Hi!

Recently I had cause to build an effect that utilized an op amp buffer for input and output buffers. I'll be doing a post in the DIY effects forum in a few days to showcase that once I have proper samples recorded. But here's a teaser, and possibly a useful thing for those of you with etching capabilities but who haven't looked into buffer design yet.

This board assumes you're using any op amp with the standard (in reality, conventional) pin-out, such as the *4558, TL072, LM833, etc....

I'm looking to make this PAIA vcf, ir something like it.

I don't quite get how it functions though. Looking at it, there are two passive lowpass filters in series, with diodes in series with the capacitors. The CV is split with a voltage divider and injected between the caps and diodes. So how exactly would this modify the cutoff frequency?

The series diodes look like they'd block any voltage to ground unless their forward voltage is exceeded, which would mean they charge the caps, right?...

This question is about Marshall or Fender style tone stacks in JFET distortion pedals, specifically those which have sequential J201 stages.

The J201 gain stages are always in the common source configuration designed to give amplification and clipping. In some designs one of the later stages is a common drain (source follower) which is designed not to boost, but to buffer and have a high impedance in and a low impedance out.

I've read that:
a) a common source JFET stage has a higher output...

Hi, experimenting with a simple buffer (figure on the left)
I come out taking the signal from the source of a biased fet (figure on the right)

Seems to me that it is a way to improve the sound... but I don't know whether it is only my feeling or the two circuits are really different.
Any comments/explanation is appreciated.

Thanks in advance

Hi guys,

I like a lot the CMOS inverters distortions, but there is more noise at high-gain than in other circuits, at least for me.

What do you think can be done to fight the noise?

One of the more used methods seems to be limiting the bandwidth by filtering the highs pre- or/and post- clipping. My problem with this is that the lower gain sound now lacks the highs. Seems like the gain control should also control the filtering.

Another one is highs pre-boost/post-cut, either statically (like...

Many effects are include RC filters. Help me understand it, please.

Is there area №1 its a high-pass filter? If this is true, why resistor R1 is in series with the capacitor?
How to calculate cut-off frequency?

Is this true?

Area №2 its a Low-pass filter i understand it.

Thanks!

Hi chaps, sorry to drag this one up again. I've previously added an independant buffer circuit board to a pedal, having two circuits in one box wired up via a 3pdt. This allowed me to have the buffer active all the time then kick in the effect, no problem. Now I've moved on & want to put these two circuits onto one pcb, different ball game or am i making it harder than it actually is? Do I simply run the buffer output to the input of the main effect or would I have to have a double output, one...

Hey folks,

I think this should be a simple one, but I was wondering what the 2.2k resistor and 100uF cap combo at the +9v input on this Tim Escobedo, 'Calavera', circuit snippet was for? Is it simply a filter (low pass?)? Also, are the other 0.1uF caps just for DC filtering?

Thanks!

ff

I did search.

What is it that makes the Folk Fuzz circuit be a fuzz pedal and a Tube Screamer circuit
be an overdrive pedal? Or to say the same thing in a bit different way, why isn't the
Folk Fuzz an overdrive pedal?

If my question isn't clear I'll try to come up with another way of asking it.

I'm a technical person so feel free to be as technical as you want in an answer.
I've checked through the other topics in this section of the forum and followed
some of the links they mentioned which were helpful...

So, I have built the minimixer from GGG and I'm experiencing some problems on one of the channels.That happens because before the mixer I'm splitting the signal, passively, and then blending back again.So, I have clean bass on one channel and Turbo Rat on the other.One thing I did was to alter the 10k to a 1M on the clean channel and also changed the 100k gain resistor to 22k in this channel o balance the volume of this channel.The problem then relys on the other channel.The rat sounds bad with...

Hi all

would like to know just where is best to wire the I/O of the Big Muff Tone Control - E.g - to the existing circuit boards I/O
or to a foot switch, or the Jack Sockets etc. Also what if your Output is coming out from a Vol Pot lug? :hmmm:

Big Muff Tone control as using :

Thanks for your help :wink:

Hi

Hopefully some one with a little more knowledge about these things will be able to answer my question(s)

The image is from the appnote for the LM833 chip. It shows a variation of the Baxendal tone control and the design formulas. However when using the shown values with the equations as shown I do not get the same results.

When using formulas I had: C values are in Farads, Resistors in Kohms ie. C1 5E-8, C2 5E-9, R1 1.1E4, R2 1.0E5, R3 1.1E4, R5 3.6E3

results (stated results in...

Hi Folks,

I know Beavisaudio is very good for presenting simple circuit snippets and breaking down the boost circuit, but Is there anywhere/one that has gone through the various pedal circuits and broken them down by section?

Cheers,

ff

I am wondering how you guys or the big companies out there develop their circuits.
Basicly you have three options

1) Copy what is out there. Change some componentes and add some pots and switches. Try different Transistors. I think this is the way most companies do it today. The circuit in this case is nothing new.
2) Develop your schematic from a pure theoretical standpoint. With a software like sSpice and calculations. I think this must be pretty hard to judge how this will sound when it's...

To elaborate on the strange title:

The reason for a buffer, be it a separate pedal, a looper, or in- and output buffers, is to supply a steady in- and output impedance, right? Usually a high input, and a low output impedance, so to drive other circuit parts or long cables and not to load down poor current sources such as pickups.

So why are there SO MANY different layouts and topologies used in stompboxes? Of course a single transistor input/output emitter follower is used most of the time,...

Hey Folks,

I have a question about the diode clipping in the Bazz Fuss...

Diagrams I have seen of diode clipping always have the diode(s) going to ground, with the signal travelling past getting diverted ( correct way of looking at it? ) once the diode's threshold voltage is exceeded. In the Bazz Fuss however you have the diode between the transistor's collector and base. In this case, what is happening here to create clipping?

Many thanks,

ff

Hi guys,

I wonder what do you like best for an mid-gain/high-gain solid-state clipping stage.
I tested or read about:
1. antiparallel small signal diodes or equivalents (LED, BJT, FET) in the negative feedbak loop
2. antiparallel small signal diodes or equivalents (LED, BJT, FET) to ground
3. gain stages with transistors (BJT, FET) or operational amplifiers
4. CMOS inverters (CD4069,CD4049,CD4007)
5. small power audio amplifier (JRC386 or LM386)
6. combinations of the above
Maybe there are...

The quest to understand the ability of some effects to be controlled by external pedals/devices started with a Mooger Fooger LPF and got truly out of control with a delay pedal. Here's what I've learned, and here's hoping it might be helpful.

The earliest use of CV was in modular synthesizers. I believe Bob Moog thought of it, although I could be wrong. His idea was that both note pitch and all the parameters available in a modular synth could be controlled by the same set of voltages (0-5v in...

I'm interested in buildling a blend pedal. I was looking at the other blend threads, and one of the ones I'm interested in is the ROG ( but I have a few questions about this circuit:

1. It looks more versatile than a simple blend dry/wet signal blender, since it has 2 parallel effects loops, so how would this circuit be used to just blend the dry signal with a single wet signal? I'm guessing it would be:
- Guitar -> In
- Send 1 -> Return 1 (to connect the dry signal)
- Send 2 -> Effect(s)...

It is nice to see that there is a Circuit Blocks section on here which means I bet one of you awesome wizards could help me take it one step further.

I am hoping to find a laymans breakdown of some classic overdrive circuits along the lines of the technology of the tubescreamer but light on the EE algorithm/jargon speak. I understand the basics of what resistors, diodes etc do and I can follow a schematic. I have done a few mods and built a few kits but I am wanting to understand how when...