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Multi-Way Conventional loudspeakers with crossovers

Kef R300 playground - measurements of raw drivers
Kef R300 playground - measurements of raw drivers
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Old 16th July 2018, 10:59 AM   #21
andy19191 is offline andy19191  Europe
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Quote:
Originally Posted by Juhazi View Post
And the winner is KEF! Coax unit is the larger one 17cm, R300 has 14cm. It looks like the Elac might benefit from some xo tweaks...
The new Q series speakers are 2 or 2.5 way speakers with the coaxial acting as a midwoofer reproducing the lowest frequencies. This is generally not a good idea because the large deflections of the midwoofer cone at low frequencies changes the shape of the waveguide for the tweeter. This will be lessened by using a larger diameter cone like the 200mm one in the Q950 but this large aluminium cone then needs to cross successfully to the tweeter. Interestingly the tweeter in Q950 has a large 38mm diameter and is crossed at 2.2kHz. With the phase plug and waveguide action of the midrange cone to handle directivity this looks a good design for a large 2 way.

The Elac is a 3 way and therefore can use a smaller midrange cone with a motor designed for midrange duty. The tweeter is a 1" crossed at 2.7 kHz and the midrange is a 4" minus the area for the tweeter making it equivalent to something like a 3". This small midrange is crossed to the 3 x 5" tiny woofers at 270 Hz! A conventional crossover for a 3" midrange would be twice that frequency. This is going to hurt the waveguide action on the tweeter and the midrange performance at higher SPLs. A rather unusual design decision.

After only a brief peruse, the KEF looks well designed given the decision to go for a 2 or 2.5 way midwoofer+tweeter coaxial. The Elac does not look so well designed given the decision to go for a midrange+tweeter coaxial in a 3 way with the potential for higher performance. However, it seems to be about 15-20% cheaper in the UK which is perhaps relevant.
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Old 16th July 2018, 12:28 PM   #22
Zvu is offline Zvu  Serbia
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I'd use Q series but only with necessary modifications. Coax in closed chamber, crossover at 300-400Hz and sharp slope on woofer.
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Last edited by Zvu; 16th July 2018 at 12:52 PM.
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Old 16th July 2018, 01:21 PM   #23
Zvu is offline Zvu  Serbia
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Q550 is so well built that i really don't know how they pull it of for that price. Woofer is similar to R300 only smaller cone. Large voice coils and large magnets, Passive radiators with double suspension to achieve better symmetry - geez

In white - they are stunning

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Last edited by Zvu; 16th July 2018 at 01:23 PM.
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Old 16th July 2018, 04:02 PM   #24
gornir is offline gornir  Sweden
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Kef R300 playground - measurements of raw drivers
Quote:
Originally Posted by Zvu View Post
I beg to differ. I think that Kef did much better job regarding diffraction than Goran with his test baffle, which is kinda expected given that he positioned R300 mid-hi on the center of the baffle. Problem is that low resolution on X axis and low resolution on Y axis (the way Goran showed his measurement) leads to wrong conclusions.

When i see 5dB or (worse) 10dB resolution on Y axis and i see, what i believe is, a problem - it always magnifies when i bring measurement resolution to what Geddes proposed: 2dB resolution with 40dB high Y axis grid.

Look how Goran's measurements look now...
Hi,

Here's three different graph resolutions (40/50/80dB, no smoothing) of the same measurement of the KEF SP1632 mid-range:

Measurement conditions:
Baffle: 90x20cm (se pictures).
Mic position: 1m on mid center-axis.

Regards

/Göran
Attached Images
File Type: jpg KEF SP1632 Midrange - 40dB Scale.jpg (198.3 KB, 202 views)
File Type: jpg KEF SP1632 Midrange - 50dB Scale.jpg (204.6 KB, 204 views)
File Type: jpg KEF SP1632 Midrange - 80dB Scale.jpg (213.9 KB, 205 views)
File Type: jpg CT-F3_3.JPG (62.8 KB, 209 views)
File Type: jpg CT-F3_5.JPG (60.3 KB, 210 views)
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Old 16th July 2018, 06:22 PM   #25
Zvu is offline Zvu  Serbia
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Here's my measurement that's a little more comparable to yours but lower frequency limit is set to 200Hz, unlike yours that is 300Hz. Gate is good to 250Hz (yours is 275 if i'm not mistaken), 1m distance, mic at tweeter axis - on axis and 45 degrees off axis. Anyhow, midranges measure superb on both baffles my opinion. Tweeters differ somewhat and Kef's looks flatter on axis. Not that that is of great importance because off axis is by far more dominant at farfield listening but it was worth noting when Juha said that yours look much better regarding diffraction than measurements done in original Kef cabinet - which was product of displayed measurement resolution, in my opinion. When i posted it my way and side by side, it looked different enough and could be compared in a rightful manner.
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File Type: png image.png (16.6 KB, 65 views)
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Last edited by Zvu; 16th July 2018 at 06:51 PM.
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Old 16th July 2018, 06:59 PM   #26
Zvu is offline Zvu  Serbia
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I'm here at the moment with crossover. Soon i'll be building test crossover and hopefully measure it with longer gate 0-180 degrees in 10 degree increments.
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File Type: gif Webp.net-gifmaker.gif (113.0 KB, 55 views)
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Old 16th July 2018, 07:12 PM   #27
Juhazi is offline Juhazi  Finland
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^^ OK, but I was looking at/commenting tweeter responses!
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Old 16th July 2018, 08:06 PM   #28
gornir is offline gornir  Sweden
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Kef R300 playground - measurements of raw drivers
Quote:
Originally Posted by Juhazi View Post
^^ OK, but I was looking at/commenting tweeter responses!
Ok,

I post the tweeter responses tomorrow!

Regards

Göran
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Old 17th July 2018, 03:09 PM   #29
gornir is offline gornir  Sweden
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Kef R300 playground - measurements of raw drivers
Quote:
Originally Posted by Juhazi View Post
^^ OK, but I was looking at/commenting tweeter responses!
Hi,

Here's some frequency responses for the KEF SP1632 tweeter.

The response is slightly better on the 56x23cm baffle with baffle edge round-overs compared to the 90x20cm baffle with sharp edges and other driver cones in the proximity of the co-axial.

Regards

/Göran
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Old 28th July 2018, 09:09 PM   #30
XMechanik is offline XMechanik  Poland
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Originally Posted by Zvu View Post
OWhen ever i made sim for R300 crossover that was flat on axis, i got a bump at 2-3KHz off axis. So, little irregularities on axis is quite acceptable if the dips fills up off axis. Since it is a diffraction issue there's no need to try to solve it on axis.

https://s15.postimg.cc/649wnq4qz/Webp.net-gifmaker.gif
Thanks for uploading the measurements.
I have been experimenting with them for a while with the following result.
The 2-3 kHz bump (45 deg characteristic, green) is still present but it's less than 1dB over the slope line.
On-axis (blue) response variations are witin +-1 dB around average level up to 17 kHz (except for the dip at 8kHz)
Attached Images
File Type: jpg Kef300XMach03.jpg (444.0 KB, 58 views)
Attached Files
File Type: zip k300_onaxis_XMach03_dxo.zip (63.3 KB, 4 views)
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