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Old 3rd July 2009, 11:49 PM   #1
Default Op -amp for MFBF

Hey guys, I'm new to the op amp thing and was wondering what op - amp would suit a spectrum analyzer I plan on building (audio) about 20-20KHz. MFBF = Multiple Feedback Bandpass Filter, the set up I plan on using. Any suggestions?

Thanks
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Old 4th July 2009, 02:09 AM   #2
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Many audio spectrum analyser circuits use a multiple-feedback-bandpass-filter circuit for each frequency band. There might be many of them.
Use an audio opamp like a TL07x or an OPAx134. They are low noise, low distortion and wideband.

A lousy old lM358, LM324 and 741 opamp is horrible for audio.
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Old 4th July 2009, 04:50 AM   #3
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Quote:
Originally Posted by audioguru View Post
Many audio spectrum analyser circuits use a multiple-feedback-bandpass-filter circuit for each frequency band. There might be many of them.
Use an audio opamp like a TL07x or an OPAx134. They are low noise, low distortion and wideband.

A lousy old lM358, LM324 and 741 opamp is horrible for audio.

AG, have you used the MCP6001? I would like to know your opinion of it. I've used this part in a few projects, mainly due to its low cost and low power consumption, but I have not evaluated it for audio circuits that demand some decent fidelity. Any comments?
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Old 4th July 2009, 05:24 AM   #4
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MCP6001?
0.6v/us is too slow for high end audio.
1mhz is too slow for gain over 10.
I do not like to use R-R input amplifiers for audio.
5 volt supply max!
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If you use inverting amplifier, gain of 20 or less, P-P output voltage of under 1 volt.....maybe
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Old 4th July 2009, 06:24 PM   #5
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I agree that the MCP6001 opamp is too slow for audio.
It also has low gain, it is noisy and since the datasheet says nothing about distortion it might have high crossover distortion like the similar low power LM358 and LM324 opamps. Its max supply voltage is so low that it might be clipping all the time.
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