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Multi-Way Conventional loudspeakers with crossovers

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Old 10th April 2013, 11:18 PM   #91
Face is offline Face  United States
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The 8" unit has a break up that's a little more work to deal with. Plus, it's a little more efficient and has a little more extension. In a 3 way, I would go with a 5.25" unit.
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Old 12th April 2013, 03:53 PM   #92
Pallas is offline Pallas  Pakistan
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Originally Posted by The Rug Doctor View Post
My question Is this - which driver'should i experiment with?? I have been looking at the Q100 and the Q300 drivers, one is a 5.25 and the other a 6.5 cone.
Having compared the Q100 and Q300 back-to-back, the Q100 drive unit is clearly superior, IMO. The Q300 struck me as sounding more like a typical "high end" speaker in the midrange, whereas the Q100 sounded more like music and less like the can it came in.

When I looked them up after the fact, I realized why: same tweeter size, same published crossover point, but the Q300 has a bigger midrange. So the Q300 does the "midrange mushroom cloud" thing that one hears in standard 7" midwoofer/flush tweeter "high end" speakers to some degree, because the woofer unavoidably narrows in coverage before the tweeter can come in, whereas the Q100 has better-controlled midrange off-axis response. The geometry of the LS50's driver is substantially similar, and the driver sets the overall directivity. So while I've not seen good polar measurements of the Q100 here's Stereophile's horizontal off-axis curve for the LS50:

Click the image to open in full size.

(The lower-diffraction cabinet will make the LS50 smoother than the Q100. The other differences in drive unit and crossover may make the LS50 superior in other ways, but don't have as much an effect on the midband directivity.)

You see a little hole developing far off axis in the midwoofer-tweeter transition, but smooth performance closer in. Holes in the off-axis response have been shown to be relatively benign. Peaks (as one typically sees at the bottom of the tweeter's range in a so-called "high end" speaker, resulting in what I call a "midrange mushroom cloud")

So I suspect that the differences I observed between Q100 and Q300 go back to the drive units themselves, rather than to implementation.

The 8" Uni-Q in the Q900 is a different animal, with a much larger tweeter and lower crossover.
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Old 12th April 2013, 08:06 PM   #93
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Thankyou Pallas, I appreciate your post a lot. So do you know the best xo point and slopes for the two drivers? (100 & 300)?? I have managed to borrow a set of Q300 to have a play with but am going to run them active..

Also, this peak you mention of the 300 driver, the swelling midrange, I'll hopefully be able to eq that out as I use Rane 30 band EQs together with an upgraded Rane active XO, what do you think?

I have REW and an audiocontrol rta to play with..
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Old 13th April 2013, 07:19 PM   #94
Pallas is offline Pallas  Pakistan
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Originally Posted by The Rug Doctor View Post
Thankyou Pallas, I appreciate your post a lot. So do you know the best xo point and slopes for the two drivers? (100 & 300)?? I have managed to borrow a set of Q300 to have a play with but am going to run them active..

Also, this peak you mention of the 300 driver, the swelling midrange, I'll hopefully be able to eq that out as I use Rane 30 band EQs together with an upgraded Rane active XO, what do you think?

I have REW and an audiocontrol rta to play with..
I wouldn't be so sanguine about the ability to EQ out the midrange mushroom cloud. It's not just an on-axis peak, but a basic difference in the amount of energy thrown out by the different drivers as one moves off-axis, because they have different radiation patterns. The only way to solve the midrange mushroom cloud issue is to cross the tweeter low enough that it matches the midrange's pattern in the crossover region. That requires taking polar measurements of each device.

But I suspect that the tweeter just won't go low enough to do it, because KEF's crossover uses the tweeter's rolloff as an element. (The Q100 has a very, very low parts-count crossover, just IIRC a single inductor on the midwoofer, and a cap + resistor on the tweeter. It's not perfect, but it's darned good.) I don't know what kind of crossover the Q300 has, because I've never owned one and never opened one up.

Still, you could probably get a very good result in your room with the Q300 driver by using your tools and perhaps some sidewall damping in the room. You'd have a higher likelihood of success if you ditch the RTA for a higher-resolution computer measurement system, such as FuzzMeasure (Mac) or Omnimic (Not-a-Mac).
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Old 17th December 2013, 05:42 PM   #95
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I have the Kef LS50 and I was a bit dissapointed at first
boomy and a bit of reverberate in midrange.

I opened them up and replaced the filling from pieces of foam to roxul safe n sound fiberglass.


MUCH, MUCH BETTER.
Bass is more realistic and extend a bit more (subjective)
Bass port have about 8db less midrange radiation vs original foam at 1K (ok, only measured with my RS splmeter)
Pink noise sound a bit more neutral.
HF seem unchanged.

I wand to remove crossover and inspect caps.
they are wrapped in a kind of wax and one can't tell type or brand...

I'm waiting for silverplated solid wire to upgrade internal wiring before opening again.

Picture to follow.
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Old 19th December 2013, 07:34 PM   #96
rpnfan is offline rpnfan  Germany
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Quote:
Originally Posted by etalon90 View Post
I have the Kef LS50 and I was a bit dissapointed at first
boomy and a bit of reverberate in midrange.

I opened them up and replaced the filling from pieces of foam to roxul safe n sound fiberglass.


MUCH, MUCH BETTER.
You might be interested in this Pimp (text in german, but the measurements and the like should be interesting):

http://www.hifi-forum.de/index.php?a...ack=&sort=&z=1

http://www.hifi-forum.de/index.php?a...ack=&sort=&z=2

Here are measurements of the stock LS:

http://www.hifi-forum.de/index.php?a...0&thread=32137
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