Opamp circuit to boost a small range of audio frequency

HankMcSpank · 29th October 2009, 12:46 PM

Well, having scoured the internet for a good while...I've not managed to find anything suitable (most circuits are boost/cut, or multiband or overly component heavy)...so I'm posting up here in the hope that someone can give a couple of pointers.

What I seek is a simple opamp based circuit to boost (I don't know by how much exactly, I'd say x2!) a very narrow range of frequencies - 280Hz-380Hz. I'm conscious that such circuits normally have a centre frequency then an envelope either side...therefore I'd say a centre frequency of 330Hz.

Erhmm...that's it!

All leads warmly received!

D!g!TaL · 29th October 2009, 01:29 PM

There's quite a lot of generic stuff over on Siegfried Linkwitz's site:

Active Filters

Regards, Ian

peranders · 03:30 PM

You should look for a plain equalizer but with only one section.

http://www.national.com/ds/LM/LM833.pdf page 14.

It's possible that you'll have to tune the Q value (sharper filter). Check formulas for gyrator circuits.

A good source is here
http://www.analog.com/library/analog..._handbook.html
See analog filters

29th October 2009, 12:46 PM	#1
HankMcSpank diyAudio Member Join Date: May 2008	Opamp circuit to boost a small range of audio frequency Well, having scoured the internet for a good while...I've not managed to find anything suitable (most circuits are boost/cut, or multiband or overly component heavy)...so I'm posting up here in the hope that someone can give a couple of pointers. What I seek is a simple opamp based circuit to boost (I don't know by how much exactly, I'd say x2!) a very narrow range of frequencies - 280Hz-380Hz. I'm conscious that such circuits normally have a centre frequency then an envelope either side...therefore I'd say a centre frequency of 330Hz. Erhmm...that's it! All leads warmly received!

29th October 2009, 03:24 PM	#3
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	You should look for a plain equalizer but with only one section. http://www.national.com/ds/LM/LM833.pdf page 14. It's possible that you'll have to tune the Q value (sharper filter). Check formulas for gyrator circuits. A good source is here http://www.analog.com/library/analog..._handbook.html See analog filters __________________ /Per-Anders (my first name) or P-A as my friends call me Last edited by peranders; 29th October 2009 at 03:30 PM.

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29th October 2009, 01:29 PM	#2
D!g!TaL diyAudio Member Join Date: Mar 2006 Location: Glasgow, Scotland	There's quite a lot of generic stuff over on Siegfried Linkwitz's site: Active Filters Regards, Ian

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