Audio equalizer

Prenz69 · May 11, 2022

I have to build a 5 band equalizer using microcontrollers. I have chosen NE5532 for the job. Is this sufficient enough? Do I need to design an amplifier as well? If so why?

AnalogKid · May 11, 2022

Prenz69 said:
I have to build a 5 band equalizer using microcontrollers.

Why?

Do you know what an equalizer is?

What are the microcontrollers for? Why do you think they are needed?

If you search for audio equalizer schematic, you will get dozens of designs to study.

ak

Prenz69 · May 12, 2022

This is an assessed project. It is compulsory to use microcontrollers for this purpose. I got a few schematics. The best one had used LM833. That is nowhere to be found in my area right now. NE5532 is the substitute I choose.

What I need to know is whether this would work?
Can the equalizer work alone or does it need an amplifier as well?

Nigel Goodwin · May 12, 2022

Prenz69 said:
This is an assessed project. It is compulsory to use microcontrollers for this purpose. I got a few schematics. The best one had used LM833. That is nowhere to be found in my area right now. NE5532 is the substitute I choose.

Both of those are opamps, not micro-controllers.

Prenz69 said:
What I need to know is whether this would work?
Can the equalizer work alone or does it need an amplifier as well?

Depends what you want to do with it, it can do either.

Prenz69 · May 12, 2022

Nigel Goodwin said:
Both of those are opamps, not micro-controllers.

Depends what you want to do with it, it can do either.

I need it to do both.

JimB · May 12, 2022

I think that there may be a translation problem here.

Prenz69 said:
I have to build a 5 band equalizer using microcontrollers.

What he should have said is:
"I have to build a 5 band equalizer using integrated circuits."

I think that the mis understanding goes like this:

An op-amp is (usually) a type of integrated circuit.
A microcontroller is a type of integrated circuit.
BUT, an op-amp is NOT the same as a microcontroller.

JimB

Prenz69 · May 12, 2022

JimB said:
I think that there may be a translation problem here.

What he should have said is:
"I have to build a 5 band equalizer using integrated circuits."

I think that the mis understanding goes like this:

An op-amp is (usually) a type of integrated circuit.
A microcontroller is a type of integrated circuit.
BUT, an op-amp is NOT the same as a microcontroller.

JimB

Yes thank you for the clarification

AnalogKid · May 12, 2022

I was about to suggest "microcircuit" instead of microcontroller.

In that case, the 5532 is an excellent choice for general purpose audio work. It is old, but readily available, and it is much better than most other opamps of its time.

Almost all 5-band or graphic equalizers use opamps to make up for the signal attenuation through the filter components. In this way, the output signal level is approximately equal to the input signal level.

For more than three bands, a common approach is to use opamps to form a synthetic inductor as par of an L-C filter circuit, with one or two opamps per frequency band.

Prenz69 said:
I got a few schematics. The best one had used LM833.

Please post a link to that project page or schematic.

ak

Prenz69 · May 12, 2022

AnalogKid said:
I was about to suggest "microcircuit" instead of microcontroller.

In that case, the 5532 is an excellent choice for general purpose audio work. It is old, but readily available, and it is much better than most other opamps of its time.

Almost all 5-band or graphic equalizers use opamps to make up for the signal attenuation through the filter components. In this way, the output signal level is approximately equal to the input signal level.

For more than three bands, a common approach is to use opamps to form a synthetic inductor as par of an L-C filter circuit, with one or two opamps per frequency band.

Please post a link to that project page or schematic.

ak

https://bestengineeringprojects.com/5-band-audio-equalizer-circuit-using-lm833/ this is what I got

AnalogKid · May 12, 2022

Pretty decent circuit. Next: power. With a few adjustments, a 5532 can be dropped into that schematic. However, consider changing the power source to two 12 supplies in a +/-12 V arrangement.

If your question is whether or not you need to design an *additional* amplifier stage, the answer is no. IC2:A is the output amplifier, and its gain can be made adjustable if you want that extra control.

Is this a school project?

Are you going to build the circuit, or is this just a design exercise?

ak

Prenz69 · May 12, 2022

AnalogKid said:
With a few adjustments, a 5532 can be dropped into that schematic.

Can you please point out the adjustments need to be done?

Is this a school project?

Yes, and I have to build the circuit

AnalogKid · May 12, 2022

Prenz69 said:
Can you please point out the adjustments need to be done?

No.

But if you put some effort into the project, we will be glad to review your work and make suggestions.

ak

Prenz69 · May 12, 2022

AnalogKid said:
No.

But if you put some effort into the project, we will be glad to review your work and make suggestions.

ak

Thank you. Will post future updates.

schmitt trigger · May 12, 2022

I second Analogkid’s suggestion: use a +/- 12 volt supply.

A +/- 15 volt would be slightly better.

danadak · May 12, 2022

You could use switch capacitor filters -

Understand How to Use Switched Capacitor Filters to Save Space and Improve Filter Performance

Use switched capacitor filters to lower parts count and get greater accuracy, temperature stability, and reliability compared to passive or active RC filters.

www.digikey.com

Interface - Filters - Active | Electronic Components Distributor DigiKey

Interface - Filters - Active are in stock at DigiKey. Order Now! Integrated Circuits (ICs) ship same day

www.digikey.com

Or google "audio equalizer FFT".....

Regards, Dana.

crutschow · May 12, 2022

You might want to consider a circuit using gyrators (which emulate an inductor), since the circuit can be somewhat simpler, such as discussed here.

Prenz69 · May 12, 2022

schmitt trigger said:
I second Analogkid’s suggestion: use a +/- 12 volt supply.

A +/- 15 volt would be slightly better.

Thank you for your insight

Prenz69 · May 12, 2022

danadak said:
You could use switch capacitor filters -

Understand How to Use Switched Capacitor Filters to Save Space and Improve Filter Performance

Use switched capacitor filters to lower parts count and get greater accuracy, temperature stability, and reliability compared to passive or active RC filters.

www.digikey.com

Interface - Filters - Active | Electronic Components Distributor DigiKey

Interface - Filters - Active are in stock at DigiKey. Order Now! Integrated Circuits (ICs) ship same day

www.digikey.com

Or google "audio equalizer FFT".....

Regards, Dana.

Thank you for your insight

Prenz69 · May 12, 2022

crutschow said:
You might want to consider a circuit using gyrators (which emulate an inductor), since the circuit can be somewhat simpler, such as discussed here.

Thank you for your insight

Ramussons · May 15, 2022

Prenz69 said:
I have to build a 5 band equalizer using microcontrollers. I have chosen NE5532 for the job. Is this sufficient enough? Do I need to design an amplifier as well? If so why?

No, those are OpAmps and they have nothing to do with microcontrollers.
There are Tone control IC's that use DC voltages instead of potentiometers for Tone Control. I do not know if these IC's are available today.
LM1036
LMC1982
You can use a uCcontroller to vary the voltages that control the tone effects.

Audio equalizer

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