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Old 13th June 2012, 11:49 AM   #31
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If your woofer is Peerless 832591, Re is 3.7 Ohm and Le is 0.8mH. C will be 37.4uF( use C=38uF), Rc will be 4.63 Ohm( use Rc=4.7 Ohm).
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Old 13th June 2012, 12:01 PM   #32
ODougbo is offline ODougbo  United States
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Okay, thank you for the clarification and specs ....I was considering contacing Madisound.
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Old 13th June 2012, 02:14 PM   #33
system7 is offline system7  United Kingdom
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I didn't get much mileage out of tuantran's Zobel correction. Really didn't help a lot, and frequency response was very awkward. It's generally agreed the Vifa tweeter needs a shunt and series resistor to get well behaved because its not ferrofluid damped so has issues at Fs and has an awkwardly low DC resistance of 3 ohms.

The below circuit looks reasonable to me. 3.3uF/0.5mH is more forgiving than 4.7/0.4mH being lower Q, and the adjustment of level will be done with the resistors AFTER the tweeter filter. But again, the values aren't too critical, say 20% will do, and you should work with what you have available.

This still has little bafflestep, which IMO is a good thing. It will work OK close to a wall. You will then adjust it by ear, because this is all very rough and ready. It remains to be seen how well behaved the woofer is. It has a peak around 4kHz. With respect to Thomas Akerlund in post #6, his circuit is a bit peculiar, and I wouldn't waste time on it.
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File Type: jpg 2ndOrder_Peerless_Circuit.JPG (21.7 KB, 157 views)
File Type: jpg 2ndOrder_Peerless_FR.JPG (58.2 KB, 156 views)
File Type: jpg 2ndOrder_Peerless_Phase.JPG (51.0 KB, 150 views)
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Well, there it is! Best regards from Steve in Portsmouth, UK.
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Old 13th June 2012, 05:59 PM   #34
ODougbo is offline ODougbo  United States
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I hate to even ask; are the 2 "black" components BSC circurts?

The graph is very convincing.
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Old 13th June 2012, 08:34 PM   #35
ODougbo is offline ODougbo  United States
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Question Ut-O

The coil changed on the woofer; can I use the .56 air (14gauge) or use the much thiner 19 gauge, .8 (as shown)?

Both are air core - in pic.

Btw, from the other builds with the 6db crossover, we thought the woofer sounded the best with the coil in the .7 range.

(They have surprizing amount of bass).
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Old 14th June 2012, 04:39 AM   #36
system7 is offline system7  United Kingdom
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The coil changed to 0.8mH based on the exact Le value of 0.8mH for the peerless bass which tuantran dug up from somewhere. That's what you use for the filter. It works best. Filters really design themselves based on the woofer characteristics.

I keep telling you not to worry about tolerances, just get it about right. You will tweak it later to correct minor faults. You might make the bass capacitor smaller, for instance, which sounds more musical. You must balance that against coloration at certain frequencies. It's the 2-5kHz area which is going to be most exacting. That's where the high metallic harmonics of guitar and vocal sibilance and high trumpet energy reside. A lot of people are very good at adjusting by ear. It can be done.
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Well, there it is! Best regards from Steve in Portsmouth, UK.
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Old 14th June 2012, 08:07 AM   #37
ODougbo is offline ODougbo  United States
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Okay, thank you again for the design. Don't have a large cap for woofer, will need to order.
I can add two together to get to up to 15uf (for now).

I have a friend with a 6th sense when it comes to speaker, he hears things (good or bad) in seconds; which can takes me days - weeks.

btw, he really liked the vifa tweeter (I took the Madisound HSD kit to his place) .

This is great - thanks again!
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Old 16th June 2012, 11:41 AM   #38
ODougbo is offline ODougbo  United States
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Parts came in - found others.

So far so good; the longer resistor is 2.2 - vs. 1.5

The 2-caps are 6 uf and 7uf, I think I need to connect them parallel for 13uf?
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Old 16th June 2012, 04:44 PM   #39
system7 is offline system7  United Kingdom
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This is very exciting, Doug. We wait with baited breath for what is essentially complete guesswork....

Oh, FWIW, the woofer capacitor damping resistor is quite fussy for phase and woofer rolloff so changing from 1.5 ohms to 2.2 will make quite a difference. But who knows? Might be good.
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Last edited by system7; 16th June 2012 at 04:46 PM.
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Old 16th June 2012, 04:49 PM   #40
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I may have been over thinking (and too many parts). I think this will work; not that much different from the 6db crossover we came up with (not bad).
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