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Multi-Way Conventional loudspeakers with crossovers

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Old 26th January 2005, 11:33 AM   #21
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Quote:
Originally posted by thomas997


Your probably going to want polypropylene caps, which will be much larger than electrolytics and will cost more as well..

If you dont want to go for that, you will need bipolar electrolytics at the very least. You can do this simply with two electrolytics in series (I think its neg to neg, or pos to pos, maybe it doesnt matter).

If you go active crossover, you can use a LM4780 chip amp (if allowed?) or similar per enclosure. Then the components needed will be very small, nano and pico farads.

neg to neg and pos to pos would be parallel, if i wanted series then it would be connect neg to pos and leave the other two...


i'll go for the 8l smallish port...thanks for all the help! now its time to go bother the amp guys
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Old 26th January 2005, 03:49 PM   #22
Greg B is offline Greg B  United States
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Since your local radio shack sells an assortment of non-polar electrolytics in sizes perfect for crossovers, you really don't need to bother with wiring south to north etc.

Electrolytics suck for crossovers anyway, really. Scrounge film caps somewhere, or at least bypass the 'lytics with a small mylar.

GB
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Old 26th January 2005, 04:12 PM   #23
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What he meant about the series electrolytics was that a capacitor used in a crossover cannot be a polar cap and that is more than likely what your local rat shack sells.... Two polar caps however can become a singal crude bipolar cap however when placed in series with + to + or - to -... I suggest at the very least get a bipolar EL cap... http://www.partsexpress.com/pe/pshow...number=027-330
I've flipped back and forth between a 4uf bipolar and a 4uf dayton polypro and there was a subtle diffrence thats for sure... Seemed like there was some smearing with the bipolar which wasnt at all bad, however there was more grain when comparing a 47uf EL with some mylar/poly caps in paralell to get to that value on a midrange, I would assume since the ear is more sensitive to changes at those frequencies. BTW I took part in some blind ABX cap testing at Dayton and had an even split on if i liked the mylar or Sonicap more.... I have never ordered from madisound so I don't know how fast they get things shipped, however with partsexpress I always got what I ordered the very next day except for once when UPS messed up so it took 3 days... Close proxcimity to Dayton Oh helps though. The Poly cap is $1.85 btw part 027-421

Also check out Madisound's sale page http://www.madisound.com/sale.html and ApexJr.com Madisound does have some nice cheap buyout iron core inductors BTW...
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Old 26th January 2005, 04:44 PM   #24
Greg B is offline Greg B  United States
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Like I said before, the shack really does sell non polar caps. They even label them as being suitable for crossovers.

Making a fake non-polar out of two normal elecrolytics sounds like a daft idea WRT crossovers.

Some lytics sound much better than others. They can vary from a pleasant soft sort of sound to nasty lowfi. I agree that once you get to film caps of any sort it becomes personal taste.

GB
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Old 26th January 2005, 08:48 PM   #25
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Quote:
Originally posted by Greg B
Like I said before, the shack really does sell non polar caps. They even label them as being suitable for crossovers.

Making a fake non-polar out of two normal elecrolytics sounds like a daft idea WRT crossovers.

Some lytics sound much better than others. They can vary from a pleasant soft sort of sound to nasty lowfi. I agree that once you get to film caps of any sort it becomes personal taste.

GB

the closest thing is a 4.7 uf...will that work? it has a frequency listed at the bottom of the page and it advertises it for xovers so i'm assuming that the frequency is the xover point that it would aquire?
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Old 26th January 2005, 09:01 PM   #26
Greg B is offline Greg B  United States
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Yes that will work with a normal 8 ohm tweeter, assuming it has fairly linear impedance. If you are purchasing a tweeter, get one with a lowish resonance (Fs) and ferrofluid if you are crossing with a single cap.

If you are using a piezo, it's all different. You don't actually need a crossover, but using one is a good idea, since it will take the edge of the low treble.

So, with a piezo, solder an 8 ohm non-inductive power resistor across the terminals, and then it can be treated as if it were a normal tweeter. (actually not quite true, but close enough for you)

You will need an L-pad to reduce the tweeter level in either case.

The values in the table will bear little resemblance to reality, but aren't a bad starting point. You will see....
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Old 27th January 2005, 12:12 AM   #27
Andy G is offline Andy G  Australia
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Default here's a link for some ideas

http://users.tpg.com.au/users/gradds...udspeakers.htm
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