Question about how tone stacks work, and linear amps
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Re: Question about how tone stacks work, and linear amps
Yes. The tone stack is a passive circuit and only removes frequencies.
Will all tone controls on "10", the tone stack still provides a broad midrange cut. This midrange cut is what makes it sound like the treble and bass have been "boosted" - they are actually "cut" less than the midrange.
So, with the tone controls bypassed, it will sound like you are now getting quite a midrange boost.
The easiest way to bypass is to lift the ground connection from the middle control - using a resistor and switch in parallel between the middle control and ground. The resistor helps to prevent "pops" due to the capacitors in the tone stack circuit.
Yes. The tone stack is a passive circuit and only removes frequencies.
Will all tone controls on "10", the tone stack still provides a broad midrange cut. This midrange cut is what makes it sound like the treble and bass have been "boosted" - they are actually "cut" less than the midrange.
So, with the tone controls bypassed, it will sound like you are now getting quite a midrange boost.
The easiest way to bypass is to lift the ground connection from the middle control - using a resistor and switch in parallel between the middle control and ground. The resistor helps to prevent "pops" due to the capacitors in the tone stack circuit.
Re: Question about how tone stacks work, and linear amps
I'm not sure I understand the question.
Take the typical Fender tone stack as found in blackface or silverface twins - we are only talking about the treble, mid and bass controls. The treble and bass controls are usually audio taper and the mid is usually a linear.
Assume all controls are on "10". The circuit essentially splits the signal at the input to the stack and there are really only two filters involved.
The 250pf cap conected to the treble control(with the combined resistance of the controls) forms a high pass (or bass cut) filter. The -3db point is approximately 1200hz and the signal is down by -7db with the signal reducing more as the frequency reduces.
The 100K resistor and the .047mfd cap forms a low pass (or treble cut) filter. The -3db point is approximately 45hz and the signal is down by -11db, with the signal reducing more as the frequency increases.
When the two signals are recombined, the composite has a midrange dip right around 300hz and the response is down to approximately -23db.
The general shape is a lazy "V". There are only two peaks, one for the bass and one for the treble.
One of the things about the tone stack is that all of the controls are highly interactive with each other - and changing one may not only change the relative level of the frequency range, it may also change the frequency of not only it's range but the other ranges as well.
Now we put all controls at their 50% rotation. The -3db point of the treble control is shifted up to 1300hz and is down to a level of -15db. the -3db point of the bass control has been shifted up to 100hz and is also down to a level of -15db. The midrange dip of the composite now occurs at 500hz at a level of -26db.
The general shape is a flatter "V" and the point of the "V" has moved up 200hz in frequency. The insertion loss is now greater at the bass and treble peaks at -8db difference and -3db lower at the notch.
So - only two frequencies and only one notch.
The Marshall tone stack works similar but with different caps and pot values which determine the frequencies. The overall insertion loss is slightly less than the Fender design because the resistance of the mid pot is not only greater but it is also always in the circuit.
Does this help or confuse?
I'm not sure I understand the question.
Take the typical Fender tone stack as found in blackface or silverface twins - we are only talking about the treble, mid and bass controls. The treble and bass controls are usually audio taper and the mid is usually a linear.
Assume all controls are on "10". The circuit essentially splits the signal at the input to the stack and there are really only two filters involved.
The 250pf cap conected to the treble control(with the combined resistance of the controls) forms a high pass (or bass cut) filter. The -3db point is approximately 1200hz and the signal is down by -7db with the signal reducing more as the frequency reduces.
The 100K resistor and the .047mfd cap forms a low pass (or treble cut) filter. The -3db point is approximately 45hz and the signal is down by -11db, with the signal reducing more as the frequency increases.
When the two signals are recombined, the composite has a midrange dip right around 300hz and the response is down to approximately -23db.
The general shape is a lazy "V". There are only two peaks, one for the bass and one for the treble.
One of the things about the tone stack is that all of the controls are highly interactive with each other - and changing one may not only change the relative level of the frequency range, it may also change the frequency of not only it's range but the other ranges as well.
Now we put all controls at their 50% rotation. The -3db point of the treble control is shifted up to 1300hz and is down to a level of -15db. the -3db point of the bass control has been shifted up to 100hz and is also down to a level of -15db. The midrange dip of the composite now occurs at 500hz at a level of -26db.
The general shape is a flatter "V" and the point of the "V" has moved up 200hz in frequency. The insertion loss is now greater at the bass and treble peaks at -8db difference and -3db lower at the notch.
So - only two frequencies and only one notch.
The Marshall tone stack works similar but with different caps and pot values which determine the frequencies. The overall insertion loss is slightly less than the Fender design because the resistance of the mid pot is not only greater but it is also always in the circuit.
Does this help or confuse?
