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Old 22nd January 2010, 05:24 PM   #31
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Originally Posted by gedlee View Post
This extension to lower frequencies is extremely expensive in terms of cost and size
Maybe expensive with waveguides but not with dipoles.
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Old 22nd January 2010, 05:47 PM   #32
gedlee is offline gedlee  United States
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Originally Posted by markus76 View Post
Maybe expensive with waveguides but not with dipoles.
Markus

Quite the contrary. I did a paper design of a system using dipoles and looked into it. In the end the added directivity was not as great as you might think when one is using very large diameter drivers like I do. Then there is the required added electronics. By my calcs, the system price jumped by almost 50%. Others will probably quote all kinds of different numbers, but that was my conclusion.
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Old 22nd January 2010, 06:02 PM   #33
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So let's build a waveguide

I don't care about the "how". All I care about is performance.
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Old 22nd January 2010, 06:47 PM   #34
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So let's build a waveguide

I don't care about the "how". All I care about is performance.
Just send the cash!!
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Old 22nd January 2010, 06:54 PM   #35
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How much? Costs are part of "performance".
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Old 22nd January 2010, 07:06 PM   #36
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Originally Posted by durwood View Post
Correct you cannot compensate for the delay, azimuth is azimuth and is directly related to the ear spacing and source angle. Not to mention moving off-axis and moving closer to room boundaries also compounds this problem. Stereo attributes are strongest in the time sensitive region while the upper region dominated by levels is soley a monophonic area in our hearing. Therefore upper frequencies do not add to the stereo effect and can actually be more confusing and degrading to stereo. This artifact was well known even from the early days and by the inventor.

This "white paper" seems more like a marketing brochure. How many times is Summa mentioned? No official references either. I do applaud the work in supporting a position for good power response.

This is not really anything ground breaking either and if you must discuss stereo any further with directivity there are better concepts. If you want to discuss a system with level controlling directivity when moving about the room:

http://www.extra.research.philips.co...ers/aar01p.pdf

I think I inspired a couple of your projects years ago, and I've really been enjoying your posts on mp3car. One thing that you haven't discussed is that your projects work very nicely in a small environment. It doesn't necessarily have to go in the car.

For instance, my home office is around five hundred square feet, and it's really a bit small for my Summas. There's a gap of nearly two feet from the two diaphragms in the speaker, and due to this huge gap, you need to sit REALLY far away to get the full benefit of the speaker's directivity. If you sit too close to the speaker, the performance of the waveguide degrades, particularly from 900 to 1800hz, which is right smack in the middle of the midrange. Subjectively I've noticed that the sound is smoother and the image is more faithful to the recording when listened at the proper distance. The biggest improvement is a big step up in articulation.

As soon as you back up, everything is roses, and the speaker sounds fantastic. But they really need a big room. At one point I'd devoted an entire floor of my house, fully 900sf, and they really shined there.

I have a friend-of-a-friend who built a BARN to house his audio equipment! And seriously, spending $5,000 to build a room around your loudspeakers makes a heck of a lot more sense than spending $5,000 on amplifiers and DACs. Particularly if you can DIY.

Now one of the cool things about using arrays to control directivity is that you can sit much closer to the speaker than if you used a large waveguide.

Click the image to open in full size.
For instance, I posted an analysis of a Snell eXpanding array this morning, which uses a very tight center-to-center spacing on the tweeter and the midrange. Due to the small size, you lose some power handling, but you gain the ability to sit much closer to the speaker than you would with a larger center-to-center spacing.

Anyways, not saying one solution is better than the other, just saying that a lot of people are clamoring for larger and larger waveguides without considering that it requires a larger room.

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Old 22nd January 2010, 07:18 PM   #37
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Originally Posted by gedlee
Regarding Ron Aarts paper, its basically the same thing that my speakers do. The difference is that mine are practical cost effective products and the Aarts paper is just a theoretical discussion.
I don't agree it's the same. Your dispersion pattern is very simple and uniform and does not alter the directivity shape. Using DSP the dispersion pattern is specifically shaped between different frequency bands. You can find this type of practice in the pro audio world with array steering. While your method might be simpler, you can do the other method for about the same price (or cheaper) and maybe get better results.

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Put into practice with real transducers, etc. and his technique won't work out all that well, or at least it must not have since we don't see any products of this type.
Perhaps you haven't noticed the market increase in "soundbar speakers" from yamaha, philips, marrantz, etc etc? While these may not be exactly like what is proposed, it is still being investigated/researched in many universities too. Stereo is and will die a slow death. It is the reason multichannel has overtaken the market and preferred over 2 channel. The problem with the current soundbar speakers is the same as with many vanilla commerical offerings...the speakers are too small to deliver the dynamics neccesary for realism.

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Originally Posted by markus76 View Post
Thanks for the link! Finally found the title of the Bauer paper I was searching for. Interesting to see that Bauer used dipoles and toe-in 50 years ago

Best, Markus
I also have the more indepth paper that seems to have been lost a while ago when they were doing maintenance on the website. If you would like I can send it to you via email.

Last edited by durwood; 22nd January 2010 at 07:20 PM.
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Old 22nd January 2010, 07:22 PM   #38
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Originally Posted by Patrick Bateman View Post
For instance, my home office is around five hundred square feet, and it's really a bit small for my Summas. There's a gap of nearly two feet from the two diaphragms in the speaker, and due to this huge gap, you need to sit REALLY far away to get the full benefit of the speaker's directivity. If you sit too close to the speaker, the performance of the waveguide degrades, particularly from 900 to 1800hz, which is right smack in the middle of the midrange. Subjectively I've noticed that the sound is smoother and the image is more faithful to the recording when listened at the proper distance. The biggest improvement is a big step up in articulation.
Hi Patrick

You stated that a couple of times in the past and I'm curious what the problem here might be. Are there any measurements that would show where the Summa's far field begins? Words like "smoother", "faithful" and "articulation" don't mean much to me when talking about loudspeaker performance.

In small rooms the big Summas should perform even better because of their higher directivity down to lower frequencies.

Best, Markus
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Old 22nd January 2010, 07:26 PM   #39
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Stereo is and will die a slow death. It is the reason multichannel has overtaken the market and preferred over 2 channel.
Don't think so. Stereo will always be a subset of multichannel.
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Old 22nd January 2010, 07:35 PM   #40
durwood is offline durwood  United States
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Originally Posted by Patrick Bateman View Post
[font=verdana]
I think I inspired a couple of your projects years ago, and I've really been enjoying your posts on mp3car. One thing that you haven't discussed is that your projects work very nicely in a small environment. It doesn't necessarily have to go in the car.
Yes I tried the bessel array but went back to a regular array. Bessel could work in the midrange if the crossover was out of the bass region but I was put off by the loss of lower frequencies due to the one inverted driver, otherwise it worked as described. That was a few years ago already.

I have a few more tricks up my sleeve but you can only do so much in a tiny space.
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