Enough theory talk, I gotta build something. Celestion FTR12-3070C - Page 17 - AVS Forum
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post #481 of 506 Old 10-21-2014, 02:59 AM
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I can't wait to hear more about it tux! Will it be available as a DIY kit in the future?
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post #482 of 506 Old 10-21-2014, 06:49 AM - Thread Starter
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No, it won't be available. I'm offering the XOers if someone wants to source all the other components themselves. Once I post the measurements and get feedback from the GtG I'll say more on that.
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post #483 of 506 Old 10-21-2014, 08:18 AM
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Quote:
Originally Posted by chalugadp View Post
Vancouver part 2
Linky?

I would love to read and follow that. The first one was cool. You guys are just on the other side of the world from me... lol.

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post #484 of 506 Old 10-21-2014, 09:59 AM
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post #485 of 506 Old 10-22-2014, 06:42 AM
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Oh my. The DO WANT feeling on theese speakers surpassed the 1099.

Quick question. You said that everything fell in place when you lowered the XO to 900ish. Do you think a Sesos 15 could be beneficial on this? Not talking a straigth swap, but with matching XO. (Question just for mental excercise/curiosity)
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post #486 of 506 Old 10-22-2014, 07:42 AM - Thread Starter
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Hi eXa.

Thanks!

Well, for mental excersize, yes, a SEOS 15 would be better. But so would adding mids and going to 15" woofers and active XOers, and... 900hz is very low for the waveguide, but I still have an excellent directivity match, which you'll see when I port my measurements. It's not so low that the woofer can't pick up the directivity in time.

Good question
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post #487 of 506 Old 10-22-2014, 08:56 AM
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Cant wait
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post #488 of 506 Old 10-29-2014, 09:45 AM - Thread Starter
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Ok, probably the last bump unless something happens/changes.

Here's the on axis response with and without the grills. Blue is without grills.



Here's 0, 30, 60 degrees.



And here's the ground plane bass response.

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post #489 of 506 Old 10-29-2014, 11:58 AM
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Nice work! I'm kind of surprised you have such a nice match running the seos 12 that low.

I see you have a dip off axis around 14khz. Probably not audible, but I've seen the same thing with my waveguides. Some plumbers putty smoothes out the little gap between the cd and the wg throat and takes care of the dip. I noticed it cleaned up the hf hash a bit as well.
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post #490 of 506 Old 10-29-2014, 12:20 PM - Thread Starter
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Thanks.

I thought it might be the phragm breaking up, hadn't considered the throat but that makes sense. I'm not sure I'll bother though. My other CD measures with less "hash", but does have some off axis irregularity.
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post #491 of 506 Old 10-29-2014, 12:45 PM
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That dip is caused by the phase plug in the compression driver. Way back when I was testing the plastic SEOS-15 samples against the fiberglass I had a similar dip show up on the plastic model but not the fiberglass. It had me perplexed and Erich was really worried something was wrong with the mold. I was playing around with it more and figured out depending upon the angle the CD is mounted the dip changed or disappeared. (I had it clamped on to try the different angles.) Try measuring the opposite side it might not be there on that side. I would post a graph but I am on my phone.
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post #492 of 506 Old 10-29-2014, 12:49 PM - Thread Starter
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I certainly tried to center the CD as best possible. If I find time I'll check it out. I would never hear that TBH.
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post #493 of 506 Old 10-29-2014, 05:19 PM
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mtg - are you talking the angle of rotation? If that's the case then I would think the phase plug is flawed. On my waveguides I noticed that off axis null measuring both sides horizontally and vertically. The plumbers putty took care of that in every direction that I measured.
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post #494 of 506 Old 10-29-2014, 09:49 PM
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Yes the angle of rotation that the CD is mounted, The fiberglass has the mounting holes vertical while they are at an angle on the plastic waveguide. Looking back at my measurements what I saw is not as severe as what is in Tux's measurement. Maybe this is not the same thing. Here is my measurement, only about 3dB when 40+ degrees off axis which is not really audible. (I went to 60 degrees with these):
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post #495 of 506 Old 10-29-2014, 10:03 PM - Thread Starter
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If you use any smoothing that may be why mtg. I don't have any smoothing on those graphs, just gating. Which leaves the top octave extremely high resolution.
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post #496 of 506 Old 10-29-2014, 10:19 PM
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Shoot I forgot, looks like it was 1/12th on that graph.



Here is 0-40-60 degrees without smoothing, it's a very narrow notch:
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post #497 of 506 Old 10-30-2014, 07:46 AM - Thread Starter
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Ours look really close now I think.
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post #498 of 506 Old 11-13-2014, 10:07 AM
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I think this is the design for me. I like the cast frame woofers and the fact that it will dig lower than some of the other designs.

Would it change the sound characteristics if these were place on a 12" high sand-filled stage or was the intent to be placed on the floor? In my case, I would place them within a foot of the front edge.

Also, is it possible to use the Tempest baffle with your port specs and crossovers?

Great job BTW! Mine will be hidden behind an A/T screen and false wall--so no need to be that aesthetic.

R/Shawn
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post #499 of 506 Old 11-13-2014, 10:23 AM - Thread Starter
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Hey Shawn.

The idea is the lower woofer is floor loaded, and that give it more kick, but if it's on the stage within 12" of the main floor I think you'd be ok. It's like any speaker you put in your room, the sound can change. When I brought them to jbrown's they were on the edge of his 12" riser and they worked great. His room has a big suckout at 80 and 250hz. But I think you're within the general intent of what I designed here.

I started making drawings and stuff in case people wanted to build these. I haven't had much interest. And I have talked to Erich about how he could sell people the parts. I do have the bill of materials done though for anyone who wants to see what's involved cost wise. It's not a cheap speaker. The XO is complex with big values too. If you'd like to have a look at that just PM me your email and I'll send it to you. I'll try and finish the CAD drawings of the box design aswell so you can see that. Or anyone who wants to see.

As for the Tempest baffle, it would work. Even the tuning is very similar. But it's tricky cause there are two woofers. So I'm not sure what you'd do there... I was thinking most people would just build one big speaker, not modular like I did. But either way would be just fine.
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post #500 of 506 Old 11-13-2014, 11:36 AM
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Quote:
Originally Posted by tuxedocivic View Post
BTW, Axel finished his bowl

Actually, your son may have just designed the ultimate speaker enclosure and we are all just too dumb to have noticed!
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post #501 of 506 Old 11-13-2014, 11:49 AM
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That is funny. When I first glance at this thread, I thought he was making wooden wave guides by hand and immediately dismissed the possibility of this build due to complexity. I'm glad I finally finished reading the whole thread, but that wasn't until I read the results of the Vancouver GTG.

Last edited by Wahoo_envy; 11-13-2014 at 01:41 PM.
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post #502 of 506 Old 11-13-2014, 12:47 PM - Thread Starter
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Ha, in retrospect, I can see how someone would have thought that! Not a bad idea. I've done small round waveguides for dome tweeters from wood.
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post #503 of 506 Old 11-13-2014, 08:27 PM
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Quote:
Originally Posted by tuxedocivic View Post
Hey Shawn.

The idea is the lower woofer is floor loaded, and that give it more kick, but if it's on the stage within 12" of the main floor I think you'd be ok. It's like any speaker you put in your room, the sound can change. When I brought them to jbrown's they were on the edge of his 12" riser and they worked great. His room has a big suckout at 80 and 250hz. But I think you're within the general intent of what I designed here.

I started making drawings and stuff in case people wanted to build these. I haven't had much interest. And I have talked to Erich about how he could sell people the parts. I do have the bill of materials done though for anyone who wants to see what's involved cost wise. It's not a cheap speaker. The XO is complex with big values too. If you'd like to have a look at that just PM me your email and I'll send it to you. I'll try and finish the CAD drawings of the box design aswell so you can see that. Or anyone who wants to see.

As for the Tempest baffle, it would work. Even the tuning is very similar. But it's tricky cause there are two woofers. So I'm not sure what you'd do there... I was thinking most people would just build one big speaker, not modular like I did. But either way would be just fine.
That will be great to see the BOM and drawings. PM with my email address has been sent.

Another question about the lower woofer--how bad would the performance of the speaker be effected with the screen frame cutting across the woofer horizontally?
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post #504 of 506 Unread Today, 08:07 AM
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Ryan,

I am coming here to continue the question I had about the speaker on the bottom. I am curious to the reasons why ? (I want to learn)


Can you explain a little in the design choice of that, versus a MTM type with a SEOS in between two. I have seen a lot of other speakers designed like that too, so I am curious to hear your thoughts on this.

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post #505 of 506 Unread Today, 09:33 AM - Thread Starter
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Thanks for coming here, didn't want to clog up that guys thread.

To do a TMM, you usually have to make it a 2.5 way XO, which is what I ended up doing here. The advantage of a 2.5 way the way I've done it is the woofer is boundary loaded, so tons of bass output. It also helps to minimize the floor reflection and ceiling reflection to a lesser extent, but doesn't do it quite as well as the MTM. It also has the practical advantage of not being as tall. This was quite important to me. A disadvantage of 2.5way is XO complexity and it robs some effeciency out of the midrange. I find the effeciency to not be an issue. Effeciency matters most at 100hz. This is where the baffle step losses are happening, sound tracks are demanding, etc.

An MTM on the other hand will have more vertical directivity (assuming not a 2.5 way with the MTM) so it'll actually do a better job at reducing floor and ceiling reflections. But as far as bass is concerned, both woofers are in full space (sorta). So it won't have quite the oomph in the bass department as my setup. It's also very tall and tippy. Another draw back of it not being 2.5way is you can get lobing, or nulls, in the vertical direction. Especially with such a large spacing between the woofers. Generally, the bigger the speaker the harder this is to deal with. The 10" size is generally ok, even with a 1500hz XO (Cinema 10 Max). But that does have nulls beyond 20 degrees vertically. But a 12", even if crossing down around 1000hz (quite low) would be worse. Then at 15" it's pretty much impossible. You'll get nulls even 10 degrees off probably. That's with the SEOS which is quite short. Most waveguides are taller than the SEOS.

Hope that helps.
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post #506 of 506 Unread Today, 09:39 AM
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Awesome! Thank you! Intelligently explained and exactly what I was looking for.

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