Simplified EQ, circuit analysis pls?

[soma89]

I made some simplications to the original by changing the eq stages and removing the MID Switches's


How do I analyze each of the 3 bands to determine what frequencies they'll be working with or "adding". I am looking for a mathematical way to do this..
(what am i looking for? cut off freq? Resonant Freq?). Tried various equations but cant seem to get numbers that make sense.

[antonis]

How do I analyze each of the 3 bands to determine what frequencies they'll be working with or "adding". I am looking for a mathematical way to do this..

Microelectronics, Circuit Analusis and Design, Donald A. Neamen, 4^th edition..






Apply the above maths hopping for each individual midband to lie away from the others..
(if not, you have to apply Laplace transformation for zeros and poles..)

[soma89]

Thanks a lot for the info. Is there any other way pther than ha ing to learn transfer functions and laplace? I was hoping a simple frequency cut off equation would do it

[antonis]

Our hopes might lie far away from cruel reality..
(after all, you didn't define maths analysis "depth"..)

Shall we try another (more simplified) approach..??

[Mark Hammer]

Or, you could just download the Duncan Tonestack Calculator, plug the values in and see what happens, graphically.

http://www.duncanamps.com/tsc/

[GibsonGM]

LT Spice.....?

[antonis]

LT Spice.....?

Just another smart guy who wants another sucker to do maths on behalf of himself..

[iainpunk]

LT Spice.....?

i always read "Lieutenant Spice" which sounds like either a advertisement mascot or a p0rn name

[pokus]

In "tone stack (the short summary)", why do R6 and C6 form a lowpass filter? It also says C6 and VR2 + VR4 form a highpass. I'm a liitle confused    Wouldn't that mean a resistor with a cap in series and a resistor to ground is a bandpass?

[GibsonGM]

The Lieutenant is IN TOWN, BABY!    I present LT Spice as an option for analyzing a 'more than simple' filter problem because it allows the builder/designer to rapidly achieve successful results that they can use, rather than have to hunt for the math.  Some just don't want to learn that much - and of course, some do! 

Or, maybe they want to learn basic HPF/LPF/BPF behavior, but at this moment they have a need to understand, graphically as Mark said, what is happening. Seems to me to be very much like etching your own PCB layout vs. using a Vero layout.   It's all good   

I still have to go to Antonis' post to figure out tone stacks the long way, and I've been playing at this hobby for 20 years, ha ha.

[antonis]

I still have to go to Antonis' post to figure out tone stacks the long way...

You're welcome, Sir...
(but only under your sole responsibility..) 

[antonis]

In "tone stack (the short summary)", why do R6 and C6 form a lowpass filter? It also says C6 and VR2 + VR4 form a highpass. I'm a liitle confused    Wouldn't that mean a resistor with a cap in series and a resistor to ground is a bandpass?

Consider figures 7.2 & 7.3 on "long" summary..
A band-pass filter needs a HPF followed by a LPF of faaaaaaar apart individual cut-off frequencies..
(or else, preceding stage is loaded by succeeding one..)

[ElectricDruid]

LT Spice.....?

LTSpice FTW!

You *could* do all the sums yourself, but then again, life is short and there already isn't enough time for drinking %^&*tails in delightful locations with beautiful members of whatever sex you prefer.

It helps to have a reasonable understanding of what the bits do so you're not just throwing mud at the wall to see what sticks in LTspice, but it's far quicker to experiment than to work out every single detail in many cases.

I suppose (or maybe hope) that people who had the benefit of a full education in these topics learned the "proper" way to do this stuff, but I don't know if that's true or not. I didn't, so I make do with the tools I have.

[PRR]

In "tone stack (the short summary)", why do R6 and C6 form a lowpass filter?

That's badly phrased. R6 and C6 *alone* do not make a low-pass.

The Gibson/Fender "tone stack" is much more complicated than it looks. Many different things happen. Back in the last century I *did* analyze the BMT stack with fingers pencil paper. Of course it was quicker to just run tone through an actual stack.

[iainpunk]

LT Spice.....?

LTSpice FTW!

You *could* do all the sums yourself, but then again, life is short and there already isn't enough time for drinking %^&*tails in delightful locations with beautiful members of whatever sex you prefer.

It helps to have a reasonable understanding of what the bits do so you're not just throwing mud at the wall to see what sticks in LTspice, but it's far quicker to experiment than to work out every single detail in many cases.

I suppose (or maybe hope) that people who had the benefit of a full education in these topics learned the "proper" way to do this stuff, but I don't know if that's true or not. I didn't, so I make do with the tools I have.

well, i did have the full education experience, but all the teachers that came from the real world with tons of experience say that it's 10% logic, 75% gut feeling and 15% slinging mud to the wall and seeing what sticks, i think i'll go with that as well

cheers, Iain

[antonis]

Tom.. (and Iain).. 

"Proper"(w or w/o "..") way is found on each one particular person and it has to do with a tremendous variety of desiratum(a)..
(e.g. one may consider much more easy/convenient to grasp any cap lies closer to his hand - junk box drawer and throw it in a tonestack waiting for desirable result while another  finds more satisfying to queeze his brain prior to grasp the very certain capacitor for the same desirable result..)

Of course, what Paul said:
>Back in the last century I *did* analyze the BMT stack with fingers pencil paper. Of course it was quicker to just run tone through an actual stack.<
is a plain reflection of objectivity..