I recall advising Markus to get rid of his couch and sit on the floor, and also being very much dismayed that he did not consider this obvious remediation to be a workable solution....
I guess designs like Duke's audiokensis designs or Emeral Physics designs will sound horrible with that larger CTC. I guess those and speakers from Geddes just do not make the audiophile grade BUT a JBL horn + Selenium D220 CD does???? I guess Im missing the disconnect here.
I guess designs like Duke's audiokensis designs or Emeral Physics designs will sound horrible with that larger CTC. I guess those and speakers from Geddes just do not make the audiophile grade BUT a JBL horn + Selenium D220 CD does???? I guess Im missing the disconnect here.
Doug, you're sure acting strangely here lately, seeming to want to pin things down into absolutes. No absolutes exist in audio, (or in most things). The geddes compromises are different from those of "Econowave" and each will have their proponents. I'm surprised none of the other Ewavers have tried my foam solution- there's obvious ripple at cutoff with that horn and it's well controlled with my foam without expanding CTC...
Do you have a link to your earlier posts on the type of foam you use and how you use it?
I'm using a round WG from DDS. Will this have the same problems as the rectangular WGs?
I've tried a few foams in different configurations and find none sound best in my case.
Thanks
I'm not saying any of that, rather, merely that there is a set of known parameters within which rational tradeoffs and compromises may be made toward an optimized design. Yes, there are performance differences between $200 builds and $2000 ones, but done intelligently, either can produce a satisfying result, and those differences are not so huge as to deter any DIYer from beginning at the entry level and learning the basics hands-on.I guess designs like Duke's audiokensis designs or Emeral Physics designs will sound horrible with that larger CTC. I guess those and speakers from Geddes just do not make the audiophile grade BUT a JBL horn + Selenium D220 CD does???? I guess Im missing the disconnect here.
We all started the same place here -- Wayne, Duke, Earl, myself, and others -- with David Smith's (who posts in these forums) and Don Keele's JBL 4430 defining the fundamentals of constant directivity loudspeaker design. It's basically open forum, and there's a lot of cross-pollination occurring as we each put our own "spin" on implementing and refining the concept, and debating the merits of different approaches, to everyone's benefit and advantage....
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I think I found the math. What we are looking for is ellipsoidal coordinates, not prolate spheroidal coordinates.
Confocal Ellipsoidal Coordinates -- from Wolfram MathWorld
Confocal Ellipsoidal Coordinates -- from Wolfram MathWorld
Actually I thought I was trying to remove the absolutes showing that great results can be obtained many ways. Zilch and a Pete recently on the PE forum are really one sided on the idea of a OS Waveguide, they believe its CTC is too much. They would rather have Dayton create a QSC clone then a OS Clone which I do not completely get. More importantly the faithful follow Pete and Zilch without hesitation on PE so their opinion is gospel (for good reason, they are EXPERT DIYers that make great designs) therefore many others end up thinking the OS Waveguide choice isnt as good as the QSC HPR152i choice which just is not true.
I was the guy that introduced the QSC HPR152i waveguide to the masses, I sent mine to Augerpro for measuring showing how good it was first, I talk about it a lot on AVS, Zilch picked up on it and ran with it building many incredible alternatives.
Im already a builder of 6 waveguide speakers. 4 with the HPR152i and 2 with the HPR122i. Im a big fan of that choice because the price tag was incredible. I have also ship 24 of them around the world for others to enjoy their benefits....so you have to understand Im not a one sided OS fan here
btw, Is your foam solution one of those that wrapped foam around the outside?
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I linked it earlier, but yeah, it's basically a beveled open-cell foam designed to act as an edge termination, but since it's only partially absorptive, it's angled to act as a decent termination even if it were a rigid material. It suppressed the peaking of the WG around the cutoff, and made for a nice improvement in smoothness.
..every measured response I've seen of the OS profile is inferior with respect to linearity.. That's a reasonably "objective" assessment of objective measurements.
THEN add-in the problems with mid driver integration.
Frankly the QSC horn needs to be bigger to enable a lower freq. transition. I'm kind of surprised Dayton hasn't already done this.
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To be fair, it's more like we are of Wayne Parham's mind with respect to circular axisymmetric OS; elliptical, another story, perhaps.
Brandon recently found that the 152i will hold pattern control down to ~1 kHz with at least one driver. Nobody has verified that yet, to the best of my knowledge, but if so, this would make it more compatible for directivity matching 15" woofers.
As Wayne points out, there is considerable crossover frequency leeway in designing for a smooth transition, but at the limits of the envelope, optimization becomes more difficult; both horizontal and vertical must be verified empirically.
I understand the desire to reach lower, and have built with 2352, H4338, and even the big Screen Arrays, but the sizes just become too large for mainstream. Earl has stated that 12" builds like Abbey are more acceptable than 15", so I believe we agree with respect to what is most rational in terms of general utility. At 14" wide, we've demonstrated that 152i yields practical designs in this context, and this is why I believe assuring its continued availability to the DIY community deserves higher priority than offering larger waveguides....
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I only have 3 extra pairs left now and a couple of people already asking me about them. I knew QSC would stop selling them, a CS called me once informing me that it would probably happen and that is when I ordered many more.
FWIW, you might be following this thread http://www.avsforum.com/avs-vb/showthread.php?p=19517000#post19517000
but Eric H is going to do some incredible baffle/waveguide work if he can get the right equipment installed.
Im also going to attempt to build a mold for a complete baffle with the QSC HPR152i and rounded over hole for rear mounting a 12" woofer. That would allow for some fibreglass or carbon fibre baffles.
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To be fair, it's more like we are of Wayne Parham's mind with respect to circular axisymmetric OS; elliptical, another story, perhaps.
Brandon recently found that the 152i will hold pattern control down to ~1 kHz with at least one driver. Nobody has verified that yet, to the best of my knowledge, but if so, this would make it more compatible for directivity matching 15" woofers.
As Wayne points out, there is considerable crossover frequency leeway in designing for a smooth transition, but at the limits of the envelope, optimization becomes more difficult; both horizontal and vertical must be verified empirically.
I understand the desire to reach lower, and have built with 2352, H4338, and even the big Screen Arrays, but the sizes just become too large for mainstream. Earl has stated that 12" builds like Abbey are more acceptable than 15", so I believe we agree with respect to what is most rational in terms of general utility. At 14" wide, we've demonstrated that 152i yields practical designs in this context, and this is why I believe assuring its continued availability to the DIY community deserves higher priority than offering larger waveguides....
Zilch those are all great points. OF course, Its the 12" OS WG that I have been discussing so I really do not see how the 14" wide 152i yields anything more practical.
Posting jzagaja's 12" OS waveguide design just had little acceptance and I really wonder why that is.
I guess I just have never seen those measurements. All measurements of Geddes Abbeys are superior to any QSC design measurements so just what did I miss?
Some measurement comparisons would help me understand.Frankly the QSC horn needs to be bigger to enable a lower freq. transition. I'm kind of surprised Dayton hasn't already done this.
I think Zilch made a great comment. I agree we all want lower req. transition but most people hate wider (monkey coffin) speakers. Im all for a 15" OS Waveguide though, I would love to have one.
I guess I just have never seen those measurements. All measurements of Geddes Abbeys are superior to any QSC design measurements so just what did I miss?
I think Zilch made a great comment. I agree we all want lower req. transition but most people hate wider (monkey coffin) speakers. Im all for a 15" OS Waveguide though, I would love to have one.
Go back an look at Brandon's polar measurements.
QSC PL-000446-GP - drivervault
Geddes 10" Waveguide - drivervault
Theses aren't equal measurements because the QSC horn is larger than Earls here, HOWEVER the same sort of discontinuities exit throughout Earl's products.
You can also look at Earl's own measurements, but they are specifically designed to highlight their directivity at the expense of exposing non-linearity. If you look *closely* you should start to see the problems. HOWEVER at the 3D3A lab's measurement of the Nathan (..though not precisely the same as current Nathans) you can more easily see the +/- db non-linearity.
The Nathan is a +/3 db alteration as just an *average*. Worse the changes are fairly broad-band with a full 3+ db difference as opposed to 1.5 db. All precisely in an area where we are most sensitive to amplitude changes.
None of this is to say that the QSC horn isn't without problems, but rather they have fewer problems.
..and sure, people want smaller loudspeakers, but that really isn't something that this "format" is for. If you want something with a lower freq. transition then you either have to make it bigger OR you have to increase directivity.. which leads to the XT1464.
Personally I don't see a large size as an impediment to someone considering horns - so the proposal of a larger version of the QSC horn seems to fit this niche market.