Joyo California Sound Mic sim mod

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Joyo California Sound Mic sim mod

Postby Hanky- » 26 May 2016, 13:38

Hi everyone,

I was looking at pics of the pcbs of the other sound pedals & noticed that the California Sound had a different Mic sim included in it. The parts are R29, C20 & C21 on the board. I put a box on image attached to locate them for ease. I removed R29 & C21 so that the mic sim now matches the other sound pedals. The mod helps bring in more presence & makes the bass a lot more manageable, compared to the stock setting there is a very slight increase in hiss since more highs are coming through but overall the pedal is much raw sounding in a good way I feel IMO

The interesting thing i noticed was the mic sim is similar to the Sansamp GT2 Off Axis position but the value of C21 might be wrong in the joyo. It measures 42nF, while the GT2 schematic shows 4.7nF. I haven't measured C20 since removing the other two components leaves it unused & in circuit measurement might be off, R28 does measure 22k though. I don't have a cap of 4.7nF to try out, it might get it to sound closer to the original T21 pedal. Here's a link to the gt2 scheme http://www.tonepad.com/project.asp?id=22
I wonder joyo got any other components wrong elsewhere.
Note that the image I've used here is from the actone sound pcb board & doesn't contain the components soldered.

I still haven't found a way to fix the noise problem at max voice knob setting with max drive. I wouldn't recommend changing the opamps trying to fix the issue, I've changed them all to the TI TLC2262 & 2264s, the improvement was subtle & not worth the effort. The noise is like insufficient filtering, maybe one of the missing components might be causing it, although i have tried changing it into the british sound pedal & it didn't exhibit that noise at max settings, so it could just be a component involved somewhere is incorrect. The original character pedal wasn't traced before it got discontinued, so this clone may not have any hopes of getting fixed since it sounds muddy stock to begin with for anyone to show any interest lol

Anyways, hope it helps anyone clear up the sound a bit.
Cheers!
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Re: Joyo California Sound Mic sim mod

Postby SiRaff » 10 Mar 2017, 17:07

Thanks for this Hanky, fascinating that the speaker sim used in the California is different to the other Joyo Sound pedals.

Before removing those components, did you find that the sound was quite lacking in low mids? I run mine direct into my amp input (I know the built in speaker sim means they're more designed for direct recording or an FX return), and I've found that the sound lacks guts / sounds quite "artificial" (not sure how else to describe it). If I use an EQ boost in the 400-800 Hz bands after the pedal it sounds a whole lot better/fuller (and more like the tone with the pedal turned off).

I know the pedal has a 3 band EQ, but boosting the mids / cutting the others does not seem to help much. It sounds like the mid control is tuned to a slightly higher frequency than I'm targeting.

I'm trying to work out:
- Is this just the way the cab sim works (in which case, the cab sim mod as described elsewhere on this forum might help for running direct into an amp)?
- or, is it a feature of the pedal - in which case, is there an obvious way to modify the tone stack? (The Tech21 schematics are a little beyond me)
- or, is my pedal built differently (I.e wrong) somehow?
- or, could it be related to the 42nF instead of 4.7nF cap thing that you spotted? There are a lot of comments that this pedal has way too much bass and I wondered (long shot) if the two might be related.

I think it makes sense for me to try the cab sim defeat mod, but I'm a little nervous about this surface mounted stuff. At the end of the day it's a dirt cheap pedal, and I don't use it at the moment because of this tone issue - so if I screw it up so be it!

I'm mostly just interested to know if I'm the only one experiencing this, what causes it, and whether it's specific to the California pedal or to the whole Joyo Sound range.
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Re: Joyo California Sound Mic sim mod

Postby Hanky- » 16 May 2017, 10:29

Sorry for the late reply, haven't logged in for awhile.

Anyways, before removing the mic sim the problem I had was with the top end being dark & dull. The pedal does have a lot of bass, actually I found it to mimic the mark II sound very well going direct for blues & vintage tones, modern sounds were not to my liking. The mic component values here aren't wrong since they work to give a off axis mic'd sound on the calif pedal. However if you perform the cab sim defeat mod on this pedal, you will also require to remove the mic sim mod exclusive to the calif, along with that a resistor R31 needs to be changed from 68k to 22k or 47k, that resistor value is also exclusive to it.
I eventually converted it into the British Sound, that one can be bassy but its more controllable than this calif sound.

I would recommend getting two cheap 12W soldering irons, it makes removing the smd parts very easy(except IC's) since you heat both sides and just move the component out without damaging/uprooting the solder pads. These are cheap enough to experiment on so I'd say go for it but first test out on some broken stuff at home like radios,mobiles, modems, motherboards or something.
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