Lynn ... I would like to try your "full-spectrum null" test. I tried to glean something from your old Audionics room but things are different now at Jamac. Could I use a TrueRTA quick sweep (ping) or does a standard frequency weep work better? If so, what type of wave?
Most enlightening on the RMAF show, thanks. I still miss the mickey mouse ones here in Portland, OR in the late 70's. Best in show was Dr. Bose's funny thing. Why aren't we (collective forum dwellers) making a modern version of the 901? Bet I know the answer?
Zene
Most enlightening on the RMAF show, thanks. I still miss the mickey mouse ones here in Portland, OR in the late 70's. Best in show was Dr. Bose's funny thing. Why aren't we (collective forum dwellers) making a modern version of the 901? Bet I know the answer?
Zene
A Journey worth taking
Patrick,
I definitely believe you're on the right track, though I think you'll be going to monopole at too low a frequency. Back in February I decided to take Dr. Geddes constant directivity approach, but in dipole form. I tried a few different WG's for full rangers. I settled on these, and they sound so good that I stopped building speakers.
Patrick,
I definitely believe you're on the right track, though I think you'll be going to monopole at too low a frequency. Back in February I decided to take Dr. Geddes constant directivity approach, but in dipole form. I tried a few different WG's for full rangers. I settled on these, and they sound so good that I stopped building speakers.
An externally hosted image should be here but it was not working when we last tested it.
Patrick Bateman said:
Mr. Bateman
Sorry, but I don;t see the connection between me and P-Audio that you are suggestiing. I hope you don't think that I use P-audio drivers.
I am also concerned with some of your psychoacoustics. In particular your claim to a very high level of time sensitivity for the ear at LF. I don't believe that this is the case. I pay no regard to timing of the LF subs in a room and I find the effects quite desirable. Smooth sopatial and spectral response at LF is the key and I don't think that timing enters into the problam at all.
What is you basis for this belief.
The rest of what you say is mostly correct -difference that I might have not being worth noting.
I wish that I could share with you results that we have for just how accuratekly one has to match the waveguide to the driver at the throat. Its become sort of a trade secret for us, but trust me, one cannot go to far doing this matching correctly. We will be completely redoing the ESP lines throat to improve it by mm's or less.
gedlee said:
After hearing the Summa, I was inspired to try something like that. The P-Audio was attractive at the time due to it's price and smooth response. It's not as sophisticated as the B&C that you used in the Summa.
gedlee said:
Inspired by Robert Hartmann's thesis, I began experimenting with the audibility of low frequency delay three years ago. He proposes that "contrary to the popular
belief that low frequencies are “hard to localize,” the horizontal position of a stereo
image is most significantly affected by moving low-to-mid frequencies as opposed to high frequencies. This can most likely be attributed to the overall perceptual dominance of low frequency interaural phase differences."
Hartmann's thesis can be downloaded here.
Experimentally, I found a high degree of correlation with what he's proposing. Moving subwoofers by even a few inches makes dramatic changes to the integration with mains. This is contrary to the commonly held belief that they can be placed anywhere. I *do* agree with what you and Keele are doing, that the use of multiple subs is preferrable.
gedlee said:
This is a point I'm glad you brought up. The amount of engineering that goes into your speakers is just staggering. I'm excited to evaluate them once they are for sale. This particular project is mostly an opportunity for me to learn what I can about dipoles. For serious listening, the AI speakers are going to be tough to beat. So hurry up and get the website up, alright?
Hey Patrick,
I just ran across this thread and am quite interested to see what develops. Perhaps by dumb luck I decided to build just what you are describing for my first attempt at DIY speakers. So I can use all the help I can get
FWIW I use the xt1086 with their nd1090 driver and a crossover they published in their "kit" section for a 2-way with a 12" woofer. My open baffle mid has been a pro170mo high passed at 250 but I have recently been playing with an old alnico 12" made by RSC.
I look forward to your impressions of the xt1086 and what you decide on for its crossover.
Russ
I just ran across this thread and am quite interested to see what develops. Perhaps by dumb luck I decided to build just what you are describing for my first attempt at DIY speakers. So I can use all the help I can get
FWIW I use the xt1086 with their nd1090 driver and a crossover they published in their "kit" section for a 2-way with a 12" woofer. My open baffle mid has been a pro170mo high passed at 250 but I have recently been playing with an old alnico 12" made by RSC.
I look forward to your impressions of the xt1086 and what you decide on for its crossover.
Russ
Patrick Bateman said:
I confused my sources; I should have attributed that research to Floyd Toole, not D.B. Keele.
http://caa-aca.ca/conferences/Charlottetown2002/PEI_Toole.htm
Patrick Bateman said:
Inspired by Robert Hartmann's thesis, I began experimenting with the audibility of low frequency delay three years ago. He proposes that "contrary to the popular
belief that low frequencies are “hard to localize,” the horizontal position of a stereo
image is most significantly affected by moving low-to-mid frequencies as opposed to high frequencies. This can most likely be attributed to the overall perceptual dominance of low frequency interaural phase differences."
This is a point I'm glad you brought up. The amount of engineering that goes into your speakers is just staggering. I'm excited to evaluate them once they are for sale. This particular project is mostly an opportunity for me to learn what I can about dipoles. For serious listening, the AI speakers are going to be tough to beat. So hurry up and get the website up, alright?
I will have to read Hartmanns thesis because, yes, what he says is contrary to prevailing beliefs and his claim would need to be supported by some very substantial psychoacoustics - not just "listening tests". I can't seem to download his thesis to Asia - probably too big.
I have always been agast at how littel scienec and engineering goes into many loudspeaker designs. Its mostly industrial design, personal beliefs and a lot of faith. No one who has heard our speakers has not bought them. But it is a long road to importing into the US.
Talk to you later when I am back in the USA.
Mark K, from Sacramento, clued me in to the location of his new website. Looks like he's doing a dipole too. Coincidentally, with the same bass driver I'm evaluating. Should be interesting:
http://www.markk.claub.net/
I am designing my dipole with Martin King's s/w. I wasn't aware that John K wrote software for dipoles too (until today.)
Fifteen bucks, what a steal!
Does anyone know if Speak is the only software that can predict polar response?
At this point I'm evaluating whether I should go with a MTM array, and a polar model would help out a lot.
http://www.markk.claub.net/
I am designing my dipole with Martin King's s/w. I wasn't aware that John K wrote software for dipoles too (until today.)
Fifteen bucks, what a steal!
Does anyone know if Speak is the only software that can predict polar response?
At this point I'm evaluating whether I should go with a MTM array, and a polar model would help out a lot.
I've selected and purchased drivers for the project. This is really turning out to be a budget speaker. The midrange is on special for $35 at PartsExpresss, and the woofer is $39. The compression driver that I'm likely to use is around $80, and the waveguide is $44. That's just $200 invested so far, very cheap for the level of performance that I'm aiming for.
After evaluating the drivers mentioned on page one, I settled on using the 8inch Dayton Reference with a Audax HT240G0 to augment the low end. The Audax has been discontinued, but Parts Express still has a few left for sale (cheap.)
I was reluctant to use a discontinued woofer, since I'd like to see others try this design as well. But the Audax is tough to beat as a dipole woofer, and it's a lot cheaper than PE's 15in dipole offering. It's just 39 bucks, so get 'em while you can.
http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=296-138&CFID=8552396&CFTOKEN=29933322
After evaluating the drivers mentioned on page one, I settled on using the 8inch Dayton Reference with a Audax HT240G0 to augment the low end. The Audax has been discontinued, but Parts Express still has a few left for sale (cheap.)
I was reluctant to use a discontinued woofer, since I'd like to see others try this design as well. But the Audax is tough to beat as a dipole woofer, and it's a lot cheaper than PE's 15in dipole offering. It's just 39 bucks, so get 'em while you can.
http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=296-138&CFID=8552396&CFTOKEN=29933322
Patrick Bateman said:
Patrick
I finally got a chance to read the Hartmann paper. I don't see how you can quote that work in regards to anything having to do with "subs". It simply does not apply at those very LFs. I have no problems with what he, its all pretty standard. But to claim that this paper supports a contention that you can hear a sub being moved a "few inches" - at least as far as localization is concerned - is, IMO, entirely incorrect. What you are likely hearing (reality of the event being assumed) is a different modal excitation pattern, which points out the extreme sensitivity to location when only a single sub is used. Use multiple subs and you can move any one of them quite a bit and there will be no noticable effect on the sound. I think that you are applying an incorrect rational to an experimental result.
The result may be real, but your cause and effect relationship is weak.
Patrick Bateman said:
I've modeled the response of the woofer and the midrange.
Here it is.
The low frequency response doesn't extend very far, but I intend to use it with a subwoofer anyways. You can see from the pdf above that the baffle is quite narrow, so our LF response is limited due to that.
On Saturday I listened to each woofer for a few hours, to get a 'feel' for the unequalized response. The Dayton sounds just as good as everyone says, and is capable of reaching high SPLs cleanly. Great for the money.
The Audax sounds far rougher in the midrange, but this is expected, the motor isn't nearly as sophisticated as the Dayton.
A search for the Audax HT240G0 turned up this thread. Did you finish this project? Any pictures/measurements/listening impressions? What compression driver/WG did you end up using?
I'm thinking about a dipole with the Audax PR170M0 midrange, as-yet-undecided compression driver/WG on top, and a pair of 10's below. I was looking at the Dayton RS270s, but then found this woofer on the PE site, and the numbers look interesting (including the price).
Any updates you have would be very helpful.
How high are you using this driver?
I'm thinking about a dipole with the Audax PR170M0 midrange, as-yet-undecided compression driver/WG on top, and a pair of 10's below. I was looking at the Dayton RS270s, but then found this woofer on the PE site, and the numbers look interesting (including the price
).Any updates you have would be very helpful.
How high are you using this driver?
I broke down and bought a pair of Summas. They sound fabulous. Despite the cost, I'm happy. In fact, they're playing right now. The project which I discussed in this thread sits 1/4 finished in my garage
Here's a PDF which describes the Summa.
Here's a PDF which describes the Summa.
John
Your link didn't work (typo), this one does; http://www.gedlee.com/downloads/Cum laude.pdf
And you should put "the cost" into perspective. They were expensive by DIY standards, but a real bargin by typical Audiophile speaker standards. They were less than a Hi-End amp or preamp, for instance.
Your link didn't work (typo), this one does; http://www.gedlee.com/downloads/Cum laude.pdf
And you should put "the cost" into perspective. They were expensive by DIY standards, but a real bargin by typical Audiophile speaker standards. They were less than a Hi-End amp or preamp, for instance.
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