I'm not intending this as a "which is better" ad nauseum circlejerk. I'm just curious, because there's a lot floating about out there, because I (think I) built one on the breadboard, but it doesn't line up with what I'm seeing from original schematics
Firstly, this is the one I built (yes, I saw it's modified, but I figured it was just tone control):
(https://4.bp.blogspot.com/-OjLd2oznI58/T8EAs1YRemI/AAAAAAAABM0/b6gUMApzhk0/s1600/od1_IG_mod.gif)
I ended up tweaking a few things, but let's just say this is what I built
(https://i.imgur.com/8ADXtQU.jpg)
(my new toy courtesy of a very, very generous friend)
Apparently the OG version utilized a quad op-amp, and is the foundation of the Aion Corona/Parhelion
https://aionfx.com/project/parhelion-vintage-overdrive/
Then I discovered (what I think is) the more "budget" version Boss released not long after the original
(https://i.imgur.com/z1rBxoO.gif)
So, bottom line: wtf did I build for myself on the breadboard? ;D It doesn't have the quad, but doesn't have all of the other stages of the circuit the rev B model has. Is it just a derivative, op-amp series feedback clipping circuit?
Much of what you are seeing in the original boss schematic is the buffered bypass switching. Here is the cliff notes of the core of the circuit. I have built both versions of the circuit and they have a different sound and feel. (https://uploads.tapatalk-cdn.com/20230610/dc8ec884fdccdff0df9bfe449ce12c46.jpg)
Sent from my Pixel 7 using Tapatalk
Quote from: Thewintersoldier on June 10, 2023, 02:20:32 AM
Much of what you are seeing in the original boss schematic is the buffered bypass switching. Here is the cliff notes of the core of the circuit. I have built both versions of the circuit and they have a different sound and feel.
Thanks for the clarification, Chris.
While I don't have an NJM chip, I have a couple of other quads I could try.
Quote from: jessenator on June 10, 2023, 04:07:46 AM
While I don't have an NJM chip, I have a couple of other quads I could try.
What would the quad accomplish?
Using the other 2 as I/O buffers?
I used that second Boss official schematic to mod a couple SD-1's to OD-1 specs. It's pretty easy to do (with the through-hole versions), and I do feel the OD-1 was a much better-sounding circuit than the SD-1 is. A key to really getting a lot out of the circuit is to mod R6 (4.7k) to a lower value, like around 2.7k. You get a lot more range out of the distortion and in fact, can go from overdrive to distortion in one pedal much better than the OS-2.
Well, after several attempts on the breadboard I've gotten it to do exactly 0-to-pass-through levels on the volume pot. Drive does nothing…
Welp, time to Humpty Dumpty this thing again
Edit: this is the quad version. I'm using the Parhelion schematic for the breadboard
Justin's schematic is far from accurate, no idea what that is.
You can still get NJM4136 from Mouser btw.
Managed to get the OG working. Can't say I prefer it to the rev B, but opinions, preferences and all that.
Found some wonderful clipping combinations. Going to continue tinkering and seeing what I like.
Quote from: lars on June 10, 2023, 08:38:55 PM
I used that second Boss official schematic to mod a couple SD-1's to OD-1 specs. It's pretty easy to do (with the through-hole versions), and I do feel the OD-1 was a much better-sounding circuit than the SD-1 is. A key to really getting a lot out of the circuit is to mod R6 (4.7k) to a lower value, like around 2.7k. You get a lot more range out of the distortion and in fact, can go from overdrive to distortion in one pedal much better than the OS-2.
Ope, sorry I skipped over this somehow... Thanks for the tip! I'll keep hacking it and see what good vibes I get.
Quote from: WonkoTheSane on June 13, 2023, 11:36:02 PM
You can still get NJM4136 from Mouser btw.
not seeing that one :/
Oops, I meant NJM3403. Sorry about that. :)
Quote from: lars on June 10, 2023, 08:38:55 PM
A key to really getting a lot out of the circuit is to mod R6 (4.7k) to a lower value, like around 2.7k. You get a lot more range out of the distortion and in fact, can go from overdrive to distortion in one pedal much better than the OS-2.
That makes a nice difference! finally tried it out on the board with a switch
these are my favorite clipping combos
--->|--->|-
4148 4148
----|<"----
blue LED (d)
--">|--->|--
red LED (d) | 4001
----|<"-----
red LED (d)
--">|---">|--
red LED (d) blue LED (d)
-----|<"-----
red LED (d)
--|<---|<--
4001 D9D
(d) = diffused LED
Maybe a no brainer, but I found Ge diodes sound like hot farts in this circuit, with the exception of that last combo.
Quote from: jessenator on June 15, 2023, 01:31:56 AM
...I found Ge diodes sound like hot farts in this circuit...
Hmm, you could have a $300-$400 circuit in there then. Now if somebody could make a pedal that makes you sound like the Shaggs...
Quote from: lars on June 22, 2023, 02:16:32 AM
Hmm, you could have a $300-$400 circuit in there then.
ha!
I actually started looking at other circuits with this topology and I really like the Clark Gainster—almost more than the OD-1. Maybe it's (HTF do you say 'hallucination' but in regard to sound?), but the Gainster's gain/drive control doesn't boost output levels as much as the OD-1 does, and makes for a nicer, not perfect, but slightly transparent drive. The presence control is nice as well. Made alterations based on my last breadboard build of it. Here's the (un)Original Gainster OG-1
(https://i.imgur.com/Y0ps6Tj.png)
hopefully no errors, but that's what I'd get for drawing this late…
.