chopped oc-2

[El Heisenberg]

I added an octave up. It's from the push me pull you. With just two transistors and a pot, it's an easy mod to add, even if you don't put the mid boost mod in the octave down, which works great. I had tried the green ringer and the neoctavia with this. The green ringer with a filter mod worked great. I tried the null mod and think I got it to sound really good, but when I tried the push me pull you, I decided to go with that.



Why isn't this chopped oc2 circuit more popular??

No perf layout out there?? I plan to use three boards to perf it.

[El Heisenberg]

Oh yea, any suggestions to this?? I didn't put in the 470 ohm resistor in the puhsmepullyou. I also tied the 10k resistor to bias not ground. without the drive transistor, the op amp drives it enough I think...at full volume it's a tiny bit louder than the bypassed signal. You could even add it to an existing chopped oc-2 build.

[oldrocker]

The chopped OC-2 is a great project for anyone looking for a nice octave down.  I suppose when there's more layouts for this it will be built more.  I will definitely try the mid boost section and hook in a Push me pull you.  A fun pedal even without modifications.

[Taylor]

I think it's not that popular because it's a little bit too complex to perf easily. I perfed one a while ago but couldn't get it to work. So I did a PCB layout (double-sided with board-mounted pots) and will be getting a run of them made up once I have a little free dough. I'm excited because it's a great effect and I've wanted a DIY version for quite a while. It fits in a 1590b.

[isildur100]

Yes, for sure it is not easy to perf! It is the build that gave me the most problems but finally sorted all the bugs in the end. It is worth it though if you want a clean octave down pedal.

John

[El Heisenberg]

Do you think there's any difference in using LM324s for both ICs? That's all I have. But if the TL074 will work some kinda wonders, then I'll wait for it.

[isildur100]

I don't think it will make a real difference. I had tried with 2 TL074s with no difference. You could always use sockets and change it to a TL074 later.

[El Heisenberg]

updated schem to include credit

[El Heisenberg]

I think I'm gunna record and post my first recordings here. This project is awesome and needs more noteriety. Plus I wanna show off how cool the octave up is.


This is the simplest usable clean octave down + octave up design around.  I've looked at Rocktave divider and Pearl Octaver and such and this was the only thing in my skill range, perf-wise. I just got done perfing the mid boost section, the octave up section and the output transistor on one board. All four pots are on that board. The octave down pot hs to have a wire to connect it to the other board. I have this board hooked up on breadboard and it worked great first time, except for a pot that was misbehaving. All I have is those stupid pots with shafts 5 inches long from radioshack. I don't get those stupid things. I suppose maybe tonight I'll work on the 2nd board, either IC1, voltage divider, and FET section, or IC2 and the 4013. Im doing it on three boards cos I want it to fit in a small enclosure. Cos what's the point of building a huge circuit in a big box, when you could buy one in a small box?

[joegagan]

i picked up an  arion MOC-1 for very cheap the other day (near clone of the oc-2)

i am very interested in trying this. looks like the in and out buffers, along with the flip flop switching is omitted. should be pretty easy to figure out.

as some people know, i am a fan of octave down effects, as demonstrated in my video from '07 , - wah and octave being simultaneously swept by my modded wah/ octave contraption:

http://www.youtube.com/watch?v=fqbT_3Bf45g

[El Heisenberg]

Ahhh! I am a huge fan of octaves too! This will be my second octave up+down effect. The firsst is this hulking box. There's a buffer splitting the signal in two, then one channel goes into a modded purple peaker with only the low end peak, then into a blue box with the switchable 2nd octave mod. The other channel goes into a green ringer with ge diodes and switchable filter and null mods, then into either two bass fuzzes, one with an inductor before it and different clipping. The GR had a switch to take out the 10k resistor to turn off the octave so I could just use the whole box as a distortion with the two choices of bass fuzz set at unity gain with trimmers. Really crazy space like box. Its so gnarly. But I wanted clean octave. And was sick of working aorund the blue boxes glitchy tracking.


This project will be much simpler, smaller, cleaner, easier to use, more versitile, prettier, be more impressive, use less current and just plain be better all around.


I just watched yer vid. You'd love this project! I was just watching your modded big muff video this morning. This thing is GNARLY through a big muff. And being able to blend in the clean tone will give you the pick attacks.

[El Heisenberg]

Ugh! Tonight I perfed up the second board. Took an hour and a half. it's the first IC with the JFET and Ge diode. It got crowded. Poor planning. Im using all recycled components besides most resistors and a couple of my caps broke. The leads just came off. So I had to dig through my old circuit trash bin and find the caps I needed. So I had problems with the length of the leads. This is what I'm workin with!

Anyway, it works but the first buffer isn't loud enough. Something's wrong. somewhere. It works, but the tone is also a little different. I'm thinkin cos of the replacement caps. Big giant ones for small values instead of the ceramics I used at first. Good thing Im building this in blocks. The first board fired up perfectly. I'll just perf the third board tomorrow, and I can re-build the second one if I feel like it. With the mid boost, the slight volume difference doesn't hurt much at all. There's still a boost in the clean mode.


But dammit this thing needs layouts.  I'll post a pic of the disaster when the third board is built.

[El Heisenberg]

really, the problem was trying to build it on the smallest square of perf I could. I only have so much of it left that I cant build the circuit and cut it out, I gotta pick a shard and fit the circuit onto it.

[Humboldts Finest]

I'm sure you're aware of this about those radio shack parts, but I'll say it anyway.

If you have or can get access to a work-mate (little clamping table) you can very easily hacksaw off most of the shaft and file it smooth. It's not  esthetically pleasing, but it's real quick and effective.

Nice additions to the chopped OC-2. This looks like my next project.

I just finished the nocto loco and am looking forward to some normal octave sounds.

[oldrocker]

Well when it comes to recycling old components I'm with ya.  I swear I spend more time looking for and unsoldering parts than actually building.  My OC-2 is 80 percent old recycled components.  But it sounds great and tracks decent.  Still on a bread board though until I'm done experimenting.

[SeanI]

You could use the XOR gate trick for the octave up.  I think it would be a smaller count than what you've got.  Google "Tim Escobedo Digital Octave Up".

[Scruffie]

What's the view on this Vs. the Pearl Octaver? I was gunna build that although I think the Octave up might be lacking so perhaps this will be a better move.

[El Heisenberg]

scruffie, you could put any octave up circuit in this that you'd like. I tweaked the push me pull you by just emitting the drive transistor and running it from the input stage in the opamp. You'd have to mess around with where you put the output and the input with different circuits and might have to tweak the octave up a little. I first had a green ringer with the filter mod and it was great, but not exactly clean since it's all ring mod sounding. When I tried this I went with this right away since it's one of the simplest clean octups I know and it only took two transistors and like 4 caps, 2 resitors and a pot. I LOVE blending the clean with the octave up. It's beautiful with chords.


I just built the third board. Of course it went alot smoother since there aren't any weird V/R connections I gotta make and only four wires out of the block. I went to take some pics, but my camera was dead. Im charging the battery now. It's too late to go get an enclosure for it, so that's for tomorrow. I hope I can get into a small box.

There is still the problem of volume. It's not as high as it was. I think there's a problem with the first buffer in IC1. Dammit. Now with the clean pot at full it's the same volume as it is bypassed. I tried checking the board connections but I crammed everything on such a small board and with such poor planning and re-used parts. I will definetly be building another one of these. This one will make a great gift once I do. Amazing pedal! Relatively easy! The only relatively exotic part is the 4013. This project should be much more popular.

[El Heisenberg]

Well when it comes to recycling old components I'm with ya.  I swear I spend more time looking for and unsoldering parts than actually building.  My OC-2 is 80 percent old recycled components.  But it sounds great and tracks decent.  Still on a bread board though until I'm done experimenting.

Oldrocker, what are you experimenting with? I think you said you were gunna try the mid boost and octave up (YOU DEFINETLY SHOULD), but are you trying other things?? I tried messing with the small caps like the .0047 and .0022 and 330p and 470p but didn't notice much difference. What do you suppose would help tracking?? How could you totally optimize the circuit. So it's sound is totally LOCKED in.

I matched alot of the resistors in the IC2 section and the octave up. I also matched all the diodes but the germanium. Really didn't pay much attention to the NPN/PNP octave up combo. I used random a 4401 and 4403. I just noticed that the big pack of PNPs i bought at radioshack had several different types. But it works fine now. I will be making another one anyway. I can wait to build ANOTHER one and I'm not even finished with this one!

[El Heisenberg]

here. You can see in some detail, the poor planning and shoddy workmanship. I'm a little embarassed to post pics of my build but here it is! Breakin it up into three blocks makes it easier IMO.