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 Post subject: Re: GRS Planar Drivers
PostPosted: October 17th, 2020, 9:06 pm 
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The long wing is 15" deep and the short wing is 2" deep. Gets the LF response of the planar down to 200Hz.

It is a folded baffle.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 17th, 2020, 10:45 pm 
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Open baffles often use asymmetric wings, or asymmetric driver-on-baffle placement, to overcome reinforcement of dipole cancellation at the same frequency.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 6:33 am 
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They did the testing on the stage of an auditorium. We just moved into the new house a week ago and are busy unpacking. I'll try to find the original research when I get time. My RD75s are mounted in asymmetrical baffles that are curved to minimize diffraction and are mirror imaged left to right.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 8:06 am 
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Walt, this is a partial assembly of BG 8 and Fountek drivers. They will be integrated to a baffle with a row of 7" midbass drivers. Actual crossover point TBD based on measured performance. The baffle will be narrow on the side of the tweeter/midranges. Tweeters to the center of the room.

The midbass drivers sound good to 3500 or so, but beaming is an issue over 2000. The idea is to cross the BG8 as low as they will comfortably work. Not sure if 500 Hz is practical, but pretty sure that 1000 is no problem. Biamp and electronic crossover.

Hopefully it will sound decent. If not, I'll move on.

Stuart


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 10:54 am 
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Location: Parkville, Maryland
Stuart Polansky wrote:
Walt, this is a partial assembly of BG 8 and Fountek drivers. They will be integrated to a baffle with a row of 7" midbass drivers. Actual crossover point TBD based on measured performance. The baffle will be narrow on the side of the tweeter/midranges. Tweeters to the center of the room.

The midbass drivers sound good to 3500 or so, but beaming is an issue over 2000. The idea is to cross the BG8 as low as they will comfortably work. Not sure if 500 Hz is practical, but pretty sure that 1000 is no problem. Biamp and electronic crossover.

Hopefully it will sound decent. If not, I'll move on.

Stuart


Well -- you do have a vertical string of them -- see where it takes you. When I was dialing in my Altecs initially -- I put to good use a capacitor decade and my RTA and diddled with crossover values on the fly until I could not "see" the crossover point.

Of course you know as well as I do that the "devil" is in the details. I don't know if you're going passive or active in terms of the crossover (please say passive), but since I have done other's speakers and expect more projects I have a nice inventory of large-value polycarbonate (mostly Electronic Concepts) and polypropylene capacitors that serve the music.

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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 12:54 pm 
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Stuart,
Conceptually that is close to the VMPS RM40 array with the ribbon center and planar mids in that configuration.

I had a pair of RM40's. They sounded the best when I used a digital crossover with high slopes to crossover the ribbon to the planars. It made the radiation pattern work out better than the low rate slopes of the original passive XO's.

Just a thought.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 2:50 pm 
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Joined: April 22nd, 2013, 12:58 pm
Posts: 208
You read Tom's statement wrong........
He's talking about offsetting the drivers on the baffle to reduce comb effects.
See Fig. 1.10 on page 23:
http://cyrille.pinton.free.fr/electroac/lectures_utiles/son/Olson.pdf

Cogito wrote:
I don’t consider that a “wing”. You have a half enclosure to avoid room reflection. A wing for me means a baffle. I read Toms statement to mean baffles of rich and left speakers are not identical.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 3:49 pm 
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Location: Parkville, Maryland
FerdinandII wrote:
You read Tom's statement wrong........
He's talking about offsetting the drivers on the baffle to reduce comb effects.
See Fig. 1.10 on page 23:
http://cyrille.pinton.free.fr/electroac/lectures_utiles/son/Olson.pdf

Cogito wrote:
I don’t consider that a “wing”. You have a half enclosure to avoid room reflection. A wing for me means a baffle. I read Toms statement to mean baffles of rich and left speakers are not identical.


Anyone who thinks it hasn't been done yet needs to read Olson, Villchur, and Read. The "wheel' was invented a long time ago. :character-oldtimer:

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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 6:22 pm 
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Joined: April 22nd, 2013, 12:58 pm
Posts: 208
Who's "Read"...?


Anyone who thinks it hasn't been done yet needs to read Olson, Villchur, and Read. The "wheel' was invented a long time ago. :character-oldtimer:


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 18th, 2020, 6:49 pm 
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Joined: July 8th, 2016, 4:34 pm
Posts: 401
See link -

https://www.amazon.com/Acoustical-engin ... B0007E672Y


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