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Old 2nd November 2012, 06:55 PM   #41
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http://www.unitedhomeproducts.com/id101.htm
The Kitharo amt from Oscar Heil is able to go down to 700 hz.
Is the diaphragm the same as the one used for the great ESS.?
It is a different magnet system.
Does anyone knov how it is made?
Can Mylar keep its shape if heated in a jig?
Many questions,but it could help me to make a AMT go deeper.

Bernt

Last edited by båndsei; 2nd November 2012 at 06:56 PM. Reason: Missing link.
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Old 5th November 2012, 10:06 AM   #42
ondesx is offline ondesx  France
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Yes it's the Kithara that I tested... Well, you'll probably find some additional info here :

www.precide.ch

I hope this helps ...

Last edited by ondesx; 5th November 2012 at 10:10 AM.
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Old 10th November 2012, 10:36 AM   #43
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I have found a dechription in German about modification of AMT diaphrame:
[IMG]Click the image to open in full size.[/IMG]
Bernt
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Old 14th November 2012, 03:46 AM   #44
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The ESS Great Heil can also go down to 700hz.
Part of the problem you will run into is that at this range the rear radiation is essentially in phase with the front, (along with the inevitable room reflections) causing cancellations, and account for some of the nasal qualities experienced at this low crossover level.
This will still happen with any dipole Heil, regardless of the type of diaphragm used.
The total sensitivity, and some minor peak/valley smoothing, along with perhaps a little different bit of voicing (do to differences in diaphragm material and pleat count) seems to be the main differences sonic wise with the non ESS Heils
Adding a transition driver to cover the fairly narrow range from 250 to 2500hz is the way to go.
The AMT3 crossover is the ideal model IMHO (and one can easily tweak the values/etc) , it sports some fairly generous driver overlaps and 12db slopes, but with the right drivers throws a wide and convincing sound stage that images for days.
No honkiness, no mid bass issues, it all falls together quite nicely.
If the speaker system is well thought out, and integrated properly, IMHO there is little advantage going 2.5 way vs 2 way.
The additional advantage of the 2.5 way is you can good to say a 10" woofer and really have some nice tight bass response.
In my modified AMT3's I used the Dayton ST255-8 with excellent results, along with the Alpha 6A/Aurasound.

Last edited by automaticmojo; 14th November 2012 at 03:56 AM.
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Old 14th November 2012, 02:34 PM   #45
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I have a midrange speaker to cover the range:100-1100.,and a subwoofer .
I am using active crossover and EQ:Mini DSP.
[IMG]Click the image to open in full size.[/IMG]
This is my messurement of the great Heil,messured at 40 cm distance and crossed at 500 hz.
It performs to 700hz. But distorsion rises much below 1000-1100 hz.
I dont belive I can make a AMT better than a great Manufactor,but it could be fun.

Bernt
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Old 14th November 2012, 05:06 PM   #46
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I have just made a very nice looking diaphragm with plastic made for laminating and alu/paper for coil :
[IMG]Click the image to open in full size.[/IMG]
I have made this tool from heatzink from CPU:
[IMG]Click the image to open in full size.[/IMG]
It don´t sound ,nor messure nice:
[IMG]Click the image to open in full size.[/IMG]
Now i am looking for some new material.The plastic i used was 60 my.
I have read about some plastic/mylar 12my and alu coated 12my.Where can i get some??

Bernt.
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Old 15th November 2012, 02:57 AM   #47
miklos is offline miklos  Canada
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"Adding a transition driver to cover the fairly narrow range from 250 to 2500hz is the way to go."
How about from 110 to 2500Hz? Then one could have a powered sub plus a two way.
I have a couple of candidates for it, an Altec 414, or a Goodmans Axiom 10.
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Old 16th November 2012, 03:20 AM   #48
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Where the transition driver crosses over to the Heil is more critical IMHO.
With a 12db/octave crossover there is some driver overlap, so matching the drivers is fairly critical. Smooth response curves, and impedance peaks out of the passband, along with high output are beneficial.
The stock AMT3 crossover is a bit strange when you break it down-a hybrid between a series and parallel. The woofer along with the midrange high pass is in parallel arrangement, but the midrange low pass, and tweeter high pass are series, with the midrange being out of phase.
There is some debate, with the stock AMT3 setup on how the speaker sounds with the mid in phase, or reversed. I prefer it reversed, along with blocking the sides of the Heil with foam.
The first schematic is a breakdown that makes it a bit easier to make up a hard wire version.
The second view is the stock O.E. schematic-which can be a bit confusing if you don't look very carefully, especially regarding the inductor values, as the print is poor.
The values can be tweaked depending on your particular drivers, but IMHO this network gives you a very easy and successful way of fully implementing the Great Heil in a DIY design, without having to deal with active crossover/amps.
Using low inductance/ESR air coils and caps, and large gauge wiring you further reduce the resistance and distortion in the network, and add a db or 2 in efficiency.
All good things IMHO.
Attached Images
File Type: png AMT3 ess network_R1.png (6.8 KB, 128 views)
File Type: jpg Auto's Super AMT3! 28.jpg (43.2 KB, 153 views)

Last edited by automaticmojo; 16th November 2012 at 03:39 AM.
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Old 16th November 2012, 04:06 AM   #49
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Also the woofer should drop off cleanly on the low end, without any doubling or artifacts of "pretend" bass.
Unless your looking for HT excitement, a clean, non doubling musical response, with room gain to 34-36 should be sufficient IMHO.
It not only cleans things up, but prevents any wasted power on non musical artifacts.
Using/matching subwoofers to a Great Heil speaker, is not unlike trying to get a good subwoofer match to a Magnepan.
Woofers with poor transient response aren't really up to the task and IMHO should be avoided, as I can guarantee you won't like the results.
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Old 16th November 2012, 04:48 AM   #50
miklos is offline miklos  Canada
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Quote:
Originally Posted by automaticmojo View Post
Also the woofer should drop off cleanly on the low end, without any doubling or artifacts of "pretend" bass.
Unless your looking for HT excitement, a clean, non doubling musical response, with room gain to 34-36 should be sufficient IMHO.
It not only cleans things up, but prevents any wasted power on non musical artifacts.
Using/matching subwoofers to a Great Heil speaker, is not unlike trying to get a good subwoofer match to a Magnepan.
Woofers with poor transient response aren't really up to the task and IMHO should be avoided, as I can guarantee you won't like the results.
Thank you for your advise. In this case i have to try the 414 for the full lower band. What do you think about active xover? THX.
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Last edited by miklos; 16th November 2012 at 04:51 AM.
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