More About the DOD 250

First time I visited and perused this site, http://rabbathrecordings.com/DOD250.htm, it didn’t make much sense to me.  It wasn’t relevant either.  After breadboarding the DOD 250, I find it so much useful now.

Yesterday, I tried putting clipping diodes in the op amp’s feedback loop and heard that  slightly-compressed-and-distorted sound, very characteristic of a tube overdrive pedal.  I also tried various combinations — clipping in the loop alone, clipping only at the original clipping section (toward the end of the circuit), clipping in both the loop and the original section, and no clipping at all.

It’s really easy to try various clipping configurations with a breadboard, which I had enclosed in a housing so the female jacks and potentiometers don’t wiggle around and most importantly to make the off-board connections more stable.  It was really fun to listen to the sound produced with the various clipping configurations.

Why am I doing this?  It’s not my goal to clone; I’m searching for a sound that’s my own.  I’m hoping to come across an overdriven or distorted sound that I really like, something that I can’t get from any mass-produced pedal, and something unlike anything I’ve ever heard.  Besides, I can’t afford custom-built pedals.  I know may not find what I’m looking for, but at least, I’m having fun in the process.

How Many True-Bypass Pedals in a Chain?

No need to worry if you got three to four true-bypass pedals in your effects chain.  Think twice if you want more.

http://www.psg.com/~dlamkins/music/musings/how-many-true-bypass

Dealing with a Crappy Pedal

After acquiring my first Boss imitation, that of an SD-1, I thought that all such pedals were actual replicas of their counterparts.  I was wrong.  I also read in one forum that Lazer/Century/Denio/Rockson and God-knows-what-else-it’s-called distortion pedals had a circuit that was designed just like this certain overdrive pedal.  Since I couldn’t find a schematic or layout diagram of the pedal, I decided to buy myself one of those for the fun of it.  I wanted to mod the pedal to practice my soldering and generally have a good time.

I couldn’t believe what I heard when I connected my newly acquired and badly battered Lazer distortion pedal between my guitar and my amp.  It terribly sucked tone!  Thinking that I would be appeased if I switched it on, I set all the knobs to 12 o’clock, turned the gadget on, and played a chord.  Man, I couldn’t describe the sound.  I couldn’t even determine what kind of sound it was.  There were highs and lows, but I couldn’t hear the sound of my guitar.  It sounded like noise.  Yes, that’s it, mostly distortion noise, very little guitar.

Tweaking the knobs didn’t help much.  Simply put, the Lazer distortion is one crappy pedal.  I couldn’t believe someone could design something like this.  The designer could’ve been partially deaf; maybe that person wasn’t even a guitar player or musician. If I may say so, this Lazer distortion pedal should be the subject of a product recall by the company if the company selling/marketing the pedal is concerned about its reputation at all.

Well, I had already thrown away 400 pesos for this piece of crap, but I’m not going to throw away the pedal.  I was determined to learn more about the pedal despite my extremely limited knowledge in electronics.  So I proceeded to open up the damned thing and check the layout.

I have to admit that trying to trace the circuit makes me dizzy and drives me to the threshold of insanity.  Hahaha.  The magnifying glass transports me to some kind of electronic Lilliput and Blefuscu, where I feel like an ant in a helicopter, trying to traverse the maze of capacitors, resistors, transistors, jumper wires, ICs, diodes, and the copper trace highways.

I saw a familiar landmark, the 4560 ICs; there were two of them.  Then I saw the clipping diodes.  My adrenaline started to pump me up and my heart began to beat a tad faster as I became more excited with the prospect of being able to change the sound of this mofo.  However, after seeing that the resistors were rated at 1/2 watts, my heart sank a bit. Anyway, I proceeded to change the clipping diodes and replaced one capacitor and one resistor for a simple mod that made my Lazer distortion pedal sound like — well, a distortion pedal.  Kidding aside, the pedal sounded like a distortion pedal and a fuzz box rolled into one.  The fuzz characteristic becomes more evident as you sustain a note.

I surfed and Googled, then found out a workaround for tone sucking pedals.  I also found out that true-bypass aren’t necessarily a good thing because connecting a number of them in series is like having a really long cord between the guitar and the amp, so you need to be able to individually disconnect them from the chain with a pedal looper or strip, or by using a buffer before or after the chain.  Anyway, more of that in some other post.

I found out that if you put a pedal with a low-impedance output before the tone-sucking pedal, it will improve your clean sound because it helps to maintain the right impedance throughout the chain.  It also means that the pedal before Tone Sucker has a good buffer similar to that of Boss pedals.  One can also use a looper or fabricate/purchase a buffer and connect it either at the beginning or at the end of the chain.  I chose the more practical solution; I knew that my first Boss imitation pedal had a nice clean sound with the effect off, so I connected it before Tone Sucker.  Yes!  Crystal clear clean guitar tone was finally coming out of my amp.

Left and Right Hand Synchronization

My youngest son’s friend wanted an exercise to synchronize his left and right hands.  He told my son that he had difficulty with his current regimen.  When I asked my son what kind of exercise his friend does, I found out that his friend was doing chromatic scales from one string down or up to the next.  I believe it’s the shift to another string that’s hindering his progress and distracting him from accomplishing what he sought to do, which is to synchronize his left and right hands.

This exercise below will definitely improve synchronization. I tried to post an ASCII tab, but because of this page’s formatting, the tab won’t come out the way it’s supposed to. I decided to write it this way instead:

ASCENDING (first measure):

E string:  |—-1-2-3-4-5-4-3-2-3-4-5-6-7-6-5-4—-| … 14th fret

DESCENDING (first measure):

E string:  |—-14-13-12-11-10-11-12-13-12-11-10-9-8-9-10-11—-| … 1st fret

Left hand fingering:  1  2  3  4  4  3  2  1  1  2  3  4  4  3  2  1

The notes above are in 16th notes.

Next, try the same pattern, this time using three fingers and three notes played in 16th note triplets.

So for the first measure, play

E string:  |—-1-2-3-4-3-2-3-4-5-6-5-4-5-6-7-8-7-6-7-8-9-10-9-8—-|

The left hand fingering pattern is

1 2 3 3 2 1 1 2 3 3 2 1 1 2 3 3 2 1 1 2 3 3 2 1

and if you want to develop your left hand at the same time, you can play the pattern this way:

2 3 4 4 3 2 2 3 4 4 3 2 2 3 4 4 3 2 2 3 4 4 3 2

Then descend like so:

E string:  |—-14-13-12-11-12-13-12-11-10-9-10-11-10-9-8-7-8-9-8-7-6-5-6-7—-|

Strictly do alternate picking, start with a downstroke.  Next time around, start with an upstroke. Then play the exercise on the next string until you reach the 1st string.  Play the same pattern up until it takes you back to the 6th string.  This will not only help with synchronization but will also teach your right hand to adapt to a slightly new position (playing on the 5th string, playing on the 4th string, and so on).

Use a metronome, start with a speed you’re comfortable with, and make sure you play each note clearly.  Then speed up gradually.  It’s up to you how much faster you want to shift to the next gear, but the increase in beats per minute should be noticeable.  This forces you to speed up, but make sure you do things cleanly, without distortion first, then with distortion to make sure you’re not making unnecessary noises.  Also try this exercise with palm muting.  Remember to relax your right hand and keep your left hand fingers as low as possible.  Well, if you’re left handed, you know what to do.

I must caution you that as your left and right hands synchronize, you will play so fast you’ll feel like a shred god and you won’t want to stop.  It’s addicting!

Breadboarding: Building a DOD 250 Clone

Here’s a worthwhile learning activity for those of you who want to learn how a DOD 250 circuit is built. I successfully recreated the circuit on my breadboard, and the circuit works fine. I later changed the clipping diodes to a germanium-silicon pair in series mated with an LED. I also used a JRC4558D chip (the first half) instead of an LM741 because I didn’t have one, but I made sure I correctly identified the pin outs. The JRC4558D was taken from my Fulltone clone, which now has an NE5532.

I can’t believe I’m blogging like this, since just a few months back, I was reading a  thread at the Philmusic board and could barely make sense of the discussion.

 

Anyway, this is my first-ever breadboarding attempt, and the first time I connected the circuit between my guitar and my amp, there wasn’t any sound at all. Upon further inspection, I realized that the JRC4558D chip’s #4 pin wasn’t connected to ground. I made the necessary correction and presto! I liked what I heard. 

Now I’ve found use for whatever I’ve learned in my high school electronics classes. What makes this activity more fun is the fact that tweaking the circuits is easy with a breadboard. The next thing I’m going to try is to increase gain and connect a small DPDT switch for a true bypass connection similar to what the Proco Rat has.

I still have one problem though. I don’t know how to transfer the circuit to a smaller board that allows soldering. I don’t intend to make my own PCBs because the process simply turns me off; I don’t feel like going that far. The board that I have has holes in a grid-like formation, but it has copper strips underneath that are arranged in three groups of several columns and are separated by a pair of horizontal strips, which isn’t quite like the pattern of a breadboard. I have a long way to go in fully understanding this schematic and actually laying it out the way I wish.

Anyway, here are the links (in order):

http://diystompboxes.com/projects/intro.html

http://diystompboxes.com/projects/power.html

http://diystompboxes.com/projects/ic.html

http://diystompboxes.com/projects/offboard.html