Tech21 Character Series  [schematic]

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

Gentlemen.

I´ve been having a hard time to find the values of C6 capacitor for the California version of the Joyo pedal... Does anyone have this beauty in hands to confirm the value of this eletrolitic capacitor? I know it does not exist in British, AC Tone and American versions.

I´ll be thankfull if someone can confirm the value of it to complete the spreadsheet with the component values.

Thank you all.

Daniel.

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Post by Stephanovitch »

C6 is a 2.2µF/50 electrolitic capacitor

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daniellp
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Post by daniellp »

And the Joyo Amp simulator family has grown...

This the brand new Joyo Oxford Sound, that claims to emulate an Orange Amp...

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I already reverse it... It have a new board, but with no big news on the effect layout. Only some new capacitors for filtering between VCC and GND, and some minor changes I will put on the revised schematic, to be released soon...

Keep tuned for the scenes of the next episodes...

Daniel.

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Post by daniellp »

And here is the schematic of the Oxford Sound...

Enjoy with no moderation..

Daniel..
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Oxford Sound Schematic.pdf
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azrael
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Post by azrael »

daniellp wrote: 28 Mar 2022, 21:52 And here is the schematic of the Oxford Sound...

Enjoy with no moderation..

Daniel..
Excellent work! Was thinking about getting one.
These things get a bit noisy, may take a whack at trying to fix that.

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Post by daniellp »

And here is my clones army, one of each type (Oxford is not on the clones yet)...

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The prototypes boards from JLCPCB arrive and I had time to assemble and test it. I found a wrong resistor value (100k where should be 10k in the CabSim input). Beside it the clone PCB is full validated...

I already made a new version with the changes for the new board (new filter capacitors) and the vaues for the Oxford version. Now a single board can build 6 versions...

I collect waveforms from original and clone boards with several control positions, I just need time to organize them in one document and I will publish them. Later I need to bult a Frequency Response Analyzer to compare the original and the clones... By the way, if someone have a good project of an automatized Frequency Response Analyzer (it can be Arduino, PIC or Raspbery PI based) with PC interface and GUI, and can share it will be highly apreciated...

Regards.

Daniel.

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Post by Lani »



Kindle Fire based analyzer if your interested

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Post by daniellp »

Lani wrote: 13 Apr 2022, 10:50

Kindle Fire based analyzer if your interested
Thank you... it is on my to watch list... I will have a look with calm later...

I found a nice project on Instructables (https://www.instructables.com/Frequency ... Generator/). I already draw it on KiCAD and did several improvements as add digital potentiometer for automatic level adjustment on signal generator and peak detector and add a 16bit ADC for better accuracy on the measurement. Hardware is fine... now comes the bad part (at least to me, the software... I am terrible on coding)...

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Post by daniellp »

Gentlemen.

Last week arrive in in my hands a Joyo California sound... For sure I reverse it... I note there are some componentes that are not present on the other versions that are mounted on this one, like the caps and the resistor on the filter after the CabSim before the Level pot.

I also change the metyhodology of measurement of the zener diodes and got the correct value of they.

Here are the updated schematics of all versions.

I also add a spreasheet with the values I measure from the pedals. The resistors were not measured, but directly readed. The SMD capacitors were removed from the board and measured case someone have interst on it...

Up to now the only one I could not put hand on was the VT Bass. I trust the values from the tables on this thread but they are a little odd. The gain is too high and the waveform is being cropped, so if someone have this beauty and can get some good hi-res gutshots from the inside of it , to get the resistor values, at least, will be a nice start point to have a consistent schematic for this version also.

Best regards for all.

Daniel.
Attachments
Part List.xlsx
(16.54 KiB) Downloaded 316 times
American Sound Schematic R1.pdf
(153.2 KiB) Downloaded 504 times
AC Tone Schematic R1.pdf
(152.51 KiB) Downloaded 392 times
British Sound Schematic R1.pdf
(153.12 KiB) Downloaded 525 times
Oxford Sound Schematic R1.pdf
(162.1 KiB) Downloaded 389 times
California Sound Schematic.pdf
(155.27 KiB) Downloaded 407 times

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Post by Hanky- »

daniellp wrote: 18 Apr 2022, 19:28 Gentlemen.

Last week arrive in in my hands a Joyo California sound... For sure I reverse it... I note there are some componentes that are not present on the other versions that are mounted on this one, like the caps and the resistor on the filter after the CabSim before the Level pot.

I also change the metyhodology of measurement of the zener diodes and got the correct value of they.

Here are the updated schematics of all versions.

I also add a spreasheet with the values I measure from the pedals. The resistors were not measured, but directly readed. The SMD capacitors were removed from the board and measured case someone have interst on it...

Up to now the only one I could not put hand on was the VT Bass. I trust the values from the tables on this thread but they are a little odd. The gain is too high and the waveform is being cropped, so if someone have this beauty and can get some good hi-res gutshots from the inside of it , to get the resistor values, at least, will be a nice start point to have a consistent schematic for this version also.

Best regards for all.

Daniel.
Thats a lot of work there. You could design a pcb with mini switches to make a all-in-one version of these.

There is an error with the California sound schematic, C20 & C21 are 4.7nF & 47nF.

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Post by daniellp »


Thats a lot of work there. You could design a pcb with mini switches to make a all-in-one version of these.

There is an error with the California sound schematic, C20 & C21 are 4.7nF & 47nF.
Hi Hanky

Thank you for the comments...

Indeed the C21 is a 47nF, but C20 the closest commercial value is a 2.7nF. I double check the values and I also measure it again on my pedal. It is correct.

It does not discard some production change on different lots of pedals.

I attach here the fixed California schematic.

Now, about to have a PCB with microswitches to cover all possibilities it is barely impossible... As we say here in Brazil, the sauce will be more expensive than the main dish... just not to mention the size of it... It will be, at least 14 sets of 3 to 5 switches.... and the working of it will not be easy to understand for most of the users. I decide to make an universal PCB with generic parts, kike Ca, Cb, Cc... and the assembler choose the correct value from a table. The bad part it is not dynamic. It will be necessary to choose a model and use only it. To change it will be necessaru to unsolder the componentes and solder the other values.

But for my experience the universe of users who keep doing changes on the pedals are less than 5%...

Best regards.

Daniel.
Attachments
California Sound Schematic R1.pdf
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Post by 80k »

daniellp, thanks so much for sharing these files! Have you made a universal PCB yet? If you end up ordering any volume of them, I'd love to chip in and buy a few from you. These Joyo pedals sound great and I'd love to build one of these myself.

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Post by VivMeLol »

I am going to start work on a Character series PCB

with either DIP switches

or CD4xxx series switches

so that all possible variants can be selected by the user.

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Post by 80k »

VivMeLol wrote: 11 Sep 2022, 16:08 I am going to start work on a Character series PCB

with either DIP switches

or CD4xxx series switches

so that all possible variants can be selected by the user.
Nice, please keep us posted. I am entertaining building a double version. Nothing fancy, switchwise... just an AC Tone and an American in the same box... each circuit gets the full separate 6 knobs so they can retain settings. And the pedal would be always on with a footswitch that swaps between the two circuits.

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Post by daniellp »

80k wrote: 08 Sep 2022, 15:17 daniellp, thanks so much for sharing these files! Have you made a universal PCB yet? If you end up ordering any volume of them, I'd love to chip in and buy a few from you. These Joyo pedals sound great and I'd love to build one of these myself.
Yes I did. I just receive some of them from JLCPCB today. But mine pcb's are like jogo or tech21 pedals. No switches for model selection.

I saw someone did a pcb with switches for model selection. I prefer to design mine as my other pedals, all onboard (jacks, potentiometers and 3PDT) and ALL parts are PTH, so there is no space for switches for model selection on a 1590BB enclosure.

Daniel.

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Post by TaperChuck »

I've been lurking here for a while and finally did the CAB SIM bypass mod on My Joyo American Sound pedal. I'm a graphics guy and couldn't resist affixing my own art on the top. I can not thank you all enough. I have tried many, many OD and amp sim pedals and this is the most useful one I have found. Especially after modifying it. I am using it after my optical compressor at the beginning of my pedal chain. I like the bypass mod (I've attached the version I used) and am using it as an almost always on pedal. My only other dirt pedal is a Timmy clone. I'm into clean tones and single coil pickups, but do have a couple humbucker guitars too.

My notes and observations...

Unmodified I had to run it with the HIGH knob almost always fully counterclockwise into the clean channel of my Fender Frontman 65R and Boss Katina amps.
With the CAB SIM OFF, it sounds much more natural when run into my amps. I have never run it as intended in the stock form into a PA with no guitar amp. I need to try that. just to see what that's like.
The VOICE knob is what makes this pedal so appealing. I know it's essentially a mid's cut/boost, but there is something about it that just works for me.
I do find that generally I like the sound of my recently acquired PRS SE Hollowbody with the CAB SIM engaged run into my amps. So, essentially I use the switch on OFF for single coils and ON for humbuckers.

Anyway, keep up the good work and again, thanks for what you all do.
Attachments
QTBr9TR-Less treble CAB mod.png
AmericanSoundFinal.jpg

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Post by Guroots »

Hey guys,

Thanks for the great job done. (schematics, circuits..) for VTBASS

I really like the VTBASS sound especially the "Characters" but unfortunatly it is not produce any more...
I go trought the schematics I am supprised the Characters" does not use clippers... ; I also do not understand the aim of the diode at the input /output -> Protects for overcurent from instruments / amps ??

Anyway I want to make my own pedal but without the drive and equalization. ->

If I just built input filter/"Characters"/"Vol contro" -> output (in other words Direct link R10 to R18/C15 ; Level Trimpot -> Output)
does it sound like VTBASS ? (DRIVE closed, All POTs 00h00 ((expect Vol) ? )
Is the opamps used (TLC2264) can be changed to TL072 or TL074 ?

See you

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Post by Guroots »

Guroots wrote: 09 Nov 2022, 16:50 Hey guys,
Finally I understood the aim of the input/output diodes. (It is written in this topic) ; There aim is to limit voltage to the TLC2264 input/output... but with passive instrument they have no use.

Regarding TL074 or 72, I think they can be used instead TLC2264 cause JOYO pedals use TL074/72...

A new questions is comming, on the different schematics, I cannot see power supply to TLC2264 (Pin 4 Vdd+ and pin 11 Vdd-) -> Something is missing on the schematics ? Should I connect +9V to Vdd+ and ground to Vdd- ?


See you

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Post by deltafred »

Guroots wrote: 16 Nov 2022, 17:55 Finally I understood the aim of the input/output diodes. (It is written in this topic) ; There aim is to limit voltage to the TLC2264 input/output... but with passive instrument they have no use.
They are there for static protection so have as much use with passive instruments as active ones.
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Post by Guroots »

deltafred wrote: 17 Nov 2022, 09:08
Guroots wrote: 16 Nov 2022, 17:55 Finally I understood the aim of the input/output diodes. (It is written in this topic) ; There aim is to limit voltage to the TLC2264 input/output... but with passive instrument they have no use.
They are there for static protection so have as much use with passive instruments as active ones.

Thanks, finally, I find all answers in this thread. (I was just too lazy to read all..)

I also understood, that the Chararcters incresed special mid range frequencies -> This "Amplified Mid range " output is clipped by the Drive part of the the circuit (even is pot is at 8) the rest of signal is not clipped (when drive pot is on 8); when character pot is on 8 and drive at 4 all frequency are clipped... so to do what I want I need to keep the drive stage...

Anyway I will try to make one but just put level stage and output buffer after C11...

I think I can get the same kind of sound with a bandpass filter set on the same frequency than Character Stage and softclipping stage and a final blend with clean signal...

See you

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