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Multi-Way Conventional loudspeakers with crossovers

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Old 19th October 2013, 01:07 PM   #21
Dissi is online now Dissi  Switzerland
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Trying to design a minimum budget speaker is a good idea, but I think, the cabinet should also be kept as simple as possible to facilitate the build. That means no edge rounding and a classic plastic tube as vent.

I would save $11 on the drivers and invest the amount in a uncompromising crossover:

The Madisound Speaker Store
The Madisound Speaker Store

The Peerless SDS164 needs more volume than the SF, around 1 cu ft should do.
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Old 19th October 2013, 01:35 PM   #22
tvrgeek is offline tvrgeek  United States
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sreten,
As I want to come to terms with SE, reproducing your simulation would be a good place to start. I have to admit, I don't see how to get an elliptical in third order. What algorithms are you using? I would love to plug them into my spreadsheet I use for crude first pass and drop them into SPICE to understand.

Of course, one has to build the crossover to see how close, but SE is usually darn close. What were the values you came up with? I found smoothing the ripple in the crossover range to be a bit more challenging than the sim suggested. Padding the tweeter became a real pain as I kept getting bigger and bigger midrange problems.

Assuming moving from second to third order, and the allowable slide to 2K, what advantages do you see in the elliptical over a Butterworth? The difference in initial rolloff is only within a few hundred Hz. Kind of where Small left off, "no obvious advantage"

Cheap drivers sure are difficult to use. This is part of what I was trying to show. Read the Santori threads and they make you drool.
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Old 19th October 2013, 01:54 PM   #23
ODougbo is offline ODougbo  United States
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Box size should be 13 liters.

Thanks for Michael C. for posting size, etc. Canned Crossover Design - What Next?

Quote:
Originally Posted by tvrgeek View Post
OK, now you are going to make me put them in a box with my style of large radius baffle and see if I can tweak the top end a tad more.
One thing that is very nice about the SF, it handles a lot of power, something to do the short throw.
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Old 19th October 2013, 02:06 PM   #24
tvrgeek is offline tvrgeek  United States
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Quote:
Originally Posted by Dissi View Post
Trying to design a minimum budget speaker is a good idea, but I think, the cabinet should also be kept as simple as possible to facilitate the build. That means no edge rounding and a classic plastic tube as vent.

I would save $11 on the drivers and invest the amount in a uncompromising crossover:

The Madisound Speaker Store
The Madisound Speaker Store

The Peerless SDS164 needs more volume than the SF, around 1 cu ft should do.
Agree totally on classic vent. Out the rear. I would argue the value of the round-over. It really is significant. If you don't have a router that can sling a 3/4 bit, you can do it with a rasp and sand paper. Seriously, it can make a very big difference. I am starting on a set as soon as I do the layout today from 3/4 particle board. Doug is building another set so we will be able to A/B them. I am betting I can squeeze $50 out of the build in the box and improve the top end at the same time. The total cost was quite a bit higher than I expected when I added it up.

The SF woofer is hard to beat for it's low end and small box. These are only 13L. That is a big attraction and was the reason to do this in the first place. They play pretty loud without getting ugly. The Peerless is definitely one to look at if planning on a AV with a sub and high crossover to a sealed cabinet. (my favorite configuration). I am not sure it could match the bass of the SF stand alone. Model it and see what it says.

I think the Dayton tweet is hard to better for the price. I have used that Vifa and I consider it to be vile. It is useless below 3K and I would not use it above 3K either. Not that there are not worse. I would say it is the most significant factor that got me to move to Seas drivers in the $50 and up range. I used to think it was more a matter of good crossover design, but now I understand the difference is in the tweeter too.

$10 more for each crossover may or may not get you much further. You can save about $5 by using electrolytics on the woofer for sure. Not enough to go third order and not enough for a LC notch. Half way there? The Peerless has the same breakup issues, so no savings there.

By all means, at least work up the alternatives on paper!
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Old 19th October 2013, 08:37 PM   #25
tvrgeek is offline tvrgeek  United States
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Doped the cone on my extra Silver FLute with RTV. It lowered Qts and Vas. I have not tested to see I gained anything in lowering the breakup Q. I hope I did not lower the frequency! I could dope the back side with something rigid to push it back up.
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Old 19th October 2013, 08:39 PM   #26
tvrgeek is offline tvrgeek  United States
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Test baffle almost done. I am mounting the tweeter sans flange from the rear in a 3/4 inch roundover hole. The suspension sits right like it did to the flange. How much contour I will need to flatten it out is unknown.
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Old 19th October 2013, 10:09 PM   #27
ODougbo is offline ODougbo  United States
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Sounds like a mini wave guide.
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Old 19th October 2013, 11:11 PM   #28
tvrgeek is offline tvrgeek  United States
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Exactly.
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Old 20th October 2013, 05:15 AM   #29
system7 is offline system7  United Kingdom
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I think you need to start again, tvrgeek.

The bass driver is Silver Flute W17RC38-08 6-1/2" Wool Cone. Main breakup resonance at 4.5kHz.

Lynn Olson is the man here:

Quote:
When working with rigid-cone drivers, there are some hard choices to make: if you lower the crossover frequency to minimize driver coloration, tweeter IM distortion skyrockets, resulting in raspy, distorted high frequencies at mid-to-high listening levels.

If you raise the crossover frequency to improve the sound of the tweeter, the rigid-driver breakup creeps in, resulting in a forward, aggressive sound at moderate listening levels, and complete breakup at high levels. (Unlike paper cones, Kevlar, metal, and carbon fibers do not go into gradual breakup.)

With the drivers we have today, the best all-around compromise is a 2nd, 3rd, or 4th-order (12-24dB/Oct.) crossover with an additional NOTCH filter tuned to remove the most significant HF resonance of the midbass driver.
Quote:
Originally Posted by tvrgeek View Post
The crossover I ended up with is a second order electrical. Not quite symmetrical. Woofer is a 3.3mH and 12uF. Q is about 1. Tweeter 15uF, .75mH with a 1 & 8 Ohm L Pad.
What I see here is too much bafflestep and heavy bass, too low a crossover (what, 1.5kHz?), and no attention to phase alignment above 5kHz.

I'll skip the elliptical/Cauer stuff here along with all the other gibberish I have read in this thread, and just do a simple tank on the bass and crossover at 3kHz, since we are keeping it simple. I think that will work much better. Red components are driver dependant, but 0.82 will be about right for the silver flute 4.5 kHz peak.
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File Type: png Silver_Flute_ W17RC38-08.PNG (8.0 KB, 128 views)
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Well, there it is! Best regards from Steve in Portsmouth, UK.
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Old 20th October 2013, 09:40 AM   #30
ODougbo is offline ODougbo  United States
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The LEAP W7 xo used a 1.5inductor; that project fell short and gave up, but looking back it was the Vifa tweeter that was breaking up.
Second sketch is TVR's xo, but not positive
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File Type: jpg TVRS.jpg (32.4 KB, 99 views)
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