New boost/over-drive Project: The Vibin' Champ

[mojotron]

This boost has a fairly unique sound - I wanted something a bit more "small Fender" sounding than the Fetzer Valve and figured out that the 2 knob tone stack on the SF champ was what did the trick. This is a very ROG-ish design - note I don't even claim doing anything towards the design of this pedal. What I did is combine a ROG Fetzer Valve (btw read the updated article - it's great!) with the rest of one of my favorite amps - the AA764 champ - using the AA764's tone stack and passive component topology and got this great sounding circuit.


Here's the layout:


Here's the PCB mask (you'll have to shrink this - note the 1" ruler)


How's it sound? Well, great - kind of sounds like you're playing through a champ if you set your amp's eq to be fairly flat with a clean sound - it has a lot of that small fender amp vibe to the sound; nice soft highs, with a bell like tone. What I really like is that since I finished this pedal and started using it (and I use it a lot) I don't feel the need to switch amps to use my Deluxe Reverb to get a Fender sound - this pedal pretty much does that better than anything else I have tried.

Notes:
0) Torchy suggested making R3=3k - I need to add that mod to the above schematic as it sounds better
1) Sw1 works like a boost to overdrive switch - it works well as either a mini-switch or a 2nd DPDT
2) As specified in the schematic, this has a very clean sound. If you crank the drive control past 50% and switch Sw1 to connect C5 to the source of JN2 you get a nice grind with humbuckers - see mods for use with single-coils
3) Mods I really like:

• If you want more of a "hot 12AX7" - or a Beefier Proph Tweed sound - use a J201 for JN2 and a 3K resistor for R1 - I also recommend this for use with vintage single coils
• If you really like the Fenderish "expander" aspect of this circuit's sound - use a 3K resistor for R1
• If you want the most authentic Champ sound - add some warmth by attaching a 220pF cap from Dr2 (the drive pot wiper) to ground

I put references to WILLING HEART MINISTRIES for anyone wanting to support the work of an artist named Kelly Willard. Kelly Willard's music is extremely inspirational, even for a rocker-Satch fan like me, and if this generates some support for her Christian ministry - I would be overjoyed. 

Well here's the sound clips for the Vibin' Champ (VC):
Note 1: I used Torchy's sugestion and made R1=R3=3k and 2 J201s - Sounds the best to me - THANKS!!!

Note 2: Its really hot here today - (no AC and I do these in my attic  - 100+ degrees.. Yikes!) I did these clips quickly so I would not pass out - please excuse the roughness of the sound and playing...

Note 3: In the heat my S470 developed a buzz, so there is some buzz in the HB clips - it's my guitar/playing not the VC

Setup1: Ibanez S470 (w/Gibson Classic '57/'57+ pickups) -> VAMP (for small combo)->computer sound card

Clip 1: Clean Neck HB: VC set to Dr:30%, Tr:50%, B:50%, Vol:70% :I played using the neck HB pickup w/out the VC on for a D-G-D chord set then added it - so you hear the change when activated, then I played the same blues like stuff in all of these clips
http://www.mojotronics.com/images/vibinchamp/vc_4_clean_HB.mp3

Clip 2: Over-Drive Neck HB: VC set to Dr:70%, Tr:70%, B:60%, Vol:50% :I played using the neck HB pickup w/out the VC on for a D-G-D-am chord set then added it -
I play one lick, turn the vol back to 80% on the guitar, play just about the same lick, then turn it back up. The rest of the clip I try to show how the VC cleans up with pick attack when used as an overdrive
http://www.mojotronics.com/images/vibinchamp/vc_5_dirt_HB_N.mp3

Clip 3: Over-Drive Bridge HB: VC set to Dr:70%, Tr:70%, B:60%, Vol:50% :I played using the bridge HB pickup w/out the VC on for a D-G-D chord set then added it... This clip I try to show how the VC has a bit of grit - as an overdrive - I should have turned the bass up a bit...
http://www.mojotronics.com/images/vibinchamp/vc_6_HB_BR_dirt.mp3


Setup2: Warmoth (Swamp Ash) strat (w/Fender Fat '50's pickups) -> VAMP (for small combo)->computer sound card

Clip 4: Squeeky Clean Strat Neck: VC set to Dr:30%, Tr:50%, B:50%, Vol:70% :I played using the neck pickup w/out the VC on for a D-G-D chord set then added it - so you hear the change when activated, then I played the same blues like stuff in all of these clips. In this clip I switch the VC in and out 3 times (the VC level is a bit louder - so you can hear it kick in) in the first 1/2 of the clip, then I use the Guitar's vol control and picking attack to control dynamics in order to demo the sensitivity
http://www.mojotronics.com/images/vibinchamp/vc_7_clran._strat.mp3

Clip 5: Over-Drive Neck Strat: VC set to Dr:70%, Tr:70%, B:60%, Vol:50% :I played using the neck pickup w/out the VC on for a D-G-D chord set then added it - so you hear the change when activated, then I played the same blues like stuff in all of these clips. In this clip I switch the VC in and out a few times (the VC level is a bit louder - so you can hear it kick in) in the first 1/2 of the clip, then I use the Guitar's vol control and picking attack to control dynamics in order to demo the sensitivity
http://www.mojotronics.com/images/vibinchamp/vc_7_dirt._strat.mp3

You can here from this last clip that it does not have a lot of overdrive using vintage strat pickups - but with a FatBooster in front of the VC it sounds very much like a small Fender being over driven with a booster... I really like that sound myself.

[beatstrat]

very cool

[KerryF]

Looks absolutely amazing!  Any sound clips?

[mojotron]

very cool

Thanks  - I certainly got a lot out of http://www.runoffgroove.com/fetzervalve.html - which is an awesome writeup on doing something like this.

Looks absolutely amazing!  Any sound clips?

I will get some sound clips out. With R1=3k and using 2 J201 JFets the sound is very much like what I get out of a small fender - reminds me very much of my SF Deluxe Reverb w/EH12AX7 tubes.

With a 2N5457 for JN2 the FET the sound is much cleaner - in fact, with vintage single coils I just get a hint of overdrive with boost on using the 2N5457 and the sound is very chimey. With a J113 the sound is even more clean.... But I prefer the gain-ier sound of the J201 using a 3k source resistor (R1) for bump up Vgs so that the input does not start clipping just due to a low Vgs. With J201s the sound is still chimey - but has much more of a sound like if I put a Mullard 12AX7 in for V1 in my SF deluxe Reverb - it's darker and more harmonically richer (I know - that's a very subjective term) with plenty of overdrive. What I was shooting for with the J201 in JN2 is to get the sound of my Delluxe Reverb amp - which has a darker sound than most Fenders and starts to breakup at Vol set to 4 and I run it with bass=4 and treb=3.5...

[markm]

Very Nice Mojotron.
I like it mucho!
Looks like MarkM may have a project for the weekend afterall......
Or should I dive back into my "projects I want to build" list that seems to get longer on a daily basis 
Thanks for sharing!

[Cliff Schecht]

Looks great, but did you really have to include all of the religious banter? I have nothing against you being religious and do try to respect everybodies beliefs as I wish they do mine, but I find it quite irritating when people try to push their beliefs onto me, especially considering the fact that religion is such a personal thing. Sorry to turn this into a thread on ethics, but if I wanted to join your church, I would have already.

[awilson40]

Cliff....
  What do you mean 'all of the religious banter' ?
He had one comment / notice at the bottom of his very informative post.
As a Christian, I find it very offensive that we are suppose to keep ALL our
"religious' comments to ourselves and cant say a thing that might upset those
who dont share our beliefs.
Why dont you practice some of that 'tolerance' that I keep hearing people talk about.
It seems to me that 'free speech' and 'tolerance' are rights and practices that are reserved
for everyone else Except Christians.

I bet you (or anyone else) wouldnt have said a thing had he mentioned Islam or Budda.

[stumper1]

As one who is guilty of trailing off topic..........

Mojo-

Looks nice.  Thanks for the work.  Way to give props to those who helped!!

Time to break out the breadboard

[george]

Looks great, but did you really have to include all of the religious banter? I have nothing against you being religious and do try to respect everybodies beliefs as I wish they do mine, but I find it quite irritating when people try to push their beliefs onto me, especially considering the fact that religion is such a personal thing. Sorry to turn this into a thread on ethics, but if I wanted to join your church, I would have already.

welcome to the land of the First Amendment ...

[Cliff Schecht]

Cliff....
  What do you mean 'all of the religious banter' ?
He had one comment / notice at the bottom of his very informative post.
As a Christian, I find it very offensive that we are suppose to keep ALL our
"religious' comments to ourselves and cant say a thing that might upset those
who dont share our beliefs.
Why dont you practice some of that 'tolerance' that I keep hearing people talk about.
It seems to me that 'free speech' and 'tolerance' are rights and practices that are reserved
for everyone else Except Christians.

I bet you (or anyone else) wouldnt have said a thing had he mentioned Islam or Budda.

Yeah it was a little hypocritical of me to go off like that, but I would have still made the point no matter what religion he was talking about. It just gets to me when people include unnecessary messages like that. I'm sure you guys would be just as irritated if I decided to include a passage about my schematic being only for those opposed to the ideas of unorganized religion. I guess his wording is what really threw me off though...

for the purpose of supporting those in the service to the Lord...

But again, let me apologize... I should be in support of anybody making an attempt to keep the DIY community alive.

[mojotron]

Very Nice Mojotron.
I like it mucho!
...
Thanks for sharing!

Thanks Dude! I felt especially inspired to start writing up as many of these design ideas I have been playing with as I can - I owe a lot to others who have helped me. I meant to do this much earlier, but recently my day job got really busy there for a few months... I hope someone else likes this one as much as I do - I hope others can build this ok - you never know since you end up being sort of subjective after building a number of boards in the process of experimenting - but I'm pretty sure I got all the notes in there that someone else would need.

Looks great, but did you really have to include all of the religious banter? I have nothing against you being religious and do try to respect every bodies beliefs as I wish they do mine, but I find it quite irritating when people try to push their beliefs onto me, especially considering the fact that religion is such a personal thing. Sorry to turn this into a thread on ethics, but if I wanted to join your church, I would have already.

Thanks for expressing your irritation with how I did this. I do respect that, and I think I can understand where you're coming from; my intent with this was not to push religion as much as just share a cool circuit and point those who might want to - to volunteerly donate to one of several worthy causes in the process.

...I'm sure you guys would be just as irritated if I decided to include a passage about my schematic being only for those opposed to the ideas of unorganized religion. I guess his wording is what really threw me off though...

for the purpose of supporting those in the service to the Lord...

...

Ahh I see what you mean, I can see how that might have been misinturpreted.

I didn't mean this circuit is only for certaiin people - I intended quite the opposite: if anyone wants to post it anywhere, claim that they drew/designed it, make comercial pedals from it without compensating me... it that's all fine with me - what I really ment to say is "I would like to support the below ministry... please send a donation if you liked it"

[MartyMart]

Looks cool Mojo, It's very similar to a lot of my recent "Jfet excursions" so I probably wont
be making one of them.
Thanks for sharing though

Peace,
MM.

[RedHouse]

A friendly word-up Bro,

There is a time and a place for everything, I also am of the Christian persuasion ...BUT... I don't think anyone's religious disclaimers should accompany schematics here, it's not the appropriate place.

In fact it makes me NOT want to try a build, as placing stuff like that on your schem-o is subliminally making (folks) feel guilty if they build one, and like it.

Bringing people to the Lord is not about guilt, it's about forgiveness.

Lets PLEASE keep our religion out of this forum. There is another forum here called "The Lounge" where it would be much more appropriate to post (and invoke) invitations to support you favorite ministries, here we discuss electronics.

[QSQCaito]

Totally agree with red house. Schematics in schematics place, religion in religion place. You don't sell Barbie on a tool store do you? I believe it's the same... (sorry if it sounded rude, trully not intended).

Well well, lets live that side apart, very nice of you posting schematics and everything! wouldnt be better if the pcb without components was in black? so it could ready for PNP or something similar?

Has anyone got a sound clip? would love to see how it sounds, and make a decission throught it!

Thanks!

Bye bye

Diego Andrés Cao

PS Excuse my english(sometimes it's hard to think in one language and express in other)

[MartyMart]

Excuse my english (sometimes it's hard to think in one language and express in other)

"Sometimes it's even harder to think in one language and express in the same"   

MM

[$uperpuma]

Yikes... either way... great circuit... tweaking the Fetzer valve was something I have wanted to do but am not quite smart enough to do ...yet...

[mojotron]

Thanks for the suggestions, I made a few updates and reposted the files.

I did not intend for anyone to feel guilty, or for anyone to support something they did not want to...  I expressed this in a way that was inclined to be misunderstood - I think I have made it clearer now that this work is offered free without any obligation for any purpose - personal, commercial or other..... Have fun! There are a few more on the way.

[Torchy]

Built this today and like the result - I used J201s (all I had) and 3k R3. Dials in quite a nice range and will definitely box this one up. Thanks for the schematic Mojotron


Oh, I have a vero layout if its ok to post it ?

[mojotron]

...Oh, I have a vero layout if its ok to post it ?

That would be great Torchy - thanks much! Glad you liked the circuit. Let me know if you need a place to host it.

I think the J201's definitely give it a nice grind and higher drive levels - that's what I'm using right now. I'll try a 3k in R3, and see how that sounds. In my simulations of this circuit I settled on 1.2k to match the Fender circuit frequency responce with triode spice models, but in my sims I totally missed R10 and I just added R10 and simulated R3. R3 at 3k seems to keep JN1's Vg from dipping too low and on the bottom swing of the signal when the input signal is strong preventing premature clipping - thanks for the suggestion I'll check this out and update the schematic. 

Let me know if anyone would like the SuperSpice sim files.

[newbie builder]

Can't wait untill torchy posts the vero- I just got some vero in today and am ready to try my hand at building a vero project and this one looks like a great one to start.