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Old 30th April 2013, 08:56 PM   #1
lbstyling is offline lbstyling  United Kingdom
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Hi all,

Im looking to evaluate a transmission line enclosure vs ported for an AE td10m or td12m.
Response needs to be down to 60hz or lower (crossed over to a sub) and up to 600hz or so to a compression driver mounted on a JMLC 350Hz horn that I have already.

M J Kings site is informative (and very confusingly laid out!) but I cant see how to graphically compare the outcome of an alignment to a ported design.

The closest I have is this thread where the guy built a TL for a pair of td10m drivers, but mine would be a single driver.

The other issue is that I have is that I want to put this in a cabinet that is narrower than the driver itself (8 inch outside width, 7 inch internal). To do this, Im going to put the driver in a sonotube and the tube will intersect a standard floorstanding cabinet (just think of a standard floorstanding speaker - the 6inch bass driver 'hifi' type, but with a 10 inch driver shoved in the front with the edges extending past the baffle width.

Will a TL work if the driver is wider than the TL tube?

Would anyone like to suggest a layout or measurements for this with an area of 7inch (W) x 110-115cm (h) x 25-30cm (depth)? driver mounted at the top of the baffle.

Any opinions/musings welcome.
Ta.
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Old 1st May 2013, 03:26 AM   #2
Inductor is offline Inductor  Portugal
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The AE TD10M is a good candidate for BR and horn.
The AE TD12M is a good candidate for BR.
The 10" doesn't go that low. The 12" is a good candidate. I'm not good at designing TL's and can only look at their final designs and simulations. Other members do and I can help you in any other case.
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Old 4th May 2013, 05:41 PM   #3
lbstyling is offline lbstyling  United Kingdom
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Ive bought a pair of td10m's and am in the process of trying to make sense of MJKing's quarterwave mathCAD worksheet.

Member OPC modeled a pair of TD10m drivers in a tapered TL here-

10" MTM with NeoPro5i Ribbon - Build Thread

As he says in post 51, he just modeled a single driver and doubled the area at each end of the pipe to correct for a pair of drivers.

I would like to deliberately target a peak in the output at approx 60-80hz in order to reduce the excursion the driver needs to make at a given spl- thereby reducing distortion as these will be crossed over at 60-70hz. This will be tamed with digital eq.

Now, If I have read correctly- the TL tube length is more or less set to a quarter of the Fs of the driver, but progressing from a tapered tube to a expanding tube pushes the resonance effects of the TL progressively higher giving you boosted spl at higher frequencies no? If this is correct, I will simply take opc's design, halve the tube area and flip it upside down!

Advice welcome.

PS- M J King's mathCAD worksheet asks for s0 and sl, but it doesn't state what the units are- inches or mm or cm - can anyone help?

Last edited by lbstyling; 4th May 2013 at 05:45 PM.
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Old 5th May 2013, 05:39 PM   #4
Jim Shearer is offline Jim Shearer  United States
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The dimensions can be in any of those units. Just label them (in, mm, cm, m) & MathCAD takes care of the rest!

Cheers, Jim
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Old 30th July 2017, 10:03 PM   #5
lbstyling is offline lbstyling  United Kingdom
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So, I finally got around to moving on with this project! ha ha!

using hornsrep, I get this......

e9zEvTG.jpg

(slightly undersized 3:1 taper)

does that look right?

I assume the red circle on the schematic page signifies the driver location? and so L12 should be 73.6?

Just to confirm, the units for s1 to s4 are CM2?

Last edited by lbstyling; 30th July 2017 at 10:26 PM.
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Old 31st July 2017, 04:02 AM   #6
GM is offline GM  United States
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Sorry, wouldn't be my first choice; import my basic Vb = ~Vas, Fp = ~Fs TTQWT to view and/or use as a baseline, though don't recommend tuning below Fs as it's already power limited to ~50 W. It looks horrible until you view it in the Wizard with stuffing to smooth it out.

Correct.

??? L12 is normally a function of the driver's upper mass corner, so with a fairly high Fs, low Qes it's out near each end.

Correct.

GM

edit: BTW, these are tapped TQWT, but just noticed that earlier you say you want a simple TQWT, so are we wasting time here?
Attached Files
File Type: txt TD10M40hzTTQWT.txt (957 Bytes, 23 views)
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Last edited by GM; 31st July 2017 at 04:07 AM.
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Old 31st July 2017, 11:24 PM   #7
lbstyling is offline lbstyling  United Kingdom
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Thanks GM,

In a standard vented box, I get a f3 of about 85hz. Of course this is in a box that is only 11.5l !

Your model requires a 59L box, which is possible, but I'm looking for a cabinet that is roughly 110cm x 20cm x 30cm maximum external dimensions, giving me about 40L to play with.

xMxzqzW.jpg

This design get me to 37.5L.

n2StGIm.jpg

The question is,
1) How accurate is Hornsrep?
2) If a satisfactory response is simulated, are there any other real world factors to be considered? I have heard:
3) Is Hornsrep only simulating the horn response or the horn and the drivers rear radiation, or is it the front as well? The response drops down as the frequency increases above 400hz in my simulations, this is obviously a problem if it includes sound output from the front.

I have heard several rules for making a horn, but I don't know how true they are?

1) That the horn length must be 1/3 of the Fs of the driver
2) The areas of each end of the horn must add up to the length of the horn (approximately)
3) The driver must tap at 1/3 of the way down the horn for a flatter response.

Basically, is this actually going to work? And is it a good idea?


In a standard vented box, I get a f3 of about 85hz. (vs 37hz for the horn) Of course this is in a box that is only 11.5l !

Last edited by lbstyling; 31st July 2017 at 11:36 PM.
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Old 1st August 2017, 08:29 PM   #8
drewan is offline drewan  United Kingdom
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Those two graphs you just posted have completely different figures for area and length? Nobody can advise you from those I think. Please also post the page with all the speaker specs. as it (I know!!!!) is VERY easy to make errors on input fields.
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Old 2nd August 2017, 08:26 PM   #9
lbstyling is offline lbstyling  United Kingdom
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Drewan,

The following are the parameters for the 37.5L design.

Qga8j6Z.jpg

Does this look right?
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Old 2nd August 2017, 09:18 PM   #10
lbstyling is offline lbstyling  United Kingdom
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with an Fs of 40.1 for the TD10M, I get a 1/4 wavelength of 214cm at 20 degrees c. this would rise a little in warm conditions I suppose. I don't know the effect of adding fiberglass or other fill on the speed of sound.

I'm most interested in the effect of using a transmission line on the sound of the driver over all. I have never felt a ported box can be optimal considering the back-wave is as loud as the sound from the front of the driver.

Surely in a standard ported design the sound radiated into the box must come back out through the driver cone delayed from the original event? I have no evidence for this, but I just cannot see how it doesn't!

Last edited by lbstyling; 2nd August 2017 at 09:26 PM.
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