Tone Stack and online calculator help

Ghostman

Ghostman

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I'm going to be tinkering with my Crate head again and found this website that allows me to see the frequency response of my tone stack and what changes are doing to the tone. But I have some questions about it because in some instances I'd like to take components out.

TSC In the Web

This is the Crate Tone stack page. The biggest question is what value would I enter into the variable if a Cap is removed? For a resistor, I've been adding in 10Meg, or 0 if I short the resistor. But I have no idea what I should enter if I remove or short a cap. I think shorting a cap would be 0 for a value. None of the scenarios I'm playing with shorts a cap though.

What I'm first interested in, is that I made some mods I got from another forum and I'm trying to tell how those changes affected the tone here on a graph. I'd like to see if I can make some changes on the website and see how that changes things before I start pulling apart a chassis and just trial and error my way around the stages.

I rebuilt the schematic in my CAD software to see the signal flow and stages a lot more clearly than in the official schematics from the manufacturer. And I've already found a few things that I changed that I really want to put back in place.

TIA

e1crXi9.gif
 
Ghostman said:
I'm going to be tinkering with my Crate head again and found this website that allows me to see the frequency response of my tone stack and what changes are doing to the tone. But I have some questions about it because in some instances I'd like to take components out.

TSC In the Web

This is the Crate Tone stack page. The biggest question is what value would I enter into the variable if a Cap is removed? For a resistor, I've been adding in 10Meg, or 0 if I short the resistor. But I have no idea what I should enter if I remove or short a cap. I think shorting a cap would be 0 for a value. None of the scenarios I'm playing with shorts a cap though.

What I'm first interested in, is that I made some mods I got from another forum and I'm trying to tell how those changes affected the tone here on a graph. I'd like to see if I can make some changes on the website and see how that changes things before I start pulling apart a chassis and just trial and error my way around the stages.

I rebuilt the schematic in my CAD software to see the signal flow and stages a lot more clearly than in the official schematics from the manufacturer. And I've already found a few things that I changed that I really want to put back in place.

TIA

e1crXi9.gif
Click to expand...
Sorry don't know jack :poo: about the subject.

Just had to tell you that is one funny meme, I almost did the coffee spit take!

Consider it stolen!
 
Ghostman said:
I'm going to be tinkering with my Crate head again and found this website that allows me to see the frequency response of my tone stack and what changes are doing to the tone. But I have some questions about it because in some instances I'd like to take components out.

TSC In the Web

This is the Crate Tone stack page. The biggest question is what value would I enter into the variable if a Cap is removed? For a resistor, I've been adding in 10Meg, or 0 if I short the resistor. But I have no idea what I should enter if I remove or short a cap. I think shorting a cap would be 0 for a value. None of the scenarios I'm playing with shorts a cap though.

What I'm first interested in, is that I made some mods I got from another forum and I'm trying to tell how those changes affected the tone here on a graph. I'd like to see if I can make some changes on the website and see how that changes things before I start pulling apart a chassis and just trial and error my way around the stages.

I rebuilt the schematic in my CAD software to see the signal flow and stages a lot more clearly than in the official schematics from the manufacturer. And I've already found a few things that I changed that I really want to put back in place.

TIA

e1crXi9.gif
Click to expand...

Because the tone stack caps are used to block DC from the audio path, you can't remove them.
The amp would cease to function.

If you have any specific question:
contact Amp Books to get the most accurate answer.

BTW:
The tone stack calculations are not entirely accurate, because it does not account for the frequencies which are blocked from entering the input of the first gain stage.

Like for example:
If the bypass cap of the first input stage does not allow 50 Hz to pass...
Then the tone stack will have no effect on 50 Hz, at all.
Because there is no frequency to start with, the tone stack can't control it...
This is what most people miss.
 
Amp Mad Scientist said:
Because the tone stack caps are used to block DC from the audio path, you can't remove them.
The amp would cease to function.

If you have any specific question:
contact Amp Books to get the most accurate answer.

BTW:
The tone stack calculations are not entirely accurate, because it does not account for the frequencies which are blocked from entering the input of the first gain stage.

Like for example:
If the bypass cap of the first input stage does not allow 50 Hz to pass...
Then the tone stack will have no effect on 50 Hz, at all.
Because there is no frequency to start with, the tone stack can't control it...
This is what most people miss.
Click to expand...
I get that about frequency response stage to stage. I've done the plots for each stage but that doesn't affect what the Tone stack is capable of adjusting, mid-point frequencies, filter shelfs, and cut-off points.

Caps in the tone stack can most certainly be removed since the ones I'm more concerned about are parallel with resistors which changes the frequency response of the filter in question.

Still have the question: If I remove a cap from a circuit, do you calculate with 0 capacitance in that regard, or extremely high capacitance? My rusty knowledge says zero.
 
Ghostman said:
I get that about frequency response stage to stage. I've done the plots for each stage but that doesn't affect what the Tone stack is capable of adjusting, mid-point frequencies, filter shelfs, and cut-off points.

Caps in the tone stack can most certainly be removed since the ones I'm more concerned about are parallel with resistors which changes the frequency response of the filter in question.

Still have the question: If I remove a cap from a circuit, do you calculate with 0 capacitance in that regard, or extremely high capacitance? My rusty knowledge says zero.
Click to expand...
Yes it would be zero but I'm not sure that the calculator will do that function.

When you say "remove,"
Are you talking about replacing the cap with a wire jumper?
Or are you talking about leaving the part out, with no jumper at all?
 
Amp Mad Scientist said:
Yes it would be zero but I'm not sure that the calculator will do that function.

When you say "remove,"
Are you talking about replacing the cap with a wire jumper?
Or are you talking about leaving the part out, with no jumper at all?
Click to expand...
Removed without a jumper. If I shorted it out then it would be bypassed.

I know the calculator isn't going to give me a perfect real-world frequency response, but it does give me some idea as to the changes being made.
 
I spent the weekend drawing out the circuit in CAD so I can make more sense of it. I copied the factory plans in a more linear way to better understand the stages. Then I plotted the frequency response of each stage and then the final stage of the tone stack.

My first intention was to understand the mods I made to the circuit years back that I found on another forum. It didn't go into the details on what each change did, just a general, "makes it sound better" statement.

The mods in the forum affected the last stage only. One was the removal of the Plate Bypass Cap, some for the Treble side of the tone stack and a whole lot of changes for the Mid portion of the tone stack. Yesterday I spent a few hours going over every component change and how that plots on the calculator I found. I think I found a good combination of things.

There's a really high frequency sizzle that I believe is the result of the Plate Bypass Cap getting removed, so step one will be to replace that. The amp was dull sounding in the first place so I went with a different value in there to open it up a bit. However, with it removed, it opens it up too much.

Anyways, parts are on order, so as soon as I get them in, I'll be doing a comparison, step by step.
 
Did the deed today.

Marked out and ready to pull the old components:

l7qQaAk.jpg


It's been a while since I worked on circuit boards and my lack of skills showed. I ended up lifting a trace and had to fix the board. Ugh. Shitty tools and out of practice skills didn't help too much. But, I got it done and turned out pretty decent.

When I ordered the new parts, I didn't consider how big the new caps were. The Orange drops look like clown cars on this board.

daAUnzd.jpg
 
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