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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 28th July 2018, 09:56 PM   #31
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by XMechanik View Post
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)
Great stuff X. How's your phase response and for what distance did you optimize your crossover for ?

I'm still waiting for capacitors to arrive. Then i'll be able to play outside of simulator a little bit (:
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Last edited by Zvu; 28th July 2018 at 10:21 PM.
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Old 28th July 2018, 10:08 PM   #32
Zvu is offline Zvu  Serbia
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Impedance of my crossover is a bit of a challenge for some amplifiers but since i've acquired 2 ohm stable amplifier i'm kinda done with looking at impedance too much.
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Last edited by Zvu; 28th July 2018 at 10:34 PM.
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Old 30th July 2018, 08:37 PM   #33
XMechanik is offline XMechanik  Poland
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Originally Posted by Zvu View Post
How's your phase response and for what distance did you optimize your crossover for ?
I did not actually assume anything about the distance in this excercise. I just took the data "as measured". The only preprocessing was determnination of mod delay (with relation to the tweeter: 0.42in mid, 1.13in woofer)
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Old 31st July 2018, 06:22 PM   #34
Zvu is offline Zvu  Serbia
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Here's one measurement that i've found on the German website i-fidelity.net

Click the image to open in full size.

When i adapt it to grid used in my measurement from post no.1 it looks like this:
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Old 31st July 2018, 06:39 PM   #35
Juhazi is offline Juhazi  Finland
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In the monolab measurement we can see typical coaxial tweeter response - it is much smoother at 15 and 30¤ than 0¤. Still, the on-axis should be smoother, I believe.

Guys, remember to listen to the speaker before saying it's done!
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Old 31st July 2018, 06:48 PM   #36
Zvu is offline Zvu  Serbia
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Naah, i insist on saying that it's done before i listen to it
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Old 16th August 2018, 11:32 PM   #37
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by XMechanik View Post
I did not actually assume anything about the distance in this excercise. I just took the data "as measured". The only preprocessing was determnination of mod delay (with relation to the tweeter: 0.42in mid, 1.13in woofer)
Only now i see that i didn't include merged woofer files in my DB folder. I've modeled your crossover with my merged woofer files so it looks like this:
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Old 18th August 2018, 07:37 PM   #38
Zvu is offline Zvu  Serbia
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Few pics of factory crossover and woofer. Few capacitors are wrapped in some sticky material. It looks like the stuff that Kef uses for CLD in LS50.
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File Type: jpg DSC_0052.jpg (403.3 KB, 73 views)
File Type: jpg DSC_0058.jpg (917.2 KB, 74 views)
File Type: jpg DSC_0055.jpg (642.8 KB, 87 views)
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File Type: jpg DSC_0057.jpg (744.5 KB, 73 views)
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Old 20th August 2018, 07:32 PM   #39
ultrakaz is offline ultrakaz  United States
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From your pic it appears that the driver hole is not chamfered/beveled. When I pulled the mid tweet section from my R300 the hole was not beveled either and I was amazed it was not. I was too lazy to set up my router so I left it alone as the speaker was listenable if not a bit dynamically constrained. Do you plan to bevel the inside of the driver hole?

I'm thinking of gutting my pair and making an outboard crossover and slowly tweak it and the box (as needed) over a period of time. Or not, just something to do when I'm bored albeit it is last in the que of speaker projects. Overall, I think Kef did a pretty good job.
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Old 20th August 2018, 10:12 PM   #40
Zvu is offline Zvu  Serbia
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I'm there - these are my test crossovers.

Click the image to open in full size.

Wires go through the port tube now and i'm listening for changes with slight changes of values. Actually crossover sounded really good without any tweaking but i want to see if i can achieve something better by tweaking it a little. For now i can make it different but not better. I'm here at the moment:

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

Transfer function of crossover:
Kef R300 playground - measurements of raw drivers-untitled1-png

Number of components can be used from factory crossover. C1 is made of 170uF and 50uF in parallel, C7 and C18 are from factory crossover, L6 is factory coil of 22mH unwinded to get 10mH, L4-L8-L10 are also salvaged unchanged from factory crossover.

Simulated impedance response:
Click the image to open in full size.
https://s15.postimg.cc/u0yjku5y3/Untitled1.png

Measured impedance:
Click the image to open in full size.
https://s15.postimg.cc/j1dc987t7/Untitled.png

In the next days i expect to find some time to measure frequency response.

As for the cabinet, there are no chamfers but the real question is if it needs it. If you do the chamfering i'd appreciate if you posted some frequency response measurements here - before/after.
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File Type: png Untitled1.png (45.5 KB, 106 views)
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