Re: Renkus-Heinz complex conic topology
I have a pair here and they are quite good both on and off axis (the 90 by 60) - the pair I have were used with the 121 12" two way. Compared to a 350 flare tractrix round horn they do not load as low - 1200 versus 800 with 1" Emilar - but are less colored and more open - the tractrix are way too directional - compared to the 18 Sound elliptical XT120 (one of my favorite little horns) they are again less colored but load a full octave lower.
dimitri said:
I have a pair here and they are quite good both on and off axis (the 90 by 60) - the pair I have were used with the 121 12" two way. Compared to a 350 flare tractrix round horn they do not load as low - 1200 versus 800 with 1" Emilar - but are less colored and more open - the tractrix are way too directional - compared to the 18 Sound elliptical XT120 (one of my favorite little horns) they are again less colored but load a full octave lower.
Actually, you had said that the combination of a 15" WG and a 12" woofer was the ideal one, which confused me since I thought you espoused the 15"+15" combo. If this is dependent on frequency, then which frequency is best to cross at?gedlee said:
Actually I think Earl said that 12" with 15" waveguide was the ideal compromize, but that 15" with 15" to be preferred and that 15" with 18" probably would be superiour ... no substitute fore size I guess 😀
Makes me wonder if Earl could sell loads of 18" waveguides ... but probably not
Makes me wonder if Earl could sell loads of 18" waveguides ... but probably not
A question for Earl:
Does a group buy need to be started to feel out interest for the larger waveguides?
I don't know if the DIYAudio crowd is large enough to support it on their own, but adding the Altec crowd, the Lansing Heritage crowd and the HE AA crowd might build it into something feasible.
Best,
Chris
Does a group buy need to be started to feel out interest for the larger waveguides?
I don't know if the DIYAudio crowd is large enough to support it on their own, but adding the Altec crowd, the Lansing Heritage crowd and the HE AA crowd might build it into something feasible.
Best,
Chris
Re: Renkus-Heinz complex conic topology
First you must keep in mind that "horns" to "waveguides" is a continuum. A "pure" horn is one in which loading is the only criteria and directivity is not a consideration. The Leqlerq devices fall into this catergory. A waveguide on the other hand has gives almost no consideration for loading as directivity control is the only consideration. Horns have totally uncontrolled directivity if one sticks to "horn theory" as this theory is devoid of any consideration of wavefronts. Hence over the years designers started to use two horns, an early stage for loading and a later stage for control. But this necessitated a sharp discontinuity in the contour which creates diffractions and reflections.
Waveguides have no discontinuities in them and do the best job possible at shaping the wavefront. The low diffraction is notably better sounding. So designers have taken a middle road, one where some diffraction exists, but the contour is smoothed to minimize diffraction.
The device that you show has a diffraction point, thus to me it is a diffraction horn. I guess to me there are only a few true waveguides. The OS, one based on the Prolate system, and another based on the ellipsoidal system. The original Waveguide Theory was quite specific about the contours. They were not arbitrary and they were not "classes" of contours like Horn theory allowed. They are very specific shapes.
Chris, if you are talking about an 18" waveguide, you have to keep in mind the costs involved. If you were to get an order for say 10, then the cost would have to be about $600 each, if not more. You would have to pay me up front (at least 1/2), since there is a huge up front tooling cost, and delivery would be several months.
If you can get the $3000 together then I'll do it. Good luck!
dimitri said:
First you must keep in mind that "horns" to "waveguides" is a continuum. A "pure" horn is one in which loading is the only criteria and directivity is not a consideration. The Leqlerq devices fall into this catergory. A waveguide on the other hand has gives almost no consideration for loading as directivity control is the only consideration. Horns have totally uncontrolled directivity if one sticks to "horn theory" as this theory is devoid of any consideration of wavefronts. Hence over the years designers started to use two horns, an early stage for loading and a later stage for control. But this necessitated a sharp discontinuity in the contour which creates diffractions and reflections.
Waveguides have no discontinuities in them and do the best job possible at shaping the wavefront. The low diffraction is notably better sounding. So designers have taken a middle road, one where some diffraction exists, but the contour is smoothed to minimize diffraction.
The device that you show has a diffraction point, thus to me it is a diffraction horn. I guess to me there are only a few true waveguides. The OS, one based on the Prolate system, and another based on the ellipsoidal system. The original Waveguide Theory was quite specific about the contours. They were not arbitrary and they were not "classes" of contours like Horn theory allowed. They are very specific shapes.
chrismercurio said:
Chris, if you are talking about an 18" waveguide, you have to keep in mind the costs involved. If you were to get an order for say 10, then the cost would have to be about $600 each, if not more. You would have to pay me up front (at least 1/2), since there is a huge up front tooling cost, and delivery would be several months.
If you can get the $3000 together then I'll do it. Good luck!
Okay. I will start a thread in the group buy forum for an 18" waveguide.
What diameter compression drivers will the waveguides be useful with?
http://www.diyaudio.com/forums/showthread.php?s=&postid=1535753#post1535753
What diameter compression drivers will the waveguides be useful with?
http://www.diyaudio.com/forums/showthread.php?s=&postid=1535753#post1535753
chrismercurio said:
All compression drivers have the same situation. The larger the throat the lower its top frequency capability. A 1" driver can just hit 16 kHz, a 1.4" about 10 kHz and a 2" about 8 kHz. In my opinion only the 1" allows for a single HF device and each of the larger diameter throats will need another higher frequency device - a singularly bad idea. The only reason for a larger format driver is higher power (and macho bigger bigger bigger). If these are for home use then higher power is most certainly not required.
In short, for me to do anything other than a 1" would require that all costs of development are paid as I would not have any further use for the device. This would push the price up quite a bit.
I just wanted to clarify. Do you have an opinion on the ring radiator compression drivers from BMS?
Thank you,
Chris
Thank you,
Chris
To my rather limited knowledge I would say that the BMS only has higher sensitivity which you will have to strugle even more to get rid of ... the B&C DE250 or DE500 appears to be high value and fair priced CDs
chrismercurio said:
No, I've no data on that device. Is it like the old JBL 075? Or do they couple it to a horn?
B&C was looking at a ring radiator, its basically a good idea if you can work out the bugs. But I think that Tinitus's point is well made. I'm not looking for better drivers, they are not the limiting factor.
I'm not familiar with the JBL model. I think BMS has built some OEM's for JBL though. The Lansing Heritage folks that kick it around here might be able to chime in. It isn't coupled to a horn. It looks just like a regular compression driver from the front.
Chris
Chris
Earl, for the BMS annular (and coax) CD design, see http://www.pat2pdf.org/pat2pdf/foo.pl?number=5878148
BTW, the 18S NSD1095N looks very promising (has a specially coated titanium diaphragm), though a bit expensive, EUR200. But not exit angle specified, as usual. And 18S makes good woofers too, in case you should ever want to switch from one italian stallion to the other 😉
- Klaus
BTW, the 18S NSD1095N looks very promising (has a specially coated titanium diaphragm), though a bit expensive, EUR200. But not exit angle specified, as usual. And 18S makes good woofers too, in case you should ever want to switch from one italian stallion to the other 😉
- Klaus
KSTR said:
I've used the BMS coaxial, and it was terrible. I've never used the non-coax. As I said, I'm not looking for "better" drivers. In fact if I do anything it will be to downgrade the drivers as they just don't make that great a difference. Certainly for me, right now, the B&C are the best choice.
And I've used 18S woofers. Didn't like them either.
200 Euro's for the compression driver would push the system cost up by nearly $200, a 33% increase on the Nathan. Thats not a good value when it won't make very much, if any, difference.
augerpro said:
The measured parameters and the advertised parameters were way off. Thats was many years ago and I haven't used them since, so maybe they got their QC under control.
But the real point to me is that drivers are a commodity. Once they are good enough, it doesn't matter anymore. And there are lots of drivers that are "good enough". It's the system design that matters, not the components.
Hello Dr Geddes!
I have a question concerning an "acoustical lens"
something like here: http://www.jblpro.com/pub/obsolete/Acoustic_Lens_Family1.pdf
They can be found in some "hi-end" or even "statement" speakers from the 70-ties, JBL and others (for example Yamaha FX-1 and Onkyo Scepter 10)
Why are they under "obsolete" now?
What was wrong with them?
best regards,
graaf
I have a question concerning an "acoustical lens"
something like here: http://www.jblpro.com/pub/obsolete/Acoustic_Lens_Family1.pdf
They can be found in some "hi-end" or even "statement" speakers from the 70-ties, JBL and others (for example Yamaha FX-1 and Onkyo Scepter 10)
Why are they under "obsolete" now?
What was wrong with them?
best regards,
graaf
graaf said:
I did my MS thesis on acoustic lenses. They work very poorly. They are resonant and don't get the job done. I'm surprised that they lasted as long as they did.
What's with the nostalgia craze!? Those old designs were basically not very good. If something hasn't survived there is usually a reason for it. Thats why the things that did work are still arround - compression drivers, shorting rings, pleated suspensions with ribbed cones, in paper. Those things have not changed very much at all and for good reason - they work! Things like short horns, acoustic lenses, diffraction horns, ring radiators - they all went away or are going away because they don't work very well. A good set of modern speakers is head and shoulders better than this older stuff.
It's the system design that matters, not the components.
So that means a us$20,00 Radio Shack compression driver would do it , and not make difference to a TAD, for example ?
So that means a us$20,00 Radio Shack compression driver would do it , and not make difference to a TAD, for example ?
Dr. Geddes,
What do you find to be the ideal angle for an Oblate Spheriod for frequencies down to 600Hz? I know you favor 1” compression drivers for the aforementioned reasons; however I already have some 1.4” compression drivers on hand and would like to use them. I would like to use them from 600Hz to 7KHz. Since I would like to use them down 600Hz, would the waveguide length become a factor for how low in frequency the waveguide can support? If so, then would going to a more narrow (i.e. less than 90 degree included angle) waveguide help increase the depth and better support the 600Hz goal? In addition, is going less than 90 degrees detrimental as far as HOMs are concerned? Would a 60 degree waveguide be a bad idea? Thank you for all the assistance you have provided thus far.
Rgs, JLH
What do you find to be the ideal angle for an Oblate Spheriod for frequencies down to 600Hz? I know you favor 1” compression drivers for the aforementioned reasons; however I already have some 1.4” compression drivers on hand and would like to use them. I would like to use them from 600Hz to 7KHz. Since I would like to use them down 600Hz, would the waveguide length become a factor for how low in frequency the waveguide can support? If so, then would going to a more narrow (i.e. less than 90 degree included angle) waveguide help increase the depth and better support the 600Hz goal? In addition, is going less than 90 degrees detrimental as far as HOMs are concerned? Would a 60 degree waveguide be a bad idea? Thank you for all the assistance you have provided thus far.
Rgs, JLH