GGG Centaur

[ampgeek]

Just finished up a General Guitar Gadgets Centaur and am really liking it!  Some great Warren Haynes, brass knuckle tones even running into an amp set up for lots of clean head room.  A Dumble'ish plan in my case.

http://www.generalguitargadgets.com/effects-projects/distortion/kc/

I built this one for a good friends 50th B-Day..but...bought another one for myself at the same time.  It will definitely be going onto my pedal board soon!

Rock on,
Dave O.

[ampgeek]

Here is a shot of the guts.

Cheers,
Dave O.

[jojokeo]

very nice Dave, how did you create & apply the graphics artwork? What does Kokaska mean?

[ampgeek]

Thank you Jo!

I am a long time CorelDraw (vector graphics program) user so I draw them up myself and print them out on water slide decal paper.

Kokaska is my friends last name and soon to be recipient.  He is a fellow amp maker and hell of a nice guy!

Cheers,
Dave O. 

[ampgeek]

I should have also mentioned that I shoot 5 or 6 coats of lacquer from a rattle-can to seal the decal once it is applied onto the enclosure.

Dave O.

 

[jojokeo]

That's what I do as well but use inkscape is all. I've mostly used the gloss clear but yours didn't look that way so hard to tell. Maybe you used a semi gloss instead? I might try that at some point but the shine from the clear sure looks pretty and hard to beat.

[ampgeek]

Right on JoJo!  Being able to scratch that artistic itch once in a while is a nice thing.  Until I get in over my head that is!!  LOL

I usually start with a powder coated enclosure but had to pull a bare one out of the pile for this one.  And...I will admit...I don't spend as much time as I should on the finish.  I guess that I have adopted my lovely wife's adage of "why would you spend so much time on something that you are just going to walk all over anyway?".  Got to give her some credit for wisdom there!

I used a glossy acrylic clear coat but, owing to the less than perfect sub layers, it does have a bit of a semi gloss appearance at the surface.   It definitely doesn't have a crystal clear shine.

Cheers,
Dave O.

[TNblueshawk]

Looks very nice and tidy inside too.

I've built a few Klones. What diodes did you go with?

I seem to fall back on the BAT41's for my ears

[ampgeek]

Thanks TN!

Although I did socket the clipping diodes, I didn't try any others before boxing it up.   I do have another one coming and will definitely play around with the BATs you suggest and others.

I installed the kit's 1N34A in this build and have no qualms over the way they sound.

Rock on,
Dave O.

[TNblueshawk]

Funny I actually tried several kinds and for some reason they all sounded good. Maybe it was the beer but I'm just a bedroom hacker so it's hard for me to really let it fly

I'm actually going to sell one of mine to help fund the AC15 build. I hate to do it but you know how it is. It's like selling one of your kids 

[ampgeek]

Yep!  It is sometimes hard to discern the differences between some clippers/clipper combinations and any other.  Variations on the same theme for the most part.

I recently built a JCM-800'ish mutation for a friend that employed a clipping circuit.  I had no idea regarding the effects of different clippers so I etched up a little test board and loaded it with sockets, poked around the interwebs for a couple evenings, and wailed away with many dozens of types and combinations.  A true shotgun approach to say the least!

After all was said and done, I loaded it up with the combinations shown below and installed it downstream of a rotary switch and stuck a pot between it and signal ground.

The hands down best clipper combo was the Marshall Jubilee circuit at position 1.  One of the gents over at the guitarpcb.com site has installed that in a number of OD boxes and says it sounds great in every one.

Hmmm....I may have to give that a shot in the Centaur!   

Dave O.

[jojokeo]

Interesting board-O-clippers and that the one liked had that cap to lower the highest notes spectrum. Were you interested at all in the total forward voltage dropping aspects of each one? Or just the different sounds you would get using various diode types?

[ampgeek]

Hey JoJo,

I was generally aware of the Vf:attenuation relationship with each trial but was more interested in the feel of the clipper combinations.  I knew from the git-go that I would be including a pot between the clipping board and ground in the final build so I know that the overall level of attenuation could be controlled somewhat.

The Jubilee clipping network came out of the blue when a friend who was building a Ceritone kit asked for some help.  Tried it on a whim and was very impressed.  I did not consider any frequency shaping effects from the entrance cap.

I am going to etch up a little board and build the network up to try on my Centaur build. I will socket the cap and experiment with the value.

Thanks for the heads up!
Dave O.

 

[pickdropper]

Very nice job!

[ampgeek]

Thanks mate!

I just finished etching and drilling a couple of boards for a mini, plug in Jubilee clipper to try in the next Centaur build.

Each is 1/2" X 1/2" so I did up a big block to improve the handling and processing.  No way I could transfer and etch something that small!

Did a 3" X 3" grid (36 total boards) just to see how small I could make them.  Worked pretty well for a first shot.  Lost only two in the batch.

The individual pads should have been a few thousands bigger in diameter (0.032" ID).  Broke through a couple of them because I missed the center while drilling.

Cheers,
Dave O.

[pickdropper]

Cool, I dig mini builds.  I did a 1590A PCB layout for a Mini Centaur a while back.  Good luck on your build.

[TNblueshawk]

Cool, I dig mini builds.  I did a 1590A PCB layout for a Mini Centaur a while back.  Good luck on your build.

Dave, they let you in here  ?

[pickdropper]

Cool, I dig mini builds.  I did a 1590A PCB layout for a Mini Centaur a while back.  Good luck on your build.

Dave, they let you in here  ?

Indeed.  There goes the neighborhood. 

[jojokeo]

Indeed.  There goes the neighborhood. 

"Would you be mine, could you be mine, won't you be my rockin' neighbor?" 

[smackoj]

Nice work and very inventive on your part. How does the GGG Centaur clone sound vs. a boutiki Centaur?  I have been looking intently at JD's ready to solder pcb of the Centaur but wondered if it was worth the effort?

 

[ampgeek]

Thanks man!  I developed a very good "homebrew" PCB capability for a very specific job a year or so ago.  Now it seems that every "new" electronics related thing (tube amp, pedals, etc..) that I hatch up must have something of that ilk included in it.  LOL.

I have to admit that the GGG Centaur is the first and only Klon type circuit that I have ever knowingly experienced in person.  So...nothing else to compare it with unfortunately.

After so many OD and booster pedal builds that just were not my cup of tea....this one REALLY got my attention right out of box.  The second one that I build will definitely be displacing something currently on my pedal board.

Cheers,
Dave O.

[ampgeek]

Pickdropper,
You have some great stuff going on in the other thread.  Love the creative graphics!!
Curious about your mini Centaur layout.
Did you eliminate elements from the circuit?  Simply tighten up the arrangement?  Both?
I look at the "always engaged" buffer part of the standard Centaur plan and wonder how important that is to the magic.  I have played around a bit with buffers and, for the most part, buy into the Pete Cornish philosophy on their use.
Did you make one up and did it work well for you?
Dave O.

[pickdropper]

Pickdropper,
You have some great stuff going on in the other thread.  Love the creative graphics!!
Curious about your mini Centaur layout.
Did you eliminate elements from the circuit?  Simply tighten up the arrangement?  Both?
I look at the "always engaged" buffer part of the standard Centaur plan and wonder how important that is to the magic.  I have played around a bit with buffers and, for the most part, buy into the Pete Cornish philosophy on their use.
Did you make one up and did it work well for you?
Dave O.

I was able to keep all of the components, I just had to work a bit to make everything fit.  I also used 1/8W resistors and smaller caps.



It is buffered just like the original.  I like the buffered version as it can help when on a pedalboard with a lot of pedals.  When the pedal is actually on, it doesn't make a difference one way or the other.

[ampgeek]

Outstanding!
Very, very well done   

Dave O.

[pickdropper]

Outstanding!
Very, very well done   

Dave O.

Thanks Dave, I appreciate that.

- Dave

[smackoj]

senor Ampgeek; do you wish to share the steps to your 'homebrew' pcb making? I have been wanting to try it but hesitant to buy chemicals before I know what the best process is.  If you ain't keeping it a secret, let the good ideas roll.

 

[TNblueshawk]

senor Ampgeek; do you wish to share the steps to your 'homebrew' pcb making? I have been wanting to try it but hesitant to buy chemicals before I know what the best process is.  If you ain't keeping it a secret, let the good ideas roll.

 

I know of some guys who have followed this vid.
 
https://www.youtube.com/watch?v=tWnfnt2rNO0
 

[ampgeek]

Absolutely no secrets here mate!

In general, I use a laser printer on dextrose backed paper and run it through a laminator to get it securely melted down onto the copper clad.  I follow that with an etch with peroxide (30% from the local health/beauty store) and muriatic acid (from the pool store) at ~50:50 vol%.  All residuals are neutralized with baking soda before going down the drain.  I use as little chemical as possible so there isn't a whole hell of a lot of waste.

I do employ a couple of little tricks along the way that got me from an original ~25% success to ~95% success rate.  The biggest one being a 3 second copper clad pre etch before the image lamination step.  That provided a HUGE improvement.  The other being the use of distilled or deionized water for all in-process rinses.  The dissolved solids in the local tap water can wreak havoc depending on where the solids deposit on the copper clad.

The biggest "limitation" to my approach is that I can't go any thicker than 1/32" copper clad thickness through the laminator.  That forces the use of a couple more stand-offs for larger boards.

Just let me know if you want any more detail on this approach.  I am very, very happy to share!

Cheers,
Dave O.

[smackoj]

thanks mucho. I will read and watch several times to get a better mental picture of the process. question; when you talk about a 'laminator' are you using one purchased at a office supply store or where does a guy find one that does this without putting a mortgage on the condo?

gracias   

[ampgeek]

My pleasure!

Here is the "system" that I bought into a year or so ago.

http://www.pulsarprofx.com/pcbfx/main_site/pages/products/transfer_paper.html

You can procure the supplies through Mouser.  I haven't found the need to use the foils but may play around with that in the future just to see how they work.

You are correct about the laminator being the biggest capital expense for getting into the game.  I bought mine through Amazon for ~$130 and it works great.  In retrospect, it was about the cost of a PT/OT set for a tube amp which isn't all that hard to justify to have that kind of DIY fabrication capacity.

You will find (or make up!  ) many uses for a laminator once you have one.  Being able to make dinner table place mats out of the kids elementary school art work was the one that sold me (or should I say my wife) on it!

Cheers,
Dave O. 

[smackoj]

I'll do some snoopin' around and see what laminators I can find out there.  thanks

jack

[ampgeek]

Jack,
I remember seeing one specific model mentioned in the literature at the link above but can't recall it at the moment.
It was a different model than the one that I bought at Amazon..but...I would be surprised if it cost much more than the one I have.
I reckon a budget of $150 will get you damned close after all is said and done.
Cheers,
Dave O.

[MakerDP]

My pleasure!

Here is the "system" that I bought into a year or so ago.

http://www.pulsarprofx.com/pcbfx/main_site/pages/products/transfer_paper.html

You can procure the supplies through Mouser.  I haven't found the need to use the foils but may play around with that in the future just to see how they work.

You are correct about the laminator being the biggest capital expense for getting into the game.  I bought mine through Amazon for ~$130 and it works great.  In retrospect, it was about the cost of a PT/OT set for a tube amp which isn't all that hard to justify to have that kind of DIY fabrication capacity.

You will find (or make up!  ) many uses for a laminator once you have one.  Being able to make dinner table place mats out of the kids elementary school art work was the one that sold me (or should I say my wife) on it!

Cheers,
Dave O.

Thanks for posting this information! I may have to invest in this. I've tried the laser transfer from photo paper with an iron and it is just a PITA. I can never quite get all the paper cleaned off the surface and then my traces are less than neat to say the least.

I know that this is supposed to work with a laminator, but do you think an iron would work using their transfer paper to mask metal pieces for etching? Like pedal enclosures and amp faceplates?

[jojokeo]

Making pcb's is just a pita period. Then there's all the drilling, messy chemicals, over-etching, and lastly better not mess up after all that work or  Then if you want to modify...forget it.

[pickdropper]

Making pcb's is just a pita period. Then there's all the drilling, messy chemicals, over-etching, and lastly better not mess up after all that work or  Then if you want to modify...forget it.

I agree.  That's why I prefer to make my own layouts and have them fabbed.

[smackoj]

ampgeek; I viewed a bunch of diff. models of laminators. the majority of them say they can use 3 mil or 5 mil thick "pouches" . Does yours work with thicker loads? I read in your post that you are limited by the thickness of the product the lam. will process.

thanks, jack

[ampgeek]

Indeed!  Homegrown pcbs are definitely not everyone's cup-o-tea.  One's visions and goals, as moderated by their tolerance levels, will always prevail in the end.

For me, it's all about waking up with an idea/design/whim and having it done, installed and functioning before lunch.  Nearly instant gratification.  Very liberating!  I
rather enjoy the whole process so it isn't a PITA by any stretch of the imagination. A true case of different strokes for different folks.  It's all good!

I started off using a home iron on the Pulsar transfer paper with poor to moderate results (about 5% to 10% success).  I even tried sandwiching the copper clad and
Pulsar paper between two 1/4" aluminum plates bound with small metal C-clamps and baking in the oven to transfer the image (moderate improvement).   It was at that
point I bought the laminator and experienced a HUGE improvement in performance.

If I were to do it all over again with what I know now, I would go back to the aluminum plates/C-clamps in the oven approach modified with a pre-etch of the copper
clad before the transfer to see if that produces acceptable results. 

That may very well be the ticket for one off production without having to invest in the laminator.  There is something about pre-prepping the copper surface with a very
quick "etch" followed by a thorough rinse with distilled water that makes it uber receptive to the toner.  The pre etched surface looks a bit ugly to the naked
eye...but...it made the world of difference for me. 

My laminator chokes with anything over 1/32".  Actually, it peels/smears the paper away from the copper clad as it passes through the laminator rollers.

I see no reason why one couldn't try the Pulsar paper on an enclosure or other receptive surface.  The trick will be holding the paper steady on the enclosure
while applying adequate pressure/heat to transfer the toner and not slip-sliding the paper/image across the surface.  Maybe a plate and C-clamps in the oven as mentioned
above?  If worse comes to worse, the toner can always be completely removed from the metal surface with acetone so there won't be any damage to "expensive" pieces.

Cheers,
Dave O.

[MakerDP]

hmm... the clamping and into the oven is a good idea for odd-sized pieces. Maybe I'll get a pack of that paper and try it out.

It looks like their DecalPro product might be good for pedal faces and amp faceplates!