Walrus Julia Chorus Vibe

phi1

Well-known member
Question about the theory of how the triangle/sine modes work.

is the triangle and sine mode directly modulating the delay t? I assume the lfo puts out triangle, and sine is roughly achieved by filtering the triangle wave.

since the pitch we hear is the rate of change (derivative) of the delay time, I think it would be as follows:

triangle mode:
Delay time: modulated by triangle wave
Pitch (rate of delay time change): square wave (oscillates hard from pitch up to pitch down)

sine mode:
Delay time: modulated by approximate sine wave
Pitch (rate of delay time change): approximate sine wave (oscillates smoothly between pitch up and pitch down)

of course given the waves are formed by analog lfo, its probably not an exactly perfect triangle wave. But roughly speaking, is this correct? I’m doing some exploring on chorus types in fv-1 and want to make sure I’m understanding correctly.

@PedalPCB
 

taxfree

Member
Sorry, I expressed it wrong. There is a Walrus Julia Chorus and another Walrus Julia Chorus / Vibe. Caesar Chorus is based on Julia Chorus. About these two pedals I want to know if there is any difference, as they are asking for a new pcb and there is already one available.
 

ADAOCE

Well-known member
Sorry, I expressed it wrong. There is a Walrus Julia Chorus and another Walrus Julia Chorus / Vibe. Caesar Chorus is based on Julia Chorus. About these two pedals I want to know if there is any difference, as they are asking for a new pcb and there is already one available.
Are you talking about the Juliana? Or the v1 Julia vs the V2
 

taxfree

Member
Are you talking about the Juliana? Or the v1 Julia vs the V2
Question resolved! This post was old. The Caesar chorus pcb had not yet been produced. The difference I was asking about was the versions of the Walrus audio pedal (v1 / v2), which I identified has no sound difference between them. thanks!
 

IPv6Freely

Active member
The Julia is one of my favorite pedals ever, as a bassist. I already have a real one, but building a clone would be really cool.

Couple questions:

  1. The D1 and D2 red LEDs... why do they not just regular diodes there? I've never opened up my Julia so never noticed if they had red LEDs in them. I see in the build doc above (but not in the official PDF) the mention of using 2.2uF MLCC capacitors. Is that in place of the red LEDs? I'm nowhere near well educated enough on electronics, but why are you replacing a diode with a ceramic capacitor?
  2. I couldn't find A3207, but I was able to find some MN3207. They should be the same, but are there any gotchas with that?
  3. Is the swap of R6 from 1M to 470K, and RATE from B100K to B1M still the recommended build?
  4. Would 1/8W metal film resistors work okay here, or should I stick with 1/4?
  5. I can't figure out which 9V1 Zener to buy. Narrowed down to both of these, but both could be totally wrong:


I think that's it for now. I already got my PCBs and just working on sourcing parts.
 

PedalPCB

Administrator
Staff member
Couple questions:
1) LEDs have a higher forward voltage drop. The LFO produces a triangle wave shape, the LEDs clip the top and bottom off to round it more into a sinewave-like shape. The 2.2uF capacitors do a slightly better job in my opinion.
2) You're looking for V3207, not A3207. MN3207 will work fine, just make sure it's coming from a reliable source.
3) Those modifications aren't necessary, just make sure C3 is 47nF.
4) 1/8W is perfectly fine
5) Either of those zeners should work fine
 

IPv6Freely

Active member
1) LEDs have a higher forward voltage drop. The LFO produces a triangle wave shape, the LEDs clip the top and bottom off to round it more into a sinewave-like shape. The 2.2uF capacitors do a slightly better job in my opinion.
2) You're looking for V3207, not A3207. MN3207 will work fine, just make sure it's coming from a reliable source.
3) Those modifications aren't necessary, just make sure C3 is 47nF.
4) 1/8W is perfectly fine
5) Either of those zeners should work fine
OOPS, yes I meant V3207!

Am I just using standard 2.2uF ceramic (light yellow/orange) caps? Or is it something special?
 

IPv6Freely

Active member
Which resistor is for the LED? I want to change to another color and want to make sure the resistor I use is sufficient.
 
Top