Passive line level crossover

rulezzz · 6th January 2004, 07:33 PM

please go first to this url
i want to know if i try to make Third Order Lowpass crossover C3 and R3 would be calculated by this formula ???:C3=C1/100 ;R3=100*R1 ,or by this C3=C1/20 ;R3=20*R1 ,or there is another formula?and please could you write formula for Fourth Order Lowpass crossover.

sreten · 6th January 2004, 08:53 PM

Voltage loss with even a second order circuit will be fairly serious.

As shown its effectively cascaded first order filters and cannot
provide any control over Q, its not really a second order circuit.

3rd and 4th order versions will have horrendous voltage
loss and will be nowhere near real 3rd or 4th order filters,
just 3 or 4 cascaded first order filters.

The high pass version can be emulated by manipulating the
input capacitors of the amplifying chain and is a waste of time.

For passive filters higher than 1st order you need some inductors.

sreten.

rulezzz · 7th January 2004, 05:50 AM

i don't care about loss i can listen without any problems with 100K resistor(connected :Pc>line level passive(R100K) >preamp>amp>speaker)
i just want to know what is the formula?
Bytheway don't know does it control Q but with Second order i could hear less high frequencies than with First..
P.S. could you give me link to crossover with real 3rd and 4th order BUT not active and without INDUCTION...

planet10 · 7th January 2004, 08:45 AM

RC PLLXOs are not suitable for anything over 2nd order (and that is pushing it) because they get real droopy (ie really low Q). If you need higher order you need to go to an LC network. And the size of the Ls needed means sourcing them gets tricky.

Marchand is selling kits http://www.marchandelec.com/xm46.htm

dave

6th January 2004, 07:33 PM	#1
rulezzz diyAudio Member Join Date: Jan 2004 Location: not nessesary	Passive line level crossover please go first to this url i want to know if i try to make Third Order Lowpass crossover C3 and R3 would be calculated by this formula ???:C3=C1/100 ;R3=100R1 ,or by this C3=C1/20 ;R3=20R1 ,or there is another formula?and please could you write formula for Fourth Order Lowpass crossover.

7th January 2004, 08:45 AM	#4
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	RC PLLXOs are not suitable for anything over 2nd order (and that is pushing it) because they get real droopy (ie really low Q). If you need higher order you need to go to an LC network. And the size of the Ls needed means sourcing them gets tricky. Marchand is selling kits http://www.marchandelec.com/xm46.htm dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

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6th January 2004, 08:53 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Voltage loss with even a second order circuit will be fairly serious. As shown its effectively cascaded first order filters and cannot provide any control over Q, its not really a second order circuit. 3rd and 4th order versions will have horrendous voltage loss and will be nowhere near real 3rd or 4th order filters, just 3 or 4 cascaded first order filters. The high pass version can be emulated by manipulating the input capacitors of the amplifying chain and is a waste of time. For passive filters higher than 1st order you need some inductors. sreten.

7th January 2004, 05:50 AM	#3
rulezzz diyAudio Member Join Date: Jan 2004 Location: not nessesary	i don't care about loss i can listen without any problems with 100K resistor(connected :Pc>line level passive(R100K) >preamp>amp>speaker) i just want to know what is the formula? Bytheway don't know does it control Q but with Second order i could hear less high frequencies than with First.. P.S. could you give me link to crossover with real 3rd and 4th order BUT not active and without INDUCTION...

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