too much treble

[Harry Muff]

trying to figure some stuff out here lol. how to get less treble in a overdrive pedal ? is that a high pass filter ? i changed some values around and it got worse

[patrick398]

Wrong way round, a high pass does just that, allows highs to pass but blocks lows determined by the corner frequency set by the rc combination. There are a few wats to reduce treble in an overdrive, it depends on the circuit. If it's op amp based you can put a small cap in parallel with the resistor setting the gain in the feedback loop of the opamp. Or you can use a passive rc low pass after the gain but you'll lose some volume and may need another gain stage to make up lost volume, thus is referred to as a recovery stage.

[Harry Muff]

Wrong way round, a high pass does just that, allows highs to pass but blocks lows determined by the corner frequency set by the rc combination. There are a few wats to reduce treble in an overdrive, it depends on the circuit. If it's op amp based you can put a small cap in parallel with the resistor setting the gain in the feedback loop of the opamp. Or you can use a passive rc low pass after the gain but you'll lose some volume and may need another gain stage to make up lost volume, thus is referred to as a recovery stage.

http://www.muzique.com/schem/filter.htm

I guess i dont understand frequency when it comes to treble and bass ..im going to have to give up until i learn some more

[Harry Muff]

i guess youre saying put a cap between pin 6 and 7 and lower the feedback resistor , parallel a variable resistor with that cap also and will change corner frequency? i was tone shaping on the wrong side of the op amp it seems. i have a good book here, and google, but it all looks like greek to me at this point.

[antonis]

You can consider it as "reverse" filter action when it's inside negative feedback loop..
(i.e. a HPF turns into LPF when is included between output & inverting input..)

Another way to face it should be to consider feedback cap (in parallel with feedback resistor or pot) as a signal leaking path (bypassing feedback resistor) so part of the signal isn't amplified by op-amp..

P.S.
I can't find anything bad for something looking greek to me..

[patrick398]

i guess youre saying put a cap between pin 6 and 7 and lower the feedback resistor , parallel a variable resistor with that cap also and will change corner frequency? i was tone shaping on the wrong side of the op amp it seems. i have a good book here, and google, but it all looks like greek to me at this point.

Worth a read for a basic understanding of op amps:
https://www.electronics-tutorials.ws/opamp/opamp_1.html

[Harry Muff]

You can consider it as "reverse" filter action when it's inside negative feedback loop..
(i.e. a HPF turns into LPF when is included between output & inverting input..)

Another way to face it should be to consider feedback cap (in parallel with feedback resistor or pot) as a signal leaking path (bypassing feedback resistor) so part of the signal isn't amplified by op-amp..

P.S.
I can't find anything bad for something looking greek to me..

im actually part greek mate lol, last name is Ladas we are good looking critters arent we lol

I think I have a lot bread boarding to do ..any particular oamp you uys prefer and why?

[antonis]

A bit more utilitarian circuit.. 

[Harry Muff]

A bit more utilitarian circuit.. 

I guess this was more of my original question, what the heck does all the frequencies mean? do I need an oscilloscope?

for example i used 1k 10nF to get 16kH ..so I am guessing thats on the ice pick trebly end or would that be sending highs to ground? im still having trouble identifying the way a lpf and a hpf look in a rc circuit  ..Ill most likely use a 25k linear pot so then I guess  t comes down to testing cap values ...but would not need bread board if I knew what Q i needed using the maths

right on my guy, when I breadboard this thing up I will use your mods




http://www.muzique.com/schem/filter.htm

[antonis]

im still having trouble identifying the way a lpf and a hpf look in a rc circuit

A LPF at a very particular point should be considered as all impedances (equivalent resistive value) in series right before this point with all impedances (equivalent capacitive value) shunting to ground - and vice versa for HPF..

[Harry Muff]

im still having trouble identifying the way a lpf and a hpf look in a rc circuit

A LPF at a very particular point should be considered as all impedances (equivalent resistive value) in series right before this point with all impedances (equivalent capacitive value) shunting to ground - and vice versa for HPF..

i like the way you drew the resistors, im going to do that and I get to use my color pencils for values 

I remember having a lot of trouble with this back in school, and the band pass. we had some lab or an exercise where a radio and its tuning stations were used as a way to teach us with an analogy - I would like to add and O scope to the bench but im afraid they are too expensive. i think I can visualize the highs bleeding to ground through the cap ..ill keep studying. One of the greatest regrets in life was turning my EE 101 book back in for 125 dollars ..it was so detailed, step by step, illustrated etc you cant find stuff like that on google ..i would pay a 500 bucks today for that book

[antonis]

I presume it's not so difficult to make things clear up your mind..

e.g. consider pin3 (non-inverting input) point:

There isn't theoretically (practically negligible) current flowing into op-amp so we say than pin3 input impedance is infinite..
So, the only path for signal current is to AC ground (470μF cap), through 1M bias resistor, 'cause this cap is considered (almost) short for AC, due to its relatively high capacitance value..
But signal comes to this point through 10nF input cap..
BY substituting 10nF cap with its equivalent resistance value for an arbitrary frequency we result into a resistive voltage divider.
So signal voltage at pin 3 will be (Vin*1M) / [(1/2π*f*C) + 1M]..
i.e. at 16Hz, Vpin3 should be 50% of Vin..
For higher frequencies, Vpin3 should be of higher Vin percentage, 'cause we deal with HPF here..
(capacitive reactance is inversely proportional to frequency)

You can use the formula 20*log(Vout/Vin) both for HPFs & LPFs taking into account for -6dB/octave attenuation added to -3dB cut-off point..
e.g. at 8Hz, signal is -9dB attenuated where at 4Hz is -15dB attenuated..

[kraal]

I guess i dont understand frequency when it comes to treble and bass ..

Hi,

Treble = high frequency, bass = low frequency (was it your question ?)
High pass filter = passes high frequencies (attenuates low frequencies that are below a given frequency)
Low pass filter = passes low frequencies (attenuates high frequencies that are above a given frequency)

[Harry Muff]

here is where I am at now

[antonis]

Some mods, if you don't mind.. 

[Harry Muff]

Some mods, if you don't mind.. 

sounds good my guy and before I go , one last mod  lets take a diode out and make here asymmetrical; open her up a little more valve like; more volume and more musical harmonics 

[Harry Muff]

I presume it's not so difficult to make things clear up your mind..

e.g. consider pin3 (non-inverting input) point:

There isn't theoretically (practically negligible) current flowing into op-amp so we say than pin3 input impedance is infinite..
So, the only path for signal current is to AC ground (470μF cap), through 1M bias resistor, 'cause this cap is considered (almost) short for AC, due to its relatively high capacitance value..
But signal comes to this point through 10nF input cap..
BY substituting 10nF cap with its equivalent resistance value for an arbitrary frequency we result into a resistive voltage divider.
So signal voltage at pin 3 will be (Vin*1M) / [(1/2π*f*C) + 1M]..
i.e. at 16Hz, Vpin3 should be 50% of Vin..
For higher frequencies, Vpin3 should be of higher Vin percentage, 'cause we deal with HPF here..
(capacitive reactance is inversely proportional to frequency)

You can use the formula 20*log(Vout/Vin) both for HPFs & LPFs taking into account for -6dB/octave attenuation added to -3dB cut-off point..
e.g. at 8Hz, signal is -9dB attenuated where at 4Hz is -15dB attenuated..

strangely enough( aha moment i took a step forward today) I do get the jist of that

[duck_arse]

Some mods, if you don't mind.. 

a question for antonis, cause I'm so hopeless at opamps [glad to see the gain set parts for first stage have arrived .....] - the cap marked "b" - is that not now a cap connected to the oppie output and ground, and therefore not allowed?

[antonis]

An answer for Stephen, b cap isn't placed there by me..
(maybe, it should be a good oscillation issue for the OP..) 

[duck_arse]

ahh, but placing or not blame, doesn't change whether allowable or immediate destruction.