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jaya000 9th February 2013 11:57 AM

3 way with 18" woofer
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I am planning to design 3 way cabinet with 18" woofer, 12" midrange & 2" compression driver.
I will test the drivers for thielsmall, impedance graph & frequency response.
I wish to use 18" upto 250 hz, then 250hz ~ 2500 hz will be midrange.

I need to use 3 way passive crossover due to some requirement.
Now where to set test microphone for woofer to test frequency response?
In the center of the box or in the center of woofer?

For midrange & cd horn i will put at the center of midrange & horn.
Then i will take the frequency response,

for combined frequency response of the all drivers, what will be the mic setting requirement.

waiting for guidance from fellow members.

Helmuth 9th February 2013 09:54 PM

Standard is 1 meter.

This isn't the situation in listening position with a MLS measurement you can do it also on 3 or 5 meter to see how the wave front mixed on distance. In fact I think this is the more practice than on short distance.

I have a 2" horn for sale like you did draw there interested? almost new with original packaging.

2" driver can be crossed 800-1000Hz.

sreten 9th February 2013 10:28 PM

Hi, 12" is far too big for a "midrange". rgds, sreten.

tinitus 9th February 2013 10:37 PM

yeah, but it can play stupidly loud :D

Face 9th February 2013 10:39 PM


Originally Posted by sreten (
Hi, 12" is far too big for a "midrange". rgds, sreten.

I respectfully disagree. A 12 or even 15 can be used as a mid when correctly matched to the right CD/horn.

wolf_teeth 9th February 2013 11:16 PM


mhtplsh 10th February 2013 12:41 AM


Originally Posted by sreten (
Hi, 12" is far too big for a "midrange". rgds, sreten.

the 12" can be attenuated according to requirement. So no problem of stupidly loud.

Russell Dawkins 10th February 2013 01:55 AM


Originally Posted by sreten (
Hi, 12" is far too big for a "midrange". rgds, sreten.

My impression is also that a 12 or 15 - or even an 18 can be excellent in the midrange, perhaps with a little help from a well-placed crossover notch.
The Bastanis, the Emerald Physics and the Gradient 1.3
The Gradient 1.3 Revisited
all did well with 12s, and Dr Geddes does well with a 15 covering to 1000 Hz.
I think what is important that is gained is headroom in the range of 200 - 500 Hz and the ability to place the crossover down around 200 - 300 Hz and not in the more dangerous 600 Hz zone.

cT equals piD 10th February 2013 02:28 AM


Originally Posted by sreten (
Hi, 12" is far too big for a "midrange". rgds, sreten.

In terms of the extent to which a 12" driver is beaming at (the cross-over frequency of ) 2500 Hz, conventional wisdom says that 12" is too big. But this can be OK if the one listener is on axis with the pair of speaker systems. My current pair of stereo speakers are two-way with a 12" woofer, and I really like them. However the vast majority of time, I am the only one listening to them, and I have the pair toed-in to my in-the-middle listening position.

For more than one listener listening to stereo speakers simultaneously, a 12" mid-range driver radiates too narrowly over much of its pass-band to give good reproduction to any listener off-axis.


DougL 10th February 2013 05:52 AM

My understanding is that a 12" woofer typically has a 6 db down at 90 degrees at about 1200 Hz. This is the optimum crossover point for a 12" midrange.
Also, my understanding is that a 2" compression driver with a 3" diaphragm starts to break up at about 8 kHz. For a 1200 Hz crossover point, a 1" exit driver is more approprate if you do not want a super-tweeter/ 4 way.



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