Boss OD-1 Clone 14 pin op amp

[ScienceFriction]

Hello, DIY stompbox newbie here I hope posting a new thread is okay.  I'm planning on attempting my first homemade stompbox, and I was hoping I could find some answers and direction here.

I want to make a clone of the Boss OD-1 RC3403ADB chip pedal clone.  I've already gotten my hands on a RC3403ADB chip, but I'm struggling to find the rest of the parts.  I want it to sound exactly like the original, or as close as I can get.  I know stompbox cafe has a parts list, but for example I'm confused by the parts numbers on the Mylar Capacitors.  Does it only matter if the capacitor is Mylar and value?  I have soldering experience, but not electronics experience.  So, does anyone have an idea where I can find the correct parts for this project?  I have no idea where to even find a 1S2473 Vintage Si Diode or Main PCB (35 X 56 mm).

Also, I want to add a tone knob and true bypass to my OD-1 clone as well, would that change the sound much?  I mean, hypothetically speaking, if I didn't use the tone knob I would assume it would sound the same as an original OD-1.  I have an OD-1D with the uPC4558C (NEC), so I have something to use as a guide, but I don't plan on messing with that pedal, I like it.  If anyone could help me I'd be incredibly grateful. 

[Earthscum]

I don't think you mean the OD-1. That is a fairly straight forward overdrive using only one IC, a dual OP Amp (uPC4558C).

[zombiwoof]

I don't think you mean the OD-1. That is a fairly straight forward overdrive using only one IC, a dual OP Amp (uPC4558C).

The very rare and very expensive early version has the 14-pin chip.  These are going for outrageous money on Ebay these days:

http://www.bossarea.com/loadpage.asp?file=boxes/od1.xml

Al

[Earthscum]

My bad...

http://www.alldatasheet.com/view.jsp?Searchword=RC3403A

For some reason I was pulling up some decade counter with those numbers yesterday, so I was thinking he may have been referring to one of the many other Boss XX-1 pedals... I love Boss, but their naming system is kinda lame. Like they are trying to capture the feeling of saying "It's an SS, dammit Bob!".

And, since I'm in the griping mood, I am about sick of the Google tracking... I assume I was getting search results for decade counters because I was looking up Flip-Flop chips earlier. Until I cleared my cache, I was getting about a weeks worth of CMOS returns on anything I searched for... just from 1 night of researching crap.    Apparently the local Farmer's Market has some link to CMOS technology, according to G.

[ScienceFriction]

Thanks for the replies, but does anyone have any ideas?  If I could at least find some of the main parts, like the ROHM diodes, I figure I could probably mod a SD-1 to the OD-1 specs..

[smallbearelec]

Good job finding the IC, though I doubt that most knowledgeable ears would hear a difference between that quad op-amp and something similar. Looking at the schematic, what gives the OD-1 a distinctive tone is the asymmetrical clipping diodes.

I don't think you are likely to find all of the "original" components that BOSS used. I won't even try to go after those diodes, because I'd have to buy a lot, and because I would have no guarantee that what I get isn't 1N4148s that have been re-packaged to sell for $$$. As for the exact makes of capacitors and other bits and pieces, as we say in Brooklyn: "fuggedaboutit."

None of this means that you can't clone the pedal. Commonly available small-signal silicon diodes (or maybe even germanium!) may sound better to you. But I think this is another situation in which breaking out the breadboard is called for. If you have never used one, here are a couple of tutorials:

http://www.smallbearelec.com/HowTos/Breadboarding/BreadboardIntro.htm
http://www.smallbearelec.com/HowTos/BreadboardICDist/ICDist.htm

The first one covers the use of the tool, and the second describes setup an tweaking of a distortion that actually is not too different from the OD-1 (and many other OD/distortions).

Happy Experimenting!

[ScienceFriction]

Correct me if I'm wrong, but the IC is the RC3403ADB 14 pin chip right?  I've got one of those, so I should be all set on that part.  Ooh, germanium does sound interesting, that wouldn't give me too much gain/fuzz would it?  Still, it's an interesting idea.  What would be the way to go with that?  So, disregarding exact makes and all the bizz, could I find everything I need here at DIY stompboxes store and your store smallbearelec?  It would be easier for me to just buy the rest of components at one place, that's a lot less to worry about!  Your breadboard suggestion is great, I think I'll go that way for this first pedal, and get more advanced later.  Thanks for all the advice and information so far.  Once I get going I'll do updates if that's cool.  

Wait, the Main PCB is just the board right?

[Earthscum]

They show 1S1588's in this schem... could be a work-alike, haven't looked too much into it.. Pedal Parts Plus has them listed, but out of stock.

http://eu11.stripper.jp/pulcino/blog/images/Od-1A.gif

From Brett Miller's doc: http://www.diystompboxes.com/smfforum/index.php?topic=76021.0

Page 16:
"Note: The 1S2473 diodes used in the original MIJ DS-1 had a Vf of 0.92 to 1.0 volts. This is much higher than the 0.65 volts Vf of the 1N4148-type diodes used in the MIT post-1994 DS-1. A few easy ways to acomplish this goal are to: a) use a silicon diode with a forward voltage (Vf) at or near 1V @300-400mA test condition, like the 1N4150 diode; b) put one 1N34A diode in series with one 1N4148 or 1N914 to replace each D4/D5 diode; or c) put three 1N34A diodes in series to replace each D4/D5 diode."

1N4148, 1N914, 1N4150 are silicon diodes, and have a fast 'break-over', so they sound harsh when they clip. Basically it means that they turn on really fast. Most pedals that sound great that have Si diodes also have filtering incorporated to smooth out the clipping by shaving off the upper frequencies created.

If you want a smoother distortion, use the Germanium diodes like 1N34A. A Ge in series with a Si diode will soften up the Si's harshness a bit.

If you want what's probably considered by most to be the smoothest clipper diode combo, use the 1N34A tied to an IRF510 mosfet: (there's lots of info on this combo on these forums)

V+ => 1N34A => S (MOSFET) G+D => GND

That make sense? V+ just denotes the positive end. Your scheme would be: Ge and fet pointing forward, Ge-Fet-Ge-Fet going reverse.

You will probably want to etch your own PCB, unless you can inquire to someone on the forums about making one for you.

Go Vero: http://www.diystompboxes.com/smfforum/index.php?topic=28572.0;prev_next=prev

Or I guess you could just get this (when they get stock): http://stompbox.cafe24.com/3

[ScienceFriction]

Thanks Earthscum, that does make sense and actually helps me a lot.  I'll probably get a few different diodes and try different combos.  I like the idea of using the germanium and mosfet diodes, I'll have to find those mosfet ones.  Too bad my MIJ DS-1 works fine, otherwise I'd break it open, haha. 

[smallbearelec]

Correct me if I'm wrong, but the IC is the RC3403ADB 14 pin chip right?

Correct for the early serial numbers. Other chips were used later.

germanium...wouldn't give me too much gain/fuzz would it?

No...just different.

disregarding exact makes and all the bizz, could I find everything I need here at DIY stompboxes store and your store smallbearelec?

Yes.

Wait, the Main PCB is just the board right?

Not sure what you are asking. The point of breadboarding in this case is to get to a version of this circuit that you want to commit to solder, since there are some uncertainties about the supporting components. Note that one of the other posters made some suggestions concerning the diodes? You will probably be tweaking A Lot to get exactly what greases your crank.

I realized that I don't have a parts list for the OD-1 in my (extensive) library of DIY pedal builds, but I will do one tonight. You had questions about capacitor types, and my spreadsheet will help you pick some things that will work. Once you have a working setup, you can tweak as you like (ceramic for poly film/tantalum for aluminum, etc.)

E-mail me at smallbearelec@ix.netcom.com and I will send.

[caspercody]

Smallbearelec,

Do you sell a package for all the parts say for a pedal one wants build? I guess what I am asking is if I wanted to build the Box of Rock, and I go to your web site you would have a kit I could buy that had all the parts to make the Box of Rock (minus the pcb board, and maybe box)? If you do not do this, maybe you should look at doing something like this, just a thought.

Thanks
Rob

[ScienceFriction]

Sorry, I'm still learning all these terms.  I just realized PCB must be the actual circuit board, haha, sorry.  I'm really thankful for all the help you guys have given me, I've always wanted to try my hand at making my own pedals, but this is my first time giving it a try.  Yeah, I figured that the best thing I can do is buy a variety of diodes and play around with different combos, but I love that.  Thanks again for all the help everyone.  

[Earthscum]

The mosfets are actually the same ones you can find at your local cell phone dealer (RShack), although SmallBear has them, and I believe they are T0-92 (maybe not, haven't ordered any).

I play a modded DS-1  (with the RHOM BA728N, which i would love to get my hands on a bunch). I use a Ge tranny one direction, and a LED in the other. To smooth out the clipping, you should use something like a 470pF cap across... I used a .47u, lol. But I did a bunch of other mods that I had to compensate for. It is basically my heavy overdrive pedal now. Your clipping should be at about 2V and -1V, while mine is running at a gigantic range of 220mV and -1.7V. The Ge clipping is smooth to begin with, but the cap across really smooths it out, and now it works as more of a compressor on one half of the signal.

I figured I'd throw that in there, since the clipping section is similar to the DS-1. With the large cap, it feeds back a lot more highs, so it doesn't boost and clip them as much. If you decide to go with the Si diodes and find them to be a bit harsh, try dropping a 150-220pF cap across the diodes. The corner frequency will drop as you increase the gain, so the more it clips, the more it filters the harshness.


EDIT: Ha! Speak of the devil... if ya pop back in, are your IRF's T0-92's? If so, I'ma gonna be ordering a couple.

[ScienceFriction]

Thanks Earthscum, I'll keep that in mind.  Once I get a solid parts list I can start making comparisons and seeing what I can tweak.  I think I need more tools, lol, otherwise I won't know what my clipping will be.  I actually have a 1986 MIJ DS-1, not exactly sure how it will help me, but having that and my OD-1 (8 pin op amp) should help when I'm testing my OD-1 clone for comparison purposes.

[zombiwoof]

And I would add that the tone knob is a good idea, even though the early OD-1 goes for big money, it is considered to be pretty trebley-sounding (the price they get is because of the rarity of that version).  I hang out on the Bossarea Forum a little, and although most of those guys would like to own the pedal (and some do), it is mostly for collecting purposes, as many of them favor the later Boss OD's that have the tone knob.  So tuning it up yourself with component changes might be suggested.  I haven't heard one myself, this is just from what I've read from the Boss freaks.

Al

[ScienceFriction]

That's exactly what I was thinking too, zombiwoof.  I don't believe in paying big $$$$ for something that can be "found" cheaper, but that is also flawed (from my perspective).  I figure with enough effort and time I can create something that is as good as the early Boss OD-1, but better for me.  That's what it's all about isn't though?  Making a better pedal in general and for yourself? 

[smallbearelec]

Do you sell a package for all the parts say for a pedal one wants build?

No...I have avoided this from the start, partly because there are multiple versions out there of many popular DIY builds, and I did not want to be filling orders for "Kit such-and-such, but with these changes..."

You Can ask me for a spreadsheet, shop on the Stock List and create your own kit. OR, there are a number of companies out there that offer full kits of classic pedals, and their stores are great resources. Try Tonepad, GeneralGuitarGadgets, Beavis Audio Research or Buildyourownclone.

NB: Customers are free to buy parts from me as they wish. However, I won't assist with cloning pedals made by ZVex, Analog Man and other independent designers.

[Mark Hammer]

The four sections of the 3403 were used in the early issue OD-1, as you can see in this schematic.  Rather than a 4558 dual, and transistor-based input and output buffers, the additional two op-amps available in the 3403 provided those buffers.  The Tube Screamer and SD-1 use a passive lowpass filter after the clipping stage to roll off the highs, but the OD-1 uses a unity-gain inverting stage to do that.  The 10k/.018uf pair in the feedback loop of that stage set the rolloff at roughly 880hz, just a bit higher than the 723hz in the TS, but the same rolloff used in the SD-1.  Based on what Earthscum wrote, use of the 1S2473 diode would have given it a fairly high forward voltage, yielding milder clipping and a relatively substantial output level.  Actually, the transition from OD-1 to SD-1 is kind of interesting.  Think of the SD-1 as essentially the next step, keeping roughly the same range of gain, and post-clip lowpass filtering, as the OD-1, but a slightly lower clipping threshold and variable - rather than fixed - tone.

Based on this schematic, it would be a simple matter to implement bypass and status indicator LED with a DPDT switch.  The common of one set of contacts would go to C8, and select between the wiper of VR2, or the junction of R3/C2, essentially replacing the two FETs and their associated support and flip-flop circuitry.  The other set of contacts are used to actuate the status LED.  Not true bypass, but adequately buffered and a suitable replication of the original with less work.

Does the 3403 add something "special"?  I have no idea.  It IS a different sort of op-amp, and is often used for its low current consumption.  Does the unit need tone control?  I guess that depends on your tastes and needs.  I can see where a person might wish to maybe adopt 2 or 3 different cap values for C6, to set different rolloffs.  Failling that, I guess the only thing to suggest is to make yourself an SD-1 tone stage.

[ScienceFriction]

Thanks Mark, that will be a big help once I get to that stage of my construction (and once I figure out what it all means  ).  I just ordered everything I need (thanks smallbearelec and diystompboxes), including a breadboard (I'm excited about prototyping, I'm sure this will get a lot of use!).  I think I'll need a few more things later on down the road, but for now I think I'm set.  Once I get everything in the mail I'll start posting updates on it.  Thanks for all the help everyone!

[Earthscum]

I've been watching this thread all day, and now I wanna build a version of this myself... I'm actually tempted to use the old LM324 rather than the TL072 just for the hell of it.

I've often considered building a DS-1 like this using a 4 amp package rather than the tranny in and out. What originally gave me the idea for that was the OPAmp Muff and the 22/7. I may just start with this design and tweak it to be DS. That would be a kewl mod... switchable OD-1 to DS-1. Switch one diode out and switch in the DS (BMP) tone stack.