Baxhandall Tone Control Simulate

[Suraj143]

I want to simulate the below tone control circuit values to get good perfomance.But in LT spice I get some wiered curves.Am I doing it wrong..??

 

[Suraj143]

I removed the virtual ground Now seems to working ok.But my circuit has a virtual ground on inverting pin.

I'm making a BASS, Treble tone control circuit. & want to fine tune it.
My major problem is, even I tun the BASS knob until 1 o'clock possition it has no any BASS increases.From 1 o'clock onwards it starts making BASS.

See the simulation.

 

[ronsimpson]

You could move to a +6V and a -6V supply.

 

[crutschow]

Post your .asc file.

 

[audioguru]

Your first circuit correctly had a virtual ground on the + input of the opamp but the - input was at 0V. The opamp is a rectifier.
The second circuit has the + input of the opamp at the minus supply voltage (0V) and the - input was also at 0V

Use the first circuit but add an input coupling capacitor.
As said by Ron, the second circuit would work if you add a negative supply.

Maybe you should do a DC analysis of the circuits showing proper biasing and a good sinewave (or showing severe clipping or a wrong DC output) before looking at the frequency response.

 

[Suraj143]

I did the changes & tried to simulate but still I couldn't get the correct waveforms.Please help me.
Potentiometeres are set to near maximum ~ 100K.

Also attached the ltspice .asc file.

 

[audioguru]

Your 0.0033uF (3.3nF) input capacitor has such a low value that it passes only very high frequencies.
Your simulation schematic is completely different from a good schematic. Your treble tone control is a huge (like a car) variable capacitor.
Your input level might be so high that the opamp is clipping.

 

[Suraj143]

Thanks.

I changed some values.Can you help me to plot the graph on these values?Also attached the .asc file.

THanks

 

[audioguru]

Your value of C1 is 200 times too small.
You have C2 and C3 connected wrongly to the slider of the bass tone control instead of only one capacitor across the tone control.
The bass control is at minimum and the treble control is at maximum.

 

[Suraj143]

Thanks.

I changed the values. Is my graph ok? I have very limited knowledge on LTspice analysis...

 

[audioguru]

Your circuit is fine but is missing a filter capacitor parallel with your R8 to keep power supply noise attenuated.
It is the same as this circuit:

 

[The Electrician]

Thanks.

I changed the values. Is my graph ok? I have very limited knowledge on LTspice analysis...

The usual thing to do to show the performance of your circuit is to plot families of curves showing the response of the bass and treble controls separately.

See figures 4.4 and 4.5 on this page: https://www.angelfire.com/electronic/funwithtubes/Amp-Tone-A.html

 

[Suraj143]

Your circuit is fine but is missing a filter capacitor parallel with your R8 to keep power supply noise attenuated.
It is the same as this circuit:

I made the changes in tone control circuit.Results are below.

1.No trebles at all.(with 560pF & 10K side resistors)
2.BASS will increase after passing the halfway mark of Bass pot.

The simulation shows it will narrow the curves near 640Hz but in real life the quality is not good

 

[audioguru]

I made the changes in tone control circuit. Results are below.

1. No treble at all.(with 560pF & 10K side resistors)

Maybe your ears (because you are old?) or your tweeter does not produce the boost shown above 8kHz?

2. BASS will increase after passing the halfway mark of Bass pot.

Maybe your woofer does not produce sounds below 100Hz?