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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 27th August 2018, 08:43 PM   #41
Zvu is offline Zvu  Serbia
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Measurements are done in room so 4,5ms gate is best i can do which translates to about 220Hz gate frequency. 1m distance. Measurements done 0-90 degrees in 10deg increments. I don't believe i'll be dragging these to the parking lot any time soon, but who knows. Until then:

Kef R300 playground - measurements of raw drivers-1-png

Averaging them:

Kef R300 playground - measurements of raw drivers-png
Attached Images
File Type: png мерење високе р.png (51.4 KB, 468 views)
File Type: png укупан одзив.png (23.1 KB, 787 views)

Last edited by Zvu; 27th August 2018 at 08:48 PM.
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Old 11th September 2018, 09:23 AM   #42
Zvu is offline Zvu  Serbia
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I've been listening these speakers past two weeks and tweaking a bit. Nothing dramatically changed but few details for better phase matching and a bit more linearity. I'm at the stage of putting the crossovers into the cabinets so here's few screenshots:

On axis:

Click the image to open in full size.
https://s15.postimg.cc/6xh5avkyj/Web...gifmaker_1.gif


Off axis:

Click the image to open in full size.
https://s15.postimg.cc/mvpv10mwb/Webp.net-gifmaker.gif


Simplistic crossover:

Click the image to open in full size.
https://s15.postimg.cc/jovbh6s3v/image.png


"Exploded" view:

Click the image to open in full size.
https://s15.postimg.cc/xvb2cfxu3/image.png
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Old 22nd October 2018, 08:43 AM   #43
Zvu is offline Zvu  Serbia
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I've made some more measurements last night to see the agreement of simulator to measured response. There is a slight upward tilt toward high frequencies but that could be due to cold (6 degrees Celsius last night). By the looks of it, if it is real, the tweeter is a 1.5-2dB hotter but final level is to be determined indoors by listening. So, without further ado...

On axis:

Напољу на оси.png

Off axis 10 and 20 degrees

на и ван осе до 20 с .png

Up to 45 degrees

на и ван осе до 45 с .png

The crossover work is pretty much done so for the winter i'll be doing nothing but listening music and maybe a little tweaking by ear. This was very enjoyable experience

Last edited by Zvu; 22nd October 2018 at 08:53 AM.
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Old 22nd October 2018, 10:13 AM   #44
maty tinman is offline maty tinman  Spain
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Default KEF Q750

Quote:
Originally Posted by Zvu View Post
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

YouTube

The KEF Q750

SoundStage! Hi-Fi | SoundStageHiFi.com - Recommended Reference Component: KEF Q750 Loudspeakers

SoundStage! Access | SoundStageAccess.com (GoodSound.com) - KEF Q750 Loudspeakers


[Polish review] KEF Q750

to English with Google: Google Translate
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Old 22nd October 2018, 08:37 PM   #45
Zvu is offline Zvu  Serbia
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Hi Maty,

I'd really like to see some measurements of q750. In the meantime, this is very good Polish site with decent measurements:

Zespoły głośnikowe | Testy w Audio.com.pl

cheers
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Old 3rd November 2018, 12:53 AM   #46
Zvu is offline Zvu  Serbia
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Here are some pics of R300's insides.

The only trace of what i presume they called constrained layer damping is this patch on the upper side of the loudspeaker, above the midrange chamber. Cabinet is upside down and i took these pics through the woofer hole.

Click the image to open in full size.
https://i.postimg.cc/yd7vPcGt/DSC-0027.jpg

Click the image to open in full size.
https://i.postimg.cc/SRB9ZpsR/DSC-0028.jpg

Click the image to open in full size.
https://i.postimg.cc/vBSfVnwW/DSC-0029.jpg


Here are integrated conectors and port. Port looks good, but the -link- buttons are something i'm going to skip.

Click the image to open in full size.
https://i.postimg.cc/rwC493Ly/DSC-0036.jpg

Click the image to open in full size.
https://i.postimg.cc/mkzMNrTK/DSC-0034.jpg

Click the image to open in full size.
https://i.postimg.cc/43s6kZ1h/DSC-0035.jpg

When you turn the link thingy, a metal part slides and touches small pcb and connects mid-high and woofer crossovers in parallel. I'll probably install L-pad's on that plate or i'll use some jumpers and link on - just to be sure.

Now here's the highlight of the loudspeaker, a little concentric driver. Maybe not the best pics, but one can easily spot some of the design features.

Click the image to open in full size.
https://i.postimg.cc/t40dkFZk/DSC-0033.jpg

Click the image to open in full size.
https://i.postimg.cc/VkjqV5X8/DSC-0030.jpg

Click the image to open in full size.
https://i.postimg.cc/rFRC5fmz/DSC-0031.jpg

Click the image to open in full size.
https://i.postimg.cc/76BMnc0J/DSC-0032.jpg

Oh, and grill looks quite nice too. It is made out of mdf with small Nd magnets at the corners. Cool stuff.

Click the image to open in full size.
https://i.postimg.cc/C5qBn6Ng/DSC-0037.jpg

Click the image to open in full size.
https://i.postimg.cc/RF8JFzwd/DSC-0038.jpg

I really like gloss Kef sign on the back. It is usually just black so it's nice that somebody thought of that.

Well that's it. I'm gonna put some bituminous coating on the outside of the midrange chamber and send the cabinets for painting.
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Old 19th November 2018, 12:16 PM   #47
Zvu is offline Zvu  Serbia
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The tweeter level adjusted and some more measurements made. Measurements made are 0-80 degrees. Blip at 900-1200Hz that shows on virtually all of mine previous measurements vanished. Trim ring around the midrange has very tight tolerance so when i centered it better, that aberration disappeared. I'm not saying that i could notice it while playing music (or that anyone could for that matter) but i prefer it gone if i'm to decide.

Click the image to open in full size.

Чистија мерења.gif

The only difference from crossover in post 42 is that series resistor on the tweeter is not 0.5 but 2 ohms.
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Old 3rd February 2019, 07:27 PM   #48
maty tinman is offline maty tinman  Spain
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Default KEF Q750

Quote:
Originally Posted by Zvu View Post
Hi Maty,

I'd really like to see some measurements of q750. In the meantime, this is very good Polish site with decent measurements:

cheers
Now we have the frequency graph:

[German] Test Lautsprecher Surround - KEF Q750 Atmos-Set - sehr gut - Seite 1

Click the image to open in full size.

Click the image to open in full size.
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Last edited by maty tinman; 3rd February 2019 at 07:42 PM.
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Old 3rd February 2019, 07:45 PM   #49
maty tinman is offline maty tinman  Spain
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Let's remember.

SoundStage! Access | SoundStageAccess.com (GoodSound.com) - KEF Q750 Loudspeakers by Hans Wetzel

Quote:
Conclusion
KEFís Q750 is a superb loudspeaker. Itís one of the most neutral transducers Iíve ever heard, and for the money offers staggeringly transparent sound. I fed it a steady diet of male and female singer-songwriters, and was always satisfied with the authenticity of what I heard. Itís not exactly a looker, but itís well engineered, and sounds far more expensive than its price suggests. If I had $1500 to spend on speakers, this is what Iíd buy. Iím not sure I can pay KEFís Q750 a higher compliment.
1.2 kHz?
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Last edited by maty tinman; 3rd February 2019 at 07:48 PM.
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Old 4th February 2019, 07:33 AM   #50
maty tinman is offline maty tinman  Spain
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Just now I have send an e-mail to Hans Wetzel, with this link.
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Last edited by maty tinman; 4th February 2019 at 07:35 AM.
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