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New Gotham N23 Skyline Diffusors

100.14.102.31
Posted on May 29, 2017 at 21:03:57
Barry
Audiophile

Posts: 1003
Location: PA
Joined: November 24, 1999
Contributor
  Since: January 18, 2009
 Just got 4 of these on a GIK introductory promo and mounted them directly behind my 3.6s.

Specs say they provide 2D diffusion from 1.25 kHz to 9.5 kHz with scattering effects down to 650 Hz. They weigh 20 pounds each - they're heavy. Also, a little more expensive compared with some other options.

Sound stage is a little more spacious. They do look pretty cool too.



 

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RE: New Gotham N23 Skyline Diffusors, posted on May 30, 2017 at 00:42:06
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I wouldn't have expected them to do much when you already diffuse the front wall where it matters - the space between the speakers.

 

Help me understand here, posted on May 30, 2017 at 10:31:01
M3 lover
Audiophile

Posts: 6604
Location: SW Mich
Joined: May 29, 2005
Contributor
  Since: July 4, 2007
 Satie, I've read your posts often enough to believe you are knowledgable, but why do you say placement matters most between the speakers?

I thought as a near line source dipole, Maggies beam their rear radiation just as the front. So why would diffusors not be helpful placed at the first reflection point on the front wall?

"The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

 

RE: Help me understand here, posted on May 30, 2017 at 15:55:36
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The reflection angle vs. the listening seat. The reflections that reach you and muddy up the imaging are the early ones. Those come mostly from the narrow midrange and tweeter reflections off the area about 1/4 into the interspeaker space on the front wall from either side. The bounce from the wall space just behind the speaker is going to the sidewalls before it reaches the listener.

It isn't that it does not matter at all, just does not matter as much. To see this you can move a mirror on the front wall to identify these first reflections.

 

RE: This is why I think, posted on May 31, 2017 at 13:51:39
BigguyinATL
Manufacturer

Posts: 3475
Joined: April 10, 2002



Maggies deserve more toe in. The first side wall reflection line of sight should be well off axis - I have my MMG's toed in 45 degree so the side wall see the dipole speaker "null". Moved the speakers out a bit - put the tweeters inside. This tool a little off the brightness so I could eliminate the system high frequency EQ I was using.

Left and Right Subs are also at the null points (approx), just out of this picture.

Third (left) "Stressless" chair is on loan to someone at the time the picture was taken.


"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: This is why I think, posted on May 31, 2017 at 17:04:20
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 MMGs are different. On 3.x and TIV/IVa models I didn't find much toe in to be beneficial and the mid/tweet sections need nearly no toe in at all. Most pre .7 series don't need toe in and the toe in required for .7 series is not that much - actually you only need it if you are placing the speakers near the front wall - in which case you are using the toe in to control early reflections and less so to get proper driver integration..

 

Is there an optimum room placement for a dipole?, posted on May 31, 2017 at 20:30:29
Barry
Audiophile

Posts: 1003
Location: PA
Joined: November 24, 1999
Contributor
  Since: January 18, 2009
 you've probably seen this but for others, here's what the foremost authority on the subject, S. Linkwitz, thinks about dipoles, room modes, and speaker and listener placement (Answer to Q31).

Also worth a read is this page:

http://www.linkwitzlab.com/rooms.htm

However, if you like what you got now, Don't worry be happy!

 

RE: Is there an optimum room placement for a dipole?, posted on May 31, 2017 at 21:18:04
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Of course it is nice in theory but it is not realistic as at high frequencies the reflection null node will be very narrow and above 5khz you will be moving in and out of it as you make normal movements of your head. And for transient events you are more concerned with the reflection of the backwave arriving as late as possible and as attenuated as can be in order to make use of the precedence effect to obtain better clarity and spatial performance. . And you want the reflection's arrival time to be spread out as possible so that the reflected peak transient is of low SPL and has a much longer rise time than the direct radiated one.
Also so long as your source is spread out horizontally - as the reflections that reach you from each driver would be from different angles they would have different path lengths, so you can have the cancellation occur for that one driver out of the 3 in a ribbon maggie. . Besides which planar radiators are fairly wide and radiate more uniformly than a cone. So reflections of output away from the center of the driver are just as strong as the central output.
I saw this argument before and tried it and it didn't work beyond the lower mids, which for maggies is not the thing you want to have cancel out, you want to use the lowest bass modes to obtain a more substantial bass balance.
The Limage placement makes more use of the room reflections and wall loading effects to get the most out of the planars - assuming room geometry works..

 

RE: Is there an optimum room placement for a dipole?, posted on June 1, 2017 at 00:36:24
BDP24
Audiophile

Posts: 1070
Location: Vancouver, Washington
Joined: September 12, 2013
 Speaking of diffusers, what 6" deep designs can anyone recommend for the space between a pair of planars, on the wall behind them? It will be inserted into a 58" wide x 46" tall window whose bottom is 3' above the floor, centered between the speakers. Is wood the only serious choice, or are ones made of foam or other lightweight materials worth consideration?

 

RE: Is there an optimum room placement for a dipole?, posted on June 1, 2017 at 06:29:44
Barry
Audiophile

Posts: 1003
Location: PA
Joined: November 24, 1999
Contributor
  Since: January 18, 2009
 Of course all of what you are talking about is covered on his site and his other presentations, except phase cancellation of side by side drivers. While it's not applicable to his speaker design, it is exhaustively covered in his crossover work for which he is famous.

I do find this, and the Genesis speaker setup guidelines, two very insightful articles about how planers work and can be optimally positioned in rooms, but I don't set my speakers up exactly as either recommends.

I am not an expert and no one will ever name xo filters after me.

 

What I see is more or less, posted on June 1, 2017 at 11:41:39
E-Stat
Audiophile

Posts: 37666
Joined: May 12, 2000
Contributor
  Since: April 5, 2002
 HP's rule of thirds in action. No cocktail napkin diagram necessary.

Which I find works quite well empirically in my room. My distance to front wall was determined by measuring the most linear bass response in the bottom octaves.

My seating position from the back wall is about the same.

 

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