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Multi-Way Conventional loudspeakers with crossovers

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Old 30th December 2012, 01:45 AM   #1
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Another project for a friend, I'm reusing a freebie box of 30 litres and I have a good enough 5 inch midrange here salvaged from an old Sony 2-way.
In my bits box I have a 5.8mH coil and a 47uF cap which should give me close to a Bessel roll-off on the low end at ~300Hz The mid should be OK using its natural roll-off but I can find a coil for a first order cut at if I need it
mid will be used in a closed box ( Actually my coffee can trick ) of 1.75 litres

My problem is not having another coil to use on the woofer ( which hasn't been found yet but I have a few cheap 8inch here and 8 is the biggest the box will take
What I do have in my box is a large selection of large caps
Has any-one tried using a shunt coil in a first order XO in combination with a normal ( parallel ) second order high pass
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Last edited by Moondog55; 30th December 2012 at 01:54 AM. Reason: Change coil value
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Old 30th December 2012, 11:43 AM   #2
AllenB is offline AllenB  Australia
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If you mean that one of the drivers will have a second order high pass filter followed by a shunt coil to cut the highs, you should consider that there will be relatively little source impedance above the passband for the shunt coil to work with and it's probably not a good idea unless given some careful consideration.
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Old 30th December 2012, 11:52 AM   #3
sreten is online now sreten  United Kingdom
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Hi,

Can't make much sense of your post.
You can't use shunt components in a parallel 1st order crossover.

Try using the coil and cap 1st order series on both drivers.

rgds, sreten.
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Old 30th December 2012, 09:51 PM   #4
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Do you mean something like a hybrid series/ parallel crossover network? What I'm thinking is,

-the low-pass (LP) coil connected across the input terminals to the second order high-pass filter,
-the tweeter connected to the output terminals of the high-pass filter (of course)
-the + terminal of the woofer connected to one terminal of the LP coil
-the - terminal of the woofer connected to - out of the amp
-finally, the other terminal of the LP coil connected to the + out of the amp.

IMO that would work in some fashion. I haven't tried it.

Regards,
Pete
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Old 30th December 2012, 10:08 PM   #5
sreten is online now sreten  United Kingdom
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Hi,

A series second order on the mid and first order on the bass
has one inductor and two capacitors, you could try that.

rgds, sreten.

No such thing as a hybrid series/parallel crossover.
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Old 30th December 2012, 10:32 PM   #6
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something like this?
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 30th December 2012, 10:56 PM   #7
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In my post #4, substitute mid for tweeter. Actually what I had in mind wouldn't work at all. In the pass-band for the mid, the impedance of network including the mid approaches being equal to the impedance of the mid itself. So in that range, the woofer would be receiving about half of the amp's voltage, assuming equal impedance of the woofer and mid.

-Pete
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Old 30th December 2012, 11:30 PM   #8
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Quote:
Originally Posted by PeteMcK View Post
something like this?
Can you explain your network? I see high-pass and maybe band-pass sections, but not a low-pass section.
Pete
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Old 30th December 2012, 11:36 PM   #9
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series, 1st order on woofer, 2nd on mid, tweeter is 1st order in parallel with the mid,
add a couple of resistors to taste...
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 30th December 2012, 11:57 PM   #10
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Quote:
Originally Posted by PeteMcK View Post
series, 1st order on woofer, 2nd on mid, tweeter is 1st order in parallel with the mid,
add a couple of resistors to taste...
Thanks, I understand it now. With schematics, I'm used to seeing wire junctions shown with a dot.

-Pete
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