Author Topic: “Sea horse” chorus not working properly  (Read 863 times)


“Sea horse” chorus not working properly
« on: January 09, 2019, 01:40:05 PM »
Hello again,
I’ve just completed a PedalPCB clone of the EQD Sea machine
And it’s not working quite right!
I haven’t had time to meter everything yet but let me describe the issue and
See if anyone has any immediate insight.
So, it works when off so signal is passing through,
Signal also passes through when on, and the LED is working correctly
I would assume so is the power and the jack wiring.
It seems as though most controls work aswell, though a bit quiet.
The main issue seems to be the “dimension” control, if it’s pushed past, say
8’oclocl it feeds back kind of like a dimed out analoge delay pedal, so it feeds back and just seems to get louder and louder.
There are two components I find to be maybe suspicious
1 is C11 which is a 3n3F cap, that cap I have is the correct
Type but I wonder if it being 68v may be causing issues
2 is IC 4 it calls for an LM324 and what I could get was a LM324N
I’m uncertain weather that makes a difference.

Hope this gives a bit of insight into my pedal problem
Here are the build docs:
And an image of the pedal

« Last Edit: January 11, 2019, 11:31:40 AM by SirHugo »


Re: “Sea horse” chorus not working properly
« Reply #1 on: January 09, 2019, 04:40:35 PM »
Those part differences should not make any material difference.
Capacitor voltage rating by itself is not an issue so long as it isn't too low.
Full part numbers of IC's are seldom specified. If it says LM324, the rest of the code isn't important and the "N" only refers to the package style.
The Dimension runaway feedback may be intentional. It can only be tamed by making the feedback level lower at maximum so low that it cannot run away, but many people like it to be able to do that. You could try increasing the value of resistor R9.

It's not clear from what I read above if by "not working"  you mean there is no chorus sound but there is some delay effect or no effect at all.
Croeso i Diystompboxes.

"We're hopeful that it will land in a place where it won't harm anyone," US Defense Secretary Lloyd Austin said. "Hopefully in the ocean, or someplace like that."


Re: “Sea horse” chorus not working properly
« Reply #2 on: January 09, 2019, 08:47:47 PM »
So, I  fiddled with it a bit more now thinking I might be able to get something to kill the feedback, unfortunately nothing seems to help, it just screams through the amp if it gose anywhere near 9 o’clock
It also seems to me that the rate and shape don’t seem to do anything either
The intensity, animate and depth absolutely make an audible difference, the shape may be too subtle for me to hear but the rate sounds like it makes no audible difference weather all the way up or turned all the way down.
There is a small volume drop when it’s on as well.


Re: “Sea horse” chorus not working properly
« Reply #3 on: January 11, 2019, 11:31:20 AM »
I’m going to try and get some reads to post from the multimeter today,
In the hopes for more clues. Dose anyone else have any insight in to what may
Be happening to cause this heinous feed back?


Re: “Sea horse” chorus not working properly
« Reply #4 on: January 11, 2019, 01:15:21 PM »
I think I found the issue, looks like my 10k resistors were mislabeled in the package they
Came in they were, in fact 100k reaistiors, I’ve already ordered new ones.
My only question now is, do you think this may have hurt the circuit at all or
Will it be fine once I replace them?
All of my ICs are socketed so they’ll be removed for safety when I remove and replace


Re: “Sea horse” chorus not working properly
« Reply #5 on: January 11, 2019, 10:21:28 PM »
That will definitely keep the rate and shape knobs from working right. Probably explains the volume drop, too, and might explain the feedback.

Shouldn't have damaged anything, though.
"I had an unfortunate combination of a very high-end medium-size system, with a "low price" phono preamp (external; this was the decade when phono was obsolete)."
 - PRR


Re: “Sea horse” chorus not working properly
« Reply #6 on: January 16, 2019, 04:27:34 PM »
Thanks man.
So I received and replaced all the culprit resistors, no more feedback!!
However the shape and rate still are non functioning, every other
One is working however. Haveing now double checked that all my parts are
Now 100% correct I’m not sure how they are not functional.
I’ve also noticed with more volume from the amp I can hear the sound of the rate
Changing as I turn the knob Distantly in the back ground in the form of static-y ticking.
« Last Edit: January 16, 2019, 08:47:07 PM by SirHugo »