Setup of CD Waveguide Speakers in the Home

[Pete B]

I remember reading many years ago that CD Waveguide speakers should be toed in to cross
1 to 3 ft in front of the center listening position. Here's a nice paper, by Bill Waslo that explains this:

Setup of WG Speakers.pdf (libinst.com)

Waveguides? Audiophiles! Try this NOW! - YouTube

BOTTOM LINE
I'll try to explain this as best as I can. I've known about the toe in rule for probably 8 or more years
but never knew the exact reason. I've also known that the goal for CD is flat but attenuated off axis
response and recently have been thinking, sure it is flat, but everyone off axis is going to hear less
output from the horn due to the attenuation if you point the speakers at the center sweet spot. Waslo's
paper made the point that listeners, for example seated on a couch, are varying distances away from
the left and right speakers. By aiming the left speaker at the furthest position to the right we give the
listener the furthest away the strongest output from the horn, and similarly for the left most seated position.
Then each position closer to one speaker moves further off axis so that the closer distance is compensated
for by reduced output from the horn.
The furthest listening position gets the max output from the horn. Now, the advantage of CD makes sense.

If people see pictures of my LA Econowaves on here, they are not properly set up in the room.
I've mostly listened to just one to try and figure out what's wrong with the tonal balance. Will set
them up properly in the near future after I do some mods to them.
Edit: I did figure out the problem with them and show a mod in post #17 in this thread:
Measuring the "Jackgiff/Bauhausler" (JB) Large Advent (LA) Econowave 2022

 

[C Hart]

That jibes with the instructions that came with my Hsu HB1s which are a small waveguide. Per Dr. Hsu, the rule of thumb is that the listener should be able to see the outer side panel of the speaker from the listening position.

 

[tomlinmgt]

I played with toe in A LOT with my Altec 19's. Many small changes were made, going from on axis and looking straight down the throat to toed out bit by bit. On axis was too hot in the upper mids, but toed out any amount from on axis compromised image and sound stage resolution. I finally decided to try exteme toe in and the pay off was immediate. Finally settled on axis crossing about three feet in front of me. Went through the same scenario with Klipsch Epic CF-4 and got the same exact result.

 

[Pete B]

@tomlinmgt Nice pictures! Which do you like better?

 

[tomlinmgt]

@tomlinmgt Nice pictures! Which do you like better?

Thanks, Pete. The 19's...but not by a long shot. My time spent with the 19's was around seven years ago and the Epics were in the system last year, so the big time gap between the two is something to consider. However, the 19's really left a strong impression, and represent the pinnacle of a long speaker journey that included models like Infinity QLS-1, Magnepan MG-IIIa, Acoustat Spectra 22, and JBL L250. All of those had unique merits and provided a compelling listening experience, but the 19's simply stood out as the most engaging and tactile with noteworthy transient speed, detail, and clarity and all delivered in a manner that's best described as "effortless authority". They sound under control and unstrained from top to bottom. Only with regard to sound stage depth and height did I find them lacking. It's not that either was significantly deficient, but compared to the line source dipole speakers they just didn't project beyond the front wall and high in the vertical plane like the latter.

The listening space in the pictures was in my garage, and I lost use of that space for a few years shortly after my time with the 19's while I took a break from the hobby. Around '17 I decided to set up a rig in the living room with the objective being to find a set of speakers that could get me as close to the 19's as I could get, but with a smaller footprint. First attempt was Klipsch Chorus II...very nice and had many of the qualities I enjoyed about the 19's, but not quite in the same league and image and sound stage resolution is not their strong suit. Next were the big Epics, and they immediately displayed capabilities that put them in a different league than the Chorus II...so good, in fact, I was compelled to set up a system in the garage again so I could hear the Epics in an environment that had undergone extensive acoustic tuning.

What I concluded is that with the D'Appolito driver configuration their image and sound stage resolution and dimensionality approached what I'd experienced with the big diploe speakers, and their big Tractrix waveguide and large-ish compression driver coupled with the radiating surface area of four 12" LF drivers gave them much of the "effortless authority" I experienced from the 19's. What I feel was a bit deficienct compared to the 19's was clarity and balance. I think the stock compression driver is to blame, and have picked up a pair of EV DH1506's to substitute. That hasn't yet happened as I once again have lost my garage listening space for good, but currently have a dedicated listening space under construction where a head to head shoot out between the 19's and CF-4's will most certainly be in the cards.