Tone Control - Volatage range for TL072/LF353-N
Hey folks,
I want to DIY a tone control. I have found a couple of schematics online that use either TL072 or LF353-N op amps. The schematics say that Vs should be +/- 15V. I only have +/-12V on hand. Will this be okay for either op amps?
Hey folks,
I want to DIY a tone control. I have found a couple of schematics online that use either TL072 or LF353-N op amps. The schematics say that Vs should be +/- 15V. I only have +/-12V on hand. Will this be okay for either op amps?
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Another question. Sorry for being so naive about this stuff. I guess this is the reason why forums exist.😀
1. Basing on the manufacturer's schematic, if I were to add a potentiometer before the first opamp to serve as volume control, would I need to change anything in the circuit?
2. I will be using 2 of the circuits to make it stereo. Would a potentiometer be ok to be used as a balance for the 2 channels? I would be adding it after the volume potentiometer.
Schematic can be found here: Operational Amplifier (Op Amp) - General Purpose Amplifier - LF353-N - TI.com
1. Basing on the manufacturer's schematic, if I were to add a potentiometer before the first opamp to serve as volume control, would I need to change anything in the circuit?
2. I will be using 2 of the circuits to make it stereo. Would a potentiometer be ok to be used as a balance for the 2 channels? I would be adding it after the volume potentiometer.
Schematic can be found here: Operational Amplifier (Op Amp) - General Purpose Amplifier - LF353-N - TI.com
Maybe you could check out Rod Elliot's projects. I built a variant of this circuit and it performs exceptionally well.
Rod Elliot's Project 97 Preamp
He provides a complete description of each stage.
You can substitute better Op-Amps than a TL072, such as the OPA2134, but it is critical to address power supply noise by placing ceramic by-pass caps (i.e., .1 uF or .01 uF) as close to the power supply pins of the chip as you can.
You may need to make some other subtle adjustments to tame high-frequency oscillation. For example, I ended up with adding a 20 pF cap (C114) between pins 6 and 7 of U10 to stop a high frequency oscillation in that circuit when using LM4562 chips.
An externally hosted image should be here but it was not working when we last tested it.
Hmm, I could try that. Regarding the volume and balance controls, will it work if I put it the way as I said above?
I would put the volume and balance after the tone control stage. This ensures that any constant noise produced is attenuated and also drives the volume network from a low and defined source impedance.
Big thanks to everyone who helped me! This is my first time trying out making audio circuits. I made my first chipamp using TDA2009A. It works perfectly with very minimal noise. I can only hear it its really quiet and I need to put my ear on the speakers to hear it. I guess it has to do with my PSU. I used a cheap ATX PSU.
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Sorry for being so noob. Just got a few more questions:
What is the polarity orientation of the 5u5 and 1u1 capcitors in the schematic? Can I use 4.7uF instead of 5.5uF and 1.0uF instead of 1.1uF?
What is the polarity orientation of the 5u5 and 1u1 capcitors in the schematic? Can I use 4.7uF instead of 5.5uF and 1.0uF instead of 1.1uF?
The TL074 or TL084 would be fine.
The caps are one (1) and five (5) uF (Microfarad). The 10K resistor sets the input impedance of the tone stage. That's pretty low. You could use a 470K here and a 0.47uF poly type cap. The 1uF is just a coupling cap and can be larger if needed. A 10uF cap would work well.
If you use electroylitics for those two then the polarity shouldn't matter because there is no DC voltage present across them.
The caps are one (1) and five (5) uF (Microfarad). The 10K resistor sets the input impedance of the tone stage. That's pretty low. You could use a 470K here and a 0.47uF poly type cap. The 1uF is just a coupling cap and can be larger if needed. A 10uF cap would work well.
If you use electroylitics for those two then the polarity shouldn't matter because there is no DC voltage present across them.
Thanks. I made the circuit today with an LF353 op amp. The 5.5uF got replaced by an electolytic 4.7uF. The 10K resistor is unchanged. I changed the 11K and 3.6K resistors with 10K and 3.9K, respectively, and the 0.05uF cap to 0.56 due to unavailability.
I hooked it up to my TDA2009A amp. As far as I can tell, the sound quality is the same. There is one problem though. I get a mains hum with the tone control connected to the main amp. I grounding the case of the potentiometers and the hum was reduced but it is still quite noticeable.
Any way to eliminate or at least reduce the mains hum?
I hooked it up to my TDA2009A amp. As far as I can tell, the sound quality is the same. There is one problem though. I get a mains hum with the tone control connected to the main amp. I grounding the case of the potentiometers and the hum was reduced but it is still quite noticeable.
Any way to eliminate or at least reduce the mains hum?
🙂 Someones having fun.
0.56uf for a 0.05uf cap won't do as its a critical component in determining the frequency response of that section of the control. 0.05 can be replaced by 0.047uf (that's 47nano farad) or you can use five 0.01uf (10 nano farad) caps in parallel.
Any hum will probably be down to the wiring and grounding. That also depends on whether this is a separate unit with its own PSU or whether you have it built into the main amp. It should be possible to get it silent though. So that's not an easy one to answer without seeing exactly what you have done.
0.56uf for a 0.05uf cap won't do as its a critical component in determining the frequency response of that section of the control. 0.05 can be replaced by 0.047uf (that's 47nano farad) or you can use five 0.01uf (10 nano farad) caps in parallel.
Any hum will probably be down to the wiring and grounding. That also depends on whether this is a separate unit with its own PSU or whether you have it built into the main amp. It should be possible to get it silent though. So that's not an easy one to answer without seeing exactly what you have done.
Whoops. Typo there. The 0.05uF got replaced by 0.056uF not .56uF.
Both preamp and main amp are wired to the same power supply. The wiring I used is just plain awg 22 with single layer of insulation.
I will try to take pics but its a real mess. I'll be posting in a few.
Both preamp and main amp are wired to the same power supply. The wiring I used is just plain awg 22 with single layer of insulation.
I will try to take pics but its a real mess. I'll be posting in a few.
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