Celebrating the Autumnal Equinox with another pedal - The Mojito

[music6000]

Chuck said : I just demo'ed this for a friend and his first question was "Can you add a stomp switch to kick the Boost on and off?" His second question was "How soon can I get one?"

It took some reworking but it can be done!

 

[Chuck D. Bones]

I don't know where you buy your stomp switches, but the ones I have will not fit that close to the corner. Maybe you could have stretched the box out to 1590BB dimensions.

Nice knobs, though.

 

[music6000]

https://lovemyswitches.com/3pdt-latched-foot-switch-low-profile-solder-lugs/

 

[Chuck D. Bones]

And here I was thinking it was all a photoshop trick. I did use one of those low-profile switches once to solve a fit problem.

 

[HamishR]

I'm kinda torn... I love the extra gain stage but keep finding myself turning the Pregain right down, in which case I may as well just use my regular G pedal - which is my favourite OD right now - and keep things simple. I think being able to footswitch the Pregain in and out may be the answer.

I needed Chuck's help to get the G to where it was as good as it can be so was surprised when Chuck said he had built one and liked it only to find he had of course added another gain stage!

So I think I'll stick with my G pedal until I can get the footswitch worked out. Having a pedal like the G with Chuck's extra gain stage of the Mojito on a separate switch would be perfect.

 

[jubal81]

Talked it over with Chuck and I'm going to add the pre-gain foot switch to the layout for a 1590bb box. Chuck also gave me a workaround to use a 50KC pot instead of the now-hard-to-find 25KC.

Fingers crossed, should have those in a few weeks.

 

[Nostradoomus]

Talked it over with Chuck and I'm going to add the pre-gain foot switch to the layout for a 1590bb box. Chuck also gave me a workaround to use a 50KC pot instead of the now-hard-to-find 25KC.

Fingers crossed, should have those in a few weeks.

Sweet! I’m making an SMD/through hole mash up version haha

 

[jubal81]

Sweet! I’m making an SMD/through hole mash up version haha

I prefer SMD for semis, but the only SMD pads on my layout will be for the JFETs, which will also have a TH footprint so either SMD or TH JFETs can be soldered directly to the PCB.
It will also be compatible with the PedalPCB footswitch PCBs.

 

[zgrav]

are you looking at a pre-gain bypass of the JFET with the footswitch? or just switching to a unity setting?

also -- how different is the feel of the pre-gain pot if you use a linear taper 25K? not enough control for the most saturated part of the rotation?

 

[Nostradoomus]

I prefer SMD for semis, but the only SMD pads on my layout will be for the JFETs, which will also have a TH footprint so either SMD or TH JFETs can be soldered directly to the PCB.
It will also be compatible with the PedalPCB footswitch PCBs.

Sweet! Same here on the footswitch breakout. Mines opposite but similar...all SMD caps, resistors, 4393s...through hole diodes and IC and maybe some caps (finding 1uf smd that aren’t piezoelectric is a pain). It’ll be cool to compare!

 

[music6000]

Talked it over with Chuck and I'm going to add the pre-gain foot switch to the layout for a 1590bb box. Chuck also gave me a workaround to use a 50KC pot instead of the now-hard-to-find 25KC.

Fingers crossed, should have those in a few weeks.

For real estate purposes, 1590BB standing upright would be the best option :

 

[Chuck D. Bones]

are you looking at a pre-gain bypass of the JFET with the footswitch? or just switching to a unity setting?

also -- how different is the feel of the pre-gain pot if you use a linear taper 25K? not enough control for the most saturated part of the rotation?

I should have answered more clearly. The footswitch is in series with C3. With C3 disconnected, the Booster gain is ~6dB. I think this is the cleanest approach, and is close enough to bypassing the boost stage.

C50K with 47K in parallel has almost the exact same taper as C25K in this circuit.

Here's a snippet:

 

[music6000]

For real estate purposes, 1590BB standing upright would be the best option :

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This matches the PedalPCB Arkaim Fuzz layout minus Toggle switch!

 

[zgrav]

Oh yeah - I'd love one!

I guess I should post my layout because its better than Chuck's. I have also changed a few bits here and there to make it sound very, very close to my Model The G if the Pregain knob is on zero. So you almost have two pedals in one - a G if Pregain is off and then wind in some Pregain for an increasing powerful distortion. I'm a big fan of touch-sensitive lowish gain overdrives, and that's what this is before you touch the Pregain. It's unusual to me to have a distortion level pedal which works as well as this one does at lower gain. But then I'm biased.

View attachment 6462

I only see 6 links in the vero for this project unless there are 2 connections on 10 D. Is it 6 links or 7?

 

[Chuck D. Bones]

I'm kinda torn... I love the extra gain stage but keep finding myself turning the Pregain right down, in which case I may as well just use my regular G pedal - which is my favourite OD right now - and keep things simple. I think being able to footswitch the Pregain in and out may be the answer.

I needed Chuck's help to get the G to where it was as good as it can be so was surprised when Chuck said he had built one and liked it only to find he had of course added another gain stage!

So I think I'll stick with my G pedal until I can get the footswitch worked out. Having a pedal like the G with Chuck's extra gain stage of the Mojito on a separate switch would be perfect.

I originally built the breadboard to your Model the G schematic. Played it and liked it. Then I added the booster, similar to the Honey Beest and liked that too. I definitely use the PRE-GAIN = 0 setting. For thickening up the tone and adding some mild break-up, that nails it. For my buddy's demo, I started with everything at noon except PRE-GAIN was at zero. Dialed-in a nice rhythm tone, then brought up the PRE-GAIN to the desired dirty tone. Rolling the guitar's volume down brought the tone back to the PRE-GAIN = 0 sound.

 

[HamishR]

Aha! I'm glad you got to hear it without the extra stage too. I can't do stuff like that - you know, think "oh I'll just add another gain stage..".

But then when my son asks for a photo for his CV I get the studio lights out and do it properly because that's what I do. It must be pretty straightforward for you to modify this stuff. My brain will never work that way well enough - you have no idea how much concentration I need to muster to do a layout!

Speaking of which: Zgrav you are correct - only 6 links. I had another but got rid of it and didn't update the layout - sorry! I'll update it.

Then I think I'll look at building a Mojito with the Pregain on a separate footswitch and stick it in a 1590BB. The Pregain is very cool.

 

[jubal81]

Coming along nicely. Got a preview for you guys.

 

[Chuck D. Bones]

Yeah Bay-Bee!

 

[zgrav]

Looks great! Mixing metaphors a bit, but I'd hit that. : ^ )

 

[music6000]

This Overdrive is heavily based on the BJFe Honey Beest, a Honey Bee with a JFET booster up front. It was a collaborative effort with HamishR. In his honor, I've cracked a tuber of Foster's Lager (yeah, I know, it's that wallaby-piss export stuff). HamishR had been advocating his modified version of the BJFe Model G; he sent me a copy of the schematics for that and the Honey Beest. I finally got around to breadboarding his Model the G and liked it immensely. It's a fairly mild medium-gain overdrive with a nice fat vintage tube amp sound. When I stuck on the Honey Beest's JFET boost up front, it took on a whole new personality. The PRE-GAIN controls the booster gain, from 6dB to 28dB. Dialed-down, it's very close to the Model the G tone. Crank it up and it roars. PRE-GAIN was modded from the Honey Beest for more range. It crackles a bit when turned. The BASS & DRIVE controls are pretty much unchanged from the Honey Beest. Turn the BASS down with humbuckers, up with single-coils. We wanted more range out of the TREBLE control, so it was rewired as both a boost and a cut. The boost side of rotation is really more of a Mid Boost, but that's ok, it sounds good. I used MPF4393 FETs, but anything with Vp between -1.5V and -2V will work (J201s need not apply). Like the initial design, the BA482 diodes were imported from Oz. They have virtually the same V-I curve as the gate-source junction on a 2N5952. At full-tilt, this sucker will push all three stages into saturation. Or turn PRE-GAIN down to zero and pull back on DRIVE for a mild breakup. Got some TS tones in there as well. In keeping with my potent potables theme, I named this one The Mojito. Cool, smooth and not too sweet, not too fizzy. Vero layout available on request. Check the date code on the vintage RCA CA3130. That IC was manufactured in March 1977.

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