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Presentation at Frankenfest 4-1-2023 "Why Waveguide Speakers"

Pete B

Pete B

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I gave this presentation and demo of the Jackgiff/Bauhausler (JB) Large Advent Econowave at Frankenfest.
The slides are available for download from my google drive with this link:
https://drive.google.com/file/d/1AwAH8Sb0E3YA3Vx9huzZnakc7Xqh0nyf/view?usp=sharing
I'd known for years that WG based speakers should be toed in, but
I didn't know why until reading this paper by Bill Waslo:
http://www.libinst.com/PublicArticles/Setup of WG Speakers.pdf

More background: https://audiokarma.org/forums/index.php?threads/setup-of-cd-waveguide-speakers-in-the-home.1007329/

The speakers have my PB1 mod that is based on the measurement findings here:
https://www.audiokarma.org/forums/i...er-jb-large-advent-la-econowave-2022.1006729/

Here's a picture of the demo setup, I ran 12" woofers since we were in a large room.
Thanks to John in Ma for the picture.
JB LA ECONOWAVE AT FRANKENFEST 4-2023cp.jpg
 
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Edit: I also want to mention that Dr. Geddes fairly consistently suggests a 45 deg toe in for his speakers.
I ended up with 35 to 40 deg but close enough, and the very top end of the horn rolls off faster with those
last 10 deg, so if you want more air to the sound try 35-40 deg.

I mention in the presentation that the Summa WG speakers by Earl Geddes were an inspiration, being
very expensive, for Zilch and company to find a much cheaper way of doing it.

Here are the models from way back, the number being the size of the woofer:
Summa 15 If anyone knows the price as a kit and built I'd like to know and add it here.
Abbey 12 This was $2400 kit and $3200 complete
Nathan 10 Same, if anyone knows the original price please let me know

Here's a professional review of the Abbey 12:
GedLee Abbey 12 Loudspeaker Kit Immediately appealing with lifelike dynamics and great clarity. Article By Mike Galusha (enjoythemusic.com)

Here's the report of a HiFi person who visited Geddes to hear the Summa 15, he says it was the best sound
that he's ever heard:
A visit with Earl Geddes - Review of his Summa 15's (3 separate reviews). (audiocircle.com)

Geddes' paper on the original Summa 15 that is no longer available at his site is attached below.

There are many technical papers at Geddes' site:
GedLee LLC
 

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Links worked for me, thank you!

This looks very similar to the way a two light photographic set up is feathered for even illumination when, for example, one is recording flatwork such as paintings and drawings.
 
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I was at the presentation and found it very enlightening. Good sound, too. The role of off axis sound, both direct and reflected doesn't get as much attention as it should - too many audiophiles sit in the sweet spot and think the sound there is the only thing worth considering. Obviously omnis have similar on and off axis frequency response, but they can be hard to integrate in an imperfect room.
 
Pete B said:
I gave this presentation and demo of the Jackgiff/Bauhausler (JB) Large Advent Econowave at Frankenfest.
The slides are available for download from my google drive with this link:
https://drive.google.com/file/d/1AwAH8Sb0E3YA3Vx9huzZnakc7Xqh0nyf/view?usp=sharing
I'd known for years that WG based speakers should be toed in, but
I didn't know why until reading this paper by Bill Waslo:
http://www.libinst.com/PublicArticles/Setup of WG Speakers.pdf

More background: https://audiokarma.org/forums/index.php?threads/setup-of-cd-waveguide-speakers-in-the-home.1007329/

The speakers have my PB1 mod that is based on the measurement findings here:
https://www.audiokarma.org/forums/i...er-jb-large-advent-la-econowave-2022.1006729/

Here's a picture of the demo setup, I ran 12" woofers since we were in a large room.
Thanks to John in Ma for the picture.
View attachment 2847750
Thank you for the presentation. I have printed it so that I don't have to open it again. If I want to know something or have any questions, I will surely message you. I came across your post by chance while seeking the Best Homework Websites. If you also need a local guide, then I share the website link https://letsgradeit.com/best-homework-help-websites/ which will help you a lot. it has a great homework solutions website with a great aim to help as many students as possible with their academic needs.
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Thank you for the presentation. I have printed it so that I don't have to open it again. If I want to know something or have any questions, I will surely message you. :)
 
Added info on Earl Geddes' designs to post #2 above and am looking for prices for the
Summa 15 and the Nathan 10 finished products if anyone knows or remembers.
 
When I was at the Frankenfest, Bosstown (Jamal) gave me a bunch of old Boston Audio Society news letters from the 80s, and I was surprised to see how much space was given over to this subject. I remember years ago a snide comment in Stereophile or TAS about Tom Noussaine 'waving a mic around', and now I know what the comment was about. There were several articles about his (and other people) trying to correlate measurements all over the room to perceived sound quality. This seems to me directly related to Pete's investigations (though certainly I don't speak for him).
 
I find this thread, and everything you've posted or linked fascinating.

So, the positioning of say, klipschorns, in the corner, has more benefits then 'just' the corner loading of the bass bin, but also helps the directivity/perceived stereo of the horn? This wasn't something I'd ever considered, to be honest, although I've seen the same claims about toeing in 'traditional' cone/dome speakers, I always thought that waveguides/horns operated differently.

interesting, also this calls into mind (although fundamentally different) carvers stereo holography..... possibly trying to do the same thing, completely differently?


Dipole speakers don't work this way, because of the rear output, correct?

fascinating.
 
Interesting observations.

The K horn used conventional exponential horns, as far as I know, which tend to beam
high frequencies and any speaker that beams including typical dome tweeters will benefit
from toe by putting the listener in the sweet spot more on axis. I do not follow Klipsch
too closely but I believe that in the II and higher revisions of the Heresey, Forte, Cornwall
etc. they might have moved closer to WG type horn - not sure on this. They might have
kept the K horn original thinking that's what buyers want, again not sure.
But, yes any of the Klipsch designs that moved to a CD WG type horn would benefit from
toe in. The Jubilee does use more of a CD type horn and goes in the corner.

Wayne Parham of PiSpeakers also suggests corner placement for at least some of his designs,
and further points out that the walls of the room form a conical horn which is good for CD. His
white paper here discusses exactly what you've noticed starting at the bottom of page 6:
https://www.pispeakers.com/Pi_Speakers_Info.pdf

Back to conventional speakers with dome tweeters, as I said the tweeter will beam at HF and
toeing in will provide more air in the sweet spot but adjust the amount for best sound. However
since the dome is not CD it will not have the wide sweet spot of properly placed WG speakers.
Some discussion here with many different opinions, some suggest no toe in:
https://www.audiosciencereview.com/forum/index.php?threads/stubbed-your-toe-in.175/page-2

The main topic here is not toe in but they end up discussing it anyway:
https://www.audiosciencereview.com/...gn-for-flat-on-axis-and-smooth-off-axis.8090/

Yes, I'd say that dipoles are different but it doesn't cost anything to experiment.
 
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