Full Range vs. Point Source - Or are they the same?

cipriano

cipriano

Well-Known Member
Are these terms interchangeable or are there some instances when a driver could be full range but not point source? Like if a full range driver has an underhung voice coil, would that make it no longer point source? FR drivers with a wizzer, are they point source? I'm confused, Thanks
 
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I don't think they're interchangeable. My Thiel SCS are stated to be point source, but have a coax tweeter with the mid bass. Several others have this type arrangement. My understanding of full range is single driver only.
 
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Completely different concepts.

Point source refers to the nature of the system's radiation pattern. Most multi-way dynamic speakers are point sources. Full range dynamic drivers like Tang Band also exhibit a point source radiation pattern. You can find planar point sources like the Quad ESL 57 as well.

The alternative is a line source which can be constructed of either full range drivers (Russell IDS-25) or frequency selective drivers (Scaena, Magnepan, etc.)

My Sound Lab electrostats, for example are full range line sources. Dipolar at that.
 
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E-Stat said:
Completely different concepts.

Point source refers to the nature of the system's radiation pattern. Most multi-way dynamic speakers are point sources. Full range dynamic drivers like Tang Band also exhibit a point source radiation pattern. You can find planar point sources like the Quad ESL 57 as well.
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So all single driver full rangers (i.e. Fostex, Tang Band, Wild Burro, etc.) are automatically point source?
 
cipriano said:
So all single driver full rangers (i.e. Fostex, Tang Band, Wild Burro, etc.) are automatically point source?
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Absolutely.

Line sources involve arrays of drivers/panels to deliver vertical dispersion. Short of large MTM designs, I find only they can deliver a realistic image size.

IDS-25

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20.7

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My U-1PX

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HP's Scaena 1.4

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My HT using Acoustat 1+1

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The Dayton Audio PS 220-8 is an excellent full range driver. The PS even stands for point source. With single full range drivers you get no phase or timing issues and the sound radiates from one coherent wave form.

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Poultrygeist said:
With single full range drivers you get no phase or timing issues and the sound radiates from one coherent wave form.
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Amen!

I discovered that I was particularly sensitive to coherency when I first heard Dayton-Wrights as a teenager. Been using full range stats since '77. :)
 
Having been involved in this hobby, and also working in live sound, I've heard the term "Point Source" used in various ways. I don't know what the collective wisdom about it is, but in my experience it generally means that the sound emanates from a single point in space as opposed to an array. I think the confusion arises when you use the same term with respect to both a single driver and a single speaker cabinet, where it has a slightly different meaning. At least in pro live sound, point source generally refers to a full range single cabinet intended to provide full coverage for a space. But when speaking of drivers, a point source would have to mean a full range single driver. It's a matter of scale.
 
Full range denotes the bandwidth of the system or component. It has noting to do with the coverage angle of the speakers output pattern. If we had perfect listening spaces point source speakers might be the preferred choice. We don't, so we have to decide to place our hard earned money buying the speaker with a controlled output pattern or use some of that money to reduce room issues increasing the performance of the point source speaker.
Having delt with Altec, 604 and 605, JBL and Urei 800 series speakers and listened to Tannoys I prefer line arrays. They have there faults, but in my listing space they provide the imaging I want with high dynamic capability with low distortion. The same could be had from a horn system, but good ones tend to be a rare breed.
 
E-Stat said:
Amen!

I discovered that I was particularly sensitive to coherency when I first heard Dayton-Wrights as a teenager. Been using full range stats since '77. :)
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That word coherency reminded me of Tone Audio's review of the Bose 901's. Not a single driver, of course, but all the drivers are identical, and they wrote, "The essentially crossoverless design gives the 901 an unmistakable coherence, the model’s greatest strength." http://www.tonepublications.com/review/we-review-the-bose-901/
 
Point sources can be very good, if you have your speakers in the perfect position in reference to your listening seat. But that spot usually is the only real good point of reference for best listening. Where as a line source allows many listeners a good seat in the house, and when you move in the room you get a close resemblance to moving in front of the live venue.
 
jrtrent said:
"The essentially crossoverless design gives the 901 an unmistakable coherence, the model’s greatest strength."
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Well if it weren't for their unnaturally bloated image and lack of top end transparency, I might have liked them. :)
 
cipriano said:
Are these terms interchangeable or are there some instances when a driver could be full range but not point source? Like if a full range driver has an underhung voice coil, would that make it no longer point source? FR drivers with a wizzer, are they point source? I'm confused, Thanks
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Read a book on spkrs. Then ask intelligent questions.
 
botrytis said:
That is the same reason I dislike curved ESL's - they have the exact same problem.
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I've never been a particular fan of Martin-Logans either as they are the only curved diaphragm stats available today. And most of them are hybrids with monopole woofers and dipolar tweeters.

While the uneven tension creates certain problems, I don't know of any of their models that radiate mostly to the rear and at opposing angles which is the underlying issue with the Bose 901 design and resulting image.

Naturally, using 4" midrange drivers for tweeter duty is the other.
 
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botrytis said:
Actually I find listening to Sound Lab speakers give me the same sound, as M-L's, with less bass and mediocre mids.
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To each his own. Do you recall the model and what was driving them? Were you listening to the U-1PX which is pretty distinctive with its nearly 300 lb structure?

As for M-Ls, you don't hear the discontinuity in character between the monopole cone woofer and dipolar electrostatic panel? Did you listen to any instruments that span both drivers like piano? Voice? Since the xovers are around 300-400 hz, that includes many. I really enjoy having consistent directivity from top to bottom. As I move around the room - either in front or behind them - at any height - at any distance, the image changes very little.

As for me, I find flat response to 30 hz quite sufficient since I'm not an organ pedal freak. What you see is my in-room response curve. And yes, the bass traps helped. I cannot, however, imagine using enough absorption to tame a Bose's rear radiation bias.

Since the moving mass of the diaphragm is less than that of the air around it, they are devoid of colorations some folks favor.

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I can't explain why but while others in these and other threads seem to find so many speakers that they find not enjoyable to their ears, I have purchased quite a number of speakers of different types and makes and for the most part I find them all enjoyable, and yes some better than others but I can't recall any that I didn't find at least somewhat enjoyable. The main objection I have is when people seem to like to show me how loud their speakers play, and while the SPL is downright unbearable, the distortion due to clipping makes it that much worse.
 
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E-Stat said:
Infinity doesn't seem to agree with that assertion. At least not for the upper six octaves.

"Producing a fan-shaped cylindrical wavefront..."

Naturally, that model was just a stepping stone to the IRS and later Genesis models.

"...we could make a real line-source loudspeaker system and finally create the dynamic range of live music"
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I should have said Infinity felt successful in emulating a point source experience within the listeners space in front of the speaker.
http://www.cieri.net/Documenti/Infinity/Documenti tecnici/Infinity - QLS - White Paper (1976).pdf
 
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