In this simple circuilt in post #6http://www.diyaudio.com/forums/analog-line-level/167495-simple-stereo-gain-stage.html, would you put the volume control on the input or the output?
Also would the + and - supplies use the same ground as signal?
Rookie questions I know but got to start somewhere😉
Also would the + and - supplies use the same ground as signal?
Rookie questions I know but got to start somewhere😉
Corrected link is:
http://www.diyaudio.com/forums/analog-line-level/167495-simple-stereo-gain-stage.html
Those are very good questions.
Typically, the volume pot would be on the input side.
Use "star" grounding. That means you would want to keep the signal ground separate from the power ground, until they reached the star point, probably at the power supply smoothing caps' ground.
And use bypass caps from opamp's power pins to power ground. For many opamp circuits, you can just use a 10 uF electrolytic (with voltage rating higher than PS voltage) and a 0.1 uF ceramic (not NPO or C0G type) in parallel for each opamp power pin.
Also, try to avoid creating "loop area" with conductor pairs. That means, for example, that the signal input conductor and its ground conductor should stay as close together as possible for as long as possible, preferably twisted together (and preferably inside a shielded cable, with shield grounded at one end only, probably to the chassis). Also try to do the same thing with all other pairs, such as power/ground, AC power, output signal/ground, etc. If using a PCB, try to keep each pair's traces as close together as much as possible.
And try to run all small signal conductors as far away as possible from anything with a large signal or a very dynamic current or an AC field. If such conductor pairs must approach each other, they should cross at a right angle.
Cheers,
Tom Gootee
http://www.diyaudio.com/forums/analog-line-level/167495-simple-stereo-gain-stage.html
Those are very good questions.
Typically, the volume pot would be on the input side.
Use "star" grounding. That means you would want to keep the signal ground separate from the power ground, until they reached the star point, probably at the power supply smoothing caps' ground.
And use bypass caps from opamp's power pins to power ground. For many opamp circuits, you can just use a 10 uF electrolytic (with voltage rating higher than PS voltage) and a 0.1 uF ceramic (not NPO or C0G type) in parallel for each opamp power pin.
Also, try to avoid creating "loop area" with conductor pairs. That means, for example, that the signal input conductor and its ground conductor should stay as close together as possible for as long as possible, preferably twisted together (and preferably inside a shielded cable, with shield grounded at one end only, probably to the chassis). Also try to do the same thing with all other pairs, such as power/ground, AC power, output signal/ground, etc. If using a PCB, try to keep each pair's traces as close together as much as possible.
And try to run all small signal conductors as far away as possible from anything with a large signal or a very dynamic current or an AC field. If such conductor pairs must approach each other, they should cross at a right angle.
Cheers,
Tom Gootee
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There are a number of circuits in the thread incorrectly referenced by the URL you quoted. Without knowing exactly which circuit and exactly what the application is it's hard to be definitive about the answer. It's commonplace to have a volume control arranged at the input, but there might be reasons why it's undesirable.
Draw the exact circuit with values and how you intend to implement the volume control and specify the source.
The supplies would share the same ground as the signal.
w
Draw the exact circuit with values and how you intend to implement the volume control and specify the source.
The supplies would share the same ground as the signal.
w
Thanks for the tips.
Don't know why my link was wrong. It showed as a hyper link when writing it but when I posted it came out the way it is.
I understand about keeping the signal and power wires seperated and twisting but I do get confused by the star grounding technique.
I'm just trying to build the simplest of op amp pre-amp circuit for educational(mine) purposes.
Just a dual op-amp laid out on a circuit board.
Mooly has posted one in this thread. Post 6.
Trying again.
http://www.diyaudio.com/forums/analog-line-level/167495-simple-stereo-gain-stage.html
Don't know why my link was wrong. It showed as a hyper link when writing it but when I posted it came out the way it is.
I understand about keeping the signal and power wires seperated and twisting but I do get confused by the star grounding technique.
I'm just trying to build the simplest of op amp pre-amp circuit for educational(mine) purposes.
Just a dual op-amp laid out on a circuit board.
Mooly has posted one in this thread. Post 6.
Trying again.
http://www.diyaudio.com/forums/analog-line-level/167495-simple-stereo-gain-stage.html
Just for information, I built the simple gain stage drawn by Mooly and used an OPA2604 that I had on hand.
I'm powering it with a battery supply + and- 15v.
To me the results are staggering to say the least.
The sound is crisp, clean and very powerful.
The music does not sound manipulated in any way and no frequencies stand out.
A world of difference in my system. I've always liked minimalist approaches best.
Thanks to responders and to Mooly for helping the members with his idea.
I'm powering it with a battery supply + and- 15v.
To me the results are staggering to say the least.
The sound is crisp, clean and very powerful.
The music does not sound manipulated in any way and no frequencies stand out.
A world of difference in my system. I've always liked minimalist approaches best.
Thanks to responders and to Mooly for helping the members with his idea.
It is not his idea : everyone who study electronics learn this BASIC circuit with OA used for the last 40 years !
Read paper/books/article write by Bob Pease from National Semiconductors in 1970 ...1980 about usage of operational Amplifier IC .
Ok ?
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I was just thanking Mooly and others for bringing this to my attention.
Some of us rookies appreciate this information as we have not studied electronics but still enjoy the satisfaction of being able to tinker and improve our systems while learning new things.
Not all on this forum have EE degrees.
I think you read my post differently than it was intended.
Some of us rookies appreciate this information as we have not studied electronics but still enjoy the satisfaction of being able to tinker and improve our systems while learning new things.
Not all on this forum have EE degrees.
I think you read my post differently than it was intended.
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