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Hey guys...we need a little rallying here... - Page 57

post #1681 of 9845
Thanks Tux. As you say, its a simple trig problem for cancellation. You the maximum path length occurs at 90 degrees from on axis and is equal to the spacing between the speakers. In my case, that is about 5.25". The cancellation wavelength is 10.5". The corresponding frequency is about 1300 hz, which is outside the passband. At lesser angles cancellation occurs at even higher frequencies. So horizontal nulls aren't an issue for this configuration. My problem is to find the best directivity match between a pair of smallish mid woofers and the SEOS-12 or SEOS-15. The directivity of single piston radiator is well known and documented on the web; the horizontal directivity of two side by side pistons is more difficult to determine. I guess it won't matter if I succeed in measuring it.
post #1682 of 9845
Thread Starter 
jacknc,

welcome and great presentation that you linked to there.

the confusion seems to be coming from the fact that the presentation uses theoretical "point" sources, while in the real world, drivers with relatively large diameters are used.

a "point" source will not have any beaming effects at any frequency. theoretical "point" sources never beam. they are infinitely small and infinitely powerful. a useful model for some things, but not for others.

in the real world, a source will begin to beam based on the width of the radiating area. once that radiating area is roughly (depending on cone shape and some other things) equal to the wavelenth that it is trying to reproduce, it will be beaming at about -6db at 45 degrees off axis, or 90 degrees wide total.

this is why drivers that have a radiating area of around 1 foot wide match well to a 90 degree horn at around 1130 hz. this is somewhere in between typical 15" and typical 12" drivers where the radiating area is just over or just less than a foot.

the paper is talking about the interaction of "point" sources at various distances, which is a different topic. the crossover frequencies in the paper make the reasonable assumption that each driver will not be "beaming" in its operating range.

this is why it was noted that the off axis behavior of dual 8's would be a good match in the horizontal, but not the vertical. dual 8 cross at ~1khz will be down 6db in the horizontal at +/-45 degrees, but in the vertical, they will not be beaming at all, which is no good for the application. this is where the second set of 8's over the horn come in. now, you can use the calculations in the presentation to identify precisely how far apart they should be spaced to create a vertical polar pattern that is matched to the horn.
post #1683 of 9845
Quote:
Originally Posted by LTD02 View Post

...the off axis behavior of dual 8's would be a good match in the horizontal, but not the vertical.

Don't forget that unlike the horizontal where the woofer and horn don't affect each other's directivity, they do in the vertical where their outputs overlap.
post #1684 of 9845
Quote:
Originally Posted by pnw View Post
Given just a bit of listening distance, and a low XO, two 8's will sum fine and approximate the horizontal directivity of a 15. Two little guys may also improve system clarity by addressing the "muddy" response I hear with some large drivers crossed high. Perhaps the large drivers store energy below breakup...I dunno???
Thanks, I have a hard time explaining what I hear but "muddy" is a great term that I agree with.

Quote:
PS: Based on my tests of an 18Sound 10" midbass, the 8" will want woofers around 200Hz...4-12" would make a nice symmetrical array
Yeah the 10s don't go low at all, I thought I would have your 18sound 10" woofers in a speaker by now but I shelved the project
post #1685 of 9845
Noah,
Below XO is where the pair of 8" vertical flare is a concern. Not necessarily a deal breaker, but something to consider.

Penn,
...wondered what happened to your project. Gonna restart?

I listened to the 10NDA520's crossed to BMS 18N850's around 250-275...that worked pretty well.
post #1686 of 9845
Quote:
Originally Posted by LTD02 View Post
jacknc,

welcome and great presentation that you linked to there.

the confusion seems to be coming from the fact that the presentation uses theoretical "point" sources, while in the real world, drivers with relatively large diameters are used.

a "point" source will not have any beaming effects at any frequency. theoretical "point" sources never beam. they are infinitely small and infinitely powerful. a useful model for some things, but not for others.

in the real world, a source will begin to beam based on the width of the radiating area. once that radiating area is roughly (depending on cone shape and some other things) equal to the wavelenth that it is trying to reproduce, it will be beaming at about -6db at 45 degrees off axis, or 90 degrees wide total.

this is why drivers that have a radiating area of around 1 foot wide match well to a 90 degree horn at around 1130 hz. this is somewhere in between typical 15" and typical 12" drivers where the radiating area is just over or just less than a foot.

the paper is talking about the interaction of "point" sources at various distances, which is a different topic. the crossover frequencies in the paper make the reasonable assumption that each driver will not be "beaming" in its operating range.

this is why it was noted that the off axis behavior of dual 8's would be a good match in the horizontal, but not the vertical. dual 8 cross at ~1khz will be down 6db in the horizontal at +/-45 degrees, but in the vertical, they will not be beaming at all, which is no good for the application. this is where the second set of 8's over the horn come in. now, you can use the calculations in the presentation to identify precisely how far apart they should be spaced to create a vertical polar pattern that is matched to the horn.
Thanks for that clarification. Especially the last paragraph, which is an insight I had missed. I was thinking to just minimize the vertical spacing to avoid vertical nulls.

I'm a little surprised that a point source model predicts a wider beamwidth in this case. But that is good if it means I can use quad 6.5's around a SEOS-12because the 5.25's are wimpy!

I'm going to try and measure a pair of drivers tomorrow depending on how long it takes me to throw a test box together.

(would have responded sooner but was distracted by my day job)

Jack
post #1687 of 9845
Just expressing my wants to help Erich judge market demand...

I want to build some LCRs, so I'll want three SEOS-12 (or -15) waveguides. For aesthetic reasons, I'd prefer to build with the less-wide SEOS-12. I hope it doesn't come to this, but I could probably use the -15 if the -12 gets neglected and all the designers focus on the -15.

Plastic appeals to me. I'm more comfortable with it as a material, so I know what to expect when tightening screws, etc. It also seems like it would be easier to get identical replacements if I need them in the future, or to get more waveguides if I want to make surrounds. I'm not anti-fiberglass, but if both are available, I'd likely pick plastic.

I will flush mount the waveguide. I'm guessing that most people who care about the aesthetics will flush mount. Those that don't flush mount probably won't care that much if the edge is squarish. (Or maybe the sharp edges would be an acoustic liability that people will care about? idk)

Alternately, the waveguide + baffle combo unit could be cool. I plan to build tower speakers for aesthetic reasons (think Zu-ish in shape), so it would be at the top of a tower. My center speaker will be short, though. Perhaps the wg+baffle could provide a common aesthetic among the three?

Much like I did for my Econowave SRs, I just want to follow a recipe. That means I want to buy the horn/CD/woofer and build a crossover that someone else designed to work in combination. I won't buy the parts until someone shares a design that seems to be well regarded and that I know I can execute. I know that many really enjoy the measuring and tuning, but I just want to build stuff and end up with some good speakers. Making them look good will be enough of a challenge for me at this stage in my DIY career.

I like my Econowave SRs a lot, but I think the D220Ti CD can be a little edgy sometimes, so I am interested in trying the DE-250 CD. Or another higher-end CD.

I'll buy whatever woofer someone decides to make a crossover for.

I do like the idea that I could re-use the waveguide and try some different CD/woofer/crossover options later. It would be great if we end up with several designs clearly documented across a range of price points, much like the Econowave PCD thread over at PE. As a "recipe builder", I really liked that for the Econowaves. It made it easy for me to "dive in", even though I ended up switching from one design to another after I started the project.


That's my take. Thanks for all your hard work on this stuff!

-Max
post #1688 of 9845
Mr. Cooper-

I believe a number of people plan to contribute some Ewave Deluxe style designs for a range of drivers. I think the focus will be on the DE250 which the SEOS was designed around. It is a very nice driver, the SEOS was designed around it, availability is good and prices are relatively low (plus Erich says he can get better prices).

As far as woofers, I think we will see everything from the Eminence Deltalite 2512 to the Faital 12PR300 up to AE TD woofers.

Flush mounting is advised. How much difference it makes is debated.
post #1689 of 9845
So what's the consensus for the plastic model? Do you think there's enough interest to try to get the preorder thing going? Or should we do fiberglass? Or both?

Are we going to wait until BillW does some listening tests first on the 15?

As mentioned, I'm ready to go with this, just not sure which way you guys want to go.


By the way, 2 weeks ago I sent the file to a different company to get another estimate. Hoping to have that back very soon. My guess is that it will be higher, but we'll see.
post #1690 of 9845
It sounds like most people want the SEOS-12 so that would probably be the best plastic option. I really don't know how big the market is to be honest. If you can get enough people in on the preorder, I don't think you will have a problem with filling the whole thing. I think it would be smart and completely acceptable to accept at least a portion of funds up front.

The downside to the plastic is that you can only offer one size. I'm mainly interested in the SEOS-15 but that doesn't seem to be the case for most. I'd be most interested in the FG version since I'm not doing budget builds.

I'm interested in initial listening impressions, but I'm more interested in some measurement comparisons to the QSC. Maybe polar sonogram, CSD and wavelet formats.

I actually just sketched a design that will use the SEOS-15/DE250/TD15M with huge roundovers (~5" dia on sides that curve around the back for some L'cleach action). It is for a friend, but it will probably be my first SEOS design...unless Jzagaja can whip up a 24-30" wide SEOS with a 1.5" throat.
post #1691 of 9845
New thread with all possibilities and a multiple choice style poll to gather interest/numbers?
post #1692 of 9845
Yeh, the other sizes will still be available in fiberglass, just not as cheap as plastic. I'm going from memory, but I think the 10 was $60 and the 15 was $70. So I'm going to guess the 12 in fiberglass would be about $65. Those were estimates, but he said they were really close.

There would be a need for prepayment on the plastic ones as mentioned earlier. I'll offer up as much as I possibly can, which would be at least 20%, maybe 30% of all the orders. I wish I could do more, but the group buy money is out with flat packs and all the waveguides from Poland were paid for in full. Those won't be shipping for another week, then a few weeks to get here and get that money back in.

Anyway, that would leave 700 to be purchased......at the most, 350 people. Probably closer to 250-300 people. I really doubt that's a problem if it's spread out over 4 forums. I really want to get this figured out as soon as possible because it's going to take a while to get this all worked out.



I just got off the phone with Bill. I'll be taking the models out to him this afternoon so he can do more testing and measuring.
post #1693 of 9845
So it's not possible to get a 70/30 ratio of 12s and 15s?
post #1694 of 9845
Quote:
Originally Posted by Eternal Velocity View Post

So it's not possible to get a 70/30 ratio of 12s and 15s?

I doubt it. The cost of the plastic version is primarily tied up in the mold construction. Two molds would basically require two full orders I'd imagine.
post #1695 of 9845
Quote:
Originally Posted by coctostan View Post

I doubt it. The cost of the plastic version is primarily tied up in the mold construction. Two molds would basically require two full orders I'd imagine.

Ahh, I see. I definitely think the 12" makes a lot more sense for the mass produced version.

I'm gonna have to shell out the big bucks for the 15

and then copy that enclosure design from you!!!
post #1696 of 9845
This is a quick and dirty sketch. One tall and one short. SEOS-15 over TD15M. It is sort of a modern unusual design. The roundovers on the sides are 10.75" OD PVC schedule 40 pipe cut in half. The top and bottom are 1.5" radius roundover with stacked MDF. How's that for minimal diffraction?

I'm working on a terminated transmission line design for the internals. It would split into two paths and would terminate in the PVC endcaps. I could just go sealed instead.

It will be passive.
LL
LL
post #1697 of 9845
Quote:
Originally Posted by coctostan View Post

The roundovers on the sides are 10.75" OD PVC schedule 40 pipe cut in half.

sweet idea...!!! So sweet I might do something very similar. 10.3" sonotube CLD by 9.7" sonotube... amd hopefully a thin curved layer of thin flexible ply beneath that for more CLD.
post #1698 of 9845
Quote:
Originally Posted by pnw View Post

Noah,
Below XO is where the pair of 8" vertical flare is a concern. Not necessarily a deal breaker, but something to consider.

Penn,
...wondered what happened to your project. Gonna restart?

I listened to the 10NDA520's crossed to BMS 18N850's around 250-275...that worked pretty well.

I was going to use the 10NDA520s in a project that had a speaker that looked like the 802Ds. I spent some time building the top section but I could never make a proper female mold from it. I was also having a hard time finding a basss driver choice to match with the design.

At the same time I took a leap and bought IWATA-300s, now I just do not have any need for the "NOT802D" design.

Maybe the 18sound 10" could go in a SEOS-10 design as my surround in room, I can lower the sensitivity and have the 10" run ported down below 100Hz. Who knows, someday I might use them.
post #1699 of 9845
Quote:
Originally Posted by coctostan View Post

Mr. Cooper-

I believe a number of people plan to contribute some Ewave Deluxe style designs for a range of drivers. I think the focus will be on the DE250 which the SEOS was designed around. It is a very nice driver, the SEOS was designed around it, availability is good and prices are relatively low (plus Erich says he can get better prices).

As far as woofers, I think we will see everything from the Eminence Deltalite 2512 to the Faital 12PR300 up to AE TD woofers.

Flush mounting is advised. How much difference it makes is debated.

Yeah, a group buy on the DE250 should make it a very viable solution for most people.

As for flush mounting, its definitely an aesthetics thing.


btw, nice drawings!!! I have been wanting to use PVC rounding sides for a long time now. My PVC cuts have never been too great yet.
post #1700 of 9845
Neat idea about the 10"D PVC pipe for the sides. Have you calculated volume on these?
It would be nice to be able to use the PVC for the top roundover, too. Anyone have any clever ways to do the corners in that case?
post #1701 of 9845
45deg angles?? Bondo/similar for smoothing?
post #1702 of 9845
Quote:
Originally Posted by Erich H View Post

So what's the consensus for the plastic model? Do you think there's enough interest to try to get the preorder thing going? Or should we do fiberglass? Or both?

Are we going to wait until BillW does some listening tests first on the 15?

As mentioned, I'm ready to go with this, just not sure which way you guys want to go.


By the way, 2 weeks ago I sent the file to a different company to get another estimate. Hoping to have that back very soon. My guess is that it will be higher, but we'll see.

I think we should do wantever's most advantagious to the guys involved AND to the commercial guys that were interested in these as well. That'll take some financial burden off of you as the commercial interests would be able to secure a larger number of preordered units.
post #1703 of 9845
When can they get the FG ones going? Im in for the 15's for HT and will probably get whatever the plastic ones are for some outdoor speakers. I hope AE can supply TD's. I also want passive
post #1704 of 9845
Quote:
Originally Posted by Erich H View Post

There would be a need for prepayment on the plastic ones as mentioned earlier. I'll offer up as much as I possibly can, which would be at least 20%, maybe 30% of all the orders. I wish I could do more, but the group buy money is out with flat packs and all the waveguides from Poland were paid for in full. Those won't be shipping for another week, then a few weeks to get here and get that money back in.
.

I will take 10 SEOS-15s, I can mail you the check monday.

Oh....wait I see you have to pick one or the other. I do like the SOES-15 response curve the best but SEOS-12 will match my 4 TD12s so if you need it to be SEOS-12, I will order 10 SEOS-12s.
post #1705 of 9845
Quote:
Originally Posted by Eternal Velocity View Post

sweet idea...!!! So sweet I might do something very similar. 10.3" sonotube CLD by 9.7" sonotube... amd hopefully a thin curved layer of thin flexible ply beneath that for more CLD.

The bummer about sonotube is the seam that runs around it. The PVC can be sanded smooth. The plan is to have them filled, sanded and sprayed with car paint by a friend that owns a body shop. The SEOS will be blended in and sprayed as well. That is BMW's Laguna Seca blue. The color is not final. Those stands will be 2" DOM tubing bent to some shape like I modeled. Those will be powder coated matte black.

Quote:
Originally Posted by penngray View Post

btw, nice drawings!!! I have been wanting to use PVC rounding sides for a long time now. My PVC cuts have never been too great yet.

Thanks. I kind of prefer the old school mid-century looks with squared edges, but my buddy likes more modern looking stuff and these are like Geddes roundovers on roids. Might as well try them. The 10" PVC is expensive so we will use a well built jig.

Quote:
Originally Posted by bwaslo View Post

Neat idea about the 10"D PVC pipe for the sides. Have you calculated volume on these?
It would be nice to be able to use the PVC for the top roundover, too. Anyone have any clever ways to do the corners in that case?

I dunno. I modeled with PVC roundover on the corners and top but it looked kind of funny...and I'm not sure how I would do the corners. I actually like the look of them completely flat on the top and bottom. It gives it an iPod Mini look. The roundover is hard to pass up for ultimate performance though.

I calculated the volume of a smaller version but not this one (this can be done with 8" PVC too, but would require a small bump out on the back panel). I'd guess this is around 4-5cu ft. That should be somewhere between .5 and .7 Q.
post #1706 of 9845
Quote:
Originally Posted by coctostan View Post

This is a quick and dirty sketch. One tall and one short. SEOS-15 over TD15M. It is sort of a modern unusual design. The roundovers on the sides are 10.75" OD PVC schedule 40 pipe cut in half. The top and bottom are 1.5" radius roundover with stacked MDF. How's that for minimal diffraction?

I'm working on a terminated transmission line design for the internals. It would split into two paths and would terminate in the PVC endcaps. I could just go sealed instead.

It will be passive.

Quote:
Originally Posted by bwaslo View Post

Neat idea about the 10"D PVC pipe for the sides. Have you calculated volume on these?
It would be nice to be able to use the PVC for the top roundover, too. Anyone have any clever ways to do the corners in that case?

I can get cabinets made just like that without having to worry about the PVC. I looked into it earlier in the year. I'd just need dimensions.

Yeh, I know....I'm nuts.
post #1707 of 9845
Quote:
Originally Posted by Eternal Velocity View Post

So it's not possible to get a 70/30 ratio of 12s and 15s?



The main costs involved are with the mold. So 2 designs would be twice as much because 2 molds would have to be made.


The fiberglass units won't be THAT much more.
post #1708 of 9845
Quote:
Originally Posted by Erich H View Post

I can get cabinets made just like that without having to worry about the PVC. I looked into it earlier in the year. I'd just need dimensions.

Yeh, I know....I'm nuts.

Hmmm...that sounds much easier. Will they do 1-offs? Any idea on how long it would take to get two FG SEOS-15?
post #1709 of 9845
Thread Starter 
out of curiousity about the cnc process,

how much does it complicate the process to pre-drill pocket screw holes as in the attached image?

or is it much simpler to go with the standard ikea/walmart pre-fab design, second image.
LL
LL
post #1710 of 9845
Quote:
Originally Posted by bwaslo View Post

Neat idea about the 10"D PVC pipe for the sides. ... Anyone have any clever ways to do the corners in that case?

It can be done. A 10" blade might do 8"D. A 12" blade maybe 10"D.

A picture is worth...

I once made a jig in a millwork shop for cutting crown molding...we made mantles as a sideline. The jig allowed a depth of cut ~equal to half the diameter of the blade, less the arbor washer.
The jig was set up to cut mating sides of the miter without moving anything...just the saw blade...the accuracy was trimable and set up in the jig.
Angle the sawcut right 45 degrees. One piece is cut aligned with the fence. the other piece is cut aligned with an auxiliary fence built into the jig and 90 degrees to the fence. These fences mentioned were to position the stock above the jig, there were "toes" to restrict movement of the stock resting on the jig.

As with crown molding, you are cutting upside down and backwards.
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