Line Source vs. Point Source Speakers - AVS Forum
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post #1 of 7 Old 12-06-2002, 08:12 AM - Thread Starter
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I have not had a chance to listen to line source speakers like Magnaplanar, Martin Logan, Radia and others. Has anyone had a chance to compare these type speakers to some qood quality point source like JMLabs Utopia. I had a chance to listen to the JMLab Utopia and they were outstanding with depth of field and presence. I have heard the line source is even better and the soundstage for imaging is very wide. Any insights :)
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post #2 of 7 Old 12-06-2002, 10:06 AM
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Of the speakers you mention, the only ones that are really line-source are the Radias. The other line source speakers I can think of are the Wisdoms and the Newforms. The others you mention are planars. Point source, planar and line source all have different radiation characteristics. I've heard great sound from all of them and pathetic sound from all of them. Depends very much on how well implemented the overall design is, the room acoustics, source, and the placement of the speakers in the room.

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post #3 of 7 Old 12-06-2002, 10:14 AM - Thread Starter
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John,

Thanks for the reply. Speaking of the Radias then, what are the issues with room acoustics and setting them up. I have noticed that they come in in-wall installation and stand alone tower type speakers. The towers are monopole but the in-walls are not, Do the inwalls have to be set up to absorb the rear radiation of sound? What other issues are there with this type of speaker?
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post #4 of 7 Old 12-06-2002, 12:39 PM
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Planars also radiate sound in a line source pattern, which is that their volume decrease in loudness proportional to the squared of their distance to the listener, as opposed to cubed. That means they have less drop in sound level the farther you move away from them.

Dipole planars also produce sound from front and back, creating this uncanny you-are-there realism that is not achievable from point source speakers.

Giving that they are dipoles, their radiation pattern have a figure 8 shape, with little radiation on the side, this eliminates much of the side wall reflection that you get with monopole speakers. Some dipoles might not give the razor sharp imaging of some point source speaker due to the interaction with the rear soundwaves, so placement and behind the speaker wall treatment becomes a bit more critical.

The dipole bass in the full range planars pressurize the room in a different way compared to box speakers, giving you a fuller, more rounded bass as opposed to the hit in the chest by a truck type of bass.

Anyway, dipoles are like a religion, either you don't like it or you will never turn back from it.
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post #5 of 7 Old 12-06-2002, 01:01 PM - Thread Starter
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Quote:
The dipole bass in the full range planars pressurize the room in a different way compared to box speakers, giving you a fuller, more rounded bass as opposed to the hit in the chest by a truck type of bass.
Have you heard about Radio speakers which are ribbon speakers. The 520dx resides in a box enclosure but they have wall mounted speakers. They can be found at www.bgcorp.com

My question is how would these speakers be set up? If they are inwall then how do you get the dipole effect? Also if they are in a box enclosure then also where is the dipole effect? Do you lose that realism when they are enclosed in such a way? Has anyone heard these speakers.
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post #6 of 7 Old 12-06-2002, 01:17 PM
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Quote:
Originally posted by David Guill
John,

Thanks for the reply. Speaking of the Radias then, what are the issues with room acoustics and setting them up. I have noticed that they come in in-wall installation and stand alone tower type speakers. The towers are monopole but the in-walls are not, Do the inwalls have to be set up to absorb the rear radiation of sound? What other issues are there with this type of speaker?

The inwalls would have to be monopoles as well. A monopole just means it radiates in one = mono direction. Dipolars radiate front and rear. So if you put the Radia inwall, you're surely going to want to absorb the rear wave. Otherwise, it will bounce of the backwall and come back through the film. This bounceback will be out of phase and cause distortion.

Generally, it is very hard to get any sense of soundstage depth from inwall speakers, so if that is important to you, you probably don't want in walls.

I sure don't claim to be an expert on these so hopefully others will pipe in as well.

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post #7 of 7 Old 12-07-2002, 10:41 AM
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When you are dealing with the level of speakers like the JM Lab Utopia, then you are getting into a level where the quality of a speaker isn't the only thing you are looking for. You must also look at what type of sound you like.

Direct Radiators have their own signature to the sound. Planars have their own. Monopole, dipole, electrostatic, electromagnetic, horn, etc. all have a unique characteristic. Which you prefer is also part of the equation. Some people love horns. Some people hate them. Some love the open sound of electrostatics/electromagnetics while others love the direct radiators.

Different speakers at that level are almost always very capable, but if you like them or not is mainly a personal choice issue. I have line source speakers now and really love them. They don't sound that significantly better than my older point source speakers that used the same drivers but instead offer lower distortion at higher volume outputs. I certainly don't think that they sound worse and I am comparing identical drivers. When comparing the different brands you won't be comparing the same drivers in differing styles of speaker construction.

Many of the top speakers are arrays of point source drivers to make them into a line source, like the Genesis 1.1, the Nearfield Accoustics Pipedreams and such. The only fair way to compare line source against point source is to compare speakers with the same drivers in point/line configurations.
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