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Help with sound design
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Author:  (((o))) [ 16 Oct 2017, 21:58 ]
Post subject:  Help with sound design

Hello! I am a learning electronics by working my way through the Make:Electronics book by Charles Platt. I have a long way to go, so I was hoping someone could give me some guidance on a project I am working on.

I basically would like to have 4 small piezo microphones amplified to 4 mono speakers with volume control, mute, and a switching jack. I have attached a block diagram of sorts, which I hope is clear. Most of the amplifier designs I have looked at online and in Forest Mims' book assume a stereo pair (or two), which is not what I want.

I could build 4 discrete amplifier units, but as you can see in the diagram, I would like to add a global volume and a switching jack (which I suppose would have to combine all 4 signals somehow).

In a previous project I soldered a small impedance-matching preamp for a piezo disc mic that I plugged into a guitar amp. I am hoping the amp design I use in this project will match impedances without the use of a separate preamp.

I'd also like to point out that this is not a hi-fi project. While I would like the sound to be good, the piezos will be primarily picking up percussive-type noises, so hopefully that should help simplify the design.

My specific questions are:
1. What type of amplifier design would work? Any guidance on sources for schematics I could build or modify would be great.
2. Do I need a preamp?
3. How do I add a mute switch?
4. How and where do I add a global volume and switching jack?

I appreciate your help. As you can tell I am a novice, so I'm not sure if I have asked the right questions. Please let me know if I can clarify anything or provide more information. Thank you!

Author:  Gio [ 18 Oct 2017, 21:34 ]
Post subject:  Re: Help with sound design

Hi, welcome to the forum.

The piezo mics will need a preamp. A search for piezo mic preamp will get you started. A four-channel opamp (OPA4132/4) might offer you a neat solution in one chip. You would use the output form the preamp to the amp. For the amp, a 4 channel chipamp may work well. The choice of chip would depend on how much power you need.

I don't think you can have a separate global volume control.

Author:  (((o))) [ 19 Oct 2017, 13:30 ]
Post subject:  Re: Help with sound design

Gio wrote:
Hi, welcome to the forum.

The piezo mics will need a preamp. A search for piezo mic preamp will get you started. A four-channel opamp (OPA4132/4) might offer you a neat solution in one chip. You would use the output form the preamp to the amp. For the amp, a 4 channel chipamp may work well. The choice of chip would depend on how much power you need.

I don't think you can have a separate global volume control.


Hello, thank you Gio! And thank you for the suggestions. So to clarify, would the OPA4132/4 serve as both the preamp and the amp? I appreciate your help!

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