Joyo - JF-05 Classic Chorus  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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digitaltubes
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Post by digitaltubes »

Can you confirm the BBD is a 3207? I'm wondering if the Joyo Analog Chorus is a re-layout of the Joyo Classic Chorus, with no fly wires for footswitch.

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Ben N
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Post by Ben N »

HerrDoktor wrote: It seems more bright and it's my first chorus pedal, so I don't know, if is an issue or normal.

I thought it was a clone of BOSS CE-2 like wrote in this forum, but it seems different.
Some of you have the schematic?
I never thought of my original CE-2 as bright.

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HerrDoktor
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Post by HerrDoktor »

Hi. I bought the new analog chorus and sold the bigger one because
I had problems with the dimension of my pedalboard; the new analog chorus
is smaller than the older one.

It's absolutely better the older one; it has a warm sound and It isn't bright like I heard, but
it has a lot of hiss...

What annoying....
I've opened it to look for something.
as soon as possibile I'll post something...

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analogguru
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Post by analogguru »

Joyo Classic Chorus = Ibanez CS 9 (in mono)

analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.

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jchristo
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Post by jchristo »

I'm pretty sure that something is up with mine. It produces a nice chorus for a second and then the signal becomes dry after the volume fades to a marginal level (as if the effect is gated). I'm okay with dirt but I have no idea how to approach this one. Transistors? IC's?

Any input would be appreciated.

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jchristo
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Post by jchristo »

jchristo wrote:I'm pretty sure that something is up with mine. It produces a nice chorus for a second and then the signal becomes dry after the volume fades to a marginal level (as if the effect is gated). I'm okay with dirt but I have no idea how to approach this one. Transistors? IC's?

Any input would be appreciated.
Uh oh. It seems I should not have posted this here. Go ahead and delete. My apologies.

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AuditoryDriving
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Post by AuditoryDriving »

i have the same issue with hiss coming up just before a note decays.

it seems there is a noise gate implemented as an envelope follower as in ibanez cs-9 - i gathered this from Mark Hammer- which only affects the wet signal, which is the noisy part. The main suggestion floating around the web is to replace the main audio opamp. Yet, i doubt that this alone would solve the problem. So, is there anthing else that can be done to reduce the hiss without affecting the tone? in the Worst-case scenario i d lower the filter frequency thresholds and also increase the opamp low pass caps.

Thanks in advance!

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Post by Fender3D »

AuditoryDriving wrote:..The main suggestion floating around the web is to replace the main audio opamp...
The main suggestion is simply idiotic...
If the noise gate really annoys you, toss the FET...
You might also bias it better to obtain another threshold limit

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Post by AuditoryDriving »

Thanks @fender3D!

it s not the noise gate per se that anooys me, it s the hiss itself. My first thought when i got it was that there was a mismatch in the pre/post emphasis filter (iirc there s no compander in there). The dry signal is noise-free,so it must be he bbd that s noisy. Surprisingly enough, there are similar complaints for the ibanez cs9, which the classic chorus seem to be a clone of.

If there are no other suggestions i ll put this on hold for a rainy day and then i ll check for the pre/post emphasis filter mismatch and in case it s right (someone maybe has checked already?) i ll lowerthe lowpass threshods in the post section.

Thanks again!

Btw, has anybody actually traced it properly to confirm if it s a part for part clone of the cs9 ? in my humble opinion, this is one of the most lush choruses i ve tried!

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Post by Fender3D »

Well.. MN32xx are indeed noisier than MN30xx BBDs...
Furthermore, I don't know if Joyo is an Ibanez clone...
I just had a glimpse at CP9 schematic.

Whether they're relatives, toying with parts around IC106 should do the job...

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andmarti1424
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Post by andmarti1424 »

Hello. I am trying to decrease volume in this joyo chorus pedal (seems similar to ibanez cs9, but not exactly the same).

this is ibanez cs9 schematic (open the image completely):
Image

I have tried increasing R123 (3.9K) value to decrease dry signal.. (I actually used a variable preset), but this is not the behaviour I am after, since this change the mix of wet and dry signals..

I then though of changing R131/R141 (just one, since this is mono) 470R resitor to a higher valuer.. but it seems there is not that resistor in the output section..
27K (R130) and 91K (R129) are the two resistors at the left of the left 4558D IC.

this is joyo pcb (borrows image):
Image

then it goes to other resistors rather than the 470R one..
The resistor below the 4558D IC seems a 47K resistor..
the one below it could be a 570K.
then you have various 10K resistor.. then to a C2458 transistor / 473 cap.
Anyone know what is this arregement?
Any idea how can decrease volume?

Thanks for any help!

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Post by plush »

I guess you should play with a feedback loop of the de-emphasis filter (r129/r132 on your schematic - just for reference).
Track your resistor with dmm (or using your eyes), since joyo schematic differs from ibanez CS9.

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Post by andmarti1424 »

plush wrote:I guess you should play with a feedback loop of the de-emphasis filter (r129/r132 on your schematic - just for reference).
Track your resistor with dmm (or using your eyes), since joyo schematic differs from ibanez CS9.
thanks. actually I achieved the volume decrease with a voltage divider at the output.
i solder two legs of a 100k preset (could be a pot) to the 3pdt switch and the other preset leg to a wire to the pcb. cut a trace and thats all!

Result is just what I needed!

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Post by AuditoryDriving »

it s a great pedal minus the hiss....

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plush
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Post by plush »

andmarti1424 wrote: thanks. actually I achieved the volume decrease with a voltage divider at the output.
Yep, That's another option.

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