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Old 28th December 2004, 06:29 PM   #1
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Default Active crossover Adire KIT281

I'm looking for some input into a possible modification of my current setup. I have the Adire Audio KIT281, ported floorstanding towers.

Since they are a kit format, everything has been (hopefully) designed with audio performance, within a reasonable price range.

What I'm thinking of doing is replacing the passive crossover network with a active crossover, and bi-amping the setup.

-or-

I could just bi-amp the setup, and leave the passive network intact...

What do you guys think? Do you think I have much to gain by altering the orignal setup?
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Old 28th December 2004, 06:43 PM   #2
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Michael P. who posts over on HTT forum has built a custom active XO for the Adire 281

http://hometheatertalk.com/httalk/viewtopic.php?t=8728
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Old 28th December 2004, 06:51 PM   #3
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Wow! Thanks.

I'd like to blame google for missing this... but, it was probably what I was searching on...
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Old 28th December 2004, 07:07 PM   #4
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The link outside of the forums, btw:

http://jdprice1.home.comcast.net/activexo/
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Old 29th December 2004, 06:02 PM   #5
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Hi, I almost missed this thread. A little while ago I've updated the active crossover page here:

http://web.mit.edu/pricem/www/activexo/

And we can talk about the project here if you want.
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Old 29th December 2004, 06:57 PM   #6
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I'm seriously considering doing this. The only problem is I don't have an extra amp laying around.

I'm looking into maybe trying a gainclone amplifier DIY first, however, from what I'm reading, it might not be enough for the Kit281s.


Speaking of the 281s, this is a little off topic, but, maybe you can help.

I'm driving them with a Sony TA-N55ES 110 wpc amp.

After my initial listening impressions, they seemed to lack much of any bass. I thought it was due to the fact that they were new, or, that my 4" flared port wasn't long enough/tuned right, or even, I had used too much eggcrate foam.

So... I removed the eggcrate foam, and properly stuffed them with the recommend location and amount of polyfill...

Still no bass.

I then removed and modified the cabinet to accept a new 3" flared port, measured perfectly.

Still no bass.


Its been over 2 years now, I'm using them with a 12" shiva, but, if I don't use the subwoofer in conjunction with them, they just sound flat and lifeless. They can hit hard at times, they are actually very good for movies.

For comparision sake, I'd say my Kit LLC has much more bass, while my old Def Tech BP8's have even more.

Don't get me wrong, they are clean and very clear and detailed... Just not much of any bass...

Any ideas?

I've checked phase... Although, maybe I should check again.

Do you have the ohm readings I should get assuming they are bi-wired? Maybe that will help.

Oh, one more thing.. I used their "updated" crossovers where they were pre-built. Surprisingly, the KitLLC, which thumps much better, I had to build those crossovers myself from their parts.
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Old 29th December 2004, 07:35 PM   #7
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Quote:
Originally posted by Kilentra
Hi, I almost missed this thread. A little while ago I've updated the active crossover page here:

http://web.mit.edu/pricem/www/activexo/

And we can talk about the project here if you want.
The large schematic doesn't seem to be available. Neither is the Borbely article.
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Old 30th December 2004, 03:20 AM   #8
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Hey, a gainclone amplifier (anything with more than, say, 10 watts) is plenty for the tweeters if you have a 100w+ woofer amp. I am actually planning to build my active XO board into a little enclosure with a gainclone built from Brian Bell's kit ($45) sharing the same 44VCT toroidal transformer.

I had used the Kit281s a long time and noticed a lack of bass as well, but it turned out to be due entirely to room placement. It took a lot of experimenting with placement to find something that was practical and had decent bass in my room. The kit is set for slightly more than 4db of baffle step compensation which seems to be a good compromise for most rooms, so that probaby isn't the problem. The main catch is that placing the speakers (or your listening position) closer to boundaries lifts the low frequencies but hurts the soundstage. It might take a little time to sort out the best balance in your placement.

Interestingly enough, a couple of people have complained that the LCC doesn't have good bass compared to other similar sized speakers. I haven't had the chance to listen to one, but I'm guessing it's because of the big resistance in the woofer network. The Kit281 has much less series resistance (better damping) and the active crossover eliminates it entirely. In any case they should be capable of jump-from-your-seat or window-rattling bass especially above 40Hz. Don't even worry about the tuning point, anywhere between 24-30Hz is fine.

It can't hurt to check the phase. Some of the pre-made crossover boards, including mine, had the tweeter phase initially reversed, so that might have caused some confusion. Besides that, I don't think there's anything wrong with the premade crossovers. You should read about 2.8 ohms across the woofer terminals and no resistance reading ("infinite" resistance) across the tweeter terminals.

Bill, thanks for pointing those errors out - they must have gotten lost in the move from the Comcast server. I think it will come up correctly now, though I should note that the resistor values in the schematic are not exactly what I am using. I will check on my favorite settings and update the schematic next week. In any case, the schematic shows exactly the power supply and crossover topology for one channel (the other channel is connected to the same supply, and has its own 100uf decoupling).
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Old 30th December 2004, 01:19 PM   #9
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Well, its good to hear someone elses impression of these. Most the reviews say "amazing" bass. Pretty subjective.

Yes, I have also noticed that the bass improves with placement, at a loss of soundstage.

They can play AMAZINGLY clear and loud, with my amp.


I thought with bi-amping, using seperate amps wasn't recommended?
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Old 30th December 2004, 05:46 PM   #10
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You can use any amps you want, though preferably you'd use amps with enough power (say 10w for the tweeters, 100w woofers) and low output impedance. The setup I had that seemed to be really optimum was about 30 watts for the tweeters and 400 watts for the woofers. The difference in gain can be compensated by the output potentiometers on the crossover board. In fact I think it's not as smart to use identical amps (if purchasing new ones) since it's a waste of money getting the unnecessary power for the tweeters.

The bass is just kind of hard to describe in words. Every speaker has its own characteristic that maybe could be quantified with endless FR and distortion measurements, but it's almost pointless. The best I can do is say that I think the Kit281s have a clean natural sounding bass and the active crossover makes it noticeably better.
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