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Re: 4 Pi crossover questions [message #52506 is a reply to message #52501]

Tue, 19 August 2008 20:16

Wayne Parham
Messages: 18783
Registered: January 2001

Illuminati (33rd Degree)

The poly caps from those manufacturers all sound very good, as do Erse. As you say, there are some high end caps that sound nice also, but at 10x the price. The Daytons, Solens and Erse caps are great sounding for the money.

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Re: 4 Pi crossover questions [message #52833 is a reply to message #52506]

Wed, 29 October 2008 12:45

Wayne-o
Messages: 225
Registered: May 2009

Master

I have not heard any difference in capacitors. Is there someone out there that can ? My Ears may not be as sensitive ,but I can tune a guitar sometimes. Reliability may be better on some. Ok I am just some Yaahoo in Indiana. Cheers !!!

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Re: 4 Pi crossover questions [message #60875 is a reply to message #52463]

Tue, 15 September 2009 15:21

feket663
Messages: 28
Registered: August 2009
Location: Hungary

Chancellor

Hello everyone! I have a stupid question:
I'm sorry, i'm not familiar with electronic and crossover building. Can i replace R1 resistors with 2 piece of 50 ohm 15W and R2 resistors with 2 piece of 33 ohm 15w Caddock MP915 resistors.
I don't need drive this speakers with 600W power station, I have a simple 2a3SE amp with 3,5W.

Thanks, and sorry for bad english...

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Re: 4 Pi crossover questions [message #60878 is a reply to message #60875]

Tue, 15 September 2009 19:25

Wayne Parham
Messages: 18783
Registered: January 2001

Illuminati (33rd Degree)

If you'll only drive the speakers with low power, you can derate the max dissipation levels of the resistors, yes. Just be sure the total resistance of R1 and R2 is as designed. The pair of 50Ω resistors will work perfectly for a 25Ω part if connected in parallel. Same with the pair of 33Ω resistors, paralleled to make a 16.5Ω part, which is just fine. Just be sure to put them all in the right places, jumpering unused positions if needed.

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Re: 4 Pi crossover questions [message #60889 is a reply to message #52463]

Wed, 16 September 2009 11:30

Wayne-o
Messages: 225
Registered: May 2009

Master

Has the 4-Pi 20 uf C-4 capacitor in the low pass been changed to 10uf like the schematic shows here ? thanks

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Re: 4 Pi crossover questions [message #60897 is a reply to message #60889]

Wed, 16 September 2009 21:24

Wayne Parham
Messages: 18783
Registered: January 2001

Illuminati (33rd Degree)

Yes, I use a 10uF capacitor for C4 in the four π loudspeaker. It slightly shifts the nulls upward, about 5° going from 10uF to 20uF in this position. I didn't discover that immediately, but found it after some experimentation. The difference is very subtle, inaudible really, but measurements show it to be the better choice, if vertical symmetry is desired.

You actually could steer the pattern by choosing the proper value for C4, if you wanted. Speakers mounted high on walls would probably be better with a 20uF capacitor in that position, speakers nearer to the ground would be better with a 10uF cap. Both are pretty good choices, actually, since the nulls are separated pretty widely but for most cases, I think the 10uF value is probably better.

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Re: 4 Pi crossover questions [message #60902 is a reply to message #60878]

Thu, 17 September 2009 01:10

feket663
Messages: 28
Registered: August 2009
Location: Hungary

Chancellor

Thank you very much Mr. Parham!

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Re: 4 Pi crossover questions [message #60917 is a reply to message #52463]

Fri, 18 September 2009 05:24

feket663
Messages: 28
Registered: August 2009
Location: Hungary

Chancellor

Hello! There is another problem: what happens if I place to the C1 value a 0,68 microFarad cap, because I can't found good capacitor this 0,47uF value, but I have a 0,68 uF Auricap. Wrong idea?
Or can I use an old(1975) soviet paper in oil 0,47 uF/250V cap?
THX. Istvan

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