[Duke]

The new Planetarium Delta 15 system by AudioKinesis!



The Planetarium Delta 15 main modules continue in our tradition of paying attention to radiation pattern control, smooth driver integration, slightly forgiving voicing with excellent clarity, tube amp friendliness, extra wide sweet spot when set up correctly, killer dynamic capability, and high value for money spent.  Relative to its ancestors, the Planetarium Delta 15 incorporates improvements to:  Woofer, compression driver, crossover, and enclosure (internal damping).

The system includes the new third-generation Swarm, with upgraded dynamic capability, and extension to 20 Hz with normal boundary reinforcement.   

The Planetarium Delta 15 system outperforms its predecessor, the Planetarium Alpha, across the board.  And costs less.   

Not shown is the kilowatt-class shelf-mount subwoofer amp.  Also, stands not included.

There will be spin-offs; for instance, we can omit the Swarm (saving money), put the main modules in bigger boxes, and get down into the 30's.  Or you can build your own big boxes, saving even more money, and possibly go deeper than I could because of shipping limitations; the forthcoming kit will be based on the woofer, compression driver, waveguide-style horn, and crossover of the Planetarium Delta 15 main modules, but will not include the rear-firing tweeter.

Specifications

Type:  Controlled-pattern high efficiency mains with four-piece multisub system.

Radiation pattern:  90 degrees in the horizontal plane from about 1.4 kHz on up; 50 degrees vertical. 

Main module impedance:  8 ohms nominal, tube-friendly curve (stays between 7 and 12 ohms north of the bass impedance peaks).

Main module efficiency:  99 dB/1 watt

Some cool features:  Low-level rear-firing tweeter to fill in top end of reverberant field, can still be placed close to wall; hand-matched compression driver pairs; tilt control to adjust relative loudness of high treble; subwoofers can be operated ported (room gain complementary tuning) or sealed (Qtc = .50).

Recommended amplifier power:  2.5 to 100 watts; 400 watts permissible but contact me first.

Thermal compression:  Less than 1 dB at 40 watts (115 dB SPL).

Typical bandwidth, mains:  70 Hz to 20 kHz.

Typical low end extension, subs:  20 Hz in-room, ported mode.

Dimensions of mains:  24" tall by 18" wide by 15" deep; 55 pounds each.

Dimensions of subs:  22" tall by 12" wide by 12" deep; 40 pounds each.

Subwoofer amp:  950 watts into 4 ohms (subs wired in series-parallel), 4th order variable low-pass filter, single band of parametric EQ.

Price:  $6,000.00/system plus shipping.

Feel free to ask any questions.

Thanks for taking a look!

[Duke]

Here are a couple of shots of the Delta 15 main modules:





The woofer is a high quality prosound unit with remarkably smooth frequency response, which extends up to 4 kHz on-axis.  It has enough linear excursion capability to not need a protective high-pass filter if you don't want to use one, up to about 115 dB or so.   Beyond that a protective filter starts to make sense, though it's still arguably optional up to about 120 dB. 

By buying and measuring the compression drivers a case at a time, we're able to generate matched pairs.  Not that the quality control isn't good to begin with (these drivers match up more closely than most we've worked with), but we want good stable imaging, and matched drivers contribute to that.
 
You can see the rear-firing tweeter on the back of the cabinet, at the top.  Here is the idea behind it:  The waveguide-style horn on the front is pattern-matched to the woofer in the horizontal plane in the crossover region, but the woofer still has a wider pattern in the vertical plane.  So there is a slight mis-match in the power response.  We address that by adding some additional rear-firing high frequency energy, closely matching what the front horn is doing as far as tone, but reduced in level.  The reduced level allows us to still place the speaker very close to the wall.   You can effectively turn the tweeter off by slapping a piece of painter's tape over it, but you'll find that the sound now localizes at the speaker a bit more, instead of being detached from it. 

Next you can see a resistor in a terminal cup.  That resistor is used to tilt the front-firing compression driver's response up or down; in other words, it has a lot more effect up at 10 kHz than it does down at 2 kHz.   At lower values (resulting in a more tipped-up response) a fair amount of power goes through the resistor, so I recommend paralleling two (12-watt Mills) resistors to get the value you want if you plan on playing really loud.   So if room acoustics or amplifer characteristics or personal preference leads you to prefer a different top end than I would have picked, you can easily get there without using a scratchy, low-tolerance L-pad.

The ports I use are 3" diameter flared Precision Ports.  Yes some midrange energy escapes out the ports, but because of the flares is doesn't sound harsh like midrange energy through straight-sided port tube does.  Combined with the output of the rear-firing tweeter, the speaker is almost like a weak dipole, as you do get fullrange sound out the back.  If you need place the speakers close to the wall or in a corner, you can close one or both ports using a plumber's expandable test plug (hardware store item).   

The bevelled-off rear corners help give you visual index for the recommended 45 degree toe-in, and reduce the width of the footprint with such toe-in.  The idea is to get the speaker axes to criss-cross in front of the listening position.  With speakers having fairliy aggressive, uniform pattern control, like this one, such a configuration gives a very wide sweet spot.   What happens for off-centerline listeners is, the far speaker is actually a bit louder because you're on-axis for it but well off-axis of the near speaker, and this compensates for the earlier arrival time of the near speaker.  The secret is for the off-axis response of the near speaker to fall away smoothly and fairly rapidly.  That's why I use big cone woofers and 90-degree waveguide-style horns.  Another advantage of this setup configuration is that the first early lateral reflection of the left speaker's output is the long-path bounce off the right side wall, and vice versa.  This contributes to a sense of envelopment.    That being said, best imaging for one is with speakers aimed straight your ears.  In this configuration you might find the top end a little hot with the normal tweeter setting, so you may want to back off a bit via the resistor cup.

What you don't see is the crossover.  The speaker's target on-axis response isn't ruler flat, and this is because although the goal is "constant directivity" (and the horn we use is billed as such), the system does have some variation in the radiation pattern, and we take that into account.   Also, we find a slightly downward-sloping in-room response curve to sound more natural than "flat".  You can get back closer to "flat" by cranking in a bit of treble boost via the resistor cup on back.  Our goal is approximately flat perception (erring slightly on the warmish side), not approximately flat by any one measurement. 

Also not seen is an internal damping technique borrowed from architectural acoustics, and credit to studio designer Jeff Hedback for his consultation services. 

[mgalusha]

Very nice Duke, a lovely set of design goals that I have no doubt are well executed. 

[willswing]

What money are we talking about, for the mains, no subs?

[ted_b]

Wow, Duke...all this for $6k and acoustic design by my room's own designer, Jeff Hedback!! 

A couple of questions:
1)  what is the nominal and/or best height of the speaker/stand combo for, say, 10 ft+ distance to listening spot
2)  what is the best, no holds barred, setup for each piece in a rectangular room (short wall as front and back).  Say like this:

[Duke]

Very nice Duke, a lovely set of design goals that I have no doubt are well executed. 

Thanks, Mike!  In the course of build bass guitar cabs, I was surprised to find out that one could get really good integration between that waveguide-style horn and a 15" woofer.  I wouldn't have thought so, but then the next step was to bring that into a home audio setting.  Well the wheels turned slowly, but I found a woofer with a good combination of efficiency, smooth response, and parameters that are well suited to both stand-mount and floorstander enclosures.  Obviously this first one is the stand-mount (satellite) type enclosure.   

What money are we talking about, for the mains, no subs?

Welcome to Audio Circle!  We're talking $3600/pair for the mains, in that enclosure.   

Wow, Duke...all this for $6k and acoustic design by my room's own designer, Jeff Hedback!! 

A couple of questions:
1)  what is the nominal and/or best height of the speaker/stand combo for, say, 10 ft+ distance to listening spot
2)  what is the best, no holds barred, setup for each piece in a rectangular room (short wall as front and back).  Say like this:

Nice of you to give your wife the sweet spot!

The design listening height is roughly at the center of the horn, rather than midway between the two.   But either one will work fine.  A stand height of 18" will put the center of the horn about 38" off the floor, and that seems about right to me. 

Best no-holds-barred positioning of the subs??  Hmmm... must admit I like Jim Romeyn's configuration, which is placing each sub relative to a different corner, a distance 1.62 times greater from the corner than the preceeding sub.  So if the first sub is 12" from its corner, then the next one is 19.5" from the next corner, and the next sub is 31.5", and the last one is 51", each measured from a different (nearest to it) corner.   Then elevate the first sub so that it's closer to the ceiling than to the floor.  Finally, invert the polarity of one of the subs.   Here's Jim Romeyn's description of his approach: 

http://www.audiocircle.com/index.php?topic=106756.msg1126637#msg1126637

http://www.audiocircle.com/index.php?topic=106756.msg1140566#msg1140566 (in-room measurements in this post)

I have a customer who's using a straightforward Welti-style center-of-each-wall setup, with apparently very good results.  If the room permits, a theoretically smoother setup would be 1/4 of the way in from each wall, something Welti found to work very well but ultimatley discarded because it's generally impractical. 

To the best of my knowledge, none of my Swarm customers are using the single band of parametric EQ in the amp.  But it's there if anyone needs to nudge the response this way or that.   One nice thing about a good multisub setup is that it greatly reduces the bass variance from one location to another within the room, such that any remaining problem is likely to be global rather than local, so when you fix it for one location, you're probably fixing it for all instead of making things worse.

[ted_b]

Duke, thanks.  How about main speaker location?  The idea of having them closer to the front wall (my Revs are out almost 6 feet) is nice for the fact that video is also part of the room design....but I need to have the BEST setup for 2 channel and damn the video setup...   which is why I went with a riser, so I could get most if not all viewers in the center of the room visually, and not have the speakers in their way.

[Freo-1]

These look great!  Definitely should play well in Low Wattage circle.   
 
BTW, that was an excellent explainion you gave on amps recently. 

[richidoo]

Congrats on the new model Duke!

Kit still looking at $850? 
http://www.audiocircle.com/index.php?topic=104185.msg1060504#msg1060504

Nice choice of woofer! 

[Duke]

Duke, thanks.  How about main speaker location?  The idea of having them closer to the front wall (my Revs are out almost 6 feet) is nice for the fact that video is also part of the room design....but I need to have the BEST setup for 2 channel and damn the video setup...   which is why I went with a riser, so I could get most if not all viewers in the center of the room visually, and not have the speakers in their way.

Main speakers should criss-cross in front of the center of the sweet spot.  You want 'em wide enough apart to give good soundstage width, but too wide and you can get a hole in the middle.  In your room (15' wide by 23' long), maybe start with them about 8-10 feet apart.   Actually Jeff Hedback can probably give you better guidance than I can, as a) he's familiar with my 15" two-way speakers (he's using a pair of my bass cabs in his living room, and their room-interaction characteristics are going to be similar); and b) he's far more familiar with what's going on in your room than I am, and since he's a world-class room acoustics professional I'd never be able to catch up to him there.

I have several customers using my speakers for home theater without a center channel.  The center image is good enough for off-centerline listeners.   With no center channel, you tend to get better soundstage depth (assuming the mains are out in front of the wall a few feet).  While an active center channel probably is better for movies, you may want to experiment with phantom center mode for music or concert videos if soundstage depth is a priority.  Also if the center channel has a different voicing from the mains, that can degrade overall sound quality, which is probably more important for music and music videos than it is for movies. 

These look great!  Definitely should play well in Low Wattage circle.   
 
BTW, that was an excellent explainion you gave on amps recently.

Thank you!  The speaker I'd like to build, but it's probably too big to be practical, would put the guts of the main modules in eight to ten cubic feet, tuned very low.   Paired with a low-feedback SET or OTL amp, we'd get some "warming up" of the bass from the amp's low damping factor.   If we then tune our big box accordingly, we can get in-room response down into the 20's.  No subs needed.  The way to pull this off would be for the end user to build the box instead of paying me to build and ship such a monster, hence the parts-only kit.

Congrats on the new model Duke!

Kit still looking at $850? 
http://www.audiocircle.com/index.php?topic=104185.msg1060504#msg1060504

Nice choice of woofer! 

Sadly no, this is a considerably more expensive woofer.   Haven't decided on a price for the kit yet, but I want to use this woofer.   I just can't bring myself to "dumb it down" by going with a cheaper woofer.  DiySoundGroup and PiSpeakers offer some excellent kits already, and their 15" two-way kits certainly are not "dumbed down" - they're putting best foot forward, and I should as well.  The only thing I'm holding back on is the rear-firing tweeter, as I do want to reserve that for people who go with finished speakers from me.

The PiSpeaker 4Pi kit (drivers + horn + crossover) ranges from $800 to $1550/pair depending on choice of woofer and compression driver.   I believe the parts I'm using to be competitive with the high-end 4Pi parts, in this application at least; I don't think we normally need the extra-long excursion of the JBL in a home audio application, though there's nothing wrong with having it available.   On the other hand my woofer goes somewhat lower and over an octave higher than the JBL, how 'bout that?  Not that we're running it all the way up, but that top-end extension speaks to how comfortable our woofer is down where we are using it. 

Did I say what woofer I'm using?  I thought I was being secretive about it, but it's bound to come out eventually, especially when I sell the first kit.  Anyway, thanks! 
 

[Rclark]

That's an intriguing system there. Wish you success with these and looking forward to the first reviews and seeing them in other types of finishes.

[lonewolfny42]

Well done Duke....good luck with the new system ! 

[kgcdc]

The new Planetarium Delta 15 system by AudioKinesis!



The Planetarium Delta 15 main modules continue in our tradition of paying attention to radiation pattern control, smooth driver integration, slightly forgiving voicing with excellent clarity, tube amp friendliness, extra wide sweet spot when set up correctly, killer dynamic capability, and high value for money spent.  Relative to its ancestors, the Planetarium Delta 15 incorporates improvements to:  Woofer, compression driver, crossover, and enclosure (internal damping).

Looks awesome, Duke. I can't help but compare it to my Prismas plus new sealed Swarm sub array. This has become my favorite speaker topology.

Good luck!

Cheers,
Kendall

[borism]

Duke,

This looks like a great system! Hope to be able to hear it at some point.

I do have a question regarding the choice of wave guide. I noticed that your recent designs all incorporate the square shaped one as compared to your past use of round ones (Dream Maker, Jazz Modules). Can you elaborate on advantages and disadvantages, other than space saving with the square wave guide? Is the use of rear firing tweeter one of the consequences of the square wave guide?

Thanks,
Boris

[nullspace]

Looks great, Duke. In the big 8-10cu ft box and with a low-damping factor amp, will these be amenable to your Room Gain Complimentary tuning? I built a 1"+12" last year using those guidelines and they worked out very well.

Regards,
John

[Davo50]

If fedex tracking is accurate, the speakers above will be in my room in about 3 days.

About 6 months ago, I decided to move my system from the living room to the bonus room over the garage and finally have my dedicated room.  For years, it was the hang-out room for my teen daughters and later a junk room.  At 21 x 11 x 8, not optimal for audio, thus began a research process for optimal gear for the size room.  I sold my living room gear and eventually decided on SET / constant directivity for the new room which led me to Audiokinesis.  Duke had already been planning the new system and it seemed a perfect fit for my situation.  I will be driving them with a Line Magnetic 218IA and digital server front end.  Duke advised me to contact Jeff Hedback for my room treatment plans and the DIY panels you see in the pic are his designs / placements.  It's been a fun process building the panels and re-modeling the room, but I am finally ready for some tunes!  Jeff will also be helping me to fine tune things once I get the speakers / swarm set up to get it all dialed in.  Duke and Jeff have been a pleasure to work with and I highly recommend both of them.  I will try to post more on this set-up once I get some time with it.

[roadkingraw]

Mighty bold assumption that the woman pictured is his wife!!!  hahahahahahaha  Girls night out is not just for her!!

[Duke]

Thank you all very much for your encouragement and enthusiasm!  And Davo50, thank you for your leap of faith!

I do have a question regarding the choice of wave guide. I noticed that your recent designs all incorporate the square shaped one as compared to your past use of round ones (Dream Maker, Jazz Modules). Can you elaborate on advantages and disadvantages, other than space saving with the square wave guide? Is the use of rear firing tweeter one of the consequences of the square wave guide?

Both are very low-coloration devices (as is the SEOS 12" waveguide).  The round waveguide can be pattern-matched with the woofer in both the horizontal and vertical planes at the same time, which is theoretically ideal. 

I like to experiment with promising-looking waveguide-style horns to see how the perform, and a few years ago I saw a picture of the Pyle PH612 and thought it looked like it had potential; I was moving towards doing something in the bass guitar market around that time, and cost was an issue.  It didn't have the features one expects to see in a diffraction horn, which was encouraging.  So I ordered one and ran a family of off-axis curves.  Well, I thought my measurement system was broken:  The curves looked too good to be true.  I'd never seen anything that approached the performance of that round DDS fiberglass waveguide, but this cheap little plastic horn was right there in the same league.   So I cooked up a crossover, and once I'd compensated for its few anomalies (even the round waveguide has some anomalies), it sounded fine to me.   And it scored well with a blind listening panel that I assembled from among visiting relatives.

With the rectangular-style waveguide, the goal posts are in a little bit different place.  Instead of only looking at what's going on in the horizontal plane, I have to take what's happening in the vertical into account as well.  Okay, no big deal.  I've seen it argued that a 90-by-50 degree pattern is better than a 90-by-90 degree pattern because it has less floor and ceiling interaction, and I've seen it argued that the superior pattern matching of the 90-by-90 pattern is the better one.   I think they can both work quite well. 

The rear-firing helps fills in some of that missing reverberant field energy due to the squashed-in-the-vertical characteristic of the rectangular device.   But the system can be "voiced" to perform just fine without it. 

So if the rectangular waveguide-style horn isn't clearly superior, but rather is more like a viable alternative, why switch? 

Well, I have to spend a lot of time grinding the backs of those round fiberglass waveguides before they will mountto  the enclosure cleanly, and sometimes I have to grind them even more before i can even mount a compression driver to them.  I hate working with fiberglass.  Yes I wear long sleeves and gloves and a real respirator, but it still makes my skin itch and my lungs hurt.   So I want a lot of money if I'm going to do that.   I am currently working on a pair of Dream Makers (with Acoustic Elegance woofers), but that may well be the last pair of speakers I do with the round fiberglass waveguides.  Which would be fine with me.

Looks great, Duke. In the big 8-10cu ft box and with a low-damping factor amp, will these be amenable to your Room Gain Complimentary tuning? I built a 1"+12" last year using those guidelines and they worked out very well.

Glad that worked for you!!  Yes, room gain complementary tuning is quite possible, but if the amp's damping factor is low enough, the speakers may still need to be out in the room a bit instead of right up against the wall.  When the kit is officially announced, if you'd like, we can use your amp as an example to walk through the design process, although I'm sure you can do it on your own.   

[borism]

Duke,

Thank you for your detailed reply. Clearly, a lot of thought goes into your designs.

On a side note, we woke up this morning to 35 inches of fresh snow. It will be fun shoveling the driveway.

Boris

[rajacat]

 An advantage that a rectangular horn has over a round horn is the closer center to center distance between the tweeter and the woofer thereby a closer approximation of a single source.