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Linkerman 09-07-2012 02:34 PM

Dr. Boogey pedal build
A while ago, a friend of mine who's a gear enthusiast started dabbling on effect and amp building. He built a couple of things, kept checking for new stuff to try, and one day he came across the Dr. Boogey rectifier emulation pedal.
Knowing that i'm a fan of high-gain distortion and Mesa amps (but i can't afford one) and that my Boss MD-2 wasn't cutting it for my needs lately, he suggested it to me.
The deal was i'd pay for the parts, and he'd build the pedal for me.

Gladly i agreed, so we ordered a Dr. Boogey kit from the UK-electronic online shop, and we were off!

We never set a deadline for the completion of the pedal. The only goal was to build it the best he could, while i would design the exterior to make it look the best i could.

After a couple of months working on and off on the pedal, in mid-August it was finally at testing point:

As you can see, my friend did a great job. Everything is clean and tidy, impeccable wiring, even at this stage that we know it's temporary.

Temporary why?
  • The input/output jacks that came with the kit aren't that great. We already received new, high-quality ones to replace them.
  • The LED (3mm) is too small compared to the knobs i chose, and i want to try and keep a similar size ratio to the one on the Rectos' control panels, so it's going to be replaced with an 8mm one, which has a larger bezel.
  • The 9V battery jack is only there for testing purposes. I only use my pedals connected to a power supply unit, so it's going to come off to keep everything tidy.
  • The circuit board is secured only by tape, because everything has to come out for the enclosure to be painted, varnished, etc. Later, it will be properly secured to the enclosure with plastic support poles. That's also the reason why a couple of wires are longer than they should (so they can be cut and re-soldered later), the shrink-wrap isn't shrunk yet, and the pedal (and its components) isn't properly grounded and insulated yet.

Even so, it's an excellent distortion. Lots and lots of gain, and surprisingly not noisy at all (especially considering the lack of proper insulation at this stage).
Sustains like no other distortion i ever tried, and the feedback is very cool and easy to control.
The 3-band EQ is awesome, and the Presence knob works wonders if you want to cut through the mix in a band situation.
That said, the gain can easily become overwhelming if you're too liberal with the level and gain knobs. I used to say that "there's never enough gain"... Well, this pedal has it. Maybe a little bit too much. :p:

The 4 trim pots are regulated at 4,5V right now, but when the enclosure becomes ready to be fitted with the components we're going to try a different bias. Biasing at 5 to 6V supposedly helps to tame the distortion, which this beast could really use.
Since it's very easy to experiment with the trim pot bias, i want to hear how it sounds at different values to choose the setting that sounds the best to me.

Linkerman 09-07-2012 02:35 PM

After the testing stage, it was time for me to work on the exterior.

I had already designed the final version of the label to be printed in adhesive vinyl, so i went to a graphics shop to print it. I'll post pics of that later. ;)

Another friend of mine offered to paint and varnish the enclosure. I asked him to paint it matte black, with matte varnish (to avoid excessive light reflexes on the enclosure).

Here's the enclosure, before applying primer:

You can see that the LED hole was enlarged to fit that bigger LED bezel.

With primer applied:

The matte black paint, after being applied and drying:

Last night i went to my friend's house to apply the vinyl so that he can start applying the varnish, and that gloss has disappeared completely. The paint really is matte, even though in these pictures doesn't seem like it. :)

I'm expecting to pick up the finished enclosure by this Sunday, i'll post more pics then.

eddiehimself 09-07-2012 02:51 PM

Beautiful. Love the 8-mm LED.

R_Gallagher_Fan 09-07-2012 04:22 PM

Sweet build! Here's one my dad made :)

Linkerman 09-10-2012 05:09 PM

Small setback: today, while the varnish was drying, a bird must've entered the workshop and lifted up some dirt off the ground... And a bunch of that dirt became imbued in the drying varnish.

Now my friend is going to try to carefully polish the dirty varnish without damaging the vinyl underneath, to apply a new layer afterwards.

Fingers crossed. Worst case scenario, the vinyl gets damaged and i'll have to shell out another 5 for the graphics shop to print me a new one.

Linkerman 10-05-2012 12:51 PM

New Update
After all, it wasn't dirt.
The vinyl's protective (transparent) layer was slightly porous. So what we thought was dirt, was in fact a considerable amount of tiny air bubbles that formed on the vinyl surface, underneath the varnish.
While sanding the varnish, the vinyl got damaged and my friend had to get a new one to start again.

Today, i met with my friend who's doing the wiring and assembly. On the way, i picked up the finished enclosure from my other friend, but since i was in a rush unfortunately i didn't grab any pics. :p:

The enclosure looks very cool, but next time i'll use vinyl only for the big, multi-colored areas and logos.
The lettering for "volume", "gain", etc. would be better made with decals, because centering with the knob holes would be easier, and also the vinyl makes small creases around the washers when you screw the nuts in.

Now, after everything was inside the box, looking tidy and awesome, we closed everything up to test the pedal again.

Whenever i'm not playing, and the gain and/or volume are turned past 50%, there's an horrible, constant, high-pitched squeal.
And that didn't happen before taking everything out to paint and varnish the enclosure.

My friend is going back to the work table, and troubleshoot everything.
First thoughts on why would this happen:
  • The use of the bigger LED (i think it isn't likely, because the LED change should only increase the power consumption, supplied by a 9V Boss adapter, and not interfere with the rest of the circuit);
  • The new input/output jacks;
  • Some insulation/grounding issue with the wiring and/or the enclosure;
  • The trimpots biasing;
  • The 3PDT switch wiring.

Can anyone please help with this issue? :confused:

kurtlives91 10-05-2012 06:53 PM

It's called oscillation, very common in a high gain pedal like this.

Move the wires (especially high impedance ones). Shield the input,output and FX IN, FX OUT wires if you can.

Linkerman 10-06-2012 08:57 AM

Originally Posted by kurtlives91
It's called oscillation, very common in a high gain pedal like this.

Move the wires (especially high impedance ones). Shield the input,output and FX IN, FX OUT wires if you can.

We thought of that, that's definitely going on our to-do list. Thanks! :cheers:

But i don't think there are any FX IN and FX OUT wires, the pedal simply has input and output jacks.

kurtlives91 10-06-2012 10:58 AM

The wire going to the circuits input is the FX IN...
The wire coming from the circuit's output is the FX OUT...

Linkerman 10-07-2012 07:10 AM

Oh, ok. Thanks!

But yesterday something came up on my mind: why didn't the oscillation happen before we took the guts out to paint the enclosure?

As i said, we just swapped the input/output jacks for better ones, and the LED for a bigger one, and removed the 9V battery plug... Everything else is as it was before.

kurtlives91 10-07-2012 11:54 AM

Just moving wires around a few cm's can cause oscillation.

Linkerman 11-21-2012 11:58 AM

The Dr. Boogey is finished at last! :D

I went to my friend Marco's house to pick it up, and it came biased at 5,5V for Q1, Q2, Q3 and Q4.
It was extremely low gain, which wasn't the point of this pedal at all.

Then, after reading about a different JFET biasing method, by ear, i decided to give it a try.

I borrowed a multimeter from my friend Daniel (who painted and varnished the enclosure and polished the bottom lid, plus a couple of other details), put my PRS in my brother's hands (connected to the pedal and an amp), and started messing with the trimpots.

After less than 10min biasing the pedal by ear, following the steps mentioned on that link above, it was done.
Here are the bias values i ended up with:
Q1 = 1.75 Q2 = 2.62 Q3 = 5.17 Q4 = 2.40 (Q5 = 8.72)

As you can see, it's very far from the "all 5.50 bias" it had when i got it home.
Since JFETs aren't consistent parts, even two from the same batch of production tend to be very different from each other, i think that every bias will be different from Dr. Boogey to Dr. Boogey even if you try to make them sound alike.

And here's the gutshot before i finally closed it:

This is a great distortion pedal. The 3-band EQ is useful and very responsive, and the "Presence" knob is an excellent fine-tuning tool for your tone as well.
I biased it for LOTS of distortion but it never gets too much, overwhelming, and it's a really quiet pedal (there's no need for noise gate), which surprised me for such a powerful distortion.

It obviously doesn't clone a Dual Rectifier perfectly, but if you're looking for something in the ballpark of that kind of high-gain distortion, i'd say this project is a safe bet.
It's easily one of the most versatile and useful distortion pedals i ever tried, especially considering that you can adjust the bias to your own particular taste.

Now, before posting sexy pedal p0rn, here are some of my early designs for this project, to show the development:



Linkerman 11-21-2012 12:12 PM

I think this final version is V3.2.

Since i wanted the design of this pedal to be as similar to a Dual Rectifier as possible, i used the same knob order. Which proved to be a pain in the a$$ to do the pot wiring in a different way than the PCB was favorable to. Sorry Marco. :p: Your patience is legendary! (He must've re-done all the soldering and wiring of the pedal more than 4 times.)

In this one, you can see the polished edge of the enclosure's bottom lid. It looks very classy:

The on/off switch nut washer was covering the "On" and "Power" lettering, so i asked him to trim the washer's sides a bit. He used an emery table grinder to do it, and i really like how it turned out:

The huge red LED doesn't shine too brightly, it's more like a presence light. I think it fits beautifully with the overall design of the pedal.
I'm really proud of how it turned out! :)

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