Owston meet 27+28 Nov 21-add your name here

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vinylnvalves
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#181 Re: Owston meet 27+28 Nov 21-add your name here

Post by vinylnvalves »

The theory behind the AMT would suggest it’s a bipole as it flex’s the corrugations sidewards so the sound waves going forward and backward would be in phase. However I stand to be corrected :D
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andrew Ivimey
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#182 Re: Owston meet 27+28 Nov 21-add your name here

Post by andrew Ivimey »

This gets me thinking.... Ive long been Happy with Heil AMTs - case closed, just listen to the music.

But correct me if I'm wrong but so many modern AMTs aren't di-pole. Even a couple of Dr Heil's cheaper models were not di- pole. Ie always thought this can't be right but....

After lots of experimenting I think ESS more or less got it right a long time ago.
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chris661
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#183 Re: Owston meet 27+28 Nov 21-add your name here

Post by chris661 »

Interesting. Wiki seems to think dipole: https://en.wikipedia.org/wiki/Air_Motion_Transformer

But I think you're right - they're bipole: pushing the cleats together squeezes air out of both sides (positive pressure) at the same time.


Of course, that does leave the question about how to integrate that with the rest of the frequency range. I'd say there are two approaches: with the AMTs open-backed, or loaded into chambers. I'd probably go with the latter, but that's personal preference.

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vinylnvalves
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#184 Re: Owston meet 27+28 Nov 21-add your name here

Post by vinylnvalves »

Yes I need to play with a back chamber for the midrange one and see if the magic is lost or not. Alternative is to make some bigger ones to go down to 100 hz, as below the Schröder freq of the room - it doesn’t matter if it’s dipole or sealed.
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andrew Ivimey
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#185 Re: Owston meet 27+28 Nov 21-add your name here

Post by andrew Ivimey »

The first ESS speakers I owned were 'bookshelf' ones with the standard 12 inch bass units and grand master Heils. Although ported both drivers were boxed in, neither bi-polar nor dipole apart from the small port ( for the bass unit).

Now, as Eni fule no, American booksheles are huge compared to what UKers would call bookshelf. These speakers were generous indeed and I thought they were great.... till I got ESS AMTs and I've had three pairs since. I brought a pair of ESS AMTs to a 'do' at Witham . They had a 'german' crossover instead of ESS'. The ESS AMTs were ( still are) brilliant . The 12 inch bass units had passive sympathetic driers on the back. The Heils were truly open to the front and back - Magic!

Only bettered perhaps by a chum who got rid of the ESS bass drivers for 12 inch units from the LS5-8 BBC speakers with only one gently rolling off inductor. The Heil had the same xover as the 'german' crossover which I think crossed at 1.2kHz. Hmmmmm, it might have been more radical at 800 Hz. Don't 'member. He also cleverly added to the cabinet which allowed for more bass frequency - not needed, imho, but hey, who cares!!!
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
vinylnvalves
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#186 Re: Owston meet 27+28 Nov 21-add your name here

Post by vinylnvalves »

This website may be of interest.., claiming benefits of bipole for room effects. Hmmm .. not sure I full buy it,
https://www.rowen.ch/de/fullbipol.php
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Paul Barker
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#187 Re: Owston meet 27+28 Nov 21-add your name here

Post by Paul Barker »

andrew Ivimey wrote: Sat Dec 04, 2021 6:47 pm The first ESS speakers I owned were 'bookshelf' ones with the standard 12 inch bass units and grand master Heils. Although ported both drivers were boxed in, neither bi-polar nor dipole apart from the small port ( for the bass unit).

Now, as Eni fule no, American booksheles are huge compared to what UKers would call bookshelf. These speakers were generous indeed and I thought they were great.... till I got ESS AMTs and I've had three pairs since. I brought a pair of ESS AMTs to a 'do' at Witham . They had a 'german' crossover instead of ESS'. The ESS AMTs were ( still are) brilliant . The 12 inch bass units had passive sympathetic driers on the back. The Heils were truly open to the front and back - Magic!

Only bettered perhaps by a chum who got rid of the ESS bass drivers for 12 inch units from the LS5-8 BBC speakers with only one gently rolling off inductor. The Heil had the same xover as the 'german' crossover which I think crossed at 1.2kHz. Hmmmmm, it might have been more radical at 800 Hz. Don't 'member. He also cleverly added to the cabinet which allowed for more bass frequency - not needed, imho, but hey, who cares!!!
First time I even knew about them Andrew. I was very impressed.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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andrew Ivimey
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#188 Re: Owston meet 27+28 Nov 21-add your name here

Post by andrew Ivimey »

Ha! when I think if all the things you'e introduced to me oer the years.....

Twas the least I could do!
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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Paul Barker
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#189 Re: Owston meet 27+28 Nov 21-add your name here

Post by Paul Barker »

man hugs
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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IslandPink
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#190 Re: Owston meet 27+28 Nov 21-add your name here

Post by IslandPink »

Oh, get a room, you two !
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