Pork Barrel on bass

[icecycle66]

Madbean Pork Barrel, with JMK mix control, on bass.

MN3005 and 3101 chips.
Running at 15V.

I'm tired of Google's crap trying to make me do stuff I don't want to do; so here's a link to my new Daily Motion page.
Sometimes Daily Motion puts commercials on before the video, but all you have to do is hit refresh and it usually skips the ad. It's lame, but it's better than Google's garbage.

http://www.dailymotion.com/video/x171las_pork-barrel_music

[alanp]

Nice work Is the second LED a rate one?

[icecycle66]

Nice work Is the second LED a rate one?

Yeah.
It's the R39 mod.

[Gledison]

Niiiiice! Hey, i think in this build thwre is no chance for battery right? Do u think is necessary as well the plastic jacks?
Cheers mate

[icecycle66]

Niiiiice! Hey, i think in this build thwre is no chance for battery right? Do u think is necessary as well the plastic jacks?
Cheers mate

If you are building it to run higher than 9v, the battery is useless anyway.
If you are building the 9v type, then you could fit a battery if you wanted.  I don't know how fast this circuit would drain a normal battery.

THe plastic jacks are just because I have a bunch of those.  Normal open jacks could fit easily.

[das234]

Is the mix control just to add dry signal to the wet?  Is that necessary or can you dial the effect back with the standard controls?

[kothoma]

[...] with JMK mix control [...]

That's the Panner?
Hm. Wouldn't it have been easier and equivalent to put in a voltage divider potentiometer just before C17?

[icecycle66]

You can make the effect less intense with the standard controls, but you can't mix wet and dry signal with them.

[icecycle66]

[...] with JMK mix control [...]

That's the Panner?
Hm. Wouldn't it have been easier and equivalent to put in a voltage divider potentiometer just before C17?

Uh, sure.  I guess.  If I knew what the hell that means. 

[kothoma]

[...] with JMK mix control [...]

That's the Panner?
Hm. Wouldn't it have been easier and equivalent to put in a voltage divider potentiometer just before C17?

Uh, sure.  I guess.  If I knew what the hell that means.

Like the Mix pot in a delay or reverb circuit.

[icecycle66]

Like the Mix pot in a delay or reverb circuit.

Whoa.  Okay, you're gonna have to give me the how to on that so I can use it rather than the mix board.

[kothoma]

Like the Mix pot in a delay or reverb circuit.

Whoa.  Okay, you're gonna have to give me the how to on that so I can use it rather than the mix board.

To tell the truth, I'm not completely certain how to do this. But I'm sure it can be done.

See below the relevant section of the Pork Barrel schematic.
I've marked in red where the dry and the wet path finally get mixed.
In the blue box you have the last part of the wet path (a lowpass).
The signal gets biased (R26) after the coupling cap C17.
So I believe it would be best to put a level control just before C17, marked with a green arrow.

So perhaps one could simply replace R25 with an A10K pot. (second image)

Different approach: you could put a variable resistor in series with R27. (third image)
Edit: Right. That's what happens in the CE-2B Bass Chorus, using a C250K (VR4) in front of the 47k.

[rude]

I am trying to add a mix pot but I am not sure how to wire it. What should I do with lugs 1, 2, and 3 of the 250kC to wire it in series with R27 like in the CE-2B Bass Chorus?

[kothoma]

Coming from C17/R26 you can wire it either
a) first the pot and then R27 or
b) first R27 and then the pot
going to C5/C6/R9/R10/pin 6 of IC1.

Now have a closer look at the pot:
Enter at lug 1, bridge lugs 1 and 2, and leave at lug 3.
Or enter at lug 3, bridge lugs 2 and 1, and leave at lug 1.
Both ways will result in 250K resistance at "0" and 0K resistance at "10" (giving you the full wet signal in the mix).