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Multi-Way Conventional loudspeakers with crossovers

Why not cardioid midrange?
Why not cardioid midrange?
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Old 9th August 2019, 03:48 AM   #21
ScottG is offline ScottG  United States
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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.

A real *midrange cardioid response (the ripple on the low-end is a measurement artifact of the way it was supported):

Adventures in cardioid

-and hopefully that helps-out with dc655321's search skills.


*from a driver that isn't a midrange. (..and disregard the polar above 1.5 kHz.)
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Last edited by ScottG; 9th August 2019 at 03:51 AM.
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Old 9th August 2019, 04:04 AM   #22
ScottG is offline ScottG  United States
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Quote:
Originally Posted by ScottG View Post
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.
Here:

Seeking new build advice - please offer your .02


Note in this instance the complication is more than just a back-wall reflection.

Other than the problem with *resistance and subjective results, a line-array has merit here because it's vastly more sensitive below 1 kHz (..plus, such a design would represent a very narrow baffle if done right - something also desired by the thread-poster).


*Note: you don't have to do a resistance design, you could do an "active-delayed" design to (more or less) circumvent the problem with a resistance design in the midrange.

Active-delayed designs are where you have a secondary driver on the rear of the loudspeaker that's out-of-phase and where the front driver is delayed so that it's near in time with the rear driver; no leaky side ports needed. You can even go Hyper-Cardiod with this. Baffle effects are still a problem though - so upper freq.s always have some sort of limit to how closely (or not) they approach a real cardioid response.
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Last edited by ScottG; 9th August 2019 at 04:07 AM.
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Old 9th August 2019, 01:46 PM   #23
dc655321 is offline dc655321  United States
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Quote:
Originally Posted by ScottG View Post
Did you look at the measurements for the 8C?

If so, what did the non-linear graph represent? Why is it like that? What is different about that design from most, and why? (..connect the "loop" there and you'll have that answer on why the non-linear graph looks the way it does.)
There are several measurements published for the 8c - soundstage, stereophile, their own. I have to guess you're referring to the NRC results, and their distortion measurement in particular.

Of course, there would be no guessing required if you could communicate more clearly. Not sure if you think you're being clever, or mysterious, or you simply can't help being obtuse. Maybe all of the above?
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Old 9th August 2019, 01:55 PM   #24
Fast Eddie D is offline Fast Eddie D  United States
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Doesn't controlling the dispersion of the midrange and tweeter help smooth out the crossover? Doesn't it reduce interference between the drivers in the crossover region?

I experimented with using felt between the woofer and tweeter in a two way and it made a small audible difference with one configuration. Crossover was at 2 kHz (very audible).

I've seen the Klipsch speakers with the waveguide tweeters. It seems like there might be something to this, especially with crossover points at very audible frequencies.
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Old 9th August 2019, 07:38 PM   #25
ScottG is offline ScottG  United States
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Quote:
Originally Posted by dc655321 View Post
There are several measurements published for the 8c - soundstage, stereophile, their own. I have to guess you're referring to the NRC results, and their distortion measurement in particular.

Of course, there would be no guessing required if you could communicate more clearly. Not sure if you think you're being clever, or mysterious, or you simply can't help being obtuse. Maybe all of the above?

-ironic, I thought you were being obtuse.

ex. ..is there any other non-linear distortion *measurement available for the 8C?

ex. what was I referring to all along here?

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

I even connected the fairly obvious "dots" for you:

"..see what pressure drop (from the cardioid) and a resulting "boost" with eq. will do to non-linear distortion."


I'm really not sure what sort of clarity you are looking for - I thought I was perfectly clear.

What I'm not in the habit of doing is spending time researching and providing links for something that you could do yourself (..ESPECIALLY IF YOU ALREADY KNOW THEM). If the proof is lacking within my posts - there is a reason for that: it takes my time when it should be taking yours if you are really that interested.


*and that non-linear result with the 8C was horrific below 300 Hz, particularly when you consider that any more gain is going to substantially increase that distortion. ..and while 90db is loud (even at only 1 meter relative to a typical 2+ meter listening distance), it's not that loud - and particularly with dynamic "peaks".
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Old 9th August 2019, 08:28 PM   #26
dc655321 is offline dc655321  United States
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Going by your blathering and supposition, you haven't looked into those measurements too closely - your interpretation is flawed.

Try here and here.

See. Not so difficult.
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Old 10th August 2019, 06:10 AM   #27
Juhazi is offline Juhazi  Finland
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As a referee I want to say that Scottg wins the distortion battle!

This is what Martijn says at ASR:
Now on to distortion. The 8c is a relatively compact full-range loudspeaker that offers low distortion at normal and somewhat elevated listening levels. At high levels distortion can become audible on some program material. This is the price we choose to pay for a cardioid radiation pattern in a speaker this size. However, 96 dB at one meter at a single frequency from a single speaker is very loud. In practice, in rooms with some reflections a pair of 8c’s can be played quite loudly and they do actually sound clean at quite high levels. But if you’re into very loud music, they certainly have their limits.

96dB at 1m isn't actually very loud. 105dB would be and still something that is not terrible as peak spl.
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Last edited by Juhazi; 10th August 2019 at 06:12 AM.
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Old 10th August 2019, 12:05 PM   #28
dc655321 is offline dc655321  United States
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Fair enough. My apologies to ScottG.
Thanks, Juhazi.
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Old 10th August 2019, 11:39 PM   #29
ScottG is offline ScottG  United States
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The most troubling thing about the 8C is the that the distortion is as high as it is in the lower midrange and upper bass BEFORE signal "peaks".

Mechanically the driver is already getting enough excursion to move past the point of a mostly linear force curve, and just a little bit more could push (cause increased excursion) the driver(s) to substantially leave the magnetic gap (even with extended VC's "over-hung" design - it's really bad once the VC nears the end of the gap). Once this happens distortion goes WAY up.

So at 150 Hz for this design at 90 db 1 meter (and rarely do you listen that close, meaning the result will be bit worse at a further distance), it's about 8%? distortion (THD - which hopefully is mostly composed of 2nd instead of 3rd).
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Old 10th August 2019, 11:54 PM   #30
ScottG is offline ScottG  United States
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-btw, the "dip" at 60 Hz looks like a dsp/eq issue (not a mode in the anechoic chamber - which would show-up with similar-sized speakers measured in the same location). You can look through their listing of other measurements and it's just not there.

As to *vague comments on driver resistance, here is some *anecdotal evidence I had with another forum member:

(my comments start here, but its several posts below):

My Fostex FE 108EZ project, Part 2

-the restive vent for the cardiod effect is similar. (..and I don't have a problem with "flow" vents lower in freq., in fact they are often beneficial.)


*again, intentionally vague because it isn't regarded as fact.
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Last edited by ScottG; 10th August 2019 at 11:57 PM.
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