Ceasar chorus rate too slow

youngkong10

New member
My Julia builds rate seems to be about half of what I've seen in demos for the Julia? Ive doubled checked that all of my parts are the correct value. I tried swapping the rate potentiometer from 100k to 250k but it just seemed to mess things up. I've heard that the Julia is basically a modified CE-2 so my next thoughts would be to do some kind of CE-2 rate mod for it. I'm just trying to figure out if it's supposed to sound like this though.
 

youngkong10

New member
Ok I fixed it. If you make a ceasar chorus change r6 from 1M ohm to 470k ohm and change the rate potentiometer from b100k to b1M. This will make it so the rate goes all the way as low as it did before as well as about twice as fast.
 

Dali

Well-known member
I'm curious about this (not that I don't trust you or your ears) because usually @PedalPCB trace from the real pedal(not stuff read on freestompbox or pictures).

What do you think would explain the discrepancy?
 

youngkong10

New member
I really wish I knew, at first I thought it could be my clock chip or one of the components around it. It was very noticeably slower than the Julia though, like I said about half the rate. I would really like to know if anyone else has this issue while building one or if the mod I did is just compensation for a mistake somewhere else in my build.
 

Dan0h

Well-known member
Do you DMM each component as you put them in to make sure you didn’t get a bad one? I had two entire bags of resistors more than double off what they were supposed to be before. Also Did you adjust the trim pot?

My build works, rate goes from slow lush all the way to fast wobbles just like Julia videos. When I adjusted the trim full each way killed the pedal, the sweet spot produces the lush chorus though. Where did you get your ICs? I’m only a few pedals deep but every PedalPcb build has been very accurate, I would lean towards a faulty component.
 

PedalPCB

Administrator
Staff member
I mentioned this in the other thread, but the LFO section is identical to the CE-2 so I'm pretty confident the component values are correct.

If it's abnormally slow I would double check the values in the LFO.

The BBD clock wouldn't affect the LFO rate, but take a look at R2, R4, R6, R7, and C3.
 

youngkong10

New member
Huh, those components seem to all be the correct values. Since I like the way the CE-2 rate mod I did sounds, I think I'll leave this one. Maybe I'll add a momentary switch for max rate just for fun. I really appreciate the help, I actually have other Julia's on the way so I'll update this thread with how those turn out. I bet it was just a faulty resistor somewhere or something.
 

music6000

Well-known member
Huh, those components seem to all be the correct values. Since I like the way the CE-2 rate mod I did sounds, I think I'll leave this one. Maybe I'll add a momentary switch for max rate just for fun. I really appreciate the help, I actually have other Julia's on the way so I'll update this thread with how those turn out. I bet it was just a faulty resistor somewhere or something.
Can you post a good picture of your finished PCB?
 

manfesto

Member
I mentioned this in the other thread, but the LFO section is identical to the CE-2 so I'm pretty confident the component values are correct.

If it's abnormally slow I would double check the values in the LFO.

The BBD clock wouldn't affect the LFO rate, but take a look at R2, R4, R6, R7, and C3.
Don't have the Caesar I built anymore but my build also was notably slower than my real Julia when I had them side-by-side, I double-check the values of resistors and caps with my DMM before installing so I don't think it was that?

When the next batch of PCBs comes in I'll order one to test again
 

PedalPCB

Administrator
Staff member
Don't have the Caesar I built anymore but my build also was notably slower than my real Julia when I had them side-by-side

Is your Julia a V1 or V2? I'm wondering if maybe the maximum rate was increased in the V2.
 

PedalPCB

Administrator
Staff member
Ahh, well in that case I can't really explain it. :unsure:

The LFO is identical to the CE-2 aside from the added Shape control.

If I come across another original I'll certainly take a look and make sure nothing is off, but I'm fairly certain everything is correct.
 

youngkong10

New member
Can you post a good picture of your finished PCB?
Sorry it took me a little bit here's some pictures, the extra spst just maxes the rate pot out. Also I didn't have any 6.8k resistors at the time so u can see a 1.2k and a 5.6k soldered end to end in that spot.
 

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PedalPCB

Administrator
Staff member
Okay, so....

My LFO is running at around 3.7Hz with Rate at maximum, which is the correct rate for the circuit. You can see in the pic below that the component values are correct and do match the Boss CE-2 schematic. (the TL022 instead of TL072 has no effect on the Rate)

However, since a few people have commented about the rate being slow, I'm starting to suspect that C22 might be a different value on some units....

I suspect we're going to find that C22 (C3 on the Caesar) is 47nF in some units, but since I don't like to guess (or speculate, simulate, calculate, or measure values in-circuit) let's just remeasure the thing and be done with it. I have an original incoming. It'll be here Sunday. I'll follow up then.

1607102316479.png
 
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PedalPCB

Administrator
Staff member
Confirmed, 47nF.

"But wait! You just said you didn't measure components in-circuit!"

I didn't.

This resistor is SMD film, which melts under normal desoldering conditions... So we have to work around that by removing other components to isolate the capacitor we want to measure. Although the capacitor is still on the PCB it is no longer "in-circuit".


Capacitor.jpg
 
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manfesto

Member
Confirmed, 47nF.

"But wait! You just said you didn't measure components in-circuit!"

I didn't.

This resistor is SMD film, which melts under normal desoldering conditions... So we have to work around that by removing other components to isolate the capacitor we want to measure. Although the capacitor is still on the PCB it is no longer "in-circuit".


View attachment 8232
Nice! So the V2 for sure and probably later V1s like mine were 47nF?

ill hopefully be able to order another board this week
 

Dan0h

Well-known member
Confirmed, 47nF.
Should I consider removing C3 and replacing it with a 47nf?
I’m happy with it as is, but if there would be a drastic change in the rate’s ability to get even faster more vibratoish... are we talking a 50% bump up in speed?
 

youngkong10

New member
With 47nF the Rate is doubled (give or take, considering component tolerances)

My prototype went from 3.7Hz to 7.8Hz at maximum speed.
Do you think this would sound any different than the r6/pot mod I did? I believe I'm also getting somewhere around 7.8Hz at max. I'm just wondering if I'm losing any fidelity somehow?
 
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