W Bin -vs- L 36 Low Frequency Cutoff

[OMNIFEX]

Hello Everyone!

I found this site through Google (Gotta Love Google!) and had a question regarding cutoff frequencies between and L 36 vs W Bin

I'm too lazy to drag out the two cabinets, and coduct a test, so, here goes.............


Take in consideration the W Bin dimension is 48 x 24 x 24 and, the L 36 is 36 x 24 x 36, wouldn't the cutoff frequencies be the same?

The internal cabinet chamber (Where the driver is housed) are the same (4.5 cubic feet) and, the cabinet outer chambers are the same (13.75 cubic feet)

So, am I assuming correct, or is there more to it.

Thank you.

[BAM]

Posting more times will not get you a quicker answer.

[OMNIFEX]

There seemed to be a Delay, for posting New Threads in which I wasn't aware of.

[Brett]

Originally posted by OMNIFEX
Take in consideration the W Bin dimension is 48 x 24 x 24 and, the L 36 is 36 x 24 x 36, wouldn't the cutoff frequencies be the same?

The internal cabinet chamber (Where the driver is housed) are the same (4.5 cubic feet) and, the cabinet outer chambers are the same (13.75 cubic feet)

Internal volume has little to do with it. For a horn, these interrelated conditions will determine Fc

Driver;
- resonant frequency
- Qts / Qes
- cone area

Flare;
- type of flare (exponential, hypex etc)
- flare rate
- effective length of the horn
- throat area
- mouth area
- boundary condition (free space, wall loaded, corner loaded, multiple stacked arrays etc)
- amount of truncation of length and/or area (if any)
- rear cavity volume
- front or rear loading
- folding geometry (ie compromises in flare shape with folding; not as big a problem for bass, usually)

It's late, so I may have forgotten something, but you have to juggle all these parameters to get down low. Designing a horn is nowhere near as easy as getting acceptable performance out of a ported or sealed box. Bass horns are the hardest of the lot, because they have to be compromised soo much from the theoretical full size horn of a given flare rate.

So, am I assuming correct, or is there more to it.

Yes, considerably.

[OMNIFEX]

Thank you Brett

Yes. I know the internal chamber has nothing to do with the Horns Response. I just stated that for everyone to get a better undertstanding these boxes are identical, with the exception of
the dimesions. (Where one is taller, has less depth. Where one is shorter, has more depth)

Thank you for you help!

Best Regards,

[OMNIFEX]

As You can see, the only difference is one is taller

[OMNIFEX]

And one is deeper

[OMNIFEX]

They both use the same driver

QTS 0.19
sd 1140 sq.cm

The flares mouth are the same also, the taller one's flare is just split into two. Both mouths (of the W Bin, and, L 36) are 32 inches high by 24 inches wide total.





I tell you this processing time to see a post you've made is

[OMNIFEX]

Ok, Where's the file attachments?

[Brett]

Omni,

None of your images showed up. If you add them in, then preview, you have to add them again or they disappear when you submit the post.

If both the boxes use the same driver, and have similar flares, then the one with the longest path length will likely have the lowest bass, but that's not a given.

The rear chamber can be used to annull the throat reactance near Fc and so is often critical. On midbasses I tune them to the individual driver. If the horns ae truncated the volumes never come out near calculated values and are sometimes as much as 100% off.

If the flares are the same (dist along horn vs cross sectional area) the horn can be split into a number of smaller sections to aid folding. A W bin can be built as a straight horn of the same flare, and at low frequencies, say < 200Hz will perform the same as the folded one. As the frequencies get higher it becomes more complicated and the performance deviates greatly from the equivalent straight horn. Klipschorn, LaScala and Belle utilise this in the bass, and Altec and RCA (to name but two) have made straight midrange sectional horns that are split into 4,8, 12 or 15 sections and act (at a distance) like one large one.

Cheers