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post #11131 of 11156 Old 09-09-2014, 02:59 PM
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Adding mids just makes it a 3 way. In that case both woofers can usually play up to the mid cross over point without issue. Considering the height of the tweeter in that speaker, is just above ear height when I sit down, mean you'd want to do WTMW for that size of 3 way.
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post #11132 of 11156 Old 09-09-2014, 03:01 PM
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You mean you would crossover to the mids lower than if you just crossed to the CD ? So the negatives of the higher crossover and problems somewhat go away with the 3 way vs the 2way ?

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #11133 of 11156 Old 09-09-2014, 03:09 PM
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Originally Posted by tuxedocivic View Post
I don't think anyone would use an MMT. So that's out. Really it's about MTM or TMM.

The MTM is the one that'll have a symmetrical vertical polar response. In other words, it'll sound the same above and below. Still possibly different from on axis, but the above and below axis will be the same. It also places both mids/woofer equidistant to the tweeter so you may be able to run both mids/woofers to full bandwidth up to the XO point.

The TMM places one of the mids to far away to allow the lower woofer to play up to the XO. So you usually are forced to limit the bandwidth of the lower woofer. The trade off however is the functionality of a TMM. The TMM will not be as tall. And it naturally allows for a lot of baffle step compensation by placing one of the woofers near the floor (if it's a large speaker).



I couldn't resist
Stop.

Wait.

Backup.

Comeon man you cant post that and not divulge....

Awesome look, did you bondo in the waveguide and paint matte?

What woofers?

its that a 3 or 2.5 way?

Ive seen you hinting around about this, im calling you out man spill it!
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post #11134 of 11156 Old 09-09-2014, 03:13 PM - Thread Starter
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"I couldn't resist"


woot. cool!

Listen. It's All Good.
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post #11135 of 11156 Old 09-09-2014, 03:14 PM
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He's got a thread about it. Check it out. It's not a secret.

Enough theory talk, I gotta build something. Celestion FTR12-3070C

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post #11136 of 11156 Old 09-09-2014, 03:16 PM
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haha, hey Nick. Not hiding a thing: Enough theory talk, I gotta build something. Celestion FTR12-3070C

I have yet to do the final measurements and photos. But they were well received at a recent DIY gtg. And I've been listening all summer and am quite happy with the results. I've always hated 2.5 ways, and nearly gave up on this one multiple times. In the end as much as I have been frustrated with this speaker over the last 6 months, I really love it now.
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post #11137 of 11156 Old 09-09-2014, 03:16 PM
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Quote:
Originally Posted by NicksHitachi View Post
Stop.

Wait.

Backup.

Comeon man you cant post that and not divulge....

Awesome look, did you bondo in the waveguide and paint matte?

What woofers?

its that a 3 or 2.5 way?

Ive seen you hinting around about this, im calling you out man spill it!
Looks for Tux's "need to build something" thread from a while back, details are there. Sorry for no link, on my phone / at work / lazy.

Edit: too slow but at least I was beaten by the man himself.
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post #11138 of 11156 Old 09-09-2014, 03:21 PM
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"You mean you would crossover to the mids lower than if you just crossed to the CD ? So the negatives of the higher crossover and problems somewhat go away with the 3 way vs the 2way ?"

These frequencies are just arbitrary values and just for example.

For a 2-way (2.5 way actually) with two woofer's TMM, you have tweeter say 1500- 20000 hz, the first woofer 0-1500 hz and the bottom woofer say 0-500 hz

For a 3-way, you'd have both woofer's 0-500 hz, a mid 500-1500, and tweeter 1500-20000.

the advantage of an MTM, other than controlled vertical directivity is that usually you can run both woofers 0-1500 hz, as they are both close to the tweeter

A 3 -way design creates just as many problems as it fixes compared to a 2-way, they're just different designs. There's always going to be tradeoffs.


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Last edited by Bassment; 09-09-2014 at 03:38 PM.
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post #11139 of 11156 Old 09-09-2014, 03:22 PM
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Dang guess i better quit snoozin.....

Nice work, ill plow through the details tomorrow, im on my phone now.

Ive been waiting to see someone do an integrated waveguide in the baffle.

It looks sick. Props.
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post #11140 of 11156 Old 09-09-2014, 03:45 PM
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Thanks Nick
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post #11141 of 11156 Old 09-09-2014, 03:47 PM
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Quote:
Originally Posted by NicksHitachi View Post
Dang guess i better quit snoozin.....

Nice work, ill plow through the details tomorrow, im on my phone now.

Ive been waiting to see someone do an integrated waveguide in the baffle.

It looks sick. Props.


I'm seen Tux's speaker in person, the pictures do not do it justice!
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post #11142 of 11156 Old 09-09-2014, 05:04 PM
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Thanks Joe. The finish was a friggin' battle. Everything that could go wrong, did. I'm still not satisfied but I've learned to live with it. And I'm extremely picky. I look at it from 3 inches away in the bright sun and see a little scratch or dust fleck and I'm like, this thing is junk Thankfully when I turn the lights off and listen to music, they're quite incredible. Last night I listened to Diana Krall Live In Paris and was really impressed. When you design your own speakers your tastes becomed ruined. It's hard to impress yourself. But these do it.
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post #11143 of 11156 Old 09-09-2014, 05:07 PM
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Compared to 1099... What's your opinion on them ?
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post #11144 of 11156 Old 09-11-2014, 12:00 PM
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Hey guys. I just tossed together a customer review of the BA-750 - and by extension - SEOS-18 if anyone's interested. It'll be online as soon as it gets the green light over at DIY Sound Group so give it a read.
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post #11145 of 11156 Old 09-11-2014, 12:31 PM
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Quote:
Originally Posted by tuxedocivic View Post



I couldn't resist
That's is awesome looking. Love it.

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post #11146 of 11156 Old 09-11-2014, 12:59 PM
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I can't wait to hear these speakers again come October 25th!
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post #11147 of 11156 Old 09-11-2014, 01:49 PM
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Hey guys. I just tossed together a customer review of the BA-750 - and by extension - SEOS-18 if anyone's interested. It'll be online as soon as it gets the green light over at DIY Sound Group so give it a read.
You finally built something with them?!? Tell us more. If I come to Calgary can I hear them?
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post #11148 of 11156 Old 09-11-2014, 02:23 PM
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I can't wait to hear these speakers again come October 25th!
So ferry no issue now ?
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post #11149 of 11156 Old 09-11-2014, 03:19 PM
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I'm gonna try and make something work. Tony wanted to come as well, so maybe I can go over with him or something.
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post #11150 of 11156 Old 09-11-2014, 03:41 PM
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Originally Posted by tuxedocivic View Post
You finally built something with them?!? Tell us more.
The review is up:
http://www.diysoundgroup.com/review/...8/category/44/

This is the build thread. I'm slow. They're not "done" yet. I might be working on an unrelated project in the meantime while they are put on the temporary backburner.

Quote:
If I come to Calgary can I hear them?
It's possible, but generally we don't listen loud enough that you can hear them everywhere in a big sprawl like Calgary. So it depends which day you come.



Of course! You're always welcome to come check em out - in fact I'd love to get an unbiased set of ears on them.
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post #11151 of 11156 Old 09-11-2014, 04:31 PM
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Very nice EV.

I notice you mentioned you had to boost the low end to hit your XO point. Does your transfer function actually go above 0db or did you attenuate the tweeter then boost, such that maybe you were still below 0db at the XO. You mentioned that it would be tricky with a passive filter. Granted active is a good way to go with a speaker of that calibre!

Second thing was that you're gonna tint the baffle red with transtint. Careful with tint on birch. I've used transtint on maple, which has a similar staining properties as birch, and it was not pretty. I found doing a shellac coat then another tinted coat of shellac was much better to get the wet red (black for me) over wood look.
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post #11152 of 11156 Old 09-11-2014, 05:10 PM
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Originally Posted by tuxedocivic View Post
Very nice EV.

I notice you mentioned you had to boost the low end to hit your XO point. Does your transfer function actually go above 0db or did you attenuate the tweeter then boost, such that maybe you were still below 0db at the XO. You mentioned that it would be tricky with a passive filter. Granted active is a good way to go with a speaker of that calibre!
Good eye - you so quickly identified one of the issues to be careful with when using the miniDSP as the controller, and one of the reasons I'm going to be switching to analog-active once the later stages are complete (the other being that I like the miniDSP as a quick-prototype tool).

The input is what gets attenuated in order to "boost" the output, if that makes any sense. All actual tweeter attenuation is actually done at the next stage, not within the miniDSP itself as this helped keep electronics noise floor low.

I simply played my highest voltage source with a signal direct into the miniDSP and watched the levels to see how they would approach zero - both on the input side and the output side. The miniDSP software is really cool like that. If I had identified anything getting close to the zero mark, I would have attenuated the input until I have some headroom.

I've determined that currently there's no apparent clipping even with the boost applied. Part of that is because the boost is almost cancelled out by the simultaneous high pass. It just helps shape the frequency response more than actually boost the natural response. The most gain actually comes at ~25khz due to the treble shelf filter in the top two octaves (4khz to 16khz), and that could easily have been done differently with negative gain instead. I think one could pull off +/- 3db response passively with a big higher an XO point (maybe around 1.3khz instead) and no boost. I just don't see the point of running a 15 inch woofer up there, plus if i'm crossing that high I'd probably get the small Radian Aluminum or Be tweeter instead.

The way this system works currently is a bit unique. It's so inherently "prototype-phase" that there's no modern HT electronics there. The amp, which doubles as a volume pot, is a Marantz SR6300 (yes, you read that right). It's an old, early 2000s 6.1 channel receiver I picked up off of kijiji. I simply run the MiniDSP into its analog surround inputs and then attenuate the "surround" (tweeter) channel the correct amount. The point was just to get something working in the meantime and avoid clipping either digital or analog and I feel I've hit the objective. Once a true analog active crossover is ready, I would prefer to use some outbound fixed-gain amps and run it off the pre-outs of a modern prepro or receiver. I don't trust the miniDSP being driven by dedicated pre-outs because I've experienced it clipping first hand off of my own electronics.

Quote:
Second thing was that you're gonna tint the baffle red with transtint. Careful with tint on birch. I've used transtint on maple, which has a similar staining properties as birch, and it was not pretty. I found doing a shellac coat then another tinted coat of shellac was much better to get the wet red (black for me) over wood look.
Interesting. I had a bunch of scrap birch (that I had cut out as bracing until it ended up excess) I was going to test out on anyways before getting straight to the baffle, but I'll take your advice for sure. How do I tint the second coat of shellac the right colour? I'm all ears.

Last edited by Eternal Velocity; 09-11-2014 at 05:50 PM.
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post #11153 of 11156 Old 09-11-2014, 06:59 PM
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Lots of woods need a coat of a sealer so the absorb stain or dye evenly, else they will end up blotchey. I've used the Zinnser spray shellac for this, and you can find other products meant as base/seal coats. Whatever it is, it will be a light or thin coat.
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post #11154 of 11156 Old 09-11-2014, 08:40 PM
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Cool build Eternal, that is very similar what I'm wanting to do. I want to do a MTM though, sealed TD 15m, and no Apollo upgrade, and active.


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post #11155 of 11156 Old 09-12-2014, 05:00 AM
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Quote:
Originally Posted by tuxedocivic View Post
Thanks Joe. The finish was a friggin' battle. Everything that could go wrong, did. I'm still not satisfied but I've learned to live with it. And I'm extremely picky. I look at it from 3 inches away in the bright sun and see a little scratch or dust fleck and I'm like, this thing is junk Thankfully when I turn the lights off and listen to music, they're quite incredible. Last night I listened to Diana Krall Live In Paris and was really impressed. When you design your own speakers your tastes becomed ruined. It's hard to impress yourself. But these do it.
tux, one of the things I do in simulations with Martin's work sheets is slope the top of the cabinet. It appears you recognize the benefits for getting the mid-woof as close to the end of the line as possible.

To do this I use the back-loaded horn worksheet.

When I slope the top of the cabinet down from front to back 4", I reduce the driver position ratio by what amounts to half of that...2".

The result in the sim's is a reduction of ripple in the range centered right where you chose to place your crossover.

Interesting comments about the BA 750...I have a pair to use on the Iwata 600.

AE GB $$$ sent 10-18-11; TD15M arrive 01-16-13, ...454 days

Last edited by bg40403; 09-12-2014 at 05:22 AM.
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post #11156 of 11156 Old 09-12-2014, 07:06 AM
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Hey BG,

Ya I certainly didn't go fancy with the box shape. In the upper portion of the cab I've placed some stuffing around the waveguide as well as some chucks of close cell foam. Between the stuffing, the foam, and the waveguide I believe I've got enough dispersion and absorption that the long internal standing wave isn't a problem. I've slanted the tops of boxes before but then you can't put anything on top of them.

I hope you do a thread with your iwata horns!


Edit, you must be talking to EV about the BA-750. Actually I'm now wondering if your whole post was meant for him as he sloped the top of his cab and did a TL using king's worksheets.

Last edited by tuxedocivic; 09-12-2014 at 07:09 AM.
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