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Old 12-05-2021, 04:20 AM   #30
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Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
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Posts: 3,248
Talking Re: Op-amp preamp discussion

All pots are new. Here they are. I got 5 of them. The problem is most obvious on the volume control for MAX4410 headphone amp, because headphones sit right next to your ear and this thing gets pretty loud pretty quickly, as soon as you turn the volume pot, so to get it to sound somewhat balanced, I'd have to turn it louder than what I'm comfortable with. The main amp on the other hand is harder to notice, since it's louder and I also had the speakers right next to each other during testing, plus I have those individual "downstream" pots which I can tweak to balance it out.

I guess at this point I should provide a schematic explaining what I want to achieve. It looks something like inspiration - just came up with it on my own thinking how a car headunit works. It works in practice, save for the imbalance inconvenience. I'll use this setup to drive a subwoofer on the rear channels, hence why I needed a way to shut it off entirely if I want to. Normally that's where a balance control would go, which is NOT what this is, I'm aware of this. That would not be of use to cut off the sub entirely. This is more like individual volume controls for each of the 4 speakers, which is fine - I don't mind that. I'd have the last 4 pots all the way up, so they're basically out of the picture, adjust the main volume at the bottom as needed and simply trim the speaker that sounds louder if needed. The headphone amp is pre-master volume control.

Now that I think about it.....can I get away without the op-amps entirely and just parallel the pots on each side ? I think what would happen in that case is adjusting one of the pots, alters the volume on the other one as well. Haven't tried it. Will throw it on the simulator to see...
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