Vas as 300 and the Fs as 38 I get 92" height, width of 19.3 and depth of 27.4 which means the hypotenuse of the triangle becomes 94" so I'd have two inches to spare and the terminus will be four inches from the ceiling.
Too close?
A 40Hz Fs entered into the calculator gives me a couple more inches so basically six inches. Is that better than four?
Last edited:
Greets!
For the purposes of this type boundary loading, my SWAG is that this math defines the minimum distance for a ~optimal corner loading and as it decreases, the higher the bass roll off due to 'compressing/squeezing' the pipe horn's 1/4 WL loading [tuning to a higher frequency] with of course it becoming a leaky sealed alignment once flush against the corner, which at this point will reduce the driver's power handling to virtually nothing since it's tuning will still be way below its Fs and why these types of alignments [> 0.707x Fs] demand ZERO air leaks.
A greater distance then will lower the pipe horn's Q, extending its roll off BW a bit with of course a rapid decrease in power handling.
GM
For the purposes of this type boundary loading, my SWAG is that this math defines the minimum distance for a ~optimal corner loading and as it decreases, the higher the bass roll off due to 'compressing/squeezing' the pipe horn's 1/4 WL loading [tuning to a higher frequency] with of course it becoming a leaky sealed alignment once flush against the corner, which at this point will reduce the driver's power handling to virtually nothing since it's tuning will still be way below its Fs and why these types of alignments [> 0.707x Fs] demand ZERO air leaks.
A greater distance then will lower the pipe horn's Q, extending its roll off BW a bit with of course a rapid decrease in power handling.
GM
Okay, so the closer it is the sooner the horn rolls off in the very low frequencies, right? In that case I'll just go with six inches from the ceiling and see how that goes. Right now I'm using a 2W 45 SET amplifier, no worries about power handling. I can also press a pair of Heathkit W4-AM amps into service for parties.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.