Variac, of course you can roll on a lot of coats (because you simply don't get a very thick uniform coat by rolling), sand it real plane, wait days (weeks?) for it to cure and then polish. But who has the time? I'm now at coat 3 and it's still not thick enought to be sanded real plane.
Best, Markus
Best, Markus
markus76 said:
True, I have heard other speaker/room combinations that provide good accuracy. Your better recording studio control rooms do exactly that. But I wouldn't run a live band at full volume through most studio monitors or hi-fi speakers. With a few subs for the bottom end I would use the Summa's or maybe even the Abbey's for exactly that and have clarity I have never heard from any typical pro horn.
Markus, I am looking forward to hearing your impressions of the smaller Nathans since I have only heard or read about the full sized Summa's
4th and last coat:
Best, Markus
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
markus76 said:
Markus
The paper is http://www.gedlee.com/downloads/AES06Gedlee_ll.pdf
Regarding imaging and your comment about Dr. Blauert.
I've read his pertinent sections about three times trying to find relationships that relate to "image". Unfortunately they are few and far between. Dr. Blauert quotes existing studies which are virtually all based in "localization". "Localization" IS NOT "image". "Localization" has to do with ones ability to determine the location of a real source and "imaging" has to do with two channels ability to create multiple phantom sources simultaneously. There are some similarities, but the two things are distinctly different.
For example many people quote the "precidence" effect for loudspeakers and rooms, but this doesn't really apply. Even Blauert makes this point - the precidence efect says nothing about coloration of the source or phantom image shifts, only where the dominate source direction appears to come from.
Image involves both time delays and frequency response attributes of a loudspeaker/room situation and both have to be correct for the best "imaging". Localization studies ignore coloration effects and as such discount a very large part of the "imaging" of a loudspeaker.
All in all this is an extremely complex subject and one for which there is not even universal agreement. For example Dr. Toole and I disagree on some issues involving very early (1-3 ms.) reflections. He quotes data that is not available in the literature at the moment (he claims its in his new book), but he also appears to quote Lidia and my study - so there must be something relevent there.
By the way, on Jan. 5th, 2009 Dr. Toole will present a full day class on "Psychoacoustics of Loudspeakers and Rooms". This will be in Las Vegas. I arrainged this as Chair of the ALMA Education Committee. It will be pretty expensive (about $450) as my goal is for education to be profitable for ALMA. In 2007 and 2008 it was the classes that I developed that kept ALMA afloat. That's the capitalist in me - keep things alive by making them profitable.
Hey Earl,
thanks for the long reply. Actually there is a chapter on hearing with two or more sound sources in closed spaces in Blauerts book "Spacial Hearing". It would be nice to discuss imaging and coloration in another thread because you're absolutely right that there is very little relevant data coming from available psychoacoustic studies. And we still have no idea how sum localization is working at all. As far as I know Günther Theiles theory (http://www.hauptmikrofon.de/theile/ON_THE_LOCALISATION_english.pdf) was the last big attempt to shed some light on that issue.
Let's get back to what this thread was originally about - sanding ... errr ... building a box:
The waveguide is casted a little bit to deep so you have to sand it down to get the right throat diameter. It's very easy to incorporate uncorrectable errors in this step so it would be better to have e.g. a glass fiber reinforced waveguide. That would be pretty easy to do too. I was even thinking to spout my waveguides to get the form and build a tool from it that is simply made of two MDF boards, a longer thread rod and a couple of nuts...
Best, Markus
thanks for the long reply. Actually there is a chapter on hearing with two or more sound sources in closed spaces in Blauerts book "Spacial Hearing". It would be nice to discuss imaging and coloration in another thread because you're absolutely right that there is very little relevant data coming from available psychoacoustic studies. And we still have no idea how sum localization is working at all. As far as I know Günther Theiles theory (http://www.hauptmikrofon.de/theile/ON_THE_LOCALISATION_english.pdf) was the last big attempt to shed some light on that issue.
Let's get back to what this thread was originally about - sanding ... errr ... building a box:
An externally hosted image should be here but it was not working when we last tested it.
The waveguide is casted a little bit to deep so you have to sand it down to get the right throat diameter. It's very easy to incorporate uncorrectable errors in this step so it would be better to have e.g. a glass fiber reinforced waveguide. That would be pretty easy to do too. I was even thinking to spout my waveguides to get the form and build a tool from it that is simply made of two MDF boards, a longer thread rod and a couple of nuts...
Best, Markus
Markus
Glass fiber would not flow so that wouldn't work. At any rate its not as sensitive as you are implying and it would be pretty hard to mess up.
It is my intention to do this step myself as I now have a fixture that tells me when this is right. I'm also going to actually attach the mounting plates as it is far easier to misalign them without a fixture than it is to sand down too much. The concentrcity is the most critical thing and I can do that well while its dificult in the field. By actually attaching the mounting plates this potential error will be minimized. Each waveguide can then be fit to the mounting plate for the best possible tollerance stackup.
Glass fiber would not flow so that wouldn't work. At any rate its not as sensitive as you are implying and it would be pretty hard to mess up.
It is my intention to do this step myself as I now have a fixture that tells me when this is right. I'm also going to actually attach the mounting plates as it is far easier to misalign them without a fixture than it is to sand down too much. The concentrcity is the most critical thing and I can do that well while its dificult in the field. By actually attaching the mounting plates this potential error will be minimized. Each waveguide can then be fit to the mounting plate for the best possible tollerance stackup.
markus76 said:
Markus
Very interesting, but very difficult, reading. I often find that translated German can be very laboreous for a native English speaker. German was my language in school and I translated several papers by Schroeder, which, I am sorry to say, were very difficult to put into English. The AES wanted to publish my translations, but when they were sent to Dr. Schroeder, he just wrote them again from scratch in English. When I read his English version, it was like reading a different paper.
I will finish reading the above paper, but have to ask how it is that you came to know so much about psychoacoustics. Blauerts book is not well know and yet you have obviously read it. How is this? You do Web sites for a living right?
Did you happen to know Prof. Eberhard Zwicker? He was a friend of mine and also knew my wife.
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