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Old 5th March 2014, 03:48 AM   #11
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Joachim Gerhard's Avatar
Join Date: Mar 2009
As you can see the 6dB electrical filter does not result in an acoustic 6 dB filter.
The drivers overlap quite wide with the correct polarity. When i use the wrong polarity you see a wide suckout that is aproximately centered on the desired 1kHz crossover point.
Correctly build the responses adds nicely with no succouts. That is easy to EQ in an active system. The combination is easy to drive. The impedance minimum is 7.7 Ohm but over a very wide range it is much higher.
I measured on the upper midrange axis.
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Old 5th March 2014, 05:14 AM   #12
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Your measurements and listening impressions of the dipole Mundorf AMT will be of interest to many dipolers. Do you think you will have the curiousity to build a mid-tweet baffle with dual domes like the LX521 for comparison? The mini-DSP should simplify the work.

If you shock mount your mid-treble baffle above an H-frame dipole woofer your speaker could use 12" dipole woofers in the same volume as Linkwitz's 10" with their support stand.
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Old 5th March 2014, 12:25 PM   #13
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No, i do not have a plan to build Linkwitz original but there are some around in Germany so we could arrange a comparison.
Actually i build this in my spare time for my contribution to Frickelfest.
Thanks for the drawing.
I have two woofers that i would like to try.
One is a set of downfiring subs i build for the Enviee baffle last year and one is a cardioide with LAT drivers.
If non of them does not work i will try something similar to LX521.
I have M-Dipols with 30cm woofers but that is a fixed installation.
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Old 5th March 2014, 05:04 PM   #14
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I have now fixed the 6dB crossoveer. I am building the other channel and i will build the wiring, jacks and passive crossover into the stands.
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Old 5th March 2014, 05:19 PM   #15
koja is offline koja  Canada
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Joachim, very interesting work. I much respect your second opinion about any speaker's performance. I believe many are looking to understand what makes SL's latest design so good; how much is it to his original baffle design and/or special XO objectives for the target radiation pattern, and how much he may have just lucked out on the choice of drivers.

I also hope to learn from your work if SL's bass section can be replaced fairly easily. Bass is room dependent anyways and I like the idea of distributed bass with a couple of woofers concealed around the room. (I also have $$ invested into 4 B&C 12inchers and this is holding me from building the original LX521s ).

>>only if I could make a small suggestion : you make it hard for people on the forum to follow in your footsteps when you use proprietary drivers in your designs. do you think you could also try a derivative with something available to the rest of us? (even if your home version comes first to you).

I am also interested in your opinion: would you expect a visaton B200 to be able to make it in the lower mid if crossed to that 4inch SS (I assume we are talking 10F4424; the same you used in mini mpl?).

we are aiming to also try SL's design with slightly higher sensitivity drivers, right?

Danke Vielmals.

Last edited by koja; 5th March 2014 at 05:22 PM.
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Old 5th March 2014, 06:26 PM   #16
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You can always build the LX521 as is. It is one of the great speakers of our time.
You can get the drivers and other supplies easy. Everything is well documented and supported. I do not see a real problem when you add another woofer to the LX521 top.
Concerning my design i do not plan to trade with drivers and i will not disclose what drivers i use in the treble and in the lower midrange. I can only say that this drivers are made to my specification.
The upper mid is obvious a Scan-Speak wideband driver.
What i may offer if there is enough interest, is a complete kit.

Yes the drivers i use have higher sensitivity but that does not help much where it matters : in the lower mid, upper bass. Here excursion is necearry after the formular :
Area times excursion.. So when you use a B200 that is rather limited in throw it does not work.

Last edited by Joachim Gerhard; 5th March 2014 at 06:28 PM.
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Old 6th March 2014, 09:55 AM   #17
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I have now made the second channel.
I will listen to this in Stereo today.
OK, there is no bass and no tweeter and the frequency response is not flat.
Anyway, i may get an impression in what direction is goes.
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Old 6th March 2014, 02:54 PM   #18
Morfeus is offline Morfeus  Germany
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Can't wait to hear them in May, Joachim.

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Old 6th March 2014, 03:35 PM   #19
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Sure, if i get it halve as good as Linkwitz you are in for a surprise.
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Old 6th March 2014, 03:36 PM   #20
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I got a visitor today so i am a bit delayed. One channel is ready, the other 85%.
I also have to make some cables. I use Neutrik Speakon.
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