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Multi-Way Conventional loudspeakers with crossovers

Which driver would you choose?
Which driver would you choose?
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Old 15th April 2019, 03:47 AM   #31
jmproductions is offline jmproductions  United States
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Quote:
Originally Posted by gabdx View Post
I think the major factor for sensitivity is the magnet type and construction type. Alnico is the most sensitive, ferrite second and NEO is the worst (look at ss illum.)
Actually the VC and cone mass has more to do with sensitivity than anything else.


To clarify you're doing a 3 way, woofer passively crossed at 100hz or do I misunderstand you?
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Old 15th April 2019, 01:09 PM   #32
gabdx is offline gabdx  Canada
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The woofer will be crossed around 200 - 400, this is preliminary.

My problem is to choose midrange because I find it most critical. I know good woofers and how to use them, but from 200 hz to 2 khz it is critical and few drivers sound good in that range. I don't like full ranges because most tend to shout at you. I am looking for a good midwoofer with good dispersion, solid sound down to 100hz and a natural roll-off, I think I will acquire driver 1 (2 pairs) and driver # 10 but the price is high on #10...
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Old 15th April 2019, 02:20 PM   #33
jmproductions is offline jmproductions  United States
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The last project I used SS Illuminator 12cm midranges and they produce that band extremely well, like nothing I've heard before.... but they are NOT cheap as you know. They start to roll off a lot below 200hz however

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Old 15th April 2019, 06:17 PM   #34
mbrennwa is offline mbrennwa  Switzerland
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Quote:
Originally Posted by gabdx View Post
The woofer will be crossed around 200 - 400, this is preliminary.

My problem is to choose midrange because I find it most critical. I know good woofers and how to use them, but from 200 hz to 2 khz it is critical and few drivers sound good in that range.
Did you look at the Open Source Monkey Coffin?
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Old 15th April 2019, 06:28 PM   #35
mbrennwa is offline mbrennwa  Switzerland
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Originally Posted by jmproductions View Post
...if you are saying that a stiffer suspension on the same cone and motor will gain SPL, I would argue against that. ... Restricting cone excursion will reduce SPL... period.
I know that may seem counterintuitive, but please remember that we are looking at how the driver is operating well above it's resonance frequency. In this operation range, cone movement lags the voltage signal with a 90° phase lag. This is quite different to how the driver operates at frequencies well below the resonance, where the cone movement is in phase with the voltage input, and a stiffer suspension does indeed reduce cone movement.

You might also consider how the stiffness of the cone suspension determines the resonance frequency of the driver (fs). At a fixed mass of the cone + voice coil, higher stiffness gives higher fs. The efficiency of the driver increases with fs³ (see here). A stiffer suspension therefore results in higher SPL for the midrange.
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Old 15th April 2019, 07:08 PM   #36
ICG is online now ICG  Germany
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mbrennwa, I couldn't have described it any better. GJ!
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Old 16th April 2019, 03:59 AM   #37
jmproductions is offline jmproductions  United States
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Originally Posted by mbrennwa View Post
higher stiffness gives higher fs. The efficiency of the driver increases with fs³ (see here). A stiffer suspension therefore results in higher SPL for the midrange.
Of course efficiency is increased around resonance but I thought we were talking about frequencies outside of resonance.


As far as whether the movement is in phase with signal or not, I'm not really sure how it is relevant. I'm sure it's possible that some freq could be emphasized by certain suspension properties but that would probably not be desirable.
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Old 16th April 2019, 05:10 AM   #38
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Quote:
Originally Posted by jmproductions View Post
As far as whether the movement is in phase with signal or not, I'm not really sure how it is relevant. I'm sure it's possible that some freq could be emphasized by certain suspension properties but that would probably not be desirable.
At the fs the membrane 'wants' to move most, a stiff suspension keeps the membrane more in control so the usable lower frequency can be closer to the fs. That's relevant because you want to keep the Mms low and the motor as strong as possible to achieve a higher sensitivity but both factors lead to a rise in the fs.
That brings also a problem with it though, around the fs a phase change occurs. If the phase turn doesn't fall into the range of the crossover, it's usually much easier to design the filters. To keep the used range withing the (relatively) steady phase reduces the phase error and it mostly remains only the phase turn of the crossover itself. Besides the sound, without a good phase match you'll likely get interferences which causes lobes in the dispersion. While most HiFi enthusiasts don't care very much about the vertical dispersion, in PA it's much more important.
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Old 16th April 2019, 05:44 AM   #39
mbrennwa is offline mbrennwa  Switzerland
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Originally Posted by jmproductions View Post
Of course efficiency is increased around resonance but I thought we were talking about frequencies outside of resonance.


As far as whether the movement is in phase with signal or not, I'm not really sure how it is relevant. I'm sure it's possible that some freq could be emphasized by certain suspension properties but that would probably not be desirable.
As I wrote, you ARE looking at how the driver operates well above resonance. Neglecting beaming (which is a function of cone diameter only) and cone breakup and similar resonances (which we are not considering here) the driver efficiency is approximately constant throughout its pass band.

We are getting off topic here. I'd suggest you read up on how electrodynamic drivers work, or you start a new thread.
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Old 16th April 2019, 01:08 PM   #40
EarlK is offline EarlK  Canada
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Here's a pic that nicely shows what happens when ( & all other factors are held constant ) a drivers compliance tightens up.

This ( Japanese sourced ) pic is of a JBL le15a, before and after a reconer's re-surround.

The red trace is after the new surround is installed.

Click the image to open in full size.

Note the squashed db scale. The response changes are really quite dramatic .

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