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Old 9th October 2006, 05:28 AM   #1
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Smile yet another ill-advised project...

Ok, I started here just looking for info, and now have been bitten.

Short version: Designing a sealed 3-way, based on a 6.5" midrange and 2 x 10" woofers.

I've noticed that a typical approach to a design is to form up the goals, pick drivers, and design the enclosure(s) and crossover. What I have in mind, more or less, is to develop the drivers from the desired enclosure. An anti-causal design, if you will.

My reasoning is that I know what I want the speaker to sound like, and I know what I want it to look like...and I like a good challenge.

Many years ago, I used to play in a jazz band. I can still tell the difference between a brass and nickel-silver trombone from beyond visual range. (As could any horn player! If you want a small bore silver trombone...just buy a trumpet!) I also love the sound of a tenor sax. We would practice and generally play acoustic, with an occasional amplified performance. Reading through this forum is leading me to believe that for nearly 20 years I've been judging speakers by their ability to reproduce those horns accurately. The thought of the sound of low-end (maybe all) pro horn speakers playing jazz still makes me cringe. To me, they make a brass instrument sound like it's mixed with equal parts kazoo. On the other hand, I've heard a few consumer speakers that, to me, sound pretty good. Emphasis on "few"....

Sorry for the boring background, I'm just trying to set and explain the expectations. "Good" means different things to different people, and I'm making assumptions when I jump from "what I want", to "what I think I want". From the above, what I think I want is: A generally flat speaker, with the range of about 80 to 1200Hz to be as flat and non-distorted as possible, with an overall frequency response of 50 to 20k. (I'm old, but can still hear those annoying 19kHz tones just fine.) I don't know if I could or would hear things like phase/timing errors or diffraction from the tweaters....I have no idea what those things even sound like.

What I want it to look like is a pair of full range speakers, with 2 10" woofers, a 6.5" midrange, and some sort of tweeter, stacked WWMT. Why? Mostly because I just like that look. Partly because I want to make what I want to hear fit what I want to see. Something that looks like it should sound good, and at the same time sound better than it appears that it should.

Why not ported? I'm not keen on adding more mechanical resonance in the range that I want to listen to. The interplay of the drivers, and their harmonic distortion, combined with the interaction of the port and enclosure...just too much for me. Electrical filtering I've done, I understand, and I can model.

So am I nuts? I hope not. My primary reasoning is that the 6.5 to 10 cross shouldn't be a big stretch, and that 2x10, even in a sealed enclosure, can handle being driven flat to 50.

There also may be a hidden bit of sense in my crazy plan. A 6.5" driver is pretty much the size of what I'd call the "sweet spot" of a trombone bell, and if my memory is right, pretty close to the size of the bell of a tenor sax.

Which midrange? Most home speaker midranges seem to be 5" or less. So I'm thinking about the Eminence 6 Alpha:

http://www.partsexpress.com/pe/showd...number=290-400

If the published response is to be believed, it should be easy to work with, and I've read good things on here about Eminence.

So what am I missing? How crazy is this? and If this mid is reasonable, what should I be looking for for the woofers and tweeter? I have ideas, but would like to see how well the project and mid choice flies first.
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Old 9th October 2006, 10:08 AM   #2
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Hi Tom,
For a midrange you should have a look at this Tang Band driver: http://www.partsexpress.com/pe/showd...umber=264-852.

Listed as a woofer, it will actually play up to about 12K, tho it starts beaming around 5K. Very nice midrange indeed - light cones. 4 of them are in my living room. I haven't heard the Alpha 6, but it gets good reviews.
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Old 9th October 2006, 12:24 PM   #3
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Hey Tom, sounds like a good set up. I've been going over some speakers for a while and about to build something very simular if almost not the same. I'm at work right now, but I'll slip some info in here very soon.
The only question is, budget?
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Old 9th October 2006, 07:01 PM   #4
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So maybe I'm not nuts?

That Tag Band looks nice. It would work as a sealed midrange? Based on the Qts and Vas, it looks like it want about a 10" cube for a box. Does that sound about right? Using the numbers for the Alpha, it wants about half that volume, which fits with the spec sheet listing the recommended box size as .1-.2 ft^3.

The power ratings of the two speakers is puzzling. The Alpha with a 100W rating, the Tag at 30W. The target room for these is about 300 ft^2, carpeted, and an 8' acoustical tile ceiling. I have no idea what to expect in terms of efficiency. If the overall efficiency of the speaker, not counting any bass EQ, ends up around 90db/w, I would guess that 50W of average audio power would be more than enough to be annoyingly loud. Not something I'd normally do, but I'd like the capability. From reading here, power and efficiency ratings have to be taken with a grain of salt. Will either or both of these mids play loud enough, assuming I don't cross with the woofers too low, or am I worrying about something silly?

Not counting the electronics and wood, I'd be happy if the drivers were less than $350 a speaker. I'd love it to be less, but I could live with more. I'm not married, so if it's a bit more, I just wait a little longer.

For the woofers, I'd planned on using technology to make up for my lack of experience. My idea is to buy an inexpensive active crossover and parametric EQ, and tune a test speaker with either one of the test programs I've been reading about here, or even a signal generator and a scope.

My crazy thought for the woofers is this: At low listening levels, I should be able to use something along the lines of a Linkwitz transform to boost the low end flat to around 40-50 Hz or so (maybe lower!), and use power to make up for the roll off on the low end with sealed 10" woofers. At higher levels, I can let the woofers roll off naturally at a higher level, to avoid blowing them apart. At some point, I could add a mono subwoofer, as I believe the 10's should handle being crossed around 80, if it's steep, at a pretty high power.

If the woofer plan is halfway reasonable, what should I look for in woofers? Obviously something that can run sealed, and that will handle a bit of power, but beyond that I just don't know. Pro drivers at 10" seem to be midranges, and consumer drivers seem to be designed for a ported box. Oh, and to top it off, I'd like to find a 4 or 16 ohm woofer, to allow for the option of a simple passive crossover being driven at around 8 ohms. I'm guessing I'll want to use an active cross, and two amps, but I'd like the option of being able to use a consumer amp of around 200 watts.
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Old 9th October 2006, 10:39 PM   #5
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I don't think either mid will have any trouble with a 50 WPC amp. Obiviously the Alpha will handle more. But they should both run out of cone excursion at about 150Hz with peak power. So that's really your limit. You would be crossing above that, right?

Don't know for your 10s. I've always wondered what the Usher 1001 sounds like. It could go sealed or ported in a moderate size box. Two in parallele should be as about loud as the mid. Might be out of budget, tho.

Have a poke around to see if anyone likes-knows the Usher 1001 10".
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Old 10th October 2006, 06:37 AM   #6
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I hadn't really thought about $100+ woofers, but unless I go with something like Goldwood that may be where I'm at. None of the Dayton's seem to fit, and I really don't like the idea of a clear plastic cone.

The Usher's look OK, but not a heck of a lot of feedback on them. Looking around in the same price range, I see the Vifa PL26 at Madisound. 10" coated paper, 4 ohm version available, specs very much like the Usher.

Based on the Alpha 6 curves, I was thinking of crossing around 200-300Hz, depending on the woofer and how they sound.

For the mids, I wouldn't mind buying one of the Tags and one Alpha, to test. That actually sounds like fun. For paired woofers, I suspect I'll read what I can, and take my best guess.

Now what to do about the top? The tweeter obviously has to work with the 6.5" midrange, which leads me to think a crossover around 2500-3000 if I use the Alpha, and maybe up to 4000 if I use the Tangs. I know I don't want piezo, and I'm pretty sure I don't want ribbon...dome?
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Old 10th October 2006, 07:38 AM   #7
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Well you did say up to $350 per side driver cost. A pair of Usher 10s, + a mid leaves you about $100, for the tweeter right?

There are soooo many tweeters, how do you choose? I know you will need a pretty dynamic tweeter to keep up with the Tang Band mid. Maybe more so for the Alpha 6. I use a horn tweeter to keep up with dual TB W6-789s.

I have looked at the Vifa tens. Don't know them, but I like my Vifa 7" woofers in bookshelf speakers. Lots of Vifa fans here.

Quote:
I wouldn't mind buying one of the Tangs and one Alpha, to test.
Was hoping you would say that! Sure would like to know what you find.

My current object of desire is the Usher HM15 15" studio monitor woofer that's on sale at P.E. Don't know how it sounds, but something about the way it looks just talks to me. =)
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Old 11th October 2006, 01:13 AM   #8
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Quote:
Originally posted by panomaniac

There are soooo many tweeters, how do you choose? I know you will need a pretty dynamic tweeter to keep up with the Tang Band mid. Maybe more so for the Alpha 6. I use a horn tweeter to keep up with dual TB W6-789s.

I keep hoping someone will pop in and say "hey, you blockhead, try these: "!

In one sense, the tweeter might be easier, because I suspect that I've never heard a good one. Do the horns vs domes sound dramatically different?

I'm going to have to go back and read the Zaph site again...
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Old 11th October 2006, 01:49 AM   #9
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Quote:
Originally posted by RandomTom
Do the horns vs domes sound dramatically different?
Sure do. The domes are much easier to get right. Horns can be tricky. I think that I might drop my horns in favor of a slot type tweeter. Mostly because of the physical alignment problems. The little Selenium horn is actually a couple of inches deeper than the W6-789. I believe that this misalignment is giving me phase grief.
But I could be wrong.

Need to break out the mic and measure it. Have been thinking that a slot tweeter would be easier to align with the woofer/mids. Plenty sensitive enough for my use. Something to try....
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Old 11th October 2006, 03:06 AM   #10
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Quote:
Originally posted by RandomTom

The Usher's look OK, but not a heck of a lot of feedback on them.
Usher is supposed to be quite good. In fact, I read that the Dayton Reference Series tweeter is manufactured by Usher.
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