Bass Paralooper moosapotamus question

[Gabriel Simoes]

Hello all...
Since I know a lot of people here have already built the bass paralooper project I'd like to clear some doubts I have right now.

In the moosapotamus pcb there's no place for the frequency pot, and to me this is one of the most important things in this circuit .... but I guess I can just ad a pot in the place of the R6 (2k2) and place the 2k2 in the middle lug of the pot ... so I could place both in series like the bass thru and have the frequency control, right ?

An other thing, the volume pot could be forgotten and a linear (b) pot could be used in series with R12 so I could control the gain of the opamp and skip the necessity for volume audio pot ? they are kind of difficult to find here, and when we find they do not have good quality ...

Could the balance pot be substituted for 2 other pots and so the clean and fx loop volumes would be split appart ? I can not find those balance pots here too ....

And to finish, is there a real need for closed jacks in the fx loop and why ?
Thanks
Gabriel

PCB :

Schematic :
http://www8.plala.or.jp/KandR/cir_bassthru.html

[idiot savant]

In the moosapotamus pcb there's no place for the frequency pot, and to me this is one of the most important things in this circuit .... but I guess I can just ad a pot in the place of the R6 (2k2) and place the 2k2 in the middle lug of the pot ... so I could place both in series like the bass thru and have the frequency control, right ?

yes you could do it that way, the freq pot is wired as a variable resistor

An other thing, the volume pot could be forgotten and a linear (b) pot could be used in series with R12 so I could control the gain of the opamp and skip the necessity for volume audio pot ? they are kind of difficult to find here, and when we find they do not have good quality ...

also ok to do, but make sure to stick a 100k resistor to ground in place of the vol pot.

Could the balance pot be substituted for 2 other pots and so the clean and fx loop volumes would be split appart ? I can not find those balance pots here too ....

i don't know about that one, the balance pot is just a 100k linear pot, not anything special or hard to find.

And to finish, is there a real need for closed jacks in the fx loop and why ?

i wouldn't think closed circuit jacks are completely necessary, i think the purpose of them here is to defeat the mix knob when nothing is plugged into the send jack. that way with nothing plugged into the send jack your straight signal goes through both sides of the circuit.

[tommy.genes]

In the moosapotamus pcb there's no place for the frequency pot, and to me this is one of the most important things in this circuit .... but I guess I can just ad a pot in the place of the R6 (2k2) and place the 2k2 in the middle lug of the pot ... so I could place both in series like the bass thru and have the frequency control, right ?

Moose's layout omitted the frequency control, but did include an off-board switch to add an additional capacitor (0.22u) to ground in parallel with C5 (.047u). While this is not a continuously variable cutoff control, it does accomplish the same thing but in an "on" or "off" manner.

Your idea for adding the frequency pot while still using Moose's layout seems like a good one. If you do that though, you could omit the 0.22u cap and SW2. Or you may not want to. See my comments on this tone circuit in my BassThru build report in This Thread

An other thing, the volume pot could be forgotten and a linear (b) pot could be used in series with R12 so I could control the gain of the opamp and skip the necessity for volume audio pot ? they are kind of difficult to find here, and when we find they do not have good quality ...

This won't work because the opamp is in a non-inverting configuration where gain is determined by A = 1+(R12/R11). So no matter how small you make R12 or how large you make R11, the minimum gain you will get is still 1. Even if it did work (i.e. if this was actually an inverting opamp), I'd think you'd still want an audio taper (log) pot to control volume.

Could the balance pot be substituted for 2 other pots and so the clean and fx loop volumes would be split appart ? I can not find those balance pots here too ....

There is nothing unique about that "balance" pot. All pots have three terminals, it's just a matter of how you connect them. Also, doing two volume controls would work (although you would have to change the wiring), but then you'd have to use audio taper pots, which you've already said are hard to get.

And to finish, is there a real need for closed jacks in the fx loop and why ?

I didn't use them. When would you ever plan to use this pedal without anything else connected in the loop? Otherwise, all you're doing is blending your clean signal with a filtered version of your clean signal. If you just want a bass boost, there are other simpler pedals for that (e.g. EH Hog's Foot).

-- T. G. --

[Gabriel Simoes]

Thanks for your replies ...
While the paralooper is already good, there's always "room" for mods!
One of them could be the tone control, and maybe active filters, there are a lot of stuff that could be implemented ...
2 loops would be great too! but this way with 3 pots for volume ....
And I think the gain control is a lot better than the passive volume control, so we can use linear pots =)
Thats it, I will definitely build this tomorrow ...
Thank you...
and sorry for my bad english,
Gabriel