Agreed the dipole compression options generally aren't cheap (beyma 380 will also work). If franks's crossing high might also consider two of these http://www.parts-express.com/pe/sho...-166&FTR=beyma&CFID=10983233&CFTOKEN=92904035
Radiused edges
Telstar,
The attached sketch shows the use of 8 inch diameter PVC tubing cut lengthwise into quarters to provide 4 inch radius edges to my proposed OB.
Ang,
Thanks for the lead to the Beyma CP09 tweeter. It would work well XO at 7.5 KHz. Are you suggesting I should have second CP09's facing the rear on these OB's?
Telstar,
The attached sketch shows the use of 8 inch diameter PVC tubing cut lengthwise into quarters to provide 4 inch radius edges to my proposed OB.
Ang,
Thanks for the lead to the Beyma CP09 tweeter. It would work well XO at 7.5 KHz. Are you suggesting I should have second CP09's facing the rear on these OB's?
Attachments
open baffle edge radius
Ang,
While using CP09 tweeters for forward & rear facing sounds like the simplest way to go, I wonder if replacing the rear CP09 (that has a focused output) with the four Super 3 coned tweeters might not provide a beneficial spread of reflections across the front wall. Or is that a bad idea? I see conflicting methods of aiming any rear facing tweeters to obtain a better soundstage.
Frank
Ang,
While using CP09 tweeters for forward & rear facing sounds like the simplest way to go, I wonder if replacing the rear CP09 (that has a focused output) with the four Super 3 coned tweeters might not provide a beneficial spread of reflections across the front wall. Or is that a bad idea? I see conflicting methods of aiming any rear facing tweeters to obtain a better soundstage.
Frank
I am Skorpion, Erling Petersson, Söderköping, Sweden, my last contribution to the OB-world is the MJAO G 098 speaker, a JAMO R 909 look-alike as presented here: http://www.audiocircle.com/index.php?topic=65570.0 . It does sound very good and have had some followers.
I wrote quite a sharp contribution here a while ago which has passed totally ignored, mainly complaining about mige0's write up about his dipole horn experiments. As a writeup it is quite useless, because it does not tell you anything about what is actually measured or how it is done. I may assume that this is alright in this community. Or I may assume that some rigor should be applied when trying to prove some points for us other fellows.
I don't want to say that mige0 is cheating, but for a person who is able to portray himself and some lying around old Shackman electrostatic panels, I find it very serious that the write up is lacking any pictures of the dipole horns actually estimated.
There may be information in the thread that I have missed, but for a write up to be selfcontained you would assume a lot of information about how various measurements acctually were done. I find this information missing all together.
So what am I as a diy-audio member to think ? Should I react ?
Or is this something that all togehter should be ignored, in the name of corruption ?
/Erling
I wrote quite a sharp contribution here a while ago which has passed totally ignored, mainly complaining about mige0's write up about his dipole horn experiments. As a writeup it is quite useless, because it does not tell you anything about what is actually measured or how it is done. I may assume that this is alright in this community. Or I may assume that some rigor should be applied when trying to prove some points for us other fellows.
I don't want to say that mige0 is cheating, but for a person who is able to portray himself and some lying around old Shackman electrostatic panels, I find it very serious that the write up is lacking any pictures of the dipole horns actually estimated.
There may be information in the thread that I have missed, but for a write up to be selfcontained you would assume a lot of information about how various measurements acctually were done. I find this information missing all together.
So what am I as a diy-audio member to think ? Should I react ?
Or is this something that all togehter should be ignored, in the name of corruption ?
/Erling
gedlee said:
So you developed on this !@@!! active sonar systems?
http://www.nrdc.org/wildlife/marine/sonar.asp
Michael
skorpion said:I think this thread is long overdue. Mostly internal mirror looking. Like this last write up with claims not at all documented as to what is estimated or how. But maybe blueprints can be estimated ?
This can be seen as tragic or just as a case among a lot of others when nothing is to be achieved but more to provide a playground.And yes of course, it's just a hobby !
/Erling
skorpion said:
Hi, Erling from Sweden.
I read your comments and took it as a statements of general criticism which I might respect – though not really understand.
- is it my formalism you do not like?
- is it due to the basic problem you do not understand?
- is it the solution you do not appreciate?
Seeing that you've built some OB's yourself, I think you are fairly familiar with the topic and should not have any bigger problems to spot the point.
What I presented marks (to my knowledge) the most recent development in speaker design – a follow up to the last "inventions" of "wave guides" and "open baffles" if you will.
Thus, of course my paper naturally differs form a mere "how to DIY build a XY-speaker" – its more a contemplation and reflection about what's currently top notch and a multi-layered description to tackle the topic form a variety of points of view - some of which being more theoretically related, some more after practically aspects.
That I focused less on measurement details I found legitimate as all plots *I* present will be under question as long as the general benefits are not affirmed by many, many others (that this will happen in the long run I have no doubt about).
The basic measurement setup I thought should be pretty clear to anyone that has done so himself.
But anyway - what *exactly* would you like to know / is not clear for you ?
Michael
skorpion said:
Ok then, fine.
As for the pictures you requested :
No pix for now, just the CAD drawings shown that reflect the basic form and are also meant as an inspiration for any DIY. All the design work for beauty and WAV will be delayed until the core of the acoustic design roughly meets my expectations.
There still is some "slight room for improvement" in refinement of the overall system but also and especially for the dipole horn layout that's high in my list of "to do's" right now.
Michael
Well I can report I have a pair of GPA 288-H and Azurahorn AH-425 working and I'm finding the combination addictive to the point that Lynn's Ariel speakers are sidelined !!
...this despite the 750-8500Hz bandwidth .
Playlist restricted...guitar music sounds sensational . Leo Kottke rules !
Planning to add Aurum Cantus G3 ribbons v. soon .
Dave Slagle working on autoformers to match the horn to the ribbons, right now .
More soon, but don't hold your breath with my current workrate .
Onken cabs with Supravox 285GMF will be the foundation .
Mark J
...this despite the 750-8500Hz bandwidth .
Playlist restricted...guitar music sounds sensational . Leo Kottke rules !
Planning to add Aurum Cantus G3 ribbons v. soon .
Dave Slagle working on autoformers to match the horn to the ribbons, right now .
More soon, but don't hold your breath with my current workrate .
Onken cabs with Supravox 285GMF will be the foundation .
Mark J
Results of the Azura horn and Altec 288 combo are now up on my site:
http://sites.google.com/site/drivervault/driver-measurements/horns-and-waveguides/azura-425hz-horn
http://sites.google.com/site/driver...nts/acoustic-elegance-td12m/gpa-altec-288-16h
http://sites.google.com/site/drivervault/driver-measurements/horns-and-waveguides/azura-425hz-horn
http://sites.google.com/site/driver...nts/acoustic-elegance-td12m/gpa-altec-288-16h
Augerpro, thanks again for the measurements! The horn looks beautiful - any idea what shipping is to the US for them?
I had a question though - I'll state firstly that I know very little about horns, and have no experience with them, although I'd love to try them sometime. The Azura horn looks really nice - the wife might not consider them a monstrosity But looking at the horn/drivers data, the frequency response isn't anywhere near flat, the nonlinear distortion looks high, and the impedance is way crazier than dynamic drivers. Is this supposed to be a good horn/driver?
I had a question though - I'll state firstly that I know very little about horns, and have no experience with them, although I'd love to try them sometime. The Azura horn looks really nice - the wife might not consider them a monstrosity
But looking at the horn/drivers data, the frequency response isn't anywhere near flat, the nonlinear distortion looks high, and the impedance is way crazier than dynamic drivers. Is this supposed to be a good horn/driver?
Seperating the horn from the driver, maybe I can answer your questions. The response-while not very smooth-behaves consistently as you move off axis. Maybe this is an effect of the Le'Cleach profile...But I think it points to the driver as the culprit. Since the peaks and dips never really change much it doesn't seem the horn is doing anything other than showing response of the driver itself. I'm hoping to get my standard DE250 with an adaptor on this by the end of the week and see what happens. Of course with three different profiles of the CD exit, adaptor, and horn entrance it may not bring all the answers we're looking for. They only concern I have is the way the horn dominates the impedance of the CD. The original impedance was bad, but with the horn attached it's still got issues even if they are not that provable of an impact.
As for the compression driver I'm sure there may be a reason why alnico is still so preferred. But I haven't found it. You just can't get around the fact these motors are old designs and the distortion is pretty high. I even tried looking at orders individually in the spectrum plots thinking maybe they make a lot low order but very little high order. But when the get pushed they make ALL teh orders so that's a dead end. And it's audible. From 400hz-800hz not only is spectrum lit up but you can hear it clear as day. You can here a raspy harshness that is loud enough that identifying the fundamental tone is immpossible. Vintage is cool, but GPA should form a new branch that uses modern methods to reduce distortion, but still using the alnico motor and those smooth soft parts.
As for the compression driver I'm sure there may be a reason why alnico is still so preferred. But I haven't found it. You just can't get around the fact these motors are old designs and the distortion is pretty high. I even tried looking at orders individually in the spectrum plots thinking maybe they make a lot low order but very little high order. But when the get pushed they make ALL teh orders so that's a dead end. And it's audible. From 400hz-800hz not only is spectrum lit up but you can hear it clear as day. You can here a raspy harshness that is loud enough that identifying the fundamental tone is immpossible. Vintage is cool, but GPA should form a new branch that uses modern methods to reduce distortion, but still using the alnico motor and those smooth soft parts.
Thanks Brandon!
Good measurements and synopsis.
I think the ND1460A is potentially the "right" 1.4" exit driver.
That horn is fantastic. Usable to pretty low freq.s/low order crossover for a horn AND with only a modest decrease in spl off-axis at upper freq.s (..relative to the lower freq.s).
BTW, nice find with that Celestion driver! (.."budget" doesn't have to mean "cheap".)
Hi,
Why is that?
The published FR shows larger and larger rises and falls above 10kHz. And it looks a periodic trend, no? The impedance is very flat, though.
The NSD1480N looks smoother in the FR, only with a 'hiccup' at about 13~14k which is also shown in the impedance.
Of course those are only a part of the story and I'm looking forward to see the more thorough evaluations and tests.....
Mylar suspension for Al vs. a titanium suspension for the Ti. Lower fs for the Al vs. the Ti. Likely less non-linear distortion on the low end of the Al makes the driver's operation less critical. Should give a better developed subjective sense of depth and "3d" imaging (..though of course this is speculation). (..note that the 1" exit Ti nitride from 18 Sound does not have a titanium suspension.)
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