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Multi-Way Conventional loudspeakers with crossovers

Kairos 3-way cabinet
Kairos 3-way cabinet
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Old 22nd July 2018, 12:01 AM   #41
jtgofish is offline jtgofish
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Join Date: Mar 2018
I have built the Kairos Three Way using the SB Acoustics SB29NRX75-6 ten inch woofer and the recommended crossover from Meniscus.
In my opinion this crossover design does not match that woofer.It might be fine with a 4 ohm woofer but the SB Acoustics is a 6 ohm and simply sounds wrong.Changing from a 4 ohm to 6 ohm driver surely must change the crossover points significantly-well technically it does anyway.
There seems to be a lot of overlap in the mid/upper bass area between about 110Hz and 250 Hz.This is mentioned in the white paper but I really think it sounds a lot more obvious than the measurements would appear to indicate and the excellent sound qualities of the two way module are spoiled by this overlap.


I think I have largely fixed this problem by some quite simple modifications to the crossover but would be reluctant to post these changes here as they may be technically imperfect -but the sound is MUCH better to my ears [and anyone else who has heard the difference].

Last edited by jtgofish; 22nd July 2018 at 12:13 AM.
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Old 22nd July 2018, 04:07 AM   #42
bvan is offline bvan  Denmark
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Thanks for posting. Would you be happy to outline the general change, i.e did you go to 2nd order or lower the woofer xo point of level, etc.

Cheers
B
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Old 22nd July 2018, 07:57 AM   #43
jtgofish is offline jtgofish
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I left the woofer crossover as it was except for removing the 3 ohm resistor..You could try a 75 -100 uF capacitor on the high pass crossover to the two way instead of the 150uF in conjuction with removing the 10 ohm resistors.That sounds radical because those resistors must be there for a good technical reason [damping resistors] but they seem to also damp the life and vibrancy out of the speaker.As I said this might be technically imperfect but to me sounds a lot better.
What sounds best may also be impacted by which inductor is used in the two way section,Mine is the basic laminated core so probably has less insertion loss than the air core alternative.
Also try a bit lower value resistor in place of the 6.2 ohm on the tweeter.My Kairos sounded a bit dull but that could also be due to the inductor on the mid .

Last edited by jtgofish; 22nd July 2018 at 08:15 AM.
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Old 22nd July 2018, 10:11 AM   #44
bvan is offline bvan  Denmark
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Thanks for that, interesting.
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Old 22nd July 2018, 10:53 AM   #45
jtgofish is offline jtgofish
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Quote:
Originally Posted by bvan View Post
Thanks for that, interesting.

There are of course other solutions-either move the crossover on the woofer down or make the high pass crossover slope steeper but I chose the simpler and less parts approach which is probably preferable if you can get away with it.
Why waste power heating up resistors and driving higher value inductors?
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Old 29th July 2018, 06:29 AM   #46
jtgofish is offline jtgofish
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Another update.
If you are using the SB Acoustics 29NRX woofer I think it pays to change the inductor on the low pass to something like 7.5 mH rather than the 5mh specified.That is more in keeping with a 6 ohm speaker crossover.I used a 7.8mH because that is what I had.In the Parts Express forum a crossover for this was woofer in a Kairos type 3 way was specified to use a 7.5uF inductor and a 200uF cap- just to confirm my experiments-.Wish I had have known that before! Getting the sound sorted was driving me nuts!
And to contradict myself in the above posts leave the 150uF caps as they are and also use the 10R resistor parallel resistor.-they are fine like that once you correct the woofer crossover point [make it lower] by increasing the inductor value there.[getting rid of the obvious overlap].
I still prefer it with the 3 ohm resistor on the low pass removed.


It sounds very good.Just have to make a better bass cabinet.

Last edited by jtgofish; 29th July 2018 at 06:46 AM.
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Old 19th May 2019, 03:30 AM   #47
parb is offline parb  United States
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Linesource, I love the design. How does this speaker sound?
Any measurements?


Par

Quote:
Originally Posted by LineSource View Post
The rectangular cabinet volume is a standard, well braced box like Troels vertical beveled-baffle Ekta Grande, or stepped-baffle Ekta mk2. Use a 2"-2.2" thick (3*0.75") stacked baffle which allows deep top+side edge bevel cuts as used by Avalon, and the Hulgich Ella_mk2 example with dimensions H45 W13 D17

Use the attached crossover schematic component values. I made a couple changes from earlier ckts to both smooth the baffle step compensation for a modest volume room, and to select common values for the large 5mH-7mH inductors from Erse / Sledgehammer. Metalized film capacitors like the 400V Audyn family can be used. The C1=140uF midrange capacitor in the schematic should be built from one 100uf cap and two 20uF capacitors in parallel, because you may favor C1=120uF for slightly less midbass gain if the speakers are near the wall. The C8=150uF woofer capacitor can be a low cost bennic-bipolar, or built from 2-3 metalized film capacitors like the 400V Audyn family if cost is not an issue.
===============
If you decide to use a passive crossover, the modest efficiency of the single WO24P-8 woofer, especially after baffle step correction SPL reductions, requires attenuation of the midrange(ckt diagram). This can lead to selection of the lower efficiency MW13P-8 midbass with Xmax=5mm and lower sealed box -F3 frequency instead of the MR13P-8 with Xmax=3mm. Passive crossovers often favor lower component count circuits with larger Xmax demands from the modest slopes.

If you decide to use an active crossover with one amplifier per driver and steeper crossover slopes, you can consider the MR13P-8 with lower Le and Mms.
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Old 12th June 2019, 10:43 AM   #48
Mistertaz is offline Mistertaz  Australia
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Hi! I’m getting the parts to build the Kairos 2-way, but have an opportunity to pick up some used Satori WO24-8 woofers.

Would a pair of the WO24-8 in sealed cabinets as stands for the Kairos work well to extend the bass? Should I purchase two pairs and wire them in parallel? I have a miniDSP for now and could eventually try and workout a passive crossover for them.

Thanks for your advice!
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Old 12th June 2019, 05:30 PM   #49
LineSource is offline LineSource  United States
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Quote:
Originally Posted by Mistertaz View Post
Would a pair of the WO24-8 in sealed cabinets as stands for the Kairos work well to extend the bass?
The WO24P is a medium power capacity woofer:
_Effective piston area Sd = 255 cm2
_Sensitivity (2.83 V / 1 m) = 88 dB
_Linear coil travel (p-p) = 17 mm
_Rated power handling = 90 W

If you have a small-modest volume room, one sealed 90W WO24P with a dsp (30Hz Linkwitz transform requires 2x Apparent power) and a powerful amp should satisfy most listeners.
Two 90W WO24P with a minidsp (30Hz Linkwitz transform requires 2x Apparent power) and powerful amp would deliver effortless bass even in a large room.

If you want to experiment with the Kairos time-phase coherent crossover, a crude option is to build a straight/flat baffle Aldephos TM cabinet and add a 14-degree front wedge on top of the woofer cabinet to tilt the TM top cabinet. You can experiment with different tilts for different listening distances. You can experiment with a flat baffle crossover circuit like the Adelphos for comparison.
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File Type: jpg kairos plus woof.jpg (127.9 KB, 77 views)
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Old 13th June 2019, 01:12 AM   #50
Mistertaz is offline Mistertaz  Australia
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Thanks for your input Linesource!

I’ve got a few more questions...

1. To time align the woofers with the Kairos I was tossing up exactly these options! Thanks for saving me the effort of working out the measurements! I’m still wondering however, where is the optimal point to align the driver. Is it the base of the cone? Or midpoint of the front-to-back measurement of the cone?

2. Also, I realise that using DSP I should be able to integrate the woofers to make a three way speaker, but would these drivers be suitable in terms of sensitivity and other specs for eventually making a passive crossover with the Kairos? I currently know nothing about passive crossovers, but that’s a project for the future.

3. Should I even bother with this? If the sealed Kairos reaches down to approximately 50Hz, should I instead build multiple mono subwoofers rather than stereo woofer modules.

4. If I plan to bevel the front baffle to reduce diffraction, is there any issue with doubling the thickness of the panel? As long as I adequately chamfer out space behind the drivers? I’m worried about the bevel reducing the rigidity of the front baffle toward the edges.

Thanks for the help!
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