Caballero cab sim [documentation]

[jhergonz]

update, I simulate the gyrator using 2N3904, and the response changed. I should stick with TL072.

but I also change the Sealed/Open switch with a potentiometer. Maybe I will call it Cab size? I still don't know.


Once I tested it, I will record a short demo and share the schematics here.

Of course it changed, but can you compensate for it reducing the 470r, without occurring into distortion?
For me the switch is subtle enough that it's not worth having settings in between. If you want to share the schematic remember that mine is ShareAlike for derivatives, thanks (also in your best interests).

according to my simulation, transistors also change the gain.

[micmac]

PCB is verified by Dylan159. Attached you will find transfers as well as gerbers. All should be good and ready to go. Ordered a few boards Saturday so I will report back once I get mine up and running. Enjoy!!

Hi Lani & everbody,

Did anybody box this up? I ordered a couple of PCBs using your Gerber files and now I'm wondering how to put it into a 125b. Can anybody share a pic?

My thinking right now is to move the PCB a bit to the right side of the enclosure and then but the two switches for Bass and C/J on the left side. So the pots would be off-center a bit but I don't think I'd care about that.

Or center the PCB and put the switches between the PCB and the foot switch. The switches would be awfully close to the foot switch then I reckon, but on the other hand this is not your usual pedal, I guess in the end I'd operate it with my hands only anyway.

Or go for side mounted jacks and put the two switches on top and the PCB underneath. Usually I prefer top mounted jacks, but for this pedal I might prefer side mounted.

Just pondering this

[dylan159]

Hi Lani & everbody,

Did anybody box this up? I ordered a couple of PCBs using your Gerber files and now I'm wondering how to put it into a 125b. Can anybody share a pic?

My thinking right now is to move the PCB a bit to the right side of the enclosure and then but the two switches for Bass and C/J on the left side. So the pots would be off-center a bit but I don't think I'd care about that.

Or center the PCB and put the switches between the PCB and the foot switch. The switches would be awfully close to the foot switch then I reckon, but on the other hand this is not your usual pedal, I guess in the end I'd operate it with my hands only anyway.

Or go for side mounted jacks and put the two switches on top and the PCB underneath. Usually I prefer top mounted jacks, but for this pedal I might prefer side mounted.

Just pondering this

You can find my build pics here on my blog https://bentfishbowl.wixsite.com/electr ... ro-cab-sim
This is with a 125B and side jacks, all controls should be on top and under the PCB. I don't know if there's enough space for top jacks. I'm a fan of side jacks, but what's important is to commit to one or the other.

[micmac]

Thank you Dylan!

I had seen your pictures before, but I hadn't realized that you etched the PCB from Lani's layout.

So I'll also not put a foot switch. And then I should have plenty of space under the PCB (meaning the area where the foot switch would be) to put the two switches, the jacks and the LED. I think I should be able to use PCB mounted pots with this PCB.

One more question: I want to put the Caballero between the line-out of my load box/attenuator and the line-in of my USB sound card. Do I need special cables or can I just use instrument cables?

Kind regards,
Seb

[dylan159]

Thank you Dylan!

I had seen your pictures before, but I hadn't realized that you etched the PCB from Lani's layout.

So I'll also not put a foot switch. And then I should have plenty of space under the PCB (meaning the area where the foot switch would be) to put the two switches, the jacks and the LED. I think I should be able to use PCB mounted pots with this PCB.

One more question: I want to put the Caballero between the line-out of my load box/attenuator and the line-in of my USB sound card. Do I need special cables or can I just use instrument cables?

Kind regards,
Seb

Yes, I can't think of many situations where you need to bypass your cabsim. Even a toggle would be more than what's necessary. You can use normal, small-gauge, shielded unbalanced cables. I personally don't bother with a load box unless the amp NEEDS a load (tube), but then not all amps have their own line out.

[micmac]

Thank you Dylan! I didn't even think that my amp would have a line out, but I just checked and it does have a DI out. I'll just check once I have the Caballero ready if I like it better than the line out of the attenuator.

Kind regards,
Seb

P.S.: Just checked the amp manual, it says DI out has added speaker simulation. So I guess I'll just check if I like the DI out more than the attenuator line out + Caballero

[micmac]

Hi all!

I had some fun with my new pedal this weekend.

C and J mode are quite different, I like both. All controls give nice options, only with the Bass switch (Loose - Tight) I can hardly hear a difference. I'm using a normal six string, maybe with anything deeper it'd be easier to tell.

I added a zip with audio files in case anybody is interested. Two samples from a looper into a distortion pedal into a Marshall Studio Classic's clean (low) channel, each recorded in three different ways:

• amp -> attenuator line out -> Caballero in J mode

• amp -> attenuator line out -> Caballero in C mode

• amp DI out (has cab sim built in according to the documentation)

Personally I think the Caballero sounds better, more real. But you be the judge.

I found one quirk. When I sweep the High control from CCW to CW, at ca. 3 o'clock the sound gets distorted. I measured the 3 o'clock position on the pot and that's where the pot resistance goes to 0.

It's easier to trigger the quirk in J mode, but with C mode it also happens. To get back to normal operation I can dial High back a bit. Sometimes this isn't enough or it takes too long, then I can move Peak temporarily to CW and that usually does it. Alternatively I can dial High back a bit and then disconnect power from the pedal for a short while, that works too.

I've added a screenshot of the wave form. It's visible that it weirdly jumps up. Then I dialed Peak to CW and lowered High a bit to push the sound back to normal operation, afterward I put Peak back to where I like it, around 9 o'clock.

I've also added a recording of this to the audio.zip file. It's called "quirk.mp3".

I think it is some weird interaction between the pedal and the sound card (Focusrite Scarlett Solo 3rs gen), because when I connect my headphones directly to the Caballero output I don't hear the same when raising High.

I connect my attenuator's unbalanced line out (560 ohm it says) to the Caballero input, then to the soundcard. On the soundcard there are level indicators, green, yellow and red. When I connect the attenuator's line out to the sound card and dial in the soundcard so that the level meter is always green, and then connect the Caballero in the middle, then the level meter often goes to yellow. So it looks like the Caballero amplifies the sound a bit. Not sure if this has any relevance for the quirk, just mentioning this.

I measured the ICs once in normal operation and once when the distortion occurs. But the voltages are always the same, they don't change.

U1

4.4
4.4
4.0
0
4.4
4.4
4.4
8.9

U2

4.4
4.4
4.4
0
4.4
4.4
4.4
8.9

U3

4.4
4.4
4.4
0
4.0
4.4
4.4
8.9

U4

4.4
4.4
4.4
0
4.4
4.1
3.9
8.9

Anyway, not a deal breaker, I just just keep the High setting a bit lower than 3 o'clock.

Regarding my build, I used what's in Lani's PDF, except I used TL072s and instead of 470u I used 220u. I didn't install any LED because space is tight in 1590b and I thought it'd probably get too cramped.

Thanks to Dylan and Lani for this fun project!

[dylan159]

Thank you Dylan! I didn't even think that my amp would have a line out, but I just checked and it does have a DI out. I'll just check once I have the Caballero ready if I like it better than the line out of the attenuator.

Kind regards,
Seb

P.S.: Just checked the amp manual, it says DI out has added speaker simulation. So I guess I'll just check if I like the DI out more than the attenuator line out + Caballero

You can also look for "preamp out" or "effects send", those won't have a cabinet simulation and would work well. Usually integrated cab sims aren't very refined, exception made for some marshall amps, so I'm not surprised you like this more! Listening to the clips, the one in the amp sounds like it's barely doing anything.

About the next message, I enjoyed the pictures and the clips. That quirk is nothing I've experienced myself. The "high" control can boost the treble quite a bit, but if it's the soundcard, it's taking a lot of time to recover. Keep in mind that the circuit is designed to work with levels similar to those coming out of guitars and normally set pedals, so watch your levels both in and out of the circuit, and see if lowering the interface gain helps. The only distortion I've experienced seemed to be caused by the gyrators in some settings, but it wasn't nearly this severe and using a 4558 op-amp for them helped.

[micmac]

Thank you Dylan,

You're a magician! I replaced U4 (upper left in the gut shot) with RC4558 and that totally fixed the issue. I cannot reproduce it anymore.

Out of curiosity I put a different TL072 into U4 position and the problem was there again, so I am definitely going to stick with the RC4558.

Thanks again!

[dylan159]

Thank you Dylan,

You're a magician! I replaced U4 (upper left in the gut shot) with RC4558 and that totally fixed the issue. I cannot reproduce it anymore.

Out of curiosity I put a different TL072 into U4 position and the problem was there again, so I am definitely going to stick with the RC4558.

Thanks again!

Yeah well, there's some truth in the claim that the TL072 behaves badly when overdriven