I am seeking a practical advantage/disadvantage write-up comparing the SEOS vs QSC 152 vs Pi Speakers vs Pyle Pro PH612 (or Dayton clone) waveguides for the DIY community. I have searched all over, and found tonnes of scattered info. Has anyone collected it into one serious write-up? For example, Augerpro (Brandon) has posted some objective data on some of these waveguides. Wayne (from Pi) has also posted his "objective" data comparing the SEOS12 to his own. Of course, I like the idea of a waveguide able to load the compression driver at lower freq's. What is the disadvantage/tradeoff of doing so (larger waveguide/deeper waveguide with more HOM's)? I also recall reading one of Erich's posts that implied the SEOS design may never have happened if the QSC 152 had not been removed from the market (of course, now PE has it available again). As I understand it, the QSC 152 also better loads the driver at lower freq's than the SEOS12, but maybe the SEOS15 is a more fairly compared to the QSC 152? Reading between the lines of several other posts (not on this site), Geddes seems to indicate that his 30ppi foam can work wonders on the worst horns shape out there (the more HOM's, the more the foam attenuates them). Indeed, I like the idea of accepting a few more HOM's in exchange for better low-freq loading of the compression driver, as I plan to use the 30ppi foam. Of course, I like the idea of minimizing vertical offset between the waveguide and the woofer (with respect to the XO freq), which implies a shorter vertical and wider horizontal waveguide. However, does this compromise the vertical polar response around the XO frequency? I have no experience in using waveguides; I am simply looking to learn more before I start. Is there a write-up that serves as a primer to answer these types of questions? I was hoping that the designers of the SEOS would have created such a document, but I was unable to find it on this site. Of course, I realize the amount of work involved in doing so, and I sincerely appreciate the selfless work that Erich has already put in to helping the DIY communitiy; I could not ask for more from him. Is there an existing practical write-up that serves as a primer to answer these types of questions for the DIY community? Thanks, JohnEP
Keep in mind the potential scope of what you are asking. It is relatively simple to measure the waveguides with the same driver....except the JBL/pyle/dayton which is threaded and not bolt-on. You'll find that information here soon I hope [SIZE=78%]http://www.avsforum.com/t/1475674/the-great-waveguide-shootout[/SIZE] Some measurements may be easy to look at and say what is better....and others will be like reading tea leaves....and then someone will suggest a different compression driver will make a "poor" performing waveguide great. What good is raw waveguide/driver performance if no one actually uses them that way? Consider that all designs will use a crossover and all crossover designs require a variety of compromises...as does the rest of speaker design. A poor crossover (or woofer choice) can defeat any minor difference in waveguide performance. I suspect room interaction can swamp many of the differences if you don't have a dedicated listening space designed to minimize room effects. Is it appropriate to compare waveguides by listening to and measuring the complete systems when each design was likely built around different compromises and objectives?
In order for the SEOS to be designed in the first-place, there must have been at least a few "agreed upon" principles regarding the advantage/disadvantage/tradeoff of various waveguide shapes, and some sort of design goal amoungst the SEOS designers. What principles and tradeoffs were actually considered and used in designing the SEOS? A write-up explaining the process that was used to arrive at the final SEOS shape would answer these questions, serve as a primer (further promote knowledge/understanding in the DIY community), and attract even more interest and discussion regarding the SEOS design. I remain surprised to find that this summary ?does not exist? I realize that this write-up involves work, but if this is truely an "open source" community design, then it deserves some meaningful attempt to summarize the design goals, and the rationale regarding the final SEOS shape created to meet those goals. No? JohnEP
JohnEP: Your summary (and all the posts in the development) are here: http://www.avsforum.com/t/1291022/hey-guys-we-need-a-little-rallying-here
bwaslo, Your link has over 7000 posts in that thread. I understand that it can be difficult to see through the eyes of a newcomer (such as myself). So, I am giving you my honest feedback through those newcomer eyes: the SEOS design deserves a summary regarding the history of it's design rationale here on this site. This seems like common sense to me: it will help explain and promote the SEOS to future newcomers. Documenting Zilch's input to the impetus of the SEOS design would also illustrate and credit the deeper roots behind the selfless work you are doing here for the DIY community. Even just the very basics: advantages/disadvantages of: choice of shape, choice of depth, choice of roundover. You guys must have something to say about how these things were chosen for the SEOS design. Why not summarize and promote those ideas here on this site?? JohnEP
Hi John. I followed behind the scenes while the WG was developed. At first it was gonna be a little higher end and cost over $100, so I didn't really offer any input. In the end it was something perfect for me so I've spent a fair amount of time with it. The "Hey Guys" thread isn't an easy read, but really that's how it was developed if you want to read about the small details. No doubt reading about Geddes' foam and Brandon's testing required quite a bit of digging as well. The development process isn't really all that important now that the product is here. What matters is how does the product perform, now. The answer to that is always application dependant, but for HT use, IMO, it performs excellent. Top it of with a $27 price tag and what's not to like. While following alongin the "Hey Guys" thread, the guys working out the details really battled CTC spacing, horizontal pattern, wide passband, exit angle match to popular CDs, and attractiveness. HOM was discussed frequently particularly around exit angles. If you're familiar with Geddes' work, I can assure you his name came up frequently in those discussions In the end, I think the waveguide that was produced was exactly what many down to earth, first hand users of the waveguide wanted based on very sound performance choices. In the end, those choices were close CTC spacing, 90d horizontal pattern extending very low in frequency, matched exit angle to the DE250, and very attractive That's just a quick summary, nothing formal of course. But hopefully helps a bit. The WG you should choose will depend on your needs/goals/wants. If you haven't designed around a waveguide yet, the SEOS12 is a good start simply because of cost. It's very innexpensive and you're getting a great product for the money. $54 bucks for a pair to play with. You could mess around and gain that side of the experience coin that reading documents cant give you. You mentioned you'd like low end gain, which is more of a pro audio need. If you're thinking of a WG for PA use, there's a lot of options out there. If you're thinking for your home environment, you may want to reconsider your priorities. Low end gain isn't all that needed. I've pushed cheap compression drivers very low and loud without issue in my HT. The DE250 has some serious balls if you ask me. And some of the AVSforum guys really push their speakers yet I haven't heard of a single popped CD. The bigger items to worry about are, IMO, those that were considered in the SEOS design. Good luck with your hunt for a WG John. Maybe one day a summary report will be done up. But Erich and the others who made this happen are really just a bunch of hobbyists having fun. So we'll see.
Hobbyists helped, but very smart ones. One of the main guys that decided on the end shape was a math whiz. He sent me the formulas for the SEOS shape that he recommended and it was a solid page of equations. As far as 'loading' a CD.....the SEOS isn't a 1 model ordeal. Decide where you need it to be, then pick the correct SEOS size. We don't have one size, there's 7 sizes. There's a model from 6" all the way up to 24". If the SEOS-10 doesn't go low enough, step up the the 12. If the 12 doesn't go low enough, step up to the 15, or 18, or 24". The other brands you listed can't claim that. If their size doesn't work, you can't do much about it. None of the other brands can go low enough to match up with an 18" woofer.....the SEOS-18 or SEOS-24 can. The other brands don't make much sense to use on a 6" woofer. But the SEOS-6 will work just fine. Generally speaking, the size of the SEOS can match well with the similar sized woofer. That's not an accident. And because a speaker box is already going to be wider than the woofer, using the corresponding SEOS size works out quite well and nestles in beautifully above it. As for the SEOS-12, it can be crossed low enough for a 12" woofer and many 15" woofers. So it would've made no sense to just make it deeper, but keep the width the same, which can increase HOM's and decrease directivity. If you need to crossover lower or match directivity, step up to the SEOS-15. That's one BIG advantage to the SEOS, you can pick what size you need for the crossover, and still get that great constant directivity. Anyone can take a narrow waveguide, make it deeper and say 'look, it loads to 900hz'. I can do that with a piece of PVC pipe. Common sense says to make entire waveguide a little larger, wider, deeper......so it loads where you want it, but keeps all the other great aspects of the SEOS design in place. Now you have a system, not just a single model that can only be used for a small number of designs.
That is a cool thing about the SEOS I hadn't given much thought. With the plastic 15 and 10 coming, a guy can do 4 SEOS 10 surrounds and an LCR of SEOS 15s. Sweet