active crossover

barossi · 13th August 2006, 07:06 AM

Hi,
i woule like to build an active crossover or better called: protection!

I would like to protect my speakers form the ultra low frequency!
Therefore i need an active filter -24dB at 60Hz. I would like to install this filter on the input of my power amp.

The amp has got the following specs:
10 kOhm / 47 pF

Did anyone build this?

Greetings Barossi

consort_ee_um · 13th August 2006, 10:15 AM

Have a look at this website:
http://www.beis.de/Elektronik/Filter/Filter.html
The usual way to do what you want is to use a Sallen and Key high pass filter

DorinD · 13th August 2006, 10:44 AM

Why you don't try a passive line level filter (2-nd order RC)? See there:

http://www.t-linespeakers.org/tech/f...ssiveHLxo.html

only for the high-pass branch. Your specs for the power input (10 kOhm / 47 pF) are perfect. Can use highest quality caps and res, nu power supply needed, no noise, highest dinamics, simple.
Can put all the parts in the power-amp box and activate on the need with a switch.

BobEllis · 13th August 2006, 10:52 AM

Usually the filter is at least second order to avoid early roll off of bass. If you mean 24 dB/octave at 60 Hz, that is fourth order. As noted on teh page linked to above, passive filters have an insertion loss that may cause problems. I prefer an active solution. It is easy to build an active filter.

I have a group buy of active filter boards and power supplies that closes on August 18th. The boards offer more features than you require, but you can just leave the parts you don't use empty. A single power supply will easily handle two boards needed for a stereo high pass filter.

Filter board WIKI

Active filter on my page includes a spreadsheet to calculate values Here

PSU page here

odering page

barossi · 13th August 2006, 02:41 PM

Hi,
i think i would like to try the passive version on t-line speakers!
Even i have losses, i could adjust the level of the Amp.
But the group buy is very very interesting!

Greetings Barossi

DorinD · 14th August 2006, 07:43 AM

See also:

http://www.audioc.com/accessories1/misc/hipass.htm

there are some of 2-nd order, I can't find the link to the producer of them, not the seller.

richie00boy · 14th August 2006, 08:14 AM

I would avoid passive filters steeper than 2nd-order, because as well as the insertion loss it becomes difficult to stop the sections interacting and meet impedance criteria, and the response is very droopy as you can't get a decent q-value.

DorinD · 14th August 2006, 08:37 AM

Or some no so cheap RLC 2-nd or 4-th order passive filter with no insertion lost:

http://www.marchandelec.com/xm46.html

13th August 2006, 07:06 AM	#1
barossi diyAudio Member Join Date: Oct 2003 Location: near hamburg	active crossover Hi, i woule like to build an active crossover or better called: protection! I would like to protect my speakers form the ultra low frequency! Therefore i need an active filter -24dB at 60Hz. I would like to install this filter on the input of my power amp. The amp has got the following specs: 10 kOhm / 47 pF Did anyone build this? Greetings Barossi

14th August 2006, 08:14 AM	#7
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	I would avoid passive filters steeper than 2nd-order, because as well as the insertion loss it becomes difficult to stop the sections interacting and meet impedance criteria, and the response is very droopy as you can't get a decent q-value. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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13th August 2006, 10:15 AM	#2
consort_ee_um diyAudio Member Join Date: May 2004 Location: Hertfordshire	Have a look at this website: http://www.beis.de/Elektronik/Filter/Filter.html The usual way to do what you want is to use a Sallen and Key high pass filter

13th August 2006, 10:44 AM	#3
DorinD diyAudio Member Join Date: Jan 2005 Location: Bucharest, Romania	Why you don't try a passive line level filter (2-nd order RC)? See there: http://www.t-linespeakers.org/tech/f...ssiveHLxo.html only for the high-pass branch. Your specs for the power input (10 kOhm / 47 pF) are perfect. Can use highest quality caps and res, nu power supply needed, no noise, highest dinamics, simple. Can put all the parts in the power-amp box and activate on the need with a switch.

13th August 2006, 10:52 AM	#4
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	Usually the filter is at least second order to avoid early roll off of bass. If you mean 24 dB/octave at 60 Hz, that is fourth order. As noted on teh page linked to above, passive filters have an insertion loss that may cause problems. I prefer an active solution. It is easy to build an active filter. I have a group buy of active filter boards and power supplies that closes on August 18th. The boards offer more features than you require, but you can just leave the parts you don't use empty. A single power supply will easily handle two boards needed for a stereo high pass filter. Filter board WIKI Active filter on my page includes a spreadsheet to calculate values Here PSU page here odering page

13th August 2006, 02:41 PM	#5
barossi diyAudio Member Join Date: Oct 2003 Location: near hamburg	Hi, i think i would like to try the passive version on t-line speakers! Even i have losses, i could adjust the level of the Amp. But the group buy is very very interesting! Greetings Barossi

14th August 2006, 07:43 AM	#6
DorinD diyAudio Member Join Date: Jan 2005 Location: Bucharest, Romania	See also: http://www.audioc.com/accessories1/misc/hipass.htm there are some of 2-nd order, I can't find the link to the producer of them, not the seller.

14th August 2006, 08:37 AM	#8
DorinD diyAudio Member Join Date: Jan 2005 Location: Bucharest, Romania	Or some no so cheap RLC 2-nd or 4-th order passive filter with no insertion lost: http://www.marchandelec.com/xm46.html

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