Dual Small Clone Chorus Build Report - Pictures

[Pushtone]

Dual Small Clone Chorus Build Report - Pictures


I finished a dual Small clone chorus on the Tonepad Rev1July.25.2005 layout.
It uses two LFOs and two sets of pots with a footswitch.



Insides
http://www3.telus.net/public/david65/pedal-pics/DualChorus/Dual-Chorus-BoardBOT2.jpg

Rear
http://www3.telus.net/public/david65/pedal-pics/DualChorus/Dual-Chorus-REAR.jpg


For a description of the laminated graphics check this thread
http://www.diystompboxes.com/smfforum/index.php?topic=52037.0



I had built TP's early layout over a year ago. An amazingly compact layout.
The revised layout is tweaked making it a little cleaner to build. 
According to the TP rating system, it's an advanced build. But it's not that advanced.
The project file is complete and leaves little to chance. Its just tight.

There seems to be one inconsistency that I also remember from my first Clone Chorus build.
The 100pf cap in the parts list is a 150pf cap in the schematic.
I only had 150pf caps on hand so I used that for the 100pf and 180pf cap too. Seems to work fine.

A little over a year ago I paid SB something like $6.00 for an MN3007.
They are up to $12.00 now so this build report holds two important points.

1.If you want to build one. Do it soon. The chips are going up in price like grandpa's pants.

2.A dual LFO build gets you virtually twice the chorus from ONE MN3007! That good financial advice.




This project came about after looking at the A-mans Bi-*horus version. I searched the forum and found this post: http://www.diystompboxes.com/smfforum/index.php?topic=42004.0
where Mark Hammer and others discuss options for a dual chorus.
That and specifically Mark Hammer's point about the dual LFO and SPDT switch pushed me over the edge to build one.

This was an interesting build to me because I wanted to use the nylon bolt standoffs
to stack two PCBs (the second LFO would be perfect to try that)
and I could use a DPDT footswitch to select LFOs and still have a pole to switch two LEDs.

In the post above there is talk about switching pots instead of LFOs.
Yes it wouldn't need the second  daughter card, but I could not find a way to get it to work.
Two LFOs and a DPDT switch is a practical solution and, thanks to Mark Hammer, I have proven it works great.

The LFO switching is completely silent and I have included my wiring layout.
(LED wiring not shown)
http://www3.telus.net/public/david65/pedal-pics/DualChorus/Bi-Chorus-Works.gif



If one was very ambitious, one could redraw the layout with a quad LFO
opamp in what would be little additional space and have one board.

One "pot-switching" wiring I did find to work was two Depth pots with a 3PDT and  LEDs.
This could be a good option for someone looking at a Small Clone build,
a Chorus with two Depth controls, a footswitch to select between Depth
pots and one Rate control. A three knob, two footswitch chorus.

But what good is that? I want full-on dual channel operation!




I duplicated the LFO section from the TP layout and etched another board.
It sits directly above the main board so the mounting holes line up to allow the nylon bolts to pass thru both boards.



There is an unused pad on the +9V trace just above the 220uF cap.
I used this pad to jump power to the identical pad on the daughter card.
I did the same board-to-board jumper on the ground trace too.
With power and ground done, all thats left is to connect the pots.




With two LEDs there was just enough need to include a power and ground distribution board.
Here is a picture of the distro board. I used leads snipped from resistors weaved in and out of perf board.
I made little loops to solder the off board wire to. There are three points for +9V and four points for ground.
Included on the distro board are the current limit resistors for the LEDs.






I wanted to mount the pots high up on the face of the box. This means a close tolerance between
the pots and rear mounted jacks. To make sure I wasn't going to short out the jacks I removed two
sections of the inner lip from the box lid to get the jacks as low as possible.






Time to stuff it in.









It worked out so well I built a second one.
The Lush Lounge Twins. Now appearing at your local Gentlemen's Club



Can you handle that boyz?

[MartyMart]

Superb work mate, both electronics and graphics   

....what are those girls doing with those large Olives 
I've used the "shave a bit off the lid" trick myself a few times

Very cool and a great report /

Marty.

[StephenGiles]

Unbelievable, a superb job!

[Auke Haarsma]

awesome! Any soundclips of this thing in action?

[RaceDriver205]

Dude that chick is fine! Im amazed at the quality and clarity of the painting. How did you do that?

[Fp-www.Tonepad.com]

awesome indeed.

[audioguy]

nice

[Dirk_Hendrik]

Lovin' It!! Great job and as said above, awesome graphics!

[Pushtone]

Thanks all. This one did turn out well although one of the decals developed air bubbles when the clear was drying.

Check this thread for details on the laminated graphics.
http://www.diystompboxes.com/smfforum/index.php?topic=52037.0

It's not my art. I emailed the artist to ask if I could use the art for a one off but he didn't reply so I took that as him not saying no. shaky ground sorta. Since then he has started selling stickers and t-shirts on his website.
Hopefully a link to his website will appease him.
http://www.bawidamann.com/store/index.html


I've been looking at some other builds with LFOs and the same "switching LFOs" technique could be used on other effects.

The EA tremolo is one that could take a second LFO and dual control pots. There must be lots more.

[sfr]

Could you somehow sum the two LFO signals and get a syncopated kind of chorus thing going on?  Could be cool.

Oh, and excellent build.  Very pro looking all around!

[Mark Hammer]

First off, thanks for the nod.  Second, that's a delightfully professional looking build.

Readers will note that the advantage of the dual LFO approach is that it allows you to have separate speed and depth.  Of course, what you forfeit in switching between LFOs is a changeover period since the changeover is instantaneous.  If you don't need separate depth adjustment, you should take a look at the two documents at Geofex outlining how to have ramp-up/ramp-down dual-speed switching in a variety of different modulation pedals.

Again, one needs to decide which feature is ultimately the more useful in the intended pedal: dual depth adjustment, or audible changeover time.  Both have their strengths.  It IS possible to have one's cake and eat it too, by having audible changeover from one LFO with its own set of speed/depth controls to another, but that starts to become a much more complicated pedal.  Pushtone's implementation allows for a relatively painless use of an existing single-LFO layout with a daughter board (how many of the generous layout providers will have a reason to provide a single-LFO and dual-LFO layout for the same modulation pedals?), and RG's circuit allows for a relatively painless add-on to permit audible speed changeover.  And for most of us, that will be enough.

But here's what I REALLY wanna know, and I can't believe nobody has asked yet (distracted by the "pimento", I imagine ).  How on earth do you manage to paint the outside AND inside of the chassis?  I'm assuming it is baked in some manner, so how do you suspend it to allow the baking to do its thing without risking some visible area touching a hot surface and deforming the smoothness of the paint finish?

[Pushtone]

Could you somehow sum the two LFO signals and get a syncopated kind of chorus thing going on?  Could be cool.

Mixing LFOs does sound cool.

From this thread
http://www.diystompboxes.com/smfforum/index.php?topic=51276.0

Processaurus offered the idea of adding an LFO panning pot...
"If you added an extra pot to pan between the LFOs, you could have your footswitch select between the mix, and the first LFO.  The mix could get you something like that nonlinear pefftronics Rand-o-matic sound, or if you panned it all the way to the second LFO, the footswitch would do what you're doing now."

And markphaser added ...
"They can have seperate DC offsets one LFO having a negative DC offset and the LFO#2 having a positive DC offset so when u add them to more of a complex waveform

Or LFO#1 is sweeping normal forward and LFO#2 is sweeping reverse"


So there are two more things to try. Just replacing the SELECT footswitch with a pot is another dumbed down option.

[John Lyons]

Wow, I commend you on space use and getting it all in there. I can't do that!
The graphic isn't  really my style (no offence really) but the job you did looks fantastic. The red with white knobs looks really nice.

Mark, notice that all the screw holes are painted over except one? That must be where Pushtone hung the box to paint...

[Mark Hammer]

So is it air-dried as opposed to baked?

[Pushtone]

How on earth do you manage to paint the outside AND inside of the chassis?

Paint on the inside is a sure sign of powder coating. 



When I need some boxes painted I show up at a small 2-man commercial powder coater with Tim Horton coffees and a box of donuts.
He hasn't charged me yet to sneak a couple of boxes into a gang run. You can't be too picky about color though.

The coolest thing is you don't need to sand or prep the boxes at all.
And I've dropped a couple boxes on a cement floor without chipping the powder coat.


And thanks again Mark for the original tip. Made me see the LFO section as a whole.

[royzic]

AMAZING!!

great work my friend

[analogmike]

Awesome job and writeup!!!

Gotta love the REAR shots

[TELEFUNKON]