Duncan Amps - Tone Stack Calculator

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modman
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Post by modman »

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

Most among you know this one already, but for reference sake: FREEWARE package to calculate your tone control response.
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

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John Lyons
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Post by John Lyons »

Yes, very usefull to work up a flat mids Big Muff tone stack or a mid cut circuit. Lots of things to simulate here.
Nice to see what the responses are with various tone stacks.

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Post by soulsonic »

That program has been useful for me on many occasions. Anyone mess with the Steve Bench LCR eq yet?
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

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Post by John Lyons »

Here's a way to simulate a T/mid notch and see what's going on easily.

T-notch filter:
Go to Duncan's amp page and download the "tone stack calculator"
Click on big muff tone stack and plug in these values
Make the resistor to ground at the top 20M or so to take it out of the circuit effectively.
Make the bridging resistors 330K or so. One will be the pot, slide that all the way to the right.
Make the bridging cap 1nf and then the cap to ground 10nf
Just tweak from there until you get something that looks good.

John

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Post by Koniec12 »

Very usufull software for free

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Post by CodeMonk »

One thing about the DTSC is setting the proper Zsrc.
Which is the output impedance of the circuit that's feeding it.
I rarely see anyone mention it.
It can make a HUGE difference in component selection with some tone controls, particularly if you are trying to get a specific response.
Jack Orman make an allusion to in in a round about way in his presence tone control article.

Anyone feel free to add to this or correct me if I'm wrong.

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Post by Duckman »

CodeMonk wrote:One thing about the DTSC is setting the proper Zsrc.
Which is the output impedance of the circuit that's feeding it.
I rarely see anyone mention it.
It can make a HUGE difference in component selection with some tone controls, particularly if you are trying to get a specific response.
Jack Orman make an allusion to in in a round about way in his presence tone control article.

Anyone feel free to add to this or correct me if I'm wrong.
I guess (as you surely do, I believe) that the pre set Big Muff source impedance value must be typical, like the values in the tone stack and sure will be enough, but I'm curious about that too, because I don't know if those different values in collector resistors, emitter resistors and so on along versions have a notorious effect on Zsrc.

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Post by CodeMonk »

Duckman wrote:
CodeMonk wrote:One thing about the DTSC is setting the proper Zsrc.
Which is the output impedance of the circuit that's feeding it.
I rarely see anyone mention it.
It can make a HUGE difference in component selection with some tone controls, particularly if you are trying to get a specific response.
Jack Orman make an allusion to in in a round about way in his presence tone control article.

Anyone feel free to add to this or correct me if I'm wrong.
I guess (as you surely do, I believe) that the pre set Big Muff source impedance value must be typical, like the values in the tone stack and sure will be enough, but I'm curious about that too, because I don't know if those different values in collector resistors, emitter resistors and so on along versions have a notorious effect on Zsrc.
Yeah, I've always assumed that the value there is typical.
I did some searching on that awhile back, and found ONE post somewhere *maybe on the other site) that said it was 15k.
But I don't recall what Muff version he was referring too and there where no conflicting replies.
1k seems kinda of low though don't you think?
Although 15k seems kinda high.

I'll search again and see if I can find the post.

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Post by CodeMonk »

OK, I can' t find it.
But I did find a lot of amp forums using it and see a lot of high Zsrc values.
Maybe thats what I read.

My pains meds haven't kicked in yet so I don't have the energy or drive to look any further ATM.

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Post by Duckman »

Take it easy :hug:
In fact, we (well, I :oops: 'cause I don't know how to do it) only need to know how to calculate the output impedance of the second clipping section, right?

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Post by CodeMonk »

Just pretend its the final output stage and use the regular way of calculating the impedance.
From the other site, from RG himself : https://www.diystompboxes.com/smfforum/ ... #msg584615
There is some interesting info in the rest of that thread as well.

Basically this (on my dropbox): https://dl.dropboxusercontent.com/u/709 ... Tester.pdf
Except point #1 should be on ground just below point #3, from what I understand (ignore the last paragraph).

You can use this as a signal generator, if you lack a function generator, allows you to save as .WAV files.
http://www.tropicalcoder.com/AudioTestFileGen.htm
Haven't tested it myself so I dunno how much voltage it will generate.

There are several others out there as well.

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Post by phatt »

CodeMonk wrote:One thing about the DTSC is setting the proper Zsrc.
Which is the output impedance of the circuit that's feeding it.
I rarely see anyone mention it.
It can make a HUGE difference in component selection with some tone controls, particularly if you are trying to get a specific response.
Jack Orman make an allusion to in in a round about way in his presence tone control article.

Anyone feel free to add to this or correct me if I'm wrong.
I'm no guru but I've likely built or at least tested most of the popular tone stacks.

Input Z to most of the common passive tone stacks has to be Very high to seriously effect tone control ability. Such is the case if one were to connect a passive Piezo pickup directly to the input of passive tone stacks with no Hi Z buffer or preamp. That's how high you need to be before it kills tone control.

In fact most magnetic pu's have low enough Z and can actually drive most tone circuits quite well with no buffer or preamp, of course the signal loss of those hi Z tone circuits is the gotcha. :(

The stage after the tone stack is the part to worry about it has to be High Z if you want to maximize the tone control ability. :secret:

There must be dozens of stomp box circuits that have a passive tone stack hung off the end of a distortion unit with no Hi Z buffer at output which is a lottery as it can only ever work well if plugged into a good rig,, tuff luck if you have several pedals before the amp that do not posses a hi Z input.
Or a very long cable from bad pedal design to good amp.
Phil.

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Post by CodeMonk »

I've played around with DTSC and do have some observations, which is what brought me to post in this thread.
Changing Zsrc even by relatively small amounts has an effect on the frequency response.
I'm talking about the Muff stack it uses.
By default, Zsrc is set to 1k.
If Duncan used a Muff to arrive at this value. which one?
Like Duckman said:
I guess (as you surely do, I believe) that the pre set Big Muff source impedance value must be typical, like the values in the tone stack and sure will be enough, but I'm curious about that too, because I don't know if those different values in collector resistors, emitter resistors and so on along versions have a notorious effect on Zsrc.
Or what if you aren't attaching it to a muff?
Say a FF, TB, Fuzzrite, etc.
I've used it on a Bosstone and liked the results, but I'm curious about the frequency response that DTSC would show.
I don't know what the output impedance of those other circuits are (just never got around to it).

I'm also working on a modified version of it (a modification of Jack Orman's Presence control), and changing the Zsrc (like from 1k to 15k) has a significant effect on the response.

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