[Duke]

I will be introducing a new loudspeaker at the Rocky Mountain Audio fest.  To the best of my knowledge, this is the first commercial loudspeaker of its type.

The speaker is a controlled-pattern offset bipole.  Briefly, it incorporates forward-firing and rearward-firing arrays consisting of a 90 degree pattern waveguide crossing over to a woofer at the frequency where the woofer's pattern has narrowed to 90 degrees.  The rear-facing array is offset vertically so that it's about a foot closer to the floor, as this give the maximum practical staggering of the locations of the low frequency sources with respect to room boundaries and the listening position.  I use the same drivers as in the Jazz Modules, for those of you familiar with that model.

I call these speakers the Dream Makers.  I have wanted to build them since about 1989, so for me they are a dream that has been a long time in the making.

The main advantage of this format is only realized if they are positioned about 6 feet out from the wall.  You see, early reflections arriving within 10 milliseconds (less than 11 feet path length) of the first-arrival sound are mostly detrimental.  But reflections arriving later then 10 milliseconds are mostly beneficial, and after 15 milliseconds they're all beneficial.  So with proper positioning, the Dream Makers give a significant increase in desirable late-arriving reverberant energy without a corresponding penalty in detrimental early-arriving reflections.

The bipolar format also neatly sidesteps the baffle step issue; at the frequency where the front woofer's output starts wrapping around the back, the back woofer's output starts wrapping around to the front.

Efficiency is in the lower 90's, impedance is 16 ohms, bass extension is down to the lower 30's, and projected price is in the nine grand ballpark.  Ouch, I know.  Don't worry, I'll try to do something similar in a less expensive package. 

Duke

[JLM]

Look forward to photos and more information.  (Having a hard time envisioning it.)

[JohnR]

I think I get it... got any pics?

[jimdgoulding]

"Ten milliseconds", etc.  Uh-huh.

[Duke]

I hope to have photos this evening.  The ones I took last night didn't turn out very well.

jimdgoulding, could you elaborate?  I'd like to reply but don't want to jump to conclusions about what you're saying.

Thanks,

Duke

[jimdgoulding]

Sure, Duke, I mean I concur is all and took a little piggyback on your information.  Best wishes at RMAF.

[Duke]

Thanks for replying, Jim!

Sometimes I do a very poor job of interpreting the tone intended in a post, and this was one of those times.   I thought your eyes were rolling and you were putting on your hip-boots.

Among my sources is physicist Earl Geddes, who doesn't really approve of bipoles but some apects of my design are consistent with what he does. 

The Dream Makers can be thought of as an attempt to combine the richness and openness of a good dipole speaker with the dynamics of a good horn speaker.   That sounds almost like ad copy, doesn't it?   Better leave out the word "attempt", though - my marketing department abhors anything that proclaims less than absolute infallibility.

Duke

[Duke]

If all goes well, here's a picture of the Dream Maker.  My brother photoshopped the background for me.  The top black circle is a fiberglass 90-degree constant-directivity waveguide, and the bottom circle is of course a woofer.  There's another waveguide and another woofer on the back of the cabinet, but down lower (closer to the floor). 



The speaker sits 42 inches tall and is 26 inches wide by 15 inches deep.  I estimate the weight at 170 pounds, or approximately one Dukeweight.

[lonewolfny42]

Looks good Duke....question.....whats the height from the bottom of the front woofer to the floor ? Thanks.....

[Duke]

Distance from bottom of front woofer to floor is 17 inches.

If you're calculating floor bounce notch frequency, the floor bounce notch is partially filled in by the wraparound from the rear woofer, which is less than 6 inches off the floor.  I discovered that mounting the rear woofer close to the floor gives much smoother response than mounting it up higher.  Althought the design looks simple, a lot of optimizing went into it.

Duke

[lonewolfny42]

Thanks Duke....looking forward to hearing them.

I enjoyed the Jazz Modules last year....so....double the fun this year.

                           Chris

[JohnR]

It's a bit confusing because in your first post you referred to "arrays" but the picture shows only two drivers - ?

[spacedghost]

Duke,

What room will you be in?

Thanks
Shaun

[Duke]

Hi JohnR -

I was probably mis-using the word "array"; I was referring to the waveguide plus woofer as constituting one "array". 

Spacedghost (from coast to coast?) -

I'll be in Room 1100, in the Tower.  Hope to meet you!

Dke

[Audiovista]

Duke - very interesting. Will you be able to make optimal placement in the room at RMAF?

Looking forward to meeting you there.

Boris

[lonewolfny42]

Found a few photo's for you Duke....







..........from audio junkies website.....

[Audiovista]

Duke,

It was a pleasure to meet you at RMAF. Even though my timing was off and I had to leave early, a friend of mine really enjoyed the sound in your room. What are your impressions about show, the sound and apparently good interest that your speakers created?

Best,
Boris

[lonewolfny42]

Duke....

Here's the photo that Captain Humble/Jeff took.......



I enjoyed the "Dream Makers"....rough room to get a good sound in, but crossing them over sharply (toe in) helped.

                              Chris