Guitar Effects Explained

[DrNomis_44]

There's a free vst plug-in Oscilloscope, called Smexoscope, that you can download and install and run in any Daw that supports vst plugins, I think there's only a pc version:

http://bram.smartelectronix.com/plugins.php?id=4

[jugglindan]

There's a free vst plug-in Oscilloscope, called Smexoscope, that you can download and install and run in any Daw that supports vst plugins, I think there's only a pc version:

http://bram.smartelectronix.com/plugins.php?id=4

Doh! That's a good reminder. I already have Friture which can capture audio from my THR amp via USB. It has very little latency. I always forget I have it though, and only used it once to see what the tone control on my Direct Drive clone is doing (not much as it turns out, just cuts a bit of high freq noise - could try changing the cap but I like the sound and don't want to mess with it). As well as a scope it also has various frequency domain displays.

It's open source and supports Linux, Mac, and PC. Worth a look.

[Simon Barden]

It's often just as easy to record the audio and then look at the captured waveforms. As you aren't generating regular sound pulses that you could set your timebase to in order to display in a stationary manner, you'd certainly need a freeze/capture function on any scope/plug-in to see a still picture of the waveform.

Once the sounds are captured, you can look at them at leisure to your heart's delight.

[jugglindan]

I frequently test pedals by putting my looper in front. Lets me just loop the test music while I adjust trimpots or whatever. That would also work for this since I don't think I can get Friture to consume a recorded track directly (might be able to fake it with a loopback or something).

[Simon Barden]

You wouldn't need it to, as DAWs will display the waveform directly.

But a looper is a good test tool (unless you are using something like a Fuzz Face or some wahs, that really need to be directly connected to the output of guitar).

[Bakersdozen]

Any ideas on this circuit? I am currently playing around with it and sounds really good, however I'm getting the fuzz dying out and a kind of starved fuzzing out once the bulk of the sustain from the signal has gone. The fuzz lasts for around 4 or 5 seconds, when playing a chord with a decent attack on the strings then dies away with a BZZT breaking up kind of decay. The chord is still ringing out of the guitar but the tail of the Singal goes towards clean then.

I have swapped opamps and the diodes with different ones and although the fuzz tone does get altered, the starved decay still occurs in the same way. I've also tried with different power supplies to ensure that the voltage isn't starved and contributing to this.

Do you rekon it's just the circuit, or would it be likely the electrolytic cap maybe leaky/possibly faulty. It would probably be the next thing I try, once I get a new cap in 10uf. Or is the issue somewhere else? I do have spare 22uf or 47uf elec caps here, should I give them a go?

[jugglindan]

I am not an expert (or a fan) of fuzzes, but it sounds a bit like gating which is just part of the design of some fuzz circuits. On some transistor fuzzes, as the signal level starts to drop, the transistors go into cutoff. I have no idea how op amp fuzz behaves.
I would try the 22u cap, as it looks like it's just used to filter out the DC offset before the signal hits the output. 22u should work for this. But there is a chance it's just part of the design.

Are you building on breadboard or soldered? I always like to breadboard unknown circuits like this to see if I like how they sound.

[Bakersdozen]

Thanks DC, this is straight on Vero, as I dont have breadboard yet. I see how breadboard will be a good investment though. Does it act like Vero in long rows? Or do you have to create the circuit as such?

[jugglindan]

I am not sure that the 10u cap would cause that sort of problem. The impedance of a cap varies with frequency not voltage level, although I am not sure how a fault would affect that.

Breadboards are not connected the same as veroboard. They are like this:




All images taken from this intro to breadboarding. It's a short read and a very well written intro to using a breadboard. For myself, I find it easier to breadboard a circuit direct from a schematic, but it can also be done by systematically working through a vero layout. I just find it a little harder since the layout is arranged for compactness not readability.

A lot of the Tagboard Effects layouts are modified from available schematics though, so it can be worth working directly from the layout you plan to build.

You can pickup a decent breadboard from Jaycar for not too much money. Here's how I have mine setup for pedals:

Other holes on the angle bracket are drilled to accept switches as required. No power switch, I just add/remove the ground lead from the battery. That circuit is 3/4 of a Rat (no tone control or output buffer at that stage).

[Bakersdozen]

Awesome, thanks DC. I will have a read and will force me to polish up on schematics.