Speaker Asylum

Radiation

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Bill the K

In Reply to: RE: Even Richard Branson posted by tomservo on November 19, 2024 at 07:33:40

What governs that radiation? Quality of driver but is it a blind shot?What exactly can a designer do. Like some doctors having God's grace in their choice of treatment, some speaker designers are blessed. How come Henry Kloss designed such great speakers. There is still a lot of mystery in the world of speakers.

Regards
Bill

Follow Ups:

Specific cases in point - E-Stat 07:04:22 11/21/24 (2)
to help illustrate Tom's scholarly answer. First of all, I find this calculator helpful to determine the frequency of a given wavelength.
Good practice is limit upper frequency of a given driver by piston size wavelength. Since you cited Henry Kloss, look at the New Advent's woofer. While nominally a 10" design, the piston size is about 9" which is about 1500 hz. Guess the crossover frequency!
Bad practice is exemplified by 70s era JBL three way bookshelves like the popular L100 Century. It uses a 5" midrange with nominal piston size around 4" which relates to about 3400 hz. Wanna guess how far they ran that driver ? 6 kHz! What that meant was instruments that spanned the top end of the midrange driver with harmonics in the tweeter possessed a weird funhouse mirror effect in terms of apparent soundstage width. Dispersion clamped down at the top of its range only to be mated with a 1" dome sitting in its sweet spot with wide dispersion. Talk about discontinuity in a range sensitive to our hearing! Sin of commission.
Under Floyd Toole's watch, later versions of that speaker like the LSR6332 using identically sized drivers lowered the upper range of both the woofer and midrange by more than an octave to get them back down in a comfortable range for consistent radiation.
Full range dynamic drivers typically break that rule but at least they let the upper frequencies narrow without shining a spotlight on the challenged response. The ceiling mounted 8" full range drivers used in our around the house system don't have the most extended top end response but don't call out to themselves. Sin of omission.
A primary reason I've been a full range electrostat fancier for decades is because of their uniform character that sounds more like real instruments to these ears. BTW, Tom's Synergy horns are unique in that while they are multi-way, all frequencies radiate from the same "mouth" for consistent radiation. Here's an SH-50 as an example:

What I find interesting is the similarity to his approach and Dr. West's electrostats. Both offer multiple full range controlled radiation angle models and are designed to be configured in arrays to increase vertical or horizontal coverage.

Edits: 11/21/24 11/21/24
- I wish I could afford the SH-50... - peppy m. 08:38:20 11/21/24 (1)
  Not super expensive but outside of my reach. I love the design, would like to find out how they sound with a decent amp...
  - Fellow over at High Eff loves his - E-Stat 09:06:02 11/21/24 (0)
    but they require subs and take up some space!
RE: Radiation - tomservo 11:16:06 11/20/24 (0)
Gosh, part A is acoustic size, how large is what ever it is compared to the wavelength being produced.
The problem here is there is a 1000:1 difference in size from 20Hz to 20KHz.

You can figure the wavelength size in inches using 1132ft/sec X 12 inches / the frequency

For a simple piston source, one finds that if the diameter is 1/4 wavelength or less, it is an omni source, radiates equally in every direction.
As the frequency climbs and the WL is smaller, when it is about 1 WL across, the radiation pattern has narrowed to around 90 degrees forward. going higher in frequency, the radiation patterns is one of lobes and nulls across the front.
It is the complex radiation that your ears use to locate the physical distance by ear and makes the speaker "stand out" as sources in stereo where a center phantom image is desired.

There is a lot of mystery, some in the aid of sales but also a great deal is known.

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