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An insane or completely sane question


vasubandu

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I am newly back to Audio and armed with just enough knowledge to ask insane questions.  Assume that wanted to build a full range, multidriver speaker with 7 separate drivers, and that I wanted to direct to each driver its own sweet spot of the sound spectrum.  And assume further that I wanted to do this with a digital crossover.  I have a concept in my head, but I do not know it it has an relation to reality.

 

So my first question is whether the idea itself makes any sense.  I am new to this and am analogizing to light, so I honestly do not know.

 

Second, if this does make sense, would the process start with identifying a digital crossover with enough outputs, and if yes, which offer the most?

 

Any thoughts, criticisms or condemnations are welcome.

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57 minutes ago, vasubandu said:

Assume that wanted to build a full range, multidriver speaker with 7 separate drivers, and that I wanted to direct to each driver its own sweet spot of the sound spectrum.  And assume further that I wanted to do this with a digital crossover.  I have a concept in my head, but I do not know it it has an relation to reality.

 

So my first question is whether the idea itself makes any sense.

 

Well yes, it could make sense.

 

The first question is "why seven drivers?", i.e., something like a high performance 7-way loudspeaker will have special needs in terms of measurements and dialing in and perhaps hepta-amping (7 amplifiers per loudspeaker) would be pretty esoteric, but definitely doable.  If you're instead talking about a "MTM"-like setup, then you'd be able to use a single DSP crossover to cross and dial in a stereo pair of loudspeakers potentially (i.e., tri-amping instead of hepta-amping). 

 

The next question: "are you prepared to use a calibration microphone to measure the response?".  This one is pretty self explanatory.  It's not really difficult, but you will need a little patience to work through the inevitable issues that arise in getting everything set up (software and hardware) and measuring the right things, i.e., avoiding measuring room acoustic reflections.  Some of this involves learning a little bit, but nothing like having to be an engineer, rather someone that doesn't mind going through the measurements and picking out the issues, one by one, until all anomalies are addressed--like setting up a home theater using "room correction software" and a measurement microphone, but only a little more manual than typical Audyssey-like "pushing a button, then sit back and watch".  Having that many drivers/channels will require a little thinking about where to place the crossover frequencies and the type of crossover filters used.  Room EQ Wizard (REW) and a calibration microphone will do it.  So will something like Dirac, etc.

 

Third question: "are you prepared to buy relatively hi-fi DSP crossover(s) with seven outputs per loudspeaker?".  This would likely entail something like multiple miniDSP 2x4 HD crossovers per loudspeaker--either hepta-amping or tri-amping, etc. based on the configuration.  Xilica crossover(s) would be even better in terms of fidelity IMHO--XP-4080.

 

"Simpler is better" has its place, but if you look at any high end loudspeaker ("high end" defined here in terms of its acoustic performance--not its price), then it wouldn't be as complicated as something like a Dunlavy SC-IV or the like.

 

Chris

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Thanks @Chris A that was very helpful. My question in fact was whether one could construct a single  speaker with a range of, for example, 10 Hz to 40 kHz, meaning in excess of the high and low of human perception, and then select the very best drivers for every segment of that range, no matter how many that might be, and the construct a suitable enclosure for all of them. Assume further that you could provide a separate amp for each for driver so that you had no issue of splitting wattage.  And assume further that you used digital crossovers and sent to each driver only its own sweet spot of spectrum.  In theory, would that not produce  a single speaker with a complete range of high quality sound?  This is a serious question, not a Socratic one.  I have no idea what the answer is.   But if this makes sense, I a inclined to explore it. The cost is not much of an issue, because if it worked, that would take care of itself in economies of scale.  This question came to me when I read that most full-range speakers has a single driver.

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31 minutes ago, vasubandu said:

My question in fact was whether one could construct a single  speaker with a range of, for example, 10 Hz to 40 kHz, meaning in excess of the high and low of human perception, and then select the very best drivers for every segment of that range, no matter how many that might be, and the construct a suitable enclosure for all of them. Assume further that you could provide a separate amp for each for driver so that you had no issue of splitting wattage.  And assume further that you used digital crossovers and sent to each driver only its own sweet spot of spectrum.  In theory, would that not produce  a single speaker with a complete range of high quality sound?

That is exactly what John Dunlavy did with his Duntech and Dunlavy Audio loudspeakers, some of which still command high resale prices today.  He constructed a box for each of his drivers and arranged them in a "MTM-like" configuration, then used carefully constructed passive crossovers for each "way", notably using first-order crossover slopes to avoid the phase growth issues, substituting instead more drivers having smaller frequencies bands each for their coverage.  These were the "most accurate loudspeakers" that John Atkinson had ever measured, and the listening trials were said to be spectacular. 

 

It's just another way to approach the problems.  A DSP crossover with multiple amplifiers significantly simplifies the problem of passive crossovers and if you choose a crossover of high enough fidelity (like the XIlicas), then the results are arguably better.  Dunlavy was working on the "SC-VI", a DSP-crossed, time aligned and EQed version, when his health turned bad and he had to sell his company, passing away within a year or two afterwards.  He was dealing with DSP crossovers of the "1st generation", whereas I believe we've got 2nd gen DSP crossovers today that perform even better.

 

For me, I'd use horn loaded drivers in a multiple entry horn (MEH) design, but there are direct radiator approaches like Dunlavy used that also will sound quite good.  I'm sure that all his loudspeakers sounded like super studio monitors and were as revealing of the music as, say, dialed in MEHs or Jubilees.

 

Chris

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Thanks @Chris A. Technology is moving very quickly today, making that part of the process both easier and cheaper.  I just think that we are at a moment what that could be leveraged to make the formerly unthinkable routine.  My own interest is in seeing what is possible, and for me that means on an economical basis.

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44 minutes ago, vasubandu said:

This should be a wonderful new era when technology allowed the little guy to have his dreams.

Exactly.  The age of "audiophile pricing" will draw to a close as the current hi-fi generation hands off to the next one.  I believe that day has already arrived, actually. Stories of "well, it costs a lot because..." have already run off a lot of people...asking why.  The tools and economies of scale for things like class D amplification and really good DSP crossovers, low-cost calibrated USB microphones, and freeware audio analysis and design software have already begun to drive high end audio products out of the market -- like Christensen's product disruption model predicts... 

 

Disruptivetechnology.png

 

Chris

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One of the tradeoffs in high end loudspeaker design is direct radiating vs. horn loading.  I think a lot of folks don't understand this...including most "high end" loudspeaker designers as it turns out. 

 

With horns you can use much less expensive drivers and/or many fewer "ways" and drivers, especially "Synergy style" multiple-entry-horn (MEH) configurations.  MEHs also effectively eliminate the polar coverage mismatches at the crossover interference bands.  MEHs facilitate the achievement of point source performance without having to use coaxial full-range drivers or otherwise very expensive midrange and woofer drivers in addition to tweeters. And they have dynamics and controlled coverage that direct radiators cannot achieve because of better loading of the drivers and fewer demands on their polar coverage characteristics vs. frequency.  Full-range MEH clarity and detail is unsurpassed.

 

Horn-loading is also quite straightforward to dial in using a good DSP crossover because of the advantages enumerated above.  Done well, they also will take up less volume in-room than their direct radiating alternatives.  Just look at the size of all of the "high end" direct radiating loudspeakers--they're not small. Horn loading can also benefit by room corner loading--something that you don't see with direct radiating loudspeakers because of their difficulties achieving constant coverage polars vs. frequency.  Only a minimal amount of acoustic treatments are necessary for corner loading of horns, i.e., a single column of 2'x2'x1" acoustic absorption pads at mouth exits on adjacent walls, thus freeing up a large amount of room real estate that large direct-radiators must use to sound good in room.

 

Chris

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I'm not sure that my knowledge is the deepest: there are others here with very good technical backgrounds--that don't advertise it very much. 

 

As far as doing it, I have produced a prototype and documented the results here.  My experience listening to my prototype center channel MEH is that it exceeded my expectations by large measure--even considering Beranek's law effects on my listening evaluations and decision making.  Now I know why so many people have said so many good things about full-range Unity and Synergy horn designs.  This is a well-kept secret, since the company that produces them commercially (Danley) doesn't design them for home hi-fi use, per se.

 

Chris

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@Chris A in all seriousness, I deal with a lot of entrepreneurs who have what I consider to be brilliant ideas.  While I am not goofing off here today, I am helping a company that has developed a device that can literally diagnose problems with smart phones using magnetic fields.  That is all public knowledge because of their patents.  It is far easier today than it was in the past to raise capital for smaller startups, and the requirements are manageable.  If you decide to try to take your prototype and turn it into a product, I would be delighted to help you. And by help, I mean help, as in not being paid.  It is what I do and what I love to do.  It you have ideas that would produce a better speaker, then you just happen to live in the right time to chase that dream on your own terms and for your own benefit instead of for the benefit of the rapacious "angel" investors.  

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Thanks!  Once I get the mold working and produce the five horns that I need for my room, perhaps it will be clearer what  the path is ahead.  I continue to hold out hope that Klipsch might see the value--but they really don't do kits and have discouraged DIYers from buying horns to build their own speakers in the past, even though I've offered the idea.  As far as starting up a concern to produce horns, kits, and/or completed speakers, no capital is needed.  It would be self-funding: it would use the customer's money to produce the products, then ship dialed-in/tested sets to the customer, or simply horns, etc.

 

I've thought about finding a bagel shop or coffee shop that might have an audiophile owner that might take on a stereo pair setup for loan/background music use and would be okay with someone scheduling demos or perhaps "listening events" for those that might be interested.  It seems that more and more people continue to express an interest in owning a pair (and in greater numbers) for themselves.  There are many rooms that can't use Jubilees-sized loudspeakers that could use MEHs. 

 

The horn itself is of a shape that requires a multi-piece casting mold.  The prototype mold is very nearly complete in my garage. Other horn sizes/coverage angles can easily be made using the same techniques as the current mold, and maybe better meet the needs of audiophiles. 

 

Chris

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You sound like you are well on your way, and your idea about a location to demo makes sense.  Starbucks would be good because of its focus on music.  As you know, Starbucks is from Seattle where I am.  I know a number of their attorneys mostly in the real estate end.  In fact, I represent one in the past and am representing another now.  If you chose Starbucks and got into something formal with them, I might be able to help. 

 

I would encourage you to look for money of some kind if you ramp up. Don't go spending it, but have it or have access to it.  A short break in the customer stream can whack you. I also would really encourage you to speak up when you have questions or difficulties.  I know that there are at least three attorneys here, and the other two that I have met strike me highly competent people.  Most attorneys are used to offering free help.  It is just part of being an attorney.  

 

I suspect that a deal with Klipsch will be harder under new management. What about people like Crites?  I don't know anything about him, so it is just a name, but you might widen your net.

 

I have to tell you that this is very exciting.  I would love to see what you came up with.

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