Sim of a slightly different Baxandall circuit:
It has only one 47nF (C3) instead of two.

Connecting CB1 and CB2 as you show, distorts the response at the mid settings in my simulation (bottom curves).

Yep thanks, I just built your circuit as well, and it works. But the reason mine didn't work was because I still had some weird paramaters scrambled all over the file. Been too long since I last used LTspice.
Now it works.

 

Connecting CB1 and CB2 as you show, distorts the response at the mid settings in my simulation (bottom curves).

Weird that TI would suggest that circuit... But I'll go with your circuit then

 

Sorry. got a bit confused there. this is actually the circuit that TI suggests - using virtual ground. I adjusted it for a symmetric supply. It seems to have a flat response at 50% wiper.





For some reason the step parameter returns this ghibberish.

 

hi d123,
I get the same plot/s as you.
I would suggest varying only 1 of the 4 for a given simulation run.
E

 

hi d123,
I get the same plot/s as you.
I would suggest varying only 1 of the 4 for a given simulation run.

Hmm. Still can't get it to work.

 

 

hi d123,
I get the same plot/s as you.
I would suggest varying only 1 of the 4 for a given simulation run.

Oh. I get it. had to click on the Phase indicator on the right side and deselect it

 

Sim of a slightly different Baxandall circuit:
It has only one 47nF (C3) instead of two.

View attachment 336860

How come the OP amp in your circuit doesn't need a dual rail supply?

The buffer OP amp that I added still requires a dual rail.

 

hi d123,
Try this alternate method of potentiometer control, using the LTSpice potentiometer.
The 1st image shows the plots over the full range of bass & treble.
2nd image shows the centre and upper/lower limits of the pots.
E
Added: NE5532 sub and asy files.

 

How come the OP amp in your circuit doesn't need a dual rail supply?

R5 and R8 bias the op amp at 1/2 the supply voltage.

 

Try this alternate method of potentiometer control, using the LTSpice potentiometer.
The 1st image shows the plots over the full range of bass & treble.

Note that there's still a slight hump/droop at around 600Hz with the midrange settings of the pots, which don't occur with only one capacitor replacing C2 and C3.

 

hi d123,
Try this alternate method of potentiometer control, using the LTSpice potentiometer.
The 1st image shows the plots over the full range of bass & treble.
2nd image shows the centre and upper/lower limits of the pots.
E
Added: NE5532 sub and asy files.

Thank you!
Unfortunately the pots don't seem to work.


Found this tutorial though, so I might try that on my machine.
Unfortunately I don't have any admin privileges on this windows machine, so I can't add any libs.

 

R5 and R8 bias the op amp at 1/2 the supply voltage.

I need a dual rail supply for the buffer anyways, so I guess it doesn't make so much sense.
Are the good old lm7(8/9)Lxx suitable for "hi fi" applications?

 

I need a dual rail supply for the buffer anyways, so I guess it doesn't make so much sense.
Are the good old lm7(8/9)Lxx suitable for "hi fi" applications?

I exchanged them for LM317/337 since they are more low noise apparently:
https://sound-au.com/project05b.htm

I guess it's quite overkill since I only have a single NE5532 per rail with ~15mA max

 

I need a dual rail supply for the buffer anyways

Not necessarily.
You could AC couple them like in my circuit, and bias them to 1/2 the supply also.

Below is an example circuit for a non-inverting buffer:

 

Not necessarily.
You could AC couple them like in my circuit, and bias them to 1/2 the supply also.

Below is an example circuit for a non-inverting buffer:

Doesn't seem work for me, unfortunately.

 

hi d123,
Please post your LTS asc circuit, it appears you are missing the coupling capacitors as shown on Carls circuit.?
E

 

hi d123,
Please post your LTS asc circuit, it appears you are missing the coupling capacitors as shown on Carls circuit.?
E

You're right.

So I can save the negative voltage regulator. Quite excellent!

 

Before I send this in for printing I want to make extra sure I didn't make any mistakes.
Pls tell me if I messed something up in the transfer from ltSpice to KiCAD

 

Check your chip VDD and VSS connections !