Phuncgnosis - what does the 1M pot do?

[tatems]

I'm just about to start building Tim Escobedo's Phuncgnoisis but i'm unsure of a few things.

With the Vr connection to the op amp, do i need to make the small circuit for every single conection or do i make the one small circuit and then connect all the vr lines to it. (if you follow me)

The other thing is, can i use a 1N4148 for the diodes?



Tatems

[Paul Perry (Frostwave)]

You only do the small section (generating Vr) once, and then connect the vrious Vr points to it.
And any silicon diode will be OK.

[tatems]

Thanks for that, now i can start!

[ethrbunny]

This looks like phun..(sorry).. whats the 'aux in' for ?

[Paul Perry (Frostwave)]

This looks like phun..(sorry).. whats the 'aux in' for ?

The aux in allows you to filter the input sifgnal, according tho the envelope of the AUX signal.
So, you could set up a drum machine & get a complex envelope structure filtering the guitar or whatever you are putting in to the input.
Note, if the drum machine is locked to midi, then you have a midi synced filter sweep!! which would not be easy (or cheap) otherwise.
And of course this idea can be extended to trem. Well Phunk Me!

[ethrbunny]

Thats pretty phuncing cool.

If you don't want the 'aux in' could you drop out alot of the lower half of the circuit?

[jmusser]

The auxilliary jack, let's you have either a guitar connection, or a drum machine connection. You cannot omit the bottom section. If you look at the aux jack, you can see where it has a connection (arrow) coming down from the input, that puts the input through that section. It is broken when you insert a plug, then the drum machine uses it. You can omit the jack, and wire the input straight into the top (#3) leg of the 1meg pot though. That's what I did

[cab42]

If you look at the aux jack, you can see where it has a connection (arrow) coming down from the input, that puts the input through that section. It is broken when you insert a plug, then the drum machine uses it. You can omit the jack, and wire the input straight into the top (#3) leg of the 1meg pot though. That's what I did

I was planning to do that as well. Glad to hear that I am not totally off.

BTW: I'm working on a veroboard layout of the Phuncgnosis, as I haven't been able to find a layout anywhere. I'm just missing the labelling. Would anyone be interested in me posting it? Well, I'll propably post it anyway!

Regards

Carsten

[tatems]

What is the 1M Pot for? Is it to increase or decrease the amount of wah?

[Ge_Whiz]

It's to match the envelope detector (=wah range) to the output level of the guitar, to ensure that the signal triggers the wah appropriately. No, you can't omit it.  :wink:

[Transmogrifox]

You could omit the 1M pot if you wanted a completely untweakable envelope filter.  Basically you would have to turn your volume pot on the guitar up and down to adjust the sensitivity.  It works, but you trade off for volume drop--just use the 1M pot.  It makes it a much nicer envelope filter when it's got some adjustable parameters.

[tatems]

Thanks for that

I was just checking to see if i could use it as the pot to control my wah in my wah pedal that i am building. Another thing, what does the pedal on a wah do exactly. Does it change the sensitivity or does it increase treble one way or increase the bass the other way?

[Transmogrifox]

A wah pedal is a tuneable filter.  Usually the most "vowel" sounding wahs are a bandpass filter with a resonant frequency that can be swept with the movement of the pedal--you're changing the group of frequencies that are being passed (likewise, the group that are rejcted).

So to answer your question, both.  A bandpass filter being swept in resonant frequency is boosting the lows when it's centered on low frequencies, then is boosting the treble when centered on high frequencies--but in addition, it boosts the mids when swept to the midrange.

No, you can't use the 1M pot to control it like a wah wah.

"Sensitivity" in this context refers strictly to envelope filters, like the phuncnosis.  This filter instead of being swept up and down the frequency range, is swept by the dynamics of the input signal:  The harder you pick, the higher the filter sweeps.  "Sensitiviy", then, determines how quickly, or how much the filter will sweep according to a certain picking strength.

There is no such thing as "sensitivity" on a wah pedal with the foot treadle.  The concept of "sensitivity" is hard set in this case, and is determined by how much the filter resonant frequency changes with respect to how far your foot rocks the pedal.

[tatems]

Thanks for that!  

Would it be possible to create a circuit that controls the bass and treble and have that connected to the output of the envelope filter and have the treble and bass controlled by the foot pedal so you would sort of get a wah wah pedal type effect?