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Old 7th March 2014, 02:48 AM   #21
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I have now made a pair of midrange-treble panels.
The measurement show left overlaid with right channel.
The first measuement is the midrange, the second the treble.
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Old 8th March 2014, 08:52 AM   #22
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I have now made a pair of baffles. I connected the tweeters with 0.82uF and listened just out of curiosity.
OK, the tonal balance is very light without any EQ but two things stand out that remind me of the experience at Mr. Linkwitz :
The speakers disappear and there is no preasure on the ear.
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Old 8th March 2014, 09:28 PM   #23
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Quote:
Originally Posted by LineSource View Post
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.
LineSource, I had a similar idea for my next pair of speakers, but I doubt this solution will be stable enough. I think I will build something like a bridge over my 2x15" horizontally placed u-frame woofers (Eminence Deltalite II 2515) to hold the baffle with a swinging 12" midbass (18sound 12NMB420) + second baffle with 8" widerange (TB W8-1772) and AMT tweeter (AC AST2560) in double waveguide.
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Old 10th March 2014, 07:56 PM   #24
6.283 is offline 6.283  Germany
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Hi hi, they look similar to mine
Welcome to the club ! Only waiting for Wavecor to come out with their new tweeter.
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Old 10th March 2014, 08:06 PM   #25
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hehe I'm also playing with this. I used a higher efficiency 8" BC 8ndl51 and currently have a lowpass shelf instead of eq the low end. Was hoping to maybe go passive on the top module and active on the bottom but looks difficult.

Eagerly waiting Mr. Gerhard's comments on presentation and implementation. Thanks for starting this thread! At some point I will probably make a pair of LX521 via the flatpacks. The baffle pics in this thread look awesome!
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Old 14th March 2014, 04:24 PM   #26
Eldam is offline Eldam  France
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Hi Johachim,

I presume the curves you show are 0 degree ? Taken from the listener position ?
Higher Mid have a beautifull curve, i like the little dip in the M-F curve where the ears are very sensible.

I have two questions please :

- With 7000 hz LP for the tweeter, do the upper mid not have directivity problems in its higher range ?

For distribued bass, what would you choose in current vendors catalogs for a 10/12"mid bass with a 80 hz XO High pass filter to the 1 Khz Low pass ? Any exists which allow avoiding Linkwitz transform or too much active filter to increase its mid-bass ?

I would like myself find a 1000 hz to 6/8 khz to avoid filtering in this range but finally was unable to find a theorical good enough mid-bass from datashhet with the few research maid with Google !

regards
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Old 16th March 2014, 12:49 PM   #27
Rudolf is offline Rudolf  Germany
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Originally Posted by Joachim Gerhard View Post
I copied more or less the shape.
Siegfried told me that the shape is critical to maintain dipole action over a wide range.
He arived at the shape by experiment.
I understand the midrange shape but i had questions about the rather clumsy shape in the treble.
" That is to avoid that the radiation from the back tweeter comes around to the front ".
OK, i dig that.
The shape i use is diffent in that it uses Bezier curves instead of straight lines.
I do not think that is has a lot of consequences to the sound but it is a visual alternative.
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Hi hi, they look similar to mine
Welcome to the club !
You both take the liberty to change drivers, change DSP and amplification. But you cling to a baffle shape that yells "LX 521". Is this respect for the master, deep insight into the finer acoustic effect of those midwoofer "ears" or just "playing it safe"?

Rudolf
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Old 16th March 2014, 05:36 PM   #28
6.283 is offline 6.283  Germany
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I'm somewhat surprised by your question. Why are you asking ?

I guess when you cling to a dipolar speaker with baffle and you're looking for the best possible off-axis behavior, then you will automatically end up with such a shape, which might as well yell NaO Note II RS.

Playing it safe ends as soon as you change drivers, especially high-mid and tweeter. At longer wavelengths there is some liberty.

In version 0.5 when I started the curved lines I actually did observe a subtle improvement in the off-axis behavior. Probably not audible and maybe unique to my drivers but this and the visual aspects made me keeping it.
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Old 16th March 2014, 09:43 PM   #29
Rudolf is offline Rudolf  Germany
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@6.283

Click the image to open in full size.

When comparing your V 0.61 baffle shape to the shapes of the Note and the LX 521, everybody would identify it as a LX 521 "clone" and not a Note "clone". There is no doubt that the upper and lower midrange baffle width of such 4-way dipoles has a common optimum value. Both loudspeakers above reflect that.
But what about the 25 "shoulder" instead of the ~45 of the Note? And what about the widening at the upper end? Is it just a bow to SL or do you see specific advantages of the LX 521 shape? That is the heart of my question.

In case of Joachims tweeter baffle I believe that it is pure mimicry yet. The polar patterns of domes and planars are too different imho to result in a common optimal shape.

Rudolf
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Old 16th March 2014, 10:23 PM   #30
6.283 is offline 6.283  Germany
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Originally Posted by Rudolf View Post
The polar patterns of domes and planars are too different imho to result in a common optimal shape.
Not only iyho but also imho.

Quote:
Originally Posted by Rudolf View Post
But what about the 25 "shoulder" instead of the ~45 of the Note?
I use a 6", not an 8". I only make sure that the lower and upper midrange mate well, horizontally and vertically. That is not really difficult at a wavelength of around 30cm. I'm not sure but I think that the angle in my shape is in between.

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Originally Posted by Rudolf View Post
And what about the widening at the upper end? Is it just a bow to SL or do you see specific advantages of the LX 521 shape? That is the heart of my question.
That jury is still out and subject to change because I am going to try a brand new tweeter. I was ready to stay with the OX20SC, which I like a lot from Demokrit-T until this guy came along. At least worth a try. There are a few more alternatives. We'll see.
It is the most difficult part of the speaker although maybe not the most critical one if you manage to pass the 5...7KHz "border" in a clean manner.
And so much about a "clone". It is the whole nine yards altogether.
But yes, I do respect the work of SL and also JK's. And of course Joachim's.
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