| my rant [message #17585 is a reply to message #17575] |
Fri, 25 February 2005 13:56   |
pgolde
Messages: 21
Registered: May 2009
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Chancellor |
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I am a student of these forums and of audio. Much of what DR. Geddes and Wayne debate is not only over my head, but I lack the proper tools for measurement and the time to invest to prove either of their theories, once I do get a good understanding of both.
I think there is more R&D money in pro audio and more lately, high end home theater. I think designs like Dr. Geddes waveguide and TD's Unity Horn are proof of progress being made to reproduce sound as accurately as possible. Compression drivers, and cone drivers are using pretty much the same technology that has existed for decades. New designs are being proven still for new ways to get the most out of these inefficient devices, but most people dont give a rats ass. Every time I try to show a someone the basshorn I built, or even discuss it, the first thing out of their mouth usually goes something like this "oh, thats like the BOSE". Though playing music through them always puts a smile on their face.
I do enjoy learning as much as I can, wish I had more to contribute than questions or observations. I do also appreciate others sharing their trials for us to learn from and build on. But there is a point that is reached with DIY that gets very expensive to do better.
Dr. Geddes has years of scientific research to pull from, and is nice enough to share some of his findings and observations with us who are willing to read and listen. But unless I have my own scientific data to back up what I believe to be good sound, it is difficult for me, or a guy like me prove.
So on to the next project, a horn based on Leach math, using a BMS coax.
Thanks
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| Re: So you are saying [message #17587 is a reply to message #17586] |
Fri, 25 February 2005 14:39 |
Earl Geddes
Messages: 220
Registered: May 2009
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Master |
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That question has no answer. Since waveguides have a directivity that is constant with frequency and domes and cones and pistons directivity narrows with frequency there is a frequency region where the pistons are wider and a frequency region where they are narrower.
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| Re: Clarification [message #17588 is a reply to message #17583] |
Sat, 26 February 2005 23:45 |
Mike.e
Messages: 471
Registered: May 2009
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Illuminati (1st Degree) |
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These are the issues ive started looking at recently,and for these reasons Im wanting to build a horn loaded system,with HF horn,15" midbass and perhaps a matching 300hz-2khz midrange rectangular mouth horn,cone driven.
Question: Why have some many,for so long aimed for this omnidirectional source ?
Another reason I want less room interaction,is because the electronica music I tend to listen to,I enjoy it so much more on headphones and I think this is why. Regards
Mike.e
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| Re: Clarification [message #17589 is a reply to message #17588] |
Sun, 27 February 2005 11:00 |
Earl Geddes
Messages: 220
Registered: May 2009
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Master |
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Its hard to understand why people hold on to obsolete views for so long. Things like "sweet spot" and omni directional patterns are dead and gone. When rooms are very dead then omni works as well as anything else and most acousticians make small rooms very dead to smooth out the bass. In this case the omni is an adequite solution. And lets face it it is a whole lot easier and cheaper to make an omni source. But the small room problem is low frequency only. That is, it is true that one wants a lot of absorption at LF in small rooms, but that does not mean that one wants a lot of HF absorption. In fact the exact opposite is true. So building the correct room acoustics is a bit problematic, but it certainly can be done (see my books). When the room has a lot of LF absorption and little HF absorption, the omni-directional source is a disaster. This is where the directional source is not only desirable but required. In fact in any room which has little sound absorption, the directional source will always sound better. So you see, that the desire to have an omni-directional response is misguided.
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| Re: Clarification [message #17592 is a reply to message #17589] |
Sun, 27 February 2005 20:29 |
Mike.e
Messages: 471
Registered: May 2009
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Illuminati (1st Degree) |
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Thanks earl,yes I agree. I see the people on 'hifi' forums buying the latest 1" + 4" + 8" and damp the hell out of their rooms to get some sort of imaging... The directive route seems so much more logical. Regards
Mike.e
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| Re: So you are saying [message #17597 is a reply to message #17596] |
Mon, 28 February 2005 08:49 |
Earl Geddes
Messages: 220
Registered: May 2009
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Master |
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I think that you said that backwards. The directivity of cones and pistons goes UP as frequency increases. But, yes, you are corect that pistons do make good sources at low to mid frequencies which is exactly how I use use. I let the directivity of a large piston narrow until it reaches the same coverage as the waveguide and then I cross it over to the waveguide. This gives me a smooth polar response transition from very low to very high frequencies. I am not aware of any work that Floyd did saying the omni-speakers are prefered. That would not agree with JBL's trend to make their loudspeakers directional. In their extreme high end system they basically do the same thing that I do. Only thiers cost ten times as much!
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| Re: So you are saying [message #17599 is a reply to message #17597] |
Mon, 28 February 2005 10:52 |
Mark Seaton
Messages: 3
Registered: May 2009
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Esquire |
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Earl Geddes wrote:
"I am not aware of any work that Floyd did saying the omni-speakers are prefered. That would not agree with JBL's trend to make their loudspeakers directional. In their extreme high end system they basically do the same thing that I do. Only thiers cost ten times as much!"Actually Earl, that should read "They are *charging* 10 times as much." Because they can! Of course those Berrilium diaphram compression drivers are certainly a bit more expensive than is warranted. Out of curiosity, Earl, have you measured or listened to the BMS 1" exit or their larger coax compression driver? Do you consider the slight increase in their high frequency extension to be of much value beyond marketing? Regards, -Mark Seaton
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