I've been looking into running an FX200 in a BIB in a small (already crowded) room. The most I want to deal with is an 18 inch depth and these really need 26-27 inches. The BIB has become a BAB (Big A$$ Box). 
I sketched up the boxes and started looking at maybe turning them 90 degrees and mounting the drivers on the long side of the box. This would keep the depth down to 18 inches, but possibly with some new problems getting them to act right. My first thought was to mount them outboard of the original baffle location in a (ambiguous) compression chamber like the drawing below. It would obviously create some kind of filter chamber, but other than trial-error experimenting, I'm way out of my league here.
Then I looked at mounting the drivers directly into the line at the same location and I'm a little more comfortable trying this approach. I suspect it'll need some pretty aggressive dampening on the back panel directly behind the driver, but other than that, do you guys see any major problems with this? I'd need to relieve the side of the baffle, but it would be minimal, and even less than I've sketched it in here.
If you have any experience doing this or any thoughts, I'd appreciate the input. Thanks.
Allan
I sketched up the boxes and started looking at maybe turning them 90 degrees and mounting the drivers on the long side of the box. This would keep the depth down to 18 inches, but possibly with some new problems getting them to act right. My first thought was to mount them outboard of the original baffle location in a (ambiguous) compression chamber like the drawing below. It would obviously create some kind of filter chamber, but other than trial-error experimenting, I'm way out of my league here.
An externally hosted image should be here but it was not working when we last tested it.
Then I looked at mounting the drivers directly into the line at the same location and I'm a little more comfortable trying this approach. I suspect it'll need some pretty aggressive dampening on the back panel directly behind the driver, but other than that, do you guys see any major problems with this? I'd need to relieve the side of the baffle, but it would be minimal, and even less than I've sketched it in here.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
If you have any experience doing this or any thoughts, I'd appreciate the input. Thanks.
Allan
You might be on to something there. I took a closer look at the drivers, and there's a good chance it'll fit with no changes at all. The basket starts to taper about 5/16" from the back of the flange, less than half way thru a single sheet of 3/4" baffle. It would probably clear both the baffle and the divider, if I were careful about the placement. Worst case would be some small dimples in either or both.
An externally hosted image should be here but it was not working when we last tested it.
Allan
Another option is adjust location of driver vertically until it clears, again, if you don't stray too far, it's probably ok. The effect would be easy to model in HornResp. And in fact, I think the ideal location is really 1/3 the distance from the closed end. It will put location of driver lower and that may not be ideal as it is lower than ear level when sitting.
I like it! I can spin the drivers 45 degrees to a diamond look and completely miss the baffle and divider. No sweat.Allan
That will make a massive change in response, as it changes the cross sectional area of the closed end by a pretty significant amount, won't it?
Right, in theory this will cause an increasingly broadband [decreasing Q] mid-bass suck out if the driver isn't shifted downward with decreasing taper [increasing 'throat' area at the closed end].
FWIW, when this situation came up with the original BIB builds, I theorized that just notching out the divider baffle as much as required and covering it with a scrap piece on the backside since the volume around the driver will be sufficiently stuffed to audibly negate any discontinuity in the expansion and on the backside the expansion has slowed/expanded so much that any effect it may have is to further attenuate any unwanted HF.
The main thing is to create enough of a clearance to not constrict the expansion much since it will create a band stop filter, adding an unwanted notch somewhere in the response.
I don't recall any negative responses WRT performance that could be attributed to this, so lacking any proof to the contrary; it's what I would do.
GM
Thanks everyone for the input. I went ahead and let the box grow to 19.5 for width (I can still live with that) and the depth out to 27.75, which is much closer to the original sim dimensions and the driver will squeak right in with no changes to the cab. The extra depth naturally increases the angle of the divider and along with the baffle thickness and basket taper, it's all good.
Allan
Allan
I've been looking into running an FX200 in a BIB in a small (already crowded) room. The most I want to deal with is an 18 inch depth and these really need 26-27 inches. The BIB has become a BAB (Big A$$ Box).
I sketched up the boxes and started looking at maybe turning them 90 degrees and mounting the drivers on the long side of the box. This would keep the depth down to 18 inches, but possibly with some new problems getting them to act right. My first thought was to mount them outboard of the original baffle location in a (ambiguous) compression chamber like the drawing below. It would obviously create some kind of filter chamber, but other than trial-error experimenting, I'm way out of my league here.
An externally hosted image should be here but it was not working when we last tested it.
Then I looked at mounting the drivers directly into the line at the same location and I'm a little more comfortable trying this approach. I suspect it'll need some pretty aggressive dampening on the back panel directly behind the driver, but other than that, do you guys see any major problems with this? I'd need to relieve the side of the baffle, but it would be minimal, and even less than I've sketched it in here.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
If you have any experience doing this or any thoughts, I'd appreciate the input. Thanks.
Allan
if you post the measurements i will simulate it for you, or post the .dwg, .3ds or sketchup file etc.
Thanks gafhenderson. I have MJK's old worksheets and I need to get a license for his new stuff. I haven't worked with them for 6-7 years so I need to catch up anyway. If I let you do it, I won't learn anything.
FWIW, the box size I'm looking at building is from the BIB calculator with a change from Fr=38 to Fr=42 to shorten the line, and a small change in the internal dims to arrive at a ratio of 1.42 and sm=459. This was done to make cutting the wood to an easy fractional dim. Recommended is sm=460 and 1.4142, so it's a pretty minor difference.
Also, Fs=38, Vas=82L, Qts=.45 (from the spec sheet, not from real-world measurements).
Allan
FWIW, the box size I'm looking at building is from the BIB calculator with a change from Fr=38 to Fr=42 to shorten the line, and a small change in the internal dims to arrive at a ratio of 1.42 and sm=459. This was done to make cutting the wood to an easy fractional dim. Recommended is sm=460 and 1.4142, so it's a pretty minor difference.
Also, Fs=38, Vas=82L, Qts=.45 (from the spec sheet, not from real-world measurements).
Allan
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