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Old 5th April 2007, 06:55 AM   #201
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I just downloaded aKaBaK also, it seems prety nifty.

If anyone here has compiled a basic list of scripts to represent various audio entities I would love to see them. The don't provide many examples in the PDF.

I haven't had much luck getting a simple vented box working yet I think looking at the script dirrectly may be and easier way to learn, than punching in values and dimensions and hoping it turns out right.

Ok thanks guys,
Time to go make sure a DJ didn't melt my BS-212 subs.
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Old 6th April 2007, 05:41 AM   #202
zobsky is offline zobsky  India
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Default Re: K couplers

Quote:
Originally posted by sumsound
For some reason I think you would get more problematic reflected high frequency energy behind the exponential slot in the K coupler, than any improved driver loading in those ranges. I'm sure one would have lots of cancelations in the upper ranges.

I think the guy who is thinking of incorporating a K coupler into a Tapped horn design is missing the point of what a K is coupler is supposed to acomplish (Not that I really understand, but I think its a bunch of esoteric sillyness). A subwoofer doesn't need extra HF loading, and its not going to do anything for LF extension.

You're missing the point talking about high frequency reflections etc. This is a subwoofer. I know most people summarily dismiss the K (most I suspect without having heard one properly implemented) but the design does have its merits, ..but I digress.

The point of the k-slot is to smoothen the transition from the horn to the air, hopefully reducing ripple. That's what Bill Woods (RCA Fan on AA) did with his K-Slot BLH.

I'm not looking at any bandwidth gain with the k-slot (it would need to be much much longer at these frequencies) but merely to optimize the profile of the (undersized mouth)

Will it work?.. I guess we'll never know until someone tries it (maybe me if I can ever find some free time in the near future).
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Old 6th April 2007, 08:32 AM   #203
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That sounds a little redundant, since a horn effectively couples the driver to the outside air.

As some people put it the horn is an accoustic transformer.

The driver alone is typicaly ill equiped to couple to the air especially at extra low frequencies where air viscosity no longer a factor and the driver becomes incapable of displacing enough air to keep realatively flat spl bandwidth.

I can see that the K-coupler probably has a little bit of a coupling effect, but probably not as effective as a circular exponential horn. I'd like to see some good measurements of the K coupler with and without the exponential coupling slot.

I also wonder what dirrection does the coupled energy propagate? For some reason my mind keeps telling me its all going to propagate toward the plane of the slot.

I guess its more a wideband resonant slot?

I can't say that I have ever experienced a K-coupler. So I wouldn't know what to expect.

Antone-
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Old 6th April 2007, 07:06 PM   #204
freddi is offline freddi  United States
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FWIW here's a two-tone test of a Beta 15CX swapped between a beat up homemade Karlson 15 and a reflex ~equal to the K's rear chamber. Both have Z minimum about 50Hz - are/were K merely advanced bandpass?

http://img474.imageshack.us/my.php?image=dop151wm4.jpg

a simulator which can handle TH might help with K although K didn't have much height

hey Don Bunce - pretty cool recycling to make a folded TH - do you have means of quick sweep graph?
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Old 7th April 2007, 12:37 AM   #205
GM is offline GM  United States
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Quote:
Originally posted by rick57
post 188
Greets!

You're welcome!

Well, if you learn all the electro-mechanical-acoustic physics like the pioneers of prosound did, then you can.

Yep. You must be using WinISD or similar, which can't come even remotely close to ~accurately simming this cab's response.

Depends of course, but basically you'll have a lot more linear dynamic headroom with acoustic gain and if the latter is damped enough, then it has much lower distortion on average to boot. If there's enough Xmax/power handling, then the max flat alignment will in theory be fine, but there's naysayers, so as always YMMV.

Right, there's a point of diminishing SD:vent area where it takes more pipe action to benefit from boundary gain.

GM
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Old 7th April 2007, 01:51 AM   #206
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Quote:
Originally posted by sumsound


I'm not sure what you bass that statement on, I have done extensive modeling on many drivers.

I haven't totally digested what Tom has said about the Tapped Horn Drivers FS Higer than the Horns Low Cut. But perhaps the rules are different in a TH.

The statement that the driver doesn't have enough mass doesn't make sense to me either. It has enough mass that its Fs is around 21Hz. The More mass you add to the driver the Weaker the BL, or motor strength. So your caught chasing your tail. Think about it.

I don't think correctumundo is an accurate response to the posters assertion.

I still belive the Lab12 is one of the best subwoofers you can buy for the price.......

Greets!

From building horns, I didn't have the benefit of the powerful simming and measurement programs available today.

A horn acoustically mass loads the driver, lowering its Fs, so normally a rear compression chamber is used to push it back up so that it has a stable work 'platform' to drive the horn efficiently. In a BLH or tapped horn with the driver near/at the terminus, there's no rear chamber to shift it back up. With all the modelling you've done, I don't understand why you're not aware of this. Or have you only modeled simple vented and/or sealed alignments?

Well, I've not only thought about it, but I've built all manner of alignments to see how they performed/functioned and if you think about it, you'll see you answered your own question. BTW, supension compliance is equally important in determining Fs: ((1/Pi)/2)*((1000/(Mms*Cms))^0.5).

Well, I do, so we'll have to agree to disagree.

I agree the LAB12 is an excellent driver for certain alignments, that was never in dispute. Bottom line, you want the right driver specs for the intended alignment, or in the Matterhorn's case, one that was 'close enough'.

GM
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Old 7th April 2007, 02:22 AM   #207
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Quote:
Originally posted by Don Bunce
I,too, am curious as to what that statement was based on.I have been using 2 LABhorns for some time, and the results so far with the tapped horns I built would indicate that the LAB12 driver is an excellent choice for a tapped horn.

Greets!

I'm sure it is for certain alignments, but a more massive one would be better for others. Anyway, I'm not convinced yours is all that optimized, but with no measurements............ Anyway, I see some folks now have TH simming capability, so they can quickly figure out what's what WRT how mass, etc., affects TH design/performance and how well yours works.

GM
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Old 7th April 2007, 03:34 AM   #208
freddi is offline freddi  United States
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lets see a sim of Don's tall TH with LAB12 - can TH be measured fairly well indoors with mic on floor and "pretty close" to speaker?

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Old 7th April 2007, 05:16 AM   #209
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I will be the first to admit that this is not an optimized design.Since I have the LAB12 drivers,it seemed to be a good place to start.I was surprised that it worked this well on the first try.As I mentioned before,I thought the folded version sounded better.I placed the original horn in the same corner next to the folded one.It wasn't the room,the folded one sounds better.The straight one seems a bit loose and boomy is comparison.Maybe the bracing isn't adequate...

If anyone is able to sim this,that would be great.Use the 14" wide dimensions.

The LAB12 driver may not be optimum(according to theory)but it is doing a fine job in this horn.It tromps the LABhorn below 30 hz,and pretty much holds even above that.Not as efficient ,but still more than enough for home use.I'm going to build four of them.hehehe...

Here's a response curve,pink noise full range into the folded horn,measured at my listening position with a Behringer 8024 ultra curve pro with a DBX mic.

http://img260.imageshack.us/img260/4...thorn00ow2.jpg
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Old 7th April 2007, 05:21 AM   #210
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Here's a photo of the horns in my room.

http://img292.imageshack.us/img292/7...thorn00cy5.jpg
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