SL's Pluto

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Drew Eckhardt

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Joined 2003
poohsticks.org/drew
Re: Gound Rules for "Contest"

sdclc126 said:
OK - it's starting to sound like being "fair" to the Pluto would be to use active filters and built-in amplification, but one of my original thoughts was that $900 might be better spent emphasizing drivers over electronics, but people seem to be a little stuck keeping it active.
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The Pluto's real cost is well below $900. $480 when you're doing the work yourself and comparing it to another fully active design that doesn't use plate amps. Perhaps $280 when you compare it to a passive design which requires amplification (I spend $200 each on my stereo amps).

The $900 price tag includes $200 in labor to assemble the electronics, $100 to cover circuit board design, $70 for a step-by-step assembly guide, $20 for a test CD so you don't need a signal generator, etc.

I'd be lazy enough to spend $100 on circuit boards and consider the rest to be an enjoyable DIY experience.
 
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catapult

Member
Joined 2002
Where are you guys getting $900? That appears to be the price if you buy the fully assembled crossover/amps supplied by SL. Considerably less if you DIY. This is the DIY forum, right?

Edit: I see Drew beat me to it. His numbers are about right. Can you design passive speakers for $280/pair that sound better? I'm pretty confident that my current speakers sound better but the crossovers cost more than $280, let alone drivers and enclosures.
 
sdclc126

sdclc126

Member
Joined 2005
catapult said:
Where are you guys getting $900?
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Yes yes - the $900 price point was too high - we've covered this in earlier posts - what I have yet to see is a detailed response to the design challenge itself at any of the price points - the question being, at the same DIY costs, if not the Pluto, what would YOU build?

Sidebar - some of the previous posts show links to some very similar omni designs - I've seen a few before but had no idea there were so many, including a few that look almost exactly like the Pluto.

What I have a hard time dealing with is that ceiling-firing woofer - it seems just like listening to a "normal" driver/speaker at 90 degrees off axis - how can any driver not lose considerable response that way, especially at the higher frequencies, even given the room reflections that might "recapture" that sound from the ceiling?

I don't recall any response graphs for the Pluto on SL's site - maybe I missed them. That might shed some light. But a lot of the similar designs referred to earlier use deflectors above the woof to disperse the sound horizontally - the tweeter mount on the Pluto would be a perfect place to put one.

I also like the idea of multiple drivers, facing forward AND upward, but then there goes your budget...
 
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catapult

Member
Joined 2002
What I have a hard time dealing with is that ceiling-firing woofer - it seems just like listening to a "normal" driver/speaker at 90 degrees off axis - how can any driver not lose considerable response that way, especially at the higher frequencies, even given the room reflections that might "recapture" that sound from the ceiling?
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That's what makes it (more or less) omnidirectional. A 5" driver is only down a dB or so 90 degrees off axis at the 1kHz XO.
 
sdclc126

sdclc126

Member
Joined 2005
That's what makes it (more or less) omnidirectional. A 5" driver is only down a dB or so 90 degrees off axis at the 1kHz XO.

Wow - this design makes more and more sense then. Am I correct that larger drivers/lower frequencies are less directional, and smaller drivers/higher frequencies are more directional? This would explain the forward firing tweet. SL knows what he's talking about - duh to me. Shows how much I know.

I'm very interested in omni/dipole designs (haven't built any yet), as they seem to add a dimension lending to realism - the "disappearing speaker" phenomenon. I listen to a lot of classical music and this would seem to enhance the live performance illusion of an auditorium, as the sound is indeed projected out as well as up, etc.

I'm starting to wonder if the two concepts could be designed into one speaker effectively? Maybe someone can run a simulation on their software (I don't have any) - like plopping Pluto's woof on top of something like the Orion? Or adding dipole bass? Or using multiple upward-firing drivers for greater spl/larger rooms?

Given the 3-D soundscape that these types of speakers (are supposed to) produce, why would someone NOT want this type of architecture? What types of goals would counter-indicate this design? Are there some of you who don't like this type of sound?
 
planet10

planet10

frugal-phile™
Joined 2001
planet10-hifi.com
Paid Member
sdclc126 said:
Given the 3-D soundscape that these types of speakers (are supposed to) produce, why would someone NOT want this type of architecture? What types of goals would counter-indicate this design? Are there some of you who don't like this type of sound?
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In some rooms this kind of speaker just doesn't work... not to mention the taste of the listener. I'm a big fan of bi-poles... the genesis of which stems back to the TLb http://www.t-linespeakers.org/projects/tlB/index.html

An externally hosted image should be here but it was not working when we last tested it.


dave
 
sdclc126

sdclc126

Member
Joined 2005
Bipoles

planet10 said:



An externally hosted image should be here but it was not working when we last tested it.


dave
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Thanks for the link Dave - I have also considered this type of design and this may be my first "from scratch" project. Basically two loudspeakers back to back - doubles your driver cost doesn't it! Doesn't Definitive Technologies build bipole towers? Don't know anything about their sound though.

I don't think I'd want to do a TL - just add a separate bass/sub module, and maybe still try that up-firing woof on top! With a little more cash I'm wondering about a small line array, with maybe 3 woofs & 2 tweets - or MTM. Lots of drivers there!

Thanks again!
 
S

ScottG

Member
Joined 2003
sdclc126 said:
That's what makes it (more or less) omnidirectional. A 5" driver is only down a dB or so 90 degrees off axis at the 1kHz XO.

Wow - this design makes more and more sense then. Am I correct that larger drivers/lower frequencies are less directional, and smaller drivers/higher frequencies are more directional? This would explain the forward firing tweet. SL knows what he's talking about - duh to me. Shows how much I know.

I'm very interested in omni/dipole designs (haven't built any yet), as they seem to add a dimension lending to realism - the "disappearing speaker" phenomenon. I listen to a lot of classical music and this would seem to enhance the live performance illusion of an auditorium, as the sound is indeed projected out as well as up, etc.

I'm starting to wonder if the two concepts could be designed into one speaker effectively? Maybe someone can run a simulation on their software (I don't have any) - like plopping Pluto's woof on top of something like the Orion? Or adding dipole bass? Or using multiple upward-firing drivers for greater spl/larger rooms?

Given the 3-D soundscape that these types of speakers (are supposed to) produce, why would someone NOT want this type of architecture? What types of goals would counter-indicate this design? Are there some of you who don't like this type of sound?
Click to expand...


Now you are seeing that the design is not so "simple" after all (..and there is W A Y more to this that even SL hasn't either picked-up-on or pointed out).

as far as output off-axis consider that if you choose a driver with the right response 80-90 degrees off-axis that you could effectivly ditch the crossover component for your lowpass on the midbass (or midrange if a 3-way) - again another reason why the design lends itself to a passive crossover.

smaller diameter drivers have LESS directivity (i.e. a wider polar pattern) than larger drivers (which are MORE directive) at higher freq.s (above 900 Hz or so). Below 900 Hz drivers are increasingly omni-directional (as long as their rear wave is suppressed/enclosed) - otherwise they have dipolar behaviour (i.e. open baffle).

As to incorporating some of the design elements into something more "reference" in character, sure it can be done - and who knows perhaps SL will even come around to a solution that incorporates some of the better design elements of the Orion and the Pluto for a better design than either.

As to why someone wouldn't want a design based on this approach - well the imaging is more diffuse (less pin-point) in part due to comb filtering from room reflections, but also because it is simply more accurate to the signal (and some people like a "hyped-up" version). Also, air presurization is not the same when using a driver like this ("axially") and results in a subjective impression that is often less dynamic as freq.s go higher. So yes, there are some that don't like the sound.
 
sdclc126

sdclc126

Member
Joined 2005
Now you are seeing that the design is not so "simple" after all (..and there is W A Y more to this that even SL hasn't either picked-up-on or pointed out).

Scott - do you want to list some specifics here? Good time/place to do it. Or, is that what you elaborated on in the rest of the post?
 
sdclc126

sdclc126

Member
Joined 2005
catapult said:


Large drivers start to beam (become directional) at lower frequencies than small ones. Beaming starts when the cone diameter becomes some significant fraction of a wavelength.
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Thanks for the clarification - it's always more complicated than I think. So the frequencies you may lose off axis will depend on the driver diam.

I should mention that I have a home theater set-up, and I use the DSP function all the time for music, to create the false "echo" of a large listening environment like an auditorium. It makes the room seem bigger of course, the whole idea, at the same time adding some depth to the soundstage.

So maybe this is the "poor man's dipole effect," and the advantage of DSP is that it works for any size room.
 
ShinOBIWAN

ShinOBIWAN

diyAudio Member
Joined 2004
planet10 said:


Not really -- i had one of the very 1st of these kinds of devices -- the Advent Sound Space Control, and the effect is quite different.

dave
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As Dave has said, the difference between the toy DSP modes and a dipole/omni speaker is large and incomparable.

DSP filters extrapolate an ambience field from the incoming signal, all that I've heard, including some of the 'best' like Lexicon, are rubbish for serious listening and seem to add a veil that clouds the detail and ambience rather than enhance it. DSP can be fun, I especially like Lexicon' Logic 7 for movies :)

A dipole does no such thing and add nothing to distort the signal but the ambience is totally natural.
 
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