DDF said:
Why so aggressive! Perhaps I don't understand you, but I certainly didn't say anything that should have offended you.
I really don't understand how you can claim that a 90 degree phase shift (at one frequency as in your crossover example) de-correlates the two sources. So please "educate" me on how that happens.
I also don't understand "I'm talking acoustic rates here. " What is an "acoustic rate"?
You were so reasonable to start, but as soon as I disagreed with you you get nasty. Is that really necessary?
Earl, I'm upset because you don't discuss, you just disagree, you were just disagreeable/crusty even when I was genuinely offerring my support and condolences and you instantly assume the other party is stupid or inexperienced. What does it take to have a respectful conversation? I've been designing xovers along a parallel path to yours for over 30 years, with a solid audio education and ptrofessional experience, but you don't see me be so assumptive and reductive about your arguments. And we've talked many times before! Think about it. You make it hard to talk with you.
"Uncorrelated' is terminology often used in signal processing for two signals 90 degrees apart. I use it as its part of the familiar lexicon in the field I worked in, a short hand perhaps but a good intuitive description.
In the case I discussed, the trick is maintaining as close to n*90 throughout xover as possible at he listening axis. Anyway, take a look at what I said, and its very easy to model and makes good sense, nit picking about terminology aside.
Anyway, I'm pissed over this and its better to "just walk away".
"Uncorrelated' is terminology often used in signal processing for two signals 90 degrees apart. I use it as its part of the familiar lexicon in the field I worked in, a short hand perhaps but a good intuitive description.
In the case I discussed, the trick is maintaining as close to n*90 throughout xover as possible at he listening axis. Anyway, take a look at what I said, and its very easy to model and makes good sense, nit picking about terminology aside.
Anyway, I'm pissed over this and its better to "just walk away".
DDF said:
I don't think that you are acknowledging your role in this. You fly off whenever I disagree with you. It sounds like you want to make your statements without any rebuttal.
Yes, I recognize that you were very polite in your first post and I appreciated that. But if you come to a thread bearing my name and expect that I will not challenge statements that you make that I don't agree with then I don't think that you are being fair.
And don't you think that telling me what "correlation" means is talking down to me just a bit!! And it doesn't mean that two signals are 90 degrees apart - thats quadrature.
If you reread the posts you (and anyone else) will see who was polite and who was not. I'll rest on that evidence.
Yes, I think it is time to move on- certainlty there is no more to add to this current diologue. There should be no more discussion of who is or is not impolite - the discussion should be on topic.
One always has the option of NOT posting.
Variac
Re: ellyptical wave guide
I've personally built both circular and elliptical horns (and waveguides.)
The only reason I've used elliptical is if the application had a physical constraint that dictated it. In other words, I've used elliptical if circular simply wouldn't fit.
Why else would you go the elliptical route? A circular waveguide is better suited to the woofer's directivity.
round > elliptical
angeloitacare said:
I've personally built both circular and elliptical horns (and waveguides.)
The only reason I've used elliptical is if the application had a physical constraint that dictated it. In other words, I've used elliptical if circular simply wouldn't fit.
Why else would you go the elliptical route? A circular waveguide is better suited to the woofer's directivity.
round > elliptical
Re: Re: ellyptical wave guide
But Earl, his speaker MUST sound better! His compression driver cost FIFTEEN TIMES as much as yours! You're not trying to tell me that there's more to good sound than spending thousands upon thousands on exotic drivers are you? 😉
gedlee said:
But Earl, his speaker MUST sound better! His compression driver cost FIFTEEN TIMES as much as yours! You're not trying to tell me that there's more to good sound than spending thousands upon thousands on exotic drivers are you? 😉
Re: Re: Re: ellyptical wave guide
😀
I can't wait to see how another price=quality debate comes out. I'm on the price=ego camp.Patrick Bateman said:
😀
This is another interesting paper. at least in that it appears to discuss the deficiencies of many horn types
http://aa.peavey.com/downloads/pdf/qwp1.pdf
These horns they are advocating would be pretty easy to make, and are of the "conical camp" I believe. Instead of foam at the mouth I think that a 4" half-round would probably work? :
http://www.tapeease.com/2rounds.htm
http://aa.peavey.com/downloads/pdf/qwp1.pdf
These horns they are advocating would be pretty easy to make, and are of the "conical camp" I believe. Instead of foam at the mouth I think that a 4" half-round would probably work? :
http://www.tapeease.com/2rounds.htm
What do you think of TOC?
Time Offset Correction - Coaxials
An externally hosted image should be here but it was not working when we last tested it.
Time Offset Correction - Coaxials
Magnetar said:
I've seen worse and I've seen better. The response is not as smooth as what I design for.
In an earlier post I mentioned that the Summas would be ideal for serious home theater. If you guys think people wouldn't spend $25K for home theater speakers, here's a guy who dropped $100,000 on his projector ALONE.
http://www.kipnis-studios.com/The_Kipnis_Studio_Standard/Cinema_Beta.html
On Saturday I had the pleasure of watching Sweeney Todd using this very same projector, and it was absolutely AMAZING. There are only 54 of these in commercial installations at this time, and 16 of them are in Riverside CA. If you live in the area, I'd highly recommend checking it out.
http://www.kipnis-studios.com/The_Kipnis_Studio_Standard/Cinema_Beta.html
On Saturday I had the pleasure of watching Sweeney Todd using this very same projector, and it was absolutely AMAZING. There are only 54 of these in commercial installations at this time, and 16 of them are in Riverside CA. If you live in the area, I'd highly recommend checking it out.
Patrick Bateman said:
A bit over the top. These days a "highly competitive" setup to that shown could be had for about $25,000 total. As with everything the next 10% might take another $225,000 (or more), and its real improvement (beyond the wow effect) is dubious.
I really object to the use of a solid screen as the speakers need to be behind a large screen like that because at the sides or above/below they will not sound right. The vinyl perforated screens don't work very well however and so I have found the bed sheet to be the best overall solution.
Thank you for the clear answer in post 494
And I have one more. Regarding to the high directivity in the upper range it seems to me that it is useful for "pinpoint" localisation but it can be of questinable quality for orchestral music in stereo (OTOH it is not true for HT, multichanel and other kinds of music). I am afraid that high directivity trades off spaciousness for localisation. There is no question whether CD or not CD but smaller DI, say half 5-6dB could allow lateral reflexion to make sense of space and "smear" exact localisation which doesn´t occur in concert hall.
gedlee said:
And I have one more. Regarding to the high directivity in the upper range it seems to me that it is useful for "pinpoint" localisation but it can be of questinable quality for orchestral music in stereo (OTOH it is not true for HT, multichanel and other kinds of music). I am afraid that high directivity trades off spaciousness for localisation. There is no question whether CD or not CD but smaller DI, say half 5-6dB could allow lateral reflexion to make sense of space and "smear" exact localisation which doesn´t occur in concert hall.
MethMan said:
I suppose it is the non-native language, but I don't see a question here. At least there is no question mark!
Spaciousness is a primarily quality of the room (influenced by speaker directivity), while localization is primarily a quality of the speaker (influenced by the rooms early reflections). One cannot correct the room with the speaker so the only choice is to design the speaker for good localization and then design the room for good spaciousness. When properly done both qualities can be achieved, but only if BOTH designs are done correctly.
Advice needed
Dear Dr. Geddes,
having read the summa white paper and this thread I intend to build a diy version of a loudspeaker based on your work. Hopefully the group by will work.
But I'm a little reluctand to use a 15' woofer up to 1kHz. Would prefere a 6' driver with a second waveguide. If I understood the summa paper correctly the mouth of the mf wavegude should match the diamater of the hf wg. to keep the directivity more or less constant. Therfore the wg for the 6' will be quite short. Will the privide reasonable loading for the driver? Is there any good tool to simulate waveguides?
Best regads
Zelter
Dear Dr. Geddes,
having read the summa white paper and this thread I intend to build a diy version of a loudspeaker based on your work. Hopefully the group by will work.
But I'm a little reluctand to use a 15' woofer up to 1kHz. Would prefere a 6' driver with a second waveguide. If I understood the summa paper correctly the mouth of the mf wavegude should match the diamater of the hf wg. to keep the directivity more or less constant. Therfore the wg for the 6' will be quite short. Will the privide reasonable loading for the driver? Is there any good tool to simulate waveguides?
Best regads
Zelter
You suppose correctly Mr. Geddes.
My doubt was about using highly directional source in fairly live room with no room treatment. I´ve thought that smaller and constant directivity can help correct imbalance due to low frequency power excess and aside, give rise to balanced lateral reflexions which could be helpful for spatiousness. Everything seems to be clear to me and gives a common sense now. Thank for your patience.
My doubt was about using highly directional source in fairly live room with no room treatment. I´ve thought that smaller and constant directivity can help correct imbalance due to low frequency power excess and aside, give rise to balanced lateral reflexions which could be helpful for spatiousness. Everything seems to be clear to me and gives a common sense now. Thank for your patience.
Re: Advice needed
I'm not, but I have found that 12"s work well, but even going down to a 10" turns out to be a real problem.
WOA! The SUMMA paper does not say that. It says that the mouth of the waveguide should be about the same size as the LF piston driver. It won't work like that with a MF waveguide. Its not that simple to change a complex design like the SUMMA and have things come out right. IMHO the use of a 6" MF driver is a mistake, but at the very least it changes everything.
The only tool that I know of that even attempts to simulate waveguide directivity is SPEAK. (Short of mega-expensive Acoustic FEA programs)
zelter said:
I'm not, but I have found that 12"s work well, but even going down to a 10" turns out to be a real problem.
WOA! The SUMMA paper does not say that. It says that the mouth of the waveguide should be about the same size as the LF piston driver. It won't work like that with a MF waveguide. Its not that simple to change a complex design like the SUMMA and have things come out right. IMHO the use of a 6" MF driver is a mistake, but at the very least it changes everything.
The only tool that I know of that even attempts to simulate waveguide directivity is SPEAK. (Short of mega-expensive Acoustic FEA programs)
Dear Dr. Geddes,
in an other tread you offered to sell blocks of foam needed to lower HOM created in a waveguide. Do you still offer the foam? If yes, what is the price for one block?
Obviously I missunderstood the summa paper. Thank you for your correction. Could you please explain why you think using a mf waveguide is an error?
Greetings from Germany
Zelter
in an other tread you offered to sell blocks of foam needed to lower HOM created in a waveguide. Do you still offer the foam? If yes, what is the price for one block?
Obviously I missunderstood the summa paper. Thank you for your correction. Could you please explain why you think using a mf waveguide is an error?
Greetings from Germany
Zelter
My horn based on Tractrix profile and standard dome tweeter without phase plug is as good or better than complicated Summa OS waveguide in terms of midrange linearity. I couldn't find solution for Linkwitz-Riley 4th order crossovers - I've got a huge dip at crossover point but maybe I did wrong time alignment. On axis horn starts rolling at 1,8kHz, off axis at 500Hz. Subtractive crossover offers attractive bump from LP section - see appended picture. Overall mix is quite good. These curves contain all room reflections.
Attachments
jzagaja said:
Tractrix horns can't do constant directivity.
Been there done that.
Please post graphs of power response which prove your tractrix horn is "better."