Programmable Active Crossover(analog)

RCBandwidth · 25th August 2005, 08:44 PM

I have designed a Software programmable active filter(analog) .The picture shows one channel of the finished circuit.
It is a 2-way Linkwitz-Riley configuration(24dB/oct).The devices shown on the blue sockets have 4 software adjustable potentiometers inside each one,by tying the wiper to one end of the pot you create an adjustable resistor.Different crossover points are achived by changing the resistor values(software controlled),256 discrete resistor values can be programmed(approx. 100hz crossover step resolution).

I am using a "Basic Stamp"microcontroller to program the resistor values.I am using the "I2C" protocol for communication with the digital pots.The quad pots are from Analog Devices(part number is AD5263).

It is my intention to further develop this project and have some PC boards made up in the near future.I will share the details for those who have an interest in this x-over.I do not have any formal documentation at this point,my main objective was to get the prototype built and get some initial data.

My initial bench tests of the prototype are very positive,It looks like the channel balance is within .2 db between the LP/HP sections at the programmed crossover point.

All comments are welcome.

Regards Bob C.

Russ White · 25th August 2005, 09:38 PM

Rob, I am definitely interested.

I will be in touch! Very cool!

bigmike216 · 26th August 2005, 02:47 AM

I am also very, very interested.

Jan Dupont · 28th August 2005, 07:04 PM

Very interesting

peranders · 29th August 2005, 07:23 PM

Very neat

Maybe I should use these IC's for my monster filter with FDNR, see my sig below.

RCBandwidth · 29th August 2005, 11:25 PM

PA: Your FDNR filter board could accomodate both techniques.The end user could have either a software programmable filter ,or by leaving out the digital pots and installing fixed value resistors,You have a conventional active filter. Bob C.

jackinnj · 29th August 2005, 11:29 PM

Good work, let me know when you want to design the PCB -- Jack

Russ White · 30th August 2005, 06:31 PM

Hi Bob,

This is going to be really cool.

I am working on my PCB with the parts you mentioned. I am about 80% done I would say. The only issues left to resolve for me are the ones related to the PIC itself and human interface.

Cheers!
Russ

analog_sa · 30th August 2005, 07:13 PM

How good do these digi pots sound? Or it doesn't matter?

Russ White · 30th August 2005, 08:10 PM

Well they should sound fine, the specs are good. Bob has actually heard them, so I will let him answer based on experience.

Cheers!
Russ

25th August 2005, 09:38 PM	#2
Russ White diyAudio Member Join Date: Jan 2005 Location: Nashville, TN, USA	Rob, I am definitely interested. I will be in touch! Very cool! __________________ Less pulp more juice Twisted Pear Audio.

28th August 2005, 07:04 PM	#4
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Very interesting __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

29th August 2005, 07:23 PM	#5
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Very neat Maybe I should use these IC's for my monster filter with FDNR, see my sig below. __________________ /Per-Anders (my first name) or P-A as my friends call me

29th August 2005, 11:25 PM	#6
RCBandwidth diyAudio Member Join Date: May 2004 Location: New York and PA	Active Filter PA: Your FDNR filter board could accomodate both techniques.The end user could have either a software programmable filter ,or by leaving out the digital pots and installing fixed value resistors,You have a conventional active filter. Bob C.

30th August 2005, 06:31 PM	#8
Russ White diyAudio Member Join Date: Jan 2005 Location: Nashville, TN, USA	Hi Bob, This is going to be really cool. I am working on my PCB with the parts you mentioned. I am about 80% done I would say. The only issues left to resolve for me are the ones related to the PIC itself and human interface. Cheers! Russ __________________ Less pulp more juice Twisted Pear Audio.


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26th August 2005, 02:47 AM	#3
bigmike216 diyAudio Member Join Date: Jul 2004 Location: BC, Canada	I am also very, very interested.

29th August 2005, 11:29 PM	#7
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Good work, let me know when you want to design the PCB -- Jack

30th August 2005, 07:13 PM	#9
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	How good do these digi pots sound? Or it doesn't matter?

30th August 2005, 08:10 PM	#10
Russ White diyAudio Member Join Date: Jan 2005 Location: Nashville, TN, USA	Well they should sound fine, the specs are good. Bob has actually heard them, so I will let him answer based on experience. Cheers! Russ __________________ Less pulp more juice Twisted Pear Audio.

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