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35-100hz ported/hybrid horn

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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Topic: 35-100hz ported/hybrid horn
    Posted: 13 April 2020 at 3:59pm
One of the arts of loudspeaker design is understanding the limitations of not only the enclosure, but the loudspeaker as well. It is the primary reason why some designers acquire end results that many dispute are not possible. Many of times, the naysayers have a lack of understanding on what the TS Parameters are saying as a whole and, focus solely on one parameter.... Xmax. 

All the calculated TS parameters work together as a team to deliver the end result. Bear in mind xmax is not attributed to the calculated TS Parameters. All xmax tells you is how far the cone will move. You could feed the driver 20 Hz in which it falls within the linear xmax range. However, if the loudspeaker cannot produce sound at 20 Hz, the end result is having the loudspeaker cone flapping around in the air. 

Best Regards,   
Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 08 April 2020 at 1:47am
Originally posted by Elliot Thompson Elliot Thompson wrote:

The loudspeaker is the limitation. It is easily shown in the TS Parameters. Because you are using Horn Response which uses parameters that do not show the weakness of a driver when constructing a reflex box, Horn Response does not tell you why you have such a peaky response. The ideal enclosure size for the driver in question is 7 cubic feet. When you take into consideration other drivers that are smaller in diameter that offers similar TS Parameters as the driver in question, it becomes obvious the driver's diameter is the limiting factor why it cannot take advantage of a large enclosure.    

The driver will offer a good response for horn loading and an adequate response for a reflex box. That is the price you pay when aiming for the best of both worlds using one driver than can execute both tasks.

All in all, the driver is at it's limit (37 Hertz) on how low it can go while maintaining a flat response. Because you are tuning the driver lower than it's limitation, you will attain a sharp peak followed by a sharp decline.

The overall frequency response is pretty much standard of a double-tuned band pass box.

 

Best Regards,

 

 


This, really does add up with what I have been coming across in hornresp. Thanks for the info, food for thought. 

I'll drop in an update on the progress I've made later on.
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VECTORDJ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 4:24pm
Hi, Have You tried the B @ C TBX100 18 inch????? VECTORSONICS
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 4:21pm
Now WE have some Bass!!!!!!
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 3:21pm

The loudspeaker is the limitation. It is easily shown in the TS Parameters. Because you are using Horn Response which uses parameters that do not show the weakness of a driver when constructing a reflex box, Horn Response does not tell you why you have such a peaky response. The ideal enclosure size for the driver in question is 7 cubic feet. When you take into consideration other drivers that are smaller in diameter that offers similar TS Parameters as the driver in question, it becomes obvious the driver's diameter is the limiting factor why it cannot take advantage of a large enclosure.    

The driver will offer a good response for horn loading and an adequate response for a reflex box. That is the price you pay when aiming for the best of both worlds using one driver than can execute both tasks.

All in all, the driver is at it's limit (37 Hertz) on how low it can go while maintaining a flat response. Because you are tuning the driver lower than it's limitation, you will attain a sharp peak followed by a sharp decline.

The overall frequency response is pretty much standard of a double-tuned band pass box.

 

Best Regards,

 

 



Edited by Elliot Thompson - 26 March 2020 at 3:29pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 1:35pm
Originally posted by fatfreddiescat fatfreddiescat wrote:

My approach that has worked for me when prototyping is to make a box that is as easy as possible to adjust re tuning, for example, build oversize ported cab, use tubes to tune, easy to cut different lengths etc, bricks to reduce internal volume. Make your different flares so as can be bolted to ported box. Doesn't need to be pretty, 'sticks like shit' type gap filling adhesive is great for speeding things up :)
With regards to tuning the reflex part, look at the frequency response without the horn, if you have a big peak then it will ring like a bell, all to often, ported horns are tuned flat, to do this the reflex part is very peaky. Bottom line is that the bit near cut off is reflex only and sets the min sensitivity. 
By building an adjustable prototype, you will soon get a feel for what works and what doesn't. Corner loading can help with it equating to a larger number of boxes.


Thanks once again @fatfreddiescat, some really useful techniques and insights. 

As for the 'sticks like shit' glue I've got a tonne of EVER BUILD 5 MIN LUMBERJACK WOOD ADHESIVE which does exactly that! 

Reflex part is definitely very peaky, thanks for the warning.




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Post Options Post Options   Thanks (1) Thanks(1)   Quote fatfreddiescat Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 10:25am
My approach that has worked for me when prototyping is to make a box that is as easy as possible to adjust re tuning, for example, build oversize ported cab, use tubes to tune, easy to cut different lengths etc, bricks to reduce internal volume. Make your different flares so as can be bolted to ported box. Doesn't need to be pretty, 'sticks like shit' type gap filling adhesive is great for speeding things up :)
With regards to tuning the reflex part, look at the frequency response without the horn, if you have a big peak then it will ring like a bell, all to often, ported horns are tuned flat, to do this the reflex part is very peaky. Bottom line is that the bit near cut off is reflex only and sets the min sensitivity. 
By building an adjustable prototype, you will soon get a feel for what works and what doesn't. Corner loading can help with it equating to a larger number of boxes.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 9:30am
With a bit of playing around here's the results with a larger mouth, also I seem to have gotten rid of the dip at 80hz.

What I've noticed with the modifications:
 
  • The horn is now outrunning the ported section in singles but of course that is to be expected
  • The horn in 0.5pi is extending and flat to 50hz   
  • the horn sensitivity drops by -3db at 40hz
  • The port output in .5pi @30hz is 4db lower than the horn at 40hz 
  • Combined in .5pi I seem to have a nice response
My worry with the larger mouth and faster flare rate is that I will loose too much space in the ported chamber and won't be able to get the sensitivity I want at my 32hz tuning. 

Here's .5pi (or 4 cabs)



2pi

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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 9:16am
Cheers VECTORDJ, here you go:


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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 1:17am
Hi, What is the horn response for 4 units?  8 units????  VECTORDJ
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 1:09am
A+
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2020 at 6:34pm
I should add, I'm happy for the horn to be less efficient in order to keep the bass extension and overall system balanced. I don't want it to be only good for... psytrance

I think the end aim is for the cab to be a compromise between 6th order bandpass enclosure and a short BPH. 
 


Edited by luthier - 25 March 2020 at 10:23pm
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