DIY Waveguide loudspeaker kit

[nycavsr2000]

Hi fellas,

Wife and kids were out the door visiting friends down south so I called up Earl and asked if I could audition his speakers yesterday. For what its worth, here are some speakers I have heard and respect:

Linkwitz Orions++, right at Siegfried's house near San Francisco
NaO II dipoles designed by John Kreskovsky
GR Research OB5's and OB7's

Earl was an excellent host, brought me down to his well treated home theatre room (about 15 feet wide and 30 feet deep with a 10 ft ceiling) where the Summa 15's were in the corners behind curtains and turned in 45 degrees to avoid the side walls. There were also 3 subwoofers setup in the room (all bandpass design!). The Summa's are about 98dB/2.83V/m efficient in full space. His electronics are extremely simple and plain by audiophile standards. A PC and Toshiba CD player as sources, a Pioneer Digital Receiver (100 watts/channel), zip cord wire and zip cord interconnects. Nothing amazing here at all.

First CD we played were various tracks from Bela Fleck & Flecktones, a Live CD.

Wow! We were playing at peaks of 100 dB from my listening position (roughly centered about 10 feet away from the speakers). No compression. Tight clean bass. Performers were in the room. Imaging was very stable over a horizontal axis of an entire sofa. Music appeared from a complete black void.

The most open midrange I have ever heard. This includes the dipole systems I have listed above. There was no real part of the frequency response that was drawing attention, although I was continuously amazed by how clean the bass was and how delineated it was. Treble was just there, never drawing attention to itself but never lacking either.

Image body, intensity were all there. Small instruments sounded small. Close miked, sounded close miked.

Neutral is a great way to describe it.

Next we listened to some cuts from Diana Krall. Her voice was so compelling that she really sounded she was right up there on stage, playing for you. A personal treat if you will.

Next, Geddes played a cut from a DVD from Phantom of the Opera. Dynamics in spades. Everything was released unshackled. And just when you thought the music may lose control, it doesn't. How quickly the Summas start and stop is uncanny. I believe this is as much a product of speaker design as it is the room. The final cut was my favorite. Eagles DVD Live! The guitar solos were electrifying, even soul searching.

I am beginning to understand why some audiophiles say they listen at 80 or 85dB. I think its because of compression. When I auditioned the Orions and NaO II's, I was a little hesitant to crank it up. With the Summas, the music just gets louder but never, ever loses control.

In any case I suggest anybody within a spitting distance of Michigan to call up Earl and give these an audition. Even if you own fancy schmancy loudspeakers, I mean TAD 3 ways, Avante Garde, etc...give it a listen. It will challenge every audiophile belief you have had. Earl was kind enough to let me have one of his books, "Premium Home Theater." I have been leafing through the book and found one paragraph regarding 'subjectivism' that I found quite eye opening (page 249):

"When dealing with subjectively oriented AV issues,I prefer to deal with the science (facts), whenever possible, and not Audio Tarot. My wife coined this wonderful phrase after she first came into contact with the audio community that I work in. She has a background in experimental psychology and knows how easily subjective opinions can be swayed by external factors. She noted that a large amount of audio folklore is accepted by its practitioners purely on faith,i.e. there is no way to either prove or disprove these beliefs. Basically, audio,in these aspects, is a religion. Mankind has always had trouble reconciling facts with their fundamental belief system when the two come into conflict (to wit Galileo). The facts are often suppressed in order to perpetuate the established belief system. The practitioners of Audio Tarot will always prefer to suppress those facts that contradict their established beliefs."

Trust me just like many of you, I am part of the (gulp) Audio Tarot as well. Will I give up some of my fancy schmancy equipment? Probably not terribly soon. But boy was this system an awakening.

What did it teach me? The speaker/room equation is the achilles heal to audiophile aural enlightenment. Until you've solved that issue, you (I mean me) will be in this perpetual audiophile merry-go-round of exchanging equipment, spending thousands of dollars, etc...

Fix that problem first. For if a loudspeaker/room with Pioneer electronics can blast me into an eargasmic orbit, what more do I want? Better question is what more can I have? Will better electronics make a better listening experience? Perhaps. However, the Summa 15's really take you 90% there, so I'm not surprised that a simple receiver can take you so far ahead of everybody else.

A few pictures to follow tomorrow.

Till then,

Anand.

[tinitus]

Nice read!

But dont let Earls amp fool you
He has written a lot about it ... its very carefully selected

[gedlee]

Anand

Thank you for your kind review. I should point out that we have never met before and that all I asked of you was that you post your impressions. I had no doubt what they would be.

And yes, the loudspeaker room interface is the key, To ignore this is to ignore the essence of audio.

(Well not zip cord interconnects, Radio Shack )

Thanks again. It was a pleasure meeting you.

[publius]

What a FANTASTIC review.

Thanks Anand!

Do you know what frequency the Summas were crossed to the subs?

[publius]

Congrats E.G. These Summas MUST be something very special.

[gedlee]

Originally posted by publius
What a FANTASTIC review.

Thanks Anand!

Do you know what frequency the Summas were crossed to the subs?

I don't "cross" to the subs. The subs all overlap with various frequency responses.

[nycavsr2000]

As Gedde said, he has 3 subs, all bandpass design, with different frequency response overlap. First time I have ever heard a bandpass system done right.

In due time, I think Gedde will reveal the details of these bandpass subwoofers as future kits perhaps.

In the meantime, I figure let the Nathan10 run full range and have a low pass set for your sub. Best to do it with measurements. Most subs nowadays whether DIY or commercial are either sealed, ported or dipole based anyway.

Anand.

[publius]

Originally posted by gedlee
I don't "cross" to the subs. The subs all overlap with various frequency responses.

So, the rolloff on the mains is sufficiently steep (>=12db/octave)to protect them from any sub-bass in the L-R channels? Then you send a combined L-R channel sum to each subwoofer where you have high and low pass filters and you use each of the three subwoofers to cover a different frequency range? Do you do this to reduce the burden on each subwoofer or to "shuffle" the room modes (or some other reason)?

How would this work for people who are running a home theater? THX assumes second order rolloff at 80hz in the mains to which it adds an additional second order filter to create a net fourth order rolloff. THX rolls off the subwoofer channel at fourth order at 80hz for a smooth transition.

[gedlee]

Originally posted by publius


So, the rolloff on the mains is sufficiently steep (>=12db/octave)to protect them from any sub-bass in the L-R channels? Then you send a combined L-R channel sum to each subwoofer where you have high and low pass filters and you use each of the three subwoofers to cover a different frequency range? Do you do this to reduce the burden on each subwoofer or to "shuffle" the room modes (or some other reason)?

How would this work for people who are running a home theater? THX assumes second order rolloff at 80hz in the mains to which it adds an additional second order filter to create a net fourth order rolloff. THX rolls off the subwoofer channel at fourth order at 80hz for a smooth transition.

Each sub does not cover a different frequency range. One does, in my case, but that not necessary. The 15's go down to about 50 Hz, monopoles with a natural rolloff. There is one very LF sub 25 - 50 Hz. one broadband sub 50-100 and another 50 - 150. So at about 50 Hz there are five sources, one below that, four to about 100 Hz, three to 150 Hz and then just the mains.

The subs feed from the LFE channel on the receiver.

My room is a home theater.

THX is not the gospel in audio.

[Salas]

Originally posted by publius
Congrats E.G. These Summas MUST be something very special.

Bravo Dr. Geddes. Congrats from me too.