Re: Directivity Index, Collapsing DI, etc. [message #17692 is a reply to message #17691] |
Tue, 29 March 2005 14:45 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18748 Registered: January 2001
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Illuminati (33rd Degree) |
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DI is directivity index. Round tractrix horns become more directional as frequency goes up. This is called collapsing DI. They sound good on axis, best if the room is very absorbent.Horns like this have wide dispersion at the lower crossover point and which becomes more narrow as you reach the upper crosover point. If you have a midrange and a tweeter with round horns like this, then the pattern widens and narrows twice, at the woofer/mid crossover and again at the mid/tweeter crossover. What this does is to make the sound in the room uneven. Sound off-axis is unbalanced, being a lot louder near the crossover points. Even when sitting on-axis in the "sweet spot," sound reflected back to you is unbalanced. You can get away with that if the room is treated to make it very absorbent, but if not, the sound is unnatural. I think it's unnatural sounding anyway, since anytime you step outside of the narrow "sweet spot," the good sound turns bad. Another thing about round horns is that energy distribution up and down is the same angle as side to side, so it is wasted on the floor and the ceiling where it is not needed or wanted. That's why they were abandoned in the 1930's for radial and sectional horns, intended to place the sound where it was wanted. Don't get me wrong. Most speakers have directional characteristics like this. Direct radiators are the same way. They begin to become directional at the frequency where wavelength roughly equals diameter. Direct radiator loudspeakers and round horn systems can be made to sound very good. At least on-axis and in a very narrow range, you can expect them to sound very nice in the right setting. If you have wall to wall furnature, some furnature and curtains, you'll probably be alright. But one of the biggest advantages of horns is their ability to direct the sound where you want it to go. So for best results, I prefer to use horns that have directional characteristics that cover the room uniformly instead of those that have collapsing DI. This is particulary true in the horizontal plane. If a person is going to use a horn, I'd want to see it used to its best advantage.
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I understand a little bit better now! [message #17695 is a reply to message #17692] |
Wed, 30 March 2005 12:01 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
spkrman57
Messages: 522 Registered: May 2009
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Illuminati (1st Degree) |
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Wayne, I wonder why I like the round horns vs the 40 X 90 horns. I think it is because I listen off-axis to the round horns in a small room and they sound quite nice and present a very nice "3-D" imaging. With the 40 X 90 horns in a small room, I find a tad bit too much of upper midrange that seems to take over the music. So I guess what I am trying to say is that with directional type horns you can set them up to better present the soundstage you like best. With the 40 X 90 horns, they spread across the soundstage to where you on off-axis less often. Ron
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Re: I understand a little bit better now! [message #17697 is a reply to message #17695] |
Wed, 30 March 2005 17:58 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18748 Registered: January 2001
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Illuminati (33rd Degree) |
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Don't get me wrong, I like the sound of the salad bowl tweeters. I like the sound of the large round horns too, like the Oris and Avantgardes. But I like my seven π's a lot better. On axis, they're about the same at low levels. But turn the volume up, and my speakers stay clear where the others get conjested. Those round horns make too much unbalanced sound bouncing around the room. Speakers that make the sound uniform throughout the room as opposed to just straight ahead sound much better to me, especially when playing complex material.But you may just like your salad bowls better. That's cool. They are very nice, and they sound good too. You might like how they look, they may just "feel" better to you. Maybe your compression driver and crossover combinations work better for you with salad bowls. I don't know. But I know that if you want to hear what I'm talking about, you can't really just compare just the tweeter horns. You have to compare the whole system. Come on down to the Great Plains Audiofest, and try to spend some time with the seven π's. Listen to Geddes speakers too, as he does the DI matching thing like four π's. That's cool too. Try to spend some time listening, maybe in the evening when there isn't so much activity and visiting with other people. Or maybe just build a pair for yourself, stick to the plans and see what you think. Live with them for a while. Listen to them in the "sweet spot." Listen to them in other areas of the room. Spend some time with them and you'll see what I mean.
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Re: I understand a little bit better now! [message #17700 is a reply to message #17697] |
Thu, 31 March 2005 06:35 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
spkrman57
Messages: 522 Registered: May 2009
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Illuminati (1st Degree) |
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Wayne, My horns on top of the 2226 in the JBL 3677 cabinet are portable(sitting on top), and the crossover is designed for quick change-out. I will do some more listening and swap between the Martinelli 650hz tractix and the Edgar 650hz round tractix. I was going to be doing a listening test between my JBL 2426 and my Altec 902 to see the "aluminum vs titanium" sound differences. Bill E. will be visiting me Saturday, so I am lucky to get a unbiased extra set of ears for the testing. Ron
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Re: I understand a little bit better now! [message #17701 is a reply to message #17700] |
Thu, 31 March 2005 07:10 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18748 Registered: January 2001
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Illuminati (33rd Degree) |
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Sounds like a real nice time.Last night, I visited with Todd White at Iconic for a long time. One of these days soon, I'm going to get some of their 515's and 416's and try out some of their compression drivers. I forget the model numbers they're using now, but they're making copies of the older Altecs of those model numbers. Kinda thinking about making a new line with them. Anyway, I know you and Bill will have a good time. I hope to see you both again real soon!
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Re: Directivity vs Omni-directional [message #17702 is a reply to message #17692] |
Thu, 31 March 2005 07:39 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
GarMan
Messages: 960 Registered: May 2009
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Illuminati (2nd Degree) |
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Not to dispute your points on directivity Wayne, but I find it strange that the exact opposite approach has been marketed as the most "natural" approach, with omni-directional speakers. Their argument is that when sound is produced naturally, it radiates out spherically in all directions. Therefore, speakers should be designed to do the same thing. I think this argument is valid in some respect but flawed in others. Not all instruments radiates sound omni-directionally. Brass and woodwinds are examples. Even natural speech is directional to some extent. One thing I don't understand is how can omni-directional speakers be marketed at producing better soundstage and larger sweetspot when a large part of what you hear from them is reflected sound? Gar.
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Re: I understand a little bit better now! [message #17704 is a reply to message #17700] |
Thu, 31 March 2005 20:28 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Bill Martinelli
Messages: 677 Registered: May 2009
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Illuminati (1st Degree) |
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You and Epstein have fun this weekend. The horns you have are 800hz exponential horn with a conical throat. Make sure there is a good blend between the throat and the horn too. The old E-series horns were just a rough bore and the customer had to finish that blend. The new models are complete in that respect since it was problematic.Bill
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Re: Directivity vs Omni-directional [message #17720 is a reply to message #17702] |
Wed, 06 April 2005 19:58 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) |
Mike.e
Messages: 471 Registered: May 2009
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Illuminati (1st Degree) |
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Just look at any number of HIFI companys,its much easier to put 4" + 1" woofers on a tiny box, than consider non WAF alternatives! Big 15"s, horns and such,higher manufacturing costs tooIts funny how almost every company does it,the little box.Linkwitz shows how a 4" can only be used so high ,2khz? before its radiation pattern is less than 90°cone,meaning 3ways are a must for a decent LE system.See the publications section. He even applies bucket brigade delay to fix up some of the fixed delay involved in the active filter chosen,i like this approach. I too dont like the idea of one woofer gradually getting more directive-then at Fc omnidirectional tweeter!A very sudden change vs Waynes and Geddes approach to have more uniform,more constant Directivity! Ive just got to try it when funds allow! harmon kandon have some whitepapers on the mainpage,they too are looking for uniform DI but most dont realise that the right horn can do this. btw just looked at some cheap PYLE bullet tweeter,the FR looks amazingly crazy! Cheers Mike.e
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