Joyo - JF-13 AC Tone  [schematic]

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Post by Hanky- »

Antigua wrote: 18 Jun 2020, 21:32
Hanky- wrote: 18 Jun 2020, 18:01 I modded my Cali sound with a bunch of mini dpdt switches to get for pedals in one housing, so basically I hve the american, actone, british & cali in one box under the hood. I considered using panel mount toggle switches but that would require a bunch of drilling, these pcb type dpdt mini switches were easier to just hot glue on the back of the pcb. I did add a cab bypass switch in there too but didn't take recent pic of it. Few more(4) could get me the oxford in there as well but I'm not a fan of that pedal much.

While at it, I put in new electrolytics throughout most places, just cause I had some with me & this pedal was from 2012 stockpile, figured I leave new ones in there.
I don't really know what sets all four of them apart, let alone that it's possible to get all four versions working on one board. How did you figure out what to do to make it work?
Like JiM pointed out above me. The big character series thread has a good breakdown & component differences among the various pedals. That and the Sansamp GT2 schematic are both helpful, in understanding these pedals work.

You have to remove the R28, R29, C20 & C21 on the Cali pedal because they are the components for the Off Axis Mic setting, the others use a jumper in the form of 0 ohms in place of R28 & empty pads for the rest cause they have the On Axis Mic setting, I figured that out following the GT2 schematic. That's why the cab sim bypass mod sounds wrong with the Cali pedal & not with the others. However if you remove the Mic sim components on the Cali then you also need to change the value of R31 because it is set higher & will give a huge dB boost without the off Axis Mic sim in there. Two 4PDT mini switches will take care of the whole switching in & out of the components involved for the cab & Mic sim bypass on the Cali except for the 3.9nF cap I think, might need additional dpdt switch. However just removing R29 & C20 & subbing R28 to a jumper or 0 ohm will take out the Cali's off Axis Mic sim.

Two mini soldering iron can help in removing these tiny smd components easily.

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Post by Antigua »

Hanky- wrote: 19 Jun 2020, 17:51
Antigua wrote: 18 Jun 2020, 21:32
Hanky- wrote: 18 Jun 2020, 18:01 I modded my Cali sound with a bunch of mini dpdt switches to get for pedals in one housing, so basically I hve the american, actone, british & cali in one box under the hood. I considered using panel mount toggle switches but that would require a bunch of drilling, these pcb type dpdt mini switches were easier to just hot glue on the back of the pcb. I did add a cab bypass switch in there too but didn't take recent pic of it. Few more(4) could get me the oxford in there as well but I'm not a fan of that pedal much.

While at it, I put in new electrolytics throughout most places, just cause I had some with me & this pedal was from 2012 stockpile, figured I leave new ones in there.
I don't really know what sets all four of them apart, let alone that it's possible to get all four versions working on one board. How did you figure out what to do to make it work?
Like JiM pointed out above me. The big character series thread has a good breakdown & component differences among the various pedals. That and the Sansamp GT2 schematic are both helpful, in understanding these pedals work.

You have to remove the R28, R29, C20 & C21 on the Cali pedal because they are the components for the Off Axis Mic setting, the others use a jumper in the form of 0 ohms in place of R28 & empty pads for the rest cause they have the On Axis Mic setting, I figured that out following the GT2 schematic. That's why the cab sim bypass mod sounds wrong with the Cali pedal & not with the others. However if you remove the Mic sim components on the Cali then you also need to change the value of R31 because it is set higher & will give a huge dB boost without the off Axis Mic sim in there. Two 4PDT mini switches will take care of the whole switching in & out of the components involved for the cab & Mic sim bypass on the Cali except for the 3.9nF cap I think, might need additional dpdt switch. However just removing R29 & C20 & subbing R28 to a jumper or 0 ohm will take out the Cali's off Axis Mic sim.

Two mini soldering iron can help in removing these tiny smd components easily.
Thanks for the detailed answer. I didn't realize the California bypass sounded wrong. Given that the bode plots of the other three are identical without the cab sim, I'd say they must be wrong too, unless the assertion is that the cab is the only thing that sets those amps apart in real life. It looks like the non-Cali's have the same "base" tone. I'm sure their associated cabs are big part of it, though. It would be cool if you could make a little how-to of what you did, but I understand that interest in modding the Joyos is probably too limited to make it worth the trouble.

I'm mostly happy with how this came out because the pedals are a bit too dark to use with a guitar amp by themselves, and this at least gives them a way to work as a 4-band dirt pedal when not serving as an amp simulator.

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Post by 287m »

Antigua wrote: 18 Jun 2020, 21:23
Yes, I did the exact same mod on all four of the models. The only significant difference is the California model, the you don't remove that R28 "0 resistor" from the board. On that model it's actually a 2.2k ohm resistor and it does something important.

The value of the cap, I used 3.9nF, sets the low pass frequency. There is still a lot of treble with the 3.9nF cap, but it's not as noisy. If you use a higher value, more treble will be dropped, so it's a matter of preference.
Thanks
Hanky- wrote: 19 Jun 2020, 17:51 Like JiM pointed out above me. The big character series thread has a good breakdown & component differences among the various pedals. That and the Sansamp GT2 schematic are both helpful, in understanding these pedals work.

You have to remove the R28, R29, C20 & C21 on the Cali pedal because they are the components for the Off Axis Mic setting, the others use a jumper in the form of 0 ohms in place of R28 & empty pads for the rest cause they have the On Axis Mic setting, I figured that out following the GT2 schematic. That's why the cab sim bypass mod sounds wrong with the Cali pedal & not with the others. However if you remove the Mic sim components on the Cali then you also need to change the value of R31 because it is set higher & will give a huge dB boost without the off Axis Mic sim in there. Two 4PDT mini switches will take care of the whole switching in & out of the components involved for the cab & Mic sim bypass on the Cali except for the 3.9nF cap I think, might need additional dpdt switch. However just removing R29 & C20 & subbing R28 to a jumper or 0 ohm will take out the Cali's off Axis Mic sim.

Two mini soldering iron can help in removing these tiny smd components easily.
So, the best buy for character series is California? Like, all in California. :thumbsup
What mod you did with cali, im (and maybe other too) interested.

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Post by Hanky- »

Antigua wrote: 19 Jun 2020, 21:13
Hanky- wrote: 19 Jun 2020, 17:51
Antigua wrote: 18 Jun 2020, 21:32
Hanky- wrote: 18 Jun 2020, 18:01 I modded my Cali sound with a bunch of mini dpdt switches to get for pedals in one housing, so basically I hve the american, actone, british & cali in one box under the hood. I considered using panel mount toggle switches but that would require a bunch of drilling, these pcb type dpdt mini switches were easier to just hot glue on the back of the pcb. I did add a cab bypass switch in there too but didn't take recent pic of it. Few more(4) could get me the oxford in there as well but I'm not a fan of that pedal much.

While at it, I put in new electrolytics throughout most places, just cause I had some with me & this pedal was from 2012 stockpile, figured I leave new ones in there.
I don't really know what sets all four of them apart, let alone that it's possible to get all four versions working on one board. How did you figure out what to do to make it work?
Like JiM pointed out above me. The big character series thread has a good breakdown & component differences among the various pedals. That and the Sansamp GT2 schematic are both helpful, in understanding these pedals work.

You have to remove the R28, R29, C20 & C21 on the Cali pedal because they are the components for the Off Axis Mic setting, the others use a jumper in the form of 0 ohms in place of R28 & empty pads for the rest cause they have the On Axis Mic setting, I figured that out following the GT2 schematic. That's why the cab sim bypass mod sounds wrong with the Cali pedal & not with the others. However if you remove the Mic sim components on the Cali then you also need to change the value of R31 because it is set higher & will give a huge dB boost without the off Axis Mic sim in there. Two 4PDT mini switches will take care of the whole switching in & out of the components involved for the cab & Mic sim bypass on the Cali except for the 3.9nF cap I think, might need additional dpdt switch. However just removing R29 & C20 & subbing R28 to a jumper or 0 ohm will take out the Cali's off Axis Mic sim.

Two mini soldering iron can help in removing these tiny smd components easily.
Thanks for the detailed answer. I didn't realize the California bypass sounded wrong. Given that the bode plots of the other three are identical without the cab sim, I'd say they must be wrong too, unless the assertion is that the cab is the only thing that sets those amps apart in real life. It looks like the non-Cali's have the same "base" tone. I'm sure their associated cabs are big part of it, though. It would be cool if you could make a little how-to of what you did, but I understand that interest in modding the Joyos is probably too limited to make it worth the trouble.

I'm mostly happy with how this came out because the pedals are a bit too dark to use with a guitar amp by themselves, and this at least gives them a way to work as a 4-band dirt pedal when not serving as an amp simulator.
There is a chart in a post by Stephanovitch on page 21 of this thread viewtopic.php?p=237567#top
The corresponding values of the components for the joyo pcbs is put in brackets in the column of the british 8)

It's got all the list of important components that are different between the pedals. That should help out with converting one to another or just putting more than one in one box. The British is easier to convert into others because it shares more components in common with american, actone & the calif.
The only component value I found odd was of R24 on the american sound in the chart, mine had 39K in place of the reported 33k, if you end up opening the american sound up again then just note down the code on the resistor R24 in there for confirmation.

The hot glue & wires technique is the only way to not end up pulling out the solder pads of the smd components, just measure the length of wire you will need from the solder pad to the point where the other end will be soldered onto a switch, hot glue the wire to the pcb surface first, at an area where there aren't any smd components underneath the glue, after that solder the wire to the smd pads last because there is a possibility to pull on them accidentally while working at the soldering part of the switch end of things. Do not try to remove the hot glue if its stuck to an smd component, if absolutely needed then do it patiently otherwise the smd part will peel off from the board along with the glue. :idea:

The cab sim bypass is very useful when trying to use these as overdrive pedals, as a preamp its useful too but I haven't played with it much in that area but there was a difference, the cab sim in these is mild sounding, it can be dialed down with the eq controls on the pedal or better with an eq pedal after it :hmmm:

Since I got all in one box I've been able to play around with mixing values of the components between the series, like actone with the british greenback sim & stuff. The calif is way too bass heavy for guitar, I did find the american with the calif mic sim components to be a far better usuable pedal for high gain type sounds. For recording anyways :D

One could get panel mount dpdt switches or 4pdt switches & be able to put most of these component changes in a single box & switch on the fly from the exterior of the enclosure. I have all four individually around with me but the calif had started to get used the least lately, so it was the one that I picked for the massive experimental surgery. :)

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Post by Hanky- »

287m wrote: 20 Jun 2020, 00:47
Antigua wrote: 18 Jun 2020, 21:23
Yes, I did the exact same mod on all four of the models. The only significant difference is the California model, the you don't remove that R28 "0 resistor" from the board. On that model it's actually a 2.2k ohm resistor and it does something important.

The value of the cap, I used 3.9nF, sets the low pass frequency. There is still a lot of treble with the 3.9nF cap, but it's not as noisy. If you use a higher value, more treble will be dropped, so it's a matter of preference.
Thanks
Hanky- wrote: 19 Jun 2020, 17:51 Like JiM pointed out above me. The big character series thread has a good breakdown & component differences among the various pedals. That and the Sansamp GT2 schematic are both helpful, in understanding these pedals work.

You have to remove the R28, R29, C20 & C21 on the Cali pedal because they are the components for the Off Axis Mic setting, the others use a jumper in the form of 0 ohms in place of R28 & empty pads for the rest cause they have the On Axis Mic setting, I figured that out following the GT2 schematic. That's why the cab sim bypass mod sounds wrong with the Cali pedal & not with the others. However if you remove the Mic sim components on the Cali then you also need to change the value of R31 because it is set higher & will give a huge dB boost without the off Axis Mic sim in there. Two 4PDT mini switches will take care of the whole switching in & out of the components involved for the cab & Mic sim bypass on the Cali except for the 3.9nF cap I think, might need additional dpdt switch. However just removing R29 & C20 & subbing R28 to a jumper or 0 ohm will take out the Cali's off Axis Mic sim.

Two mini soldering iron can help in removing these tiny smd components easily.
So, the best buy for character series is California? Like, all in California. :thumbsup
What mod you did with cali, im (and maybe other too) interested.
I started initially some time ago with removing the mic sim components of it. Had to change R31 from 68k to 47k (or 22k to match the others in the series) to keep the volume in check otherwise there was signal clipping taking place within the pedal.

Then I outgrew the sound of the Calif in stock form or with the mic sim mod I had done lol Even the cab sim bypass mod doesnt make it very appealing to me. It's too bassy a pedal, I liked it for occasional use after a long period of gap but didn't bond with its sound like the others. The British is much more manageable in comparison, it's the one I would pick as a base pedal to start with. The stock form sounds good enough not to change much, its noisy though with high gain. The mods I have in the pic I posted earlier just involve using wires for extension & connecting them to a switch to toggle between the values. You can find the chart of components in the link I posted above for the thread it's in.

So I picked the Calif to operate on & left it in there as option if I ever wanted to try it again. If you want a high gain pedal for recording, the american sound with the calif mic sim is a good candidate. the components are R28=22k, R29=6.3k, C20=4.7nF & C21=42nF. The R28 value is up for confirmation, it can be 2.2k but need a clearer pic from Antigua to verify.

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Post by JiM »

Antigua wrote: 19 Jun 2020, 21:13Given that the bode plots of the other three are identical without the cab sim, I'd say they must be wrong too, unless the assertion is that the cab is the only thing that sets those amps apart in real life.
Most changes are in EQ frequencies, so when set flat there will not be much difference in simulation.
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Post by Antigua »

JiM wrote: 22 Jun 2020, 12:45
Antigua wrote: 19 Jun 2020, 21:13Given that the bode plots of the other three are identical without the cab sim, I'd say they must be wrong too, unless the assertion is that the cab is the only thing that sets those amps apart in real life.
Most changes are in EQ frequencies, so when set flat there will not be much difference in simulation.
True, although they are not at all flat when bypassed, they have a substantial high pass disposition.

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Post by deathclash »

Hi everyone,

I'm just a newbie here. I have a couple of questions.

First thing is, I read this thread a little late so I had the 2.2K ohm resistor removed on my Joyo California Sound while doing the cab sim bypass mod and lost the resistor. May I know what specific resistor was that?

Second thing is, I also did the cab sim bypass mod on my American Sound following the picture attached below. I have added a switch to turn on/off the cab sim but when turning on the cab sim, it is not working. I have soldered the wire on C20(cab on), the mid is soldered to the level knob and the other end is soldered to R24 (cab off). Am I doing something wrong? Also I repeatedly soldered it and then the silver-like chip above C20 was removed and I can't seem to get it back. Any idea how to replace that one? Do I just solder the wire on top of it?

Thanks in advance for the help!
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actone SPKR SIM BYPASS small.jpg

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Post by Hanky- »

^
An easier way for the cab sim bypass mod that doesn't involve removing R28 or any smd component is to cut the trace between C18 & R28. After that connect wires from the points shown in the image I attached.

Note: This doesn't work with the California Sound, I've explained it above in a few posts as to why, more components need to be removed, two replaced. will require more switches.
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Post by Hanky- »

I was wondering about the addition of FX loop to the pedal, so that the pedals in the loop are placed after the preamp section rather than just placing them after the cab sim(as in after the entire pedal without a loop built in).

Looks like the cab sim bypass mod would be the place to start for the FX loop mod. My thoughts are for a serial fx loop, remove R24, place two wires in its place, One wire connects to a resistor of 33k value, in line, connecting to the hot lug of the Send socket. The other wire connects to the hot lug of the Return socket. That should effectively place the FX loop between the preamp & cab sim section. The only problem that could arise here is controlling the output level of the fx loop, A parallel loop would just require connecting wires across R24 and connecting to the S/R sockets., A blender pot could be added to control the mix level here.

Any thoughts?

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Post by Mrlee »

The value of the cap, I used 3.9nF, sets the low pass frequency. There is still a lot of treble with the 3.9nF cap, but it's not as noisy. If you use a higher value, more treble will be dropped, so it's a matter of preference.
What values is everyone using for the capacitor? I just tried 3.9nF and Im not sure much is passing through, I’ve not got a scope so hard to tell. I’ve tried 100nF and it sounded good, I haven’t got a huge amount to hand to try, but ordered some lower to try.

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Post by JiM »

Hanky- wrote: 23 Jul 2020, 08:58 I was wondering about the addition of FX loop to the pedal, so that the pedals in the loop are placed after the preamp section rather than just placing them after the cab sim(as in after the entire pedal without a loop built in).
This would then put the EQ after the loop as well, i'm not sure this is something you'd want.
It would matter for distortion devices (adding harmonics that you'd want filtered by the cab sim), but you could connect those in front of the pedal as you'd do with an amp. Modulation and time effects would live happily down the line.
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Post by Hanky- »

Revisiting these pedals once again, here's something I noticed. In the original Tech21 pedals, the V1 units, R100 to R106 were laser cut. In the joyo clones, R100(R14), R103(R18) & R104(R19) are empty while the rest are present & used. I tried removing them to see the results & what I got was a single sputter sound when plucking a string that sounded like clipped gated effect. I'm not good at knowing what purpose these serve in the joyos but the buffer is different in the joyos which might be why these resistors are needed, I have no clue.

One more detail that I had screwed up in my Calif mic sim thread. The one cap value (C21) different on the joyo Calif & T21 GT2 for the mic sim is the use of 47nF in place of 22nF. I did try using 22nF & results were bit hifi sounding, can't remember if it was modern sounding since it's been weeks that I tried the change. I guess the use of 47nF is proper based on the tech21 Calif pedal circuit cause it sounds closer to online vids of it.

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Post by Visualdistortion »

Antigua wrote: 14 Jun 2020, 03:32 I was just experimenting with treble attenuation with the cab sim bypass mod, and I found that a 3.9nF cap across the volume lugs along with the resistor gives pretty good results. The treble sound like it attenuates around 4kHz, so it's still plenty bright, but it takes away the raspy noise. I've modified the diagram posted by Mickyvai:

Image
I've broke the solder joint on "C20" where the blue wire come. I don't find the schematic, so anyone know an other place where I can put this blue wire?
Thanks a lot
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Post by Intripped »

just follow the trace that comes to the pad that you broke, and solder the blue wire at the next pad. Looking at the pic the trace seems to go to the 0 Ohm resistor (R28) so, if i'm not wrong, you could use the R28-pad (on the right in the pic) for the blue wire.

also, be sure that the trace stops at C20 (seems to be like that), otherwise you should check/restore the connection before and after the pad that you damaged.

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Post by daniellp »

Gentelmen.

I know it is a pretty old topic, but I´ve been searching for this schematic for awhile and I did not found... So I took a pedal borrowed from a colleague and reverse enginneer it... Here is the full schematic of it...

The ceramic capacitor were measured off board for better accuracy and noted on the closest commercial value. Zener diodes were also measured offboard.

Measured noted
C1 24,2nF 22nF
C2 48,5nF 47nF
C3 N.M.
C4 1,15nF 1,2nF
C5 2u2Fx25V elet
C6 N.M.
C7 23,2nF 22nF
C8 23,5nF 22nF
C9 129pF 120p
C10 2u2Fx25V elet
C11 47ufx16V elet
C12 47ufx16V elet
C13 2u2Fx25V elet
C14 47,3nF 47nF
C15 49,3nF 47nF
C16 11,5nF 10nF
C17 542pF 470pF
C18 2,48nF 2,2nF
C19 1,17nF 1,2nF
C20 N.M.
C21 N.M.
C22 1uFx50V elet
C23 137pF 150pF
C24 24,9nF 22nF
C25 24,5nF 22nF
C26 121pF 120pF
C27 1uFx50V elet
C28 112,8nF 100nF
C29 10,8nF 10nF
C30 130pF 120pF
C31 1,17nF 1,2nF
C32 4,96nF 4,7nF
C33 4,85nF 4,7nF
C34 2u2Fx25V elet
C35 2,18uF 2u2F
C36 2,21uF 2u2F r
C37 100ufx16V elet
C38 112,2nF 100nF
C39 47ufx16V elet

Soon I will have the British and AC Tone also, so I can have the values for those too. Hope is is useful...

Best regards all and stay safe...

Daniel.
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Post by JiM »

daniellp wrote: 20 Jan 2022, 16:50 I know it is a pretty old topic, but I´ve been searching for this schematic for awhile and I did not found... So I took a pedal borrowed from a colleague and reverse enginneer it... Here is the full schematic of it...
[...]
Soon I will have the British and AC Tone also, so I can have the values for those too. Hope is is useful...
Nicely drawn schematic! :thumbsup

But i'm afraid the efforts in tracing this pedal were already done. All the reverse engineering action, for both Tech21 and Joyo implementations, took place in this topic :
viewtopic.php?p=220001#p220001
Worth reading from the beginning !
There is also a table, updated along the way, of the differences between the models. Only a handful of components are changed.
I only give negative feedback.

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Post by daniellp »

JiM wrote: 24 Jan 2022, 15:44
daniellp wrote: 20 Jan 2022, 16:50 I know it is a pretty old topic, but I´ve been searching for this schematic for awhile and I did not found... So I took a pedal borrowed from a colleague and reverse enginneer it... Here is the full schematic of it...
[...]
Soon I will have the British and AC Tone also, so I can have the values for those too. Hope is is useful...
Nicely drawn schematic! :thumbsup

But i'm afraid the efforts in tracing this pedal were already done. All the reverse engineering action, for both Tech21 and Joyo implementations, took place in this topic :
viewtopic.php?p=220001#p220001
Worth reading from the beginning !
There is also a table, updated along the way, of the differences between the models. Only a handful of components are changed.
Hi JIM.

I did find this topic... And I look a lot on the forum for this schematic...

But anyway... here is another checket source... Now I will draw my own layout...

Best regards.

Daniel.

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freefrog
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Post by freefrog »

A delayed echo to the cab sim bypass mod evoked above, since I've done it on an American Sound a few minutes ago...

I've took the direct signal from the top of R33 and not from its bottom going to C14/R25. No need of 3,3k added resistor in this case IME: levels are similar with or without cab sim.

BTW, there's what looks like a testing hole on the signal path between the top of R33 and C16/R22/R23, just under C10, on its right side. This tiny narrow hole can be used as an eyelet to solder a thin wire in order to avoid any damage to the SMD R33...

I've personally left the rest of the circuit intact : instead of removing the 0 Ohm R28 before the volume and to use the C20 location, I've just cut the right leg of the level pot before to lift it. The switch jumpers the two sides of this lug that I've cut or connects its upper part to R33. It allows simpler and sturdier solder points, IMHO.

To tame the treble without cab sim, I've opted for a 4,7nF cap directly from hot to ground when the cab sim is bypassed. Maybe a higher value would be better since there's still a lot of treble with this smoothing cap... But it's OK with the treble control turned off. It even sounds more than good.

Nice pedal, definitively, with or without cab sim!

FWIW... :-)

EDIT - Frequency response of the pedal as I've modified it below. Cab sim enabled = red, disabled = yellow. Non neutral settings but people will get the picture...
AmericanSoundCabSimOnOff.jpg

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