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I am dissecting a design and I'm trying to wrap my head around the design pictured below. It is based on the TL064C amplifier and takes in single ended audio and outputs single ended audio as well.

What kind of amplifier is this?

Here's the schematic: Design Schematic

I believe R15/C1 & R16/C2 are RC filters, for what it's worth.

t3ddftw
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    it's rather easier to answer if that cartoon is redrawn as a schematic – Neil_UK Jul 14 '19 at 20:56
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    Your "schematic" shows how everything is connected without showing what the actual **functionality** of the circuit is. Learn how to draw a better circuit by reading this: https://electronics.stackexchange.com/questions/28251/rules-and-guidelines-for-drawing-good-schematics/28255#28255 and then read http://www.learningaboutelectronics.com/Articles/Active-op-amp-bandpass-filter-circuit.php to see how actual filter circuits using an opamp are supposed to be drawn. – Bimpelrekkie Jul 14 '19 at 21:00
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    You can easily calculate the cutoff frequency. But the lowpass filter is so simple with only one resistor and one capacitor that its slope is very gradual and probably not noticeable. – Audioguru Jul 14 '19 at 22:57

1 Answers1

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schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. Left channel. A proper schematic makes it easy to see the function of the circuit.

What kind of amplifier is this?

This should be pretty obvious now. If unsure then please modify your question.

Transistor
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  • Thanks @Transistor! I don't have a background in EE, and I'm actually just getting into OP Amps, hence why I didn't draw the schematic using (what I now know is) convention. Is this a distribution amplifier? Sorry, I'm trying to understand this circuit as a layman... – t3ddftw Jul 14 '19 at 21:18
  • Actually, it looks more like an Inverting Amplifier. Is that right? – t3ddftw Jul 14 '19 at 21:23
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    The left channel (I didn't check the right) has two inverting amplifiers in series so the signal out is un-inverted. The second one has a small capacitor across the feedback resistor and this will reduce the high-frequency gain. Can you work out the gain for each stage and where the high-frequency starts to roll off? – Transistor Jul 14 '19 at 21:30
  • Thanks again, @Transistor. It looks like the first stage doesn't apply any gain at all and the second stage lowers the gain (Rf / Rin) by about 32%. Am I luke warm?. Where would I be able to read more about how C1 is impacting high frequency gain? I'm not certain it's a 100pF capacitor as my DMM doesn't register a value for it, so it's extremely low. Both channels are mirror images, btw. – t3ddftw Jul 14 '19 at 21:49
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    You've got it (although technically OA1 has a gain of -1). Study this: https://www.electronics-tutorials.ws/filter/filter_5.html. – Transistor Jul 14 '19 at 21:52
  • @Transistor I think OA1 has a gain of 1 with a phase shift of 180 degrees. – Harry Svensson Jul 14 '19 at 23:03
  • @Harry, I would only use the term "phase shift" if there is an RC (or LC) delay in the circuit. There isn't one on OA1 - it's simple inversion, so I reckon that the phase-shift is zero but the gain is -1. I'm not 100% sure I'm right. – Transistor Jul 15 '19 at 06:13