C/E/X PA Flat to 30 (FT30) PA TH Awesomeness - Page 53 - diyAudio
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Old 9th January 2012, 12:46 AM   #521
Djim is offline Djim  Netherlands
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You have two ways to design your TH's, both are a matter of personal choice and for each there is something to say. The most common way is to design to get the best response. That works as long you have enough headroom to play with. The other way is to design by using all info in an attempt to make an optimum balance between driver, amp power, total efficiency and the limitation of the driver (in your case that is the limiting factor).

My attempt was about a similar low end extension but with higher efficiency between the 40Hz and your crossover point. This to give you enough headroom, using full power capability from your amps (600W) and stay within limits of the driver's excursion capability. If you want more low end you run out of headroom before full power of your amps. My suggestion was to enlarge the hornmouth to 4000cm^2 in an attempt to use the front of the cab to its fullest. I checked if this suggestion was meeting power specs, excursion and still covering a similar low end. If the 4000cm^2 is presenting the actual front of the cab I don't even know, that was more a guestimate. What I do know is that a similar approach is used in the Cyclops and that it works. In stacks that gives the max acoustic coupling possible (if that will lower the low corner or not is not even important in this story, but if you use Dan's way it is possible).

My only remark about to the other suggestions is that you are overpowering your drivers (with 600W) and that they run out of headroom up higher. If the driver runs into compression mode you can't make up the losses any longer since this is a physical driver problem. Also if your highest excursion point is on the Fs of the driver it will have higher dynamic compression figures around it.

Click the image to open in full size.

Last edited by Djim; 9th January 2012 at 01:07 AM.
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Old 9th January 2012, 07:36 AM   #522
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I would prefer the optimum balance. Isn't that what life is all about?


"Also if your highest excursion point is on the Fs of the driver it will have higher dynamic compression figures around it."

The closer to the Fs of the highest excursion point, the higher the dynamic compression figures around it, right? Do the higher compression figures affect all frequencies equally or do they affect frequencies up and down the passband, from that point, less? What does this say about the stadiumhorn's system?
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Old 9th January 2012, 03:53 PM   #523
epa is offline epa  Netherlands
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updated the pic.
its verry easy to play with the mouth dimensions.(model 1 that is)
just screw the front pannel(with washers,and no glue jet)) and adjust on the fly
when your happy glue/screw it in .
Click the image to open in full size.
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Old 9th January 2012, 04:59 PM   #524
Djim is offline Djim  Netherlands
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Life isn't always complicated. A tapped horn can be simplyfied to minimal 6 straight sections of equal length, when it doesn't need to play above it's full wavelength. So, no need for fancy angled panels. The expansion from S4 to S5 can be made fully symmetric. Something like this:

Click the image to open in full size.

Make sure the grey opening is half size the total frontal surface and that the cavity depth is 0.6 from the diagonal of the grey opening area.

In this way you can use the cavity to put in your optional wings for the stack.

Last edited by Djim; 9th January 2012 at 05:10 PM.
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Old 9th January 2012, 05:29 PM   #525
epa is offline epa  Netherlands
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i dont think i understand correctly
lets say the grey area is 60x40
diagonal is 72 cm x0.6 = 43cm deep cavity?
that would be a 200 ltr cavity

note,expanding area s3>s4 and s5 will have the same effect as just expanding s5(more 40>60 ,less 33 ,nicer roll off)
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Old 9th January 2012, 09:29 PM   #526
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by epa View Post
i dont think i understand correctly
lets say the grey area is 60x40
diagonal is 72 cm x0.6 = 43cm deep cavity?
that would be a 200 ltr cavity

note,expanding area s3>s4 and s5 will have the same effect as just expanding s5(more 40>60 ,less 33 ,nicer roll off)
To optimise the working to its fullest you have to strive to a (near) square opening (grey area). So you first calculate the opening (grey area) to set out the dimensions of the total front

But I'll use your example with a grey area of 60cm x 40cm = 2400cm^2, the total front should be twice as big = 4800cm^2.

The depth of the cavity should be calculated by the diagonal of a circle with an 2400cm^2 = 55,27cm
55,27cm x 0.6 = 33,16cm

This is the reason why I like symmetric centre openings so much. It keeps the build simple and gives the best balance. Designing this way and your stacks of two have an near equal horizontal and vertical pattern. In stacks of 4 or 8 you can use Neo Dan's trick to enlarge the system even further to make the low corner drop.
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Old 10th January 2012, 12:03 PM   #527
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Played w/Hornresp a bit - veered from a straight pipe tho.

Is this worth it? Looks pretty good, considering the drivers' restrictions. Same LF, slightly bigger, higher sensitivity, better group delay(?), excursion peak approx same distance from Fs as Djim's mod. Sanity check, please (it's 5am here).


*Also, finished my latest dnb mix not too long ago. Figure a few of you might enjoy it on the road, exercising or just to have on your mp3 player and test your systems Here's a few diff sites to stream from (not sure what your fave is):

Soundcloud
Mixcrate
Mixcloud

To skip the bs and just download it:
Here

You're welcome to share it w/friends as I'm not sellin the mix or anything (so they can test their systems, too, of course )

Hope you're doin amazing and had a great weekend!

Last edited by CRESCENDO; 10th January 2012 at 12:11 PM.
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Old 10th January 2012, 02:35 PM   #528
epa is offline epa  Netherlands
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loving it
lots of 30's and 40's in there.

the "problem" is in your sim you cant eq down low.
but less steeper rol off is good

your sim is 60(80~90 in reality)ltrs bigger .

get back l8rz
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Old 10th January 2012, 07:40 PM   #529
Djim is offline Djim  Netherlands
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Justin, I made you a full analyse of your mix with the Waves PAZ analyzer and nothing else, based on amplitude of the RMS signals. As you can see the 38Hz note is pretty strong throughout many of the tracks. Besides the high pitch tone (I'm still hearing) it was a fun 2 hours to listen too.

Click the image to open in full size.

Last edited by Djim; 10th January 2012 at 07:42 PM.
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Old 10th January 2012, 11:08 PM   #530
Djim is offline Djim  Netherlands
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A second frequency rms analyse I did on your 1hour September mix. I enlarged the low frequency area to give more detail and looked like this:

Click the image to open in full size.


After the full mix I searched for low notes, changed the feq analyses to peak signals instead of rms. Within the mix of one hour I found true extreme low notes of 27Hz at 27:45 to 27:47 (2 seconds). Maybe I have overlooked other ones...

Click the image to open in full size.
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