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Multi-Way Conventional loudspeakers with crossovers

Why not cardioid midrange?
Why not cardioid midrange?
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Old 7th August 2019, 01:37 PM   #1
Defo is offline Defo  Norway
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Default Why not cardioid midrange?

Reading about this, it seems there are some obvious benefits of a cardioid midrange in terms of reducing reflections of the back wall, meaning we can potentially place the speaker closer to the back wall.

Gradient, Amphion and Dutch & Dutch seem to be among the only ones doing this.

So why not others?
Or in the world of DIY for that matter.
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Old 7th August 2019, 02:29 PM   #2
Bill Coltrane is offline Bill Coltrane  Netherlands
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Don't forget the Linkwitz LXmini.

Atm I'm experimenting with cardioid mids. It could give a smoother frequency curve in the 100 to 500Hz range, thus eliminating the need for room eq.
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Old 7th August 2019, 07:33 PM   #3
ScottG is offline ScottG  United States
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-the LXmini only produces a cardioid-like response between 700-900 Hz.


As to reducing reflections from the back-wall, it's easier to do a 3" thick pad of rockwool on the wall near the loudspeaker (assuming it's placed close).

Alternatively (wall-dependent), you could do an in-wall design.


IMO a cardiod for reducing back-wall reflections is not a great idea.
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Old 7th August 2019, 07:47 PM   #4
dc655321 is offline dc655321  United States
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Quote:
Originally Posted by ScottG View Post
IMO a cardiod for reducing back-wall reflections is not a great idea.

I would like to hear the train of thought that fuels this opinion.
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Old 7th August 2019, 11:40 PM   #5
ScottG is offline ScottG  United States
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-well my post did have context, no?


It's MUCH cheaper to do the absorptive panel on-wall than trying to integrate it into the loudspeaker design. IF you are truly concerned with back-wall reflections then an in-wall design is MUCH better.

Plus, there are (typically) significant detriments to having it in a design:

..substantial pressure loss creating: lower sensitivity (all-else-equal), higher resulting non-linear distortion,

..and added mechanical resistance (that tend's to reduce depth, design dependent).


That's not to say that I haven't recommended it in certain instances before, even recently as a design "notion" for a particular situation.
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Old 8th August 2019, 07:15 AM   #6
Defo is offline Defo  Norway
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Quote:
Originally Posted by ScottG View Post
-well my post did have context, no?


It's MUCH cheaper to do the absorptive panel on-wall than trying to integrate it into the loudspeaker design. IF you are truly concerned with back-wall reflections then an in-wall design is MUCH better.

Plus, there are (typically) significant detriments to having it in a design:

..substantial pressure loss creating: lower sensitivity (all-else-equal), higher resulting non-linear distortion,

..and added mechanical resistance (that tend's to reduce depth, design dependent).


That's not to say that I haven't recommended it in certain instances before, even recently as a design "notion" for a particular situation.
Thanks for clarifying. Probably a good idea to have an absorptive panel on the back wall (by back wall I mean the wall behind the speakers) anyways. But WAF is low.

As I understand it, the cardioid approach cancels out sound radiation to the back and sides by some amount. Isn't this always a good thing?

Could you expand on the sensitivity loss?
I would think this was more of a bass issue and not a midrange one.
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Old 8th August 2019, 08:52 AM   #7
AllenB is online now AllenB  Australia
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To what extent are the sides spoiling the rear (comparing to lobe shaped radiation)
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Old 8th August 2019, 09:04 AM   #8
cowanaudio is offline cowanaudio  Australia
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Why not cardioid midrange?
A waveguide is the best way to control directivity in the mid and high frequency ranges. Waveguides at low frequencies are usually prohibitively large.
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Old 8th August 2019, 09:13 AM   #9
Defo is offline Defo  Norway
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Quote:
Originally Posted by cowanaudio View Post
A waveguide is the best way to control directivity in the mid and high frequency ranges. Waveguides at low frequencies are usually prohibitively large.
Problem with waveguides is that they typically have <90 degree dispersion, which means you need a large woofer to match the directivity at XO.
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Old 8th August 2019, 09:16 AM   #10
Drofdissonance is offline Drofdissonance
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Quote:
Originally Posted by Defo View Post
Could you expand on the sensitivity loss?
I would think this was more of a bass issue and not a midrange one.
Hey defo, I think some of these opinions are a bit light on the data. probably the biggest problem is that its difficult to simulate this kind of enclosure. Probably possible with akbak but I'm not aware of anybody (publicly) doing it with a midrange.

might be possible to estimate this kind of enclosure with hornresp. but I dont think you'd be able to get away from just building some enclosures and actually measuring/tuning them.

Its easy enough to get sensitivity back with a better driver/larger/waveguide. so I dont really think thats a real problem. I'm with you. the idea sounds great. its getting good results thats the hard part.
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