ADHD v2 (Fulltone OCD Ge)

[Locrian99]

Oh I forgot to mention, I didn't have a TL082 and wasn't going to place an order for a single IC. So I subbed a TL072.
I've a read some people say that the 082 are just 072 rejects that didn't meet wafer spec's or something or other.
But they're essentially the same IC with slightly different slew rates and s to n specs.

But the plan is to try some different OpAmp's later today and see if it makes any difference.
Planning to try a 4580D, LM833, hmmm, maybe a 1458 and just for giggles, a 4558.
(Oh and tack solder in those Ge diodes, they're kinda loosey goosey in the sockets but these are staying.

I'll update this post if there's any appreciable difference.

One of my first pedal builds was an ocd from coda effects, I assumed the 82 was commonly used for some reason I ordered 25 of them. I still have 24, I’d be happy to send you one if you would like to try one in there.

 

[MichaelW]

Thanks for the offer dude!! But I just ordered some for the one I'm building for my buddy.... .

You could try the 082's in some other dirt boxes and see if it makes any difference.

 

[Locrian99]

Thanks for the offer dude!! But I just ordered some for the one I'm building for my buddy.... .

You could try the 082's in some other dirt boxes and see if it makes any difference.

I should probably do that I just pretty much throw a 4558 or 72 in everything no matter what it calls for for dirt pedals anymore lol.

 

[ChrsGuit]

Good save on the switch. I like the OCD it was my first DIY pedal and sometimes consider revisiting it, but I have always been confused by the term “chewy” in the description of a dirt pedal… I still have no idea what that correlates to.

I think "chewy" best refers to that really percussive midrange that has a bit of "serration" to it... have you ever drug a rasp across a piece of wood, or a potato across a vegetable/cheese grater??? That's kinda how I'd describe "chewy"... Best audio demonstration would be Mike Lemmo's (Norms rate guitars) "guitar of the day" videos when he cranks his overdrive sound... it's almost like the audio equivalent of slowly ripping a piece of paper... if that makes sense... It's not clean, not dirty, but you can hear clarity in the sound, but the middle has "teeth" to it

 

[ChrsGuit]

So i had planned the day around building a somewhat complex modulation pedal having just built 3 overdrives.

By the time I finally got to my bench it was after lunch and as is my usual practice I start with drilling the enclosure then pick the components. Well, wouldn’t you know it I was missing an On On On toggle , bahhhhh…

I decided to start populating it anyway and then noticed the board is actually spaced for 1/8 watt resistors, this is AFTER i had pulled all the values I needed in 1/4 watt. Double bahhhhh……I checked the clearance and space and decided to go with the 1/4’s since i already had them all pulled and just soldered them standing up. I managed to get all the resistors done then decided to bail since my toggle isn’t going to get here until Monday.

So back to the drawing board, since it was getting late afternoon and I still needed to take Bonnie the wonder dog for her shnork and sniff walk around the neighborhood and visit all her little doggie buds I figured I’d better go with something I could finish this evening. I don’t think my psyche can survive TWO unfinished projects…

Thus, i wound up building @Robert ‘s latest ADHD revision. So humming away happily I drilled the enclosure. No drll template……and when I went to dry fit everything before populating the board I realized I drilled the toggle on the wrong side…..Triple bahhhhhh…..

I wasn’t going to waste a nice Tayda enclosure so I rigged up the toggle off board and came up with a makeshift insulator by cutting up a pot condom and using hot glue. It makes the board fit a little wonky but it worked!

I’ve owned a couple of OCD’s over the years but for some reason they never stuck around. Even though I liked the way they sound. One version I never owned was the Ge version, so I decided to build that.

I have to say I’m pretty stunned at how good this thing sounds. Much better than the retail OCD’s I’ve owned.
It could be that I used some NOS Mullard CV7364 diodes with a very low Vf (.258 & .263).

The classic chewy distortion is all there but there’s a bit of extra creaminess and saturation from the Ge diodes that’s very cool. I’ve heard a lot of people say that the retail Ge version was all hype and didn’t sound any different. I dunno, I never played one. But I’m totally digging my Ge ADHD. And it’s following the same them of the last few Mad Professor drives I’ve built in that it’s a really “chewy” kind of gain. But like the stock OCD you can turn the gain all the way down and use it as a clean boost to push your amp. I’m still not sure I’d shell out the $$ for a retail OCD as it’s not a sound I would use a lot but I’m very glad to add the ADHD to my arsenal over drive sounds.

I used the Tayda gray sand enclosure with a water clear 5mm led. It’s hard for me to see the led in this spot when sitting down so the extra brightness (blinding brightness actually) of the water clear helps.

View attachment 40690

I was also missing the correct slider for the buffered bypass selector so I hardwired it with the buffer always on.….cuz…I dig buffers

View attachment 40691

Fixing my little drilling boo-boo

View attachment 40692

View attachment 40693

Just curious as to the benefits of the buffer opposed to just wiring it true bypass.
I'm currently building one of these and just saw the option to use the buffered bypass. I wire all my pedals true bypass and this is the first build I've ever encountered a buffer option

 

[MichaelW]

Just curious as to the benefits of the buffer opposed to just wiring it true bypass.
I'm currently building one of these and just saw the option to use the buffered bypass. I wire all my pedals true bypass and this is the first build I've ever encountered a buffer option

That's a whole can of worms subject heh.....

 

[ChrsGuit]

That's a whole can of worms subject heh.....

I just finished building my OCD. It sounds good, but compared to a real one, it's very weak in drive and doesn't have the (pardon the term) "girth" of the OCD v1.7 I have for comparison... It sounds more like a Bluesbreaker, as if the clipping and the overall body is missing from the sound.
my first instinct was an incorrect capacitor value but those all seem to be correct. I had to use a 50v electrolytic in C7 as im low on 25v caps right now, but that shouldn't cause an issue should it? Here's a photo of my build...

 

[MichaelW]

I just finished building my OCD. It sounds good, but compared to a real one, it's very weak in drive and doesn't have the (pardon the term) "girth" of the OCD v1.7 I have for comparison... It sounds more like a Bluesbreaker, as if the clipping and the overall body is missing from the sound.
my first instinct was an incorrect capacitor value but those all seem to be correct. I had to use a 50v electrolytic in C7 as im low on 25v caps right now, but that shouldn't cause an issue should it? Here's a photo of my build...

Not sure, I've built two of them with the revised board with the same Ge diodes. (Mullard). One with buffered bypass for myself and one with true bypass for my buddy. They both have a lot of volume and gain.

Which diodes did you use? Did you measure them?

 

[ChrsGuit]

Not sure, I've built two of them with the revised board with the same Ge diodes. (Mullard). One with buffered bypass for myself and one with true bypass for my buddy. They both have a lot of volume and gain.

Which diodes did you use? Did you measure them?

1n34a's.
UF= 773mv
C= 7pf

 

[MichaelW]

1n34a's.
UF= 773mv
C= 7pf

Hmmm, I didn't do a demo for this one that I can think of. I'll try to throw something up here to compare. It's been a while since I owned a real OCD but the only different is that the one I built used Ge diodes. I didn't have the Ge version of the OCD. But I don't recall it being weak or "un-girthy" compared the retail pedal.

 

[ChrsGuit]

Not sure, I've built two of them with the revised board with the same Ge diodes. (Mullard). One with buffered bypass for myself and one with true bypass for my buddy. They both have a lot of volume and gain.

Which diodes did you use? Did you measure them?

Here's a little better photo of the board. I thought I had found a bridge

Hmmm, I didn't do a demo for this one that I can think of. I'll try to throw something up here to compare. It's been a while since I owned a real OCD but the only different is that the one I built used Ge diodes. I didn't have the Ge version of the OCD. But I don't recall it being weak or "un-girthy" compared the retail pedal.

Here's a little better gut shot. I THOUGHT I found the issue, a solder bridge between two sockets on one of the mosfets, but it was a little glob of Flux paste... My understanding is in this circuit that any issue between the mosfets and the diodes will still allow the pedal to function and have op amp distortion, but no hard clipping. This is my first time using sockets on my mosfets and I honestly prefer just to solder them... that was the first place I looked. I suppose I'll get the multimeter out and check some voltages there to make sure all is well

 

[jimilee]

In my experience, you have to push 1n34a diodes a little bit harder for volume. I’m not a fan, myself.

 

[ChrsGuit]

In my experience, you have to push 1n34a diodes a little bit harder for volume. I’m not a fan, myself.

I'm building it for a friend of mine who loves his version 1.7 ocd. I told him I'd take a shot at my own and I have his for comparison... To me the one I built just doesn't sound nearly as close as I'd like it to. Just seems almost Klon-like, in that the distortion is buried below a cleaner signal... whereas the OCD is very saturated and "up front" with the drive

 

[ChrsGuit]

In my experience, you have to push 1n34a diodes a little bit harder for volume. I’m not a fan, myself.

and to be honest, I want it to sound BETTER. I made a "Boteh" (paisley drive) and it absolutely smokes the real deal side to side in comparison...

 

[MichaelW]

I'm building it for a friend of mine who loves his version 1.7 ocd. I told him I'd take a shot at my own and I have his for comparison... To me the one I built just doesn't sound nearly as close as I'd like it to. Just seems almost Klon-like, in that the distortion is buried below a cleaner signal... whereas the OCD is very saturated and "up front" with the drive

There's something wrong. The OCD a pretty saturated and compressed sounding drive. Especially with Ge's. Did you try checking your pots? Maybe a bad one?

 

[ChrsGuit]

There's something wrong. The OCD a pretty saturated and compressed sounding drive. Especially with Ge's. Did you try checking your pots? Maybe a bad one?

You know, I have gotten a couple bad ones lately. all seem to be functioning. I noticed something curious... and if this is a "duh, it's supposed to be that way" I apologize... I'm getting voltage on every jfet pin... (more or less 4.2-4.5 volts)... I can pull the jfets out of socket and the sound changes very little...

 

[ChrsGuit]

There's something wrong. The OCD a pretty saturated and compressed sounding drive. Especially with Ge's. Did you try checking your pots? Maybe a bad one?

Ok I think you guessed right. I tested the gain pot with a meter on the left leg to center I'm getting the proper ramp-up from zero to 500k... on the right leg to center, the meter reads for a split second and then nothing... turning the pot up or down produces nothing on the meter... I compared it to the adjacent volume pot, which ramps up and down on both legs...
Would I be safe to assume this is the issue... and would make sense why I'm not getting a big difference in gain unless fully cranked (zero resistance)?

There's something wrong. The OCD a pretty saturated and compressed sounding drive. Especially with Ge's. Did you try checking your pots? Maybe a bad one?

 

[MichaelW]

@ChrsGuit

Did you lift any of the legs off the board?

In either case, I made a demo for you of how mine sounds. The PPCB ADHD and the MPB EgoDeath. Both are germanium clippers.

Also an update to my Filtertron Tele. I installed a Bigsby B5. Fixing to update my build thread next.

 

[ChrsGuit]

@ChrsGuit

Did you lift any of the legs off the board?

In either case, I made a demo for you of how mine sounds. The PPCB ADHD and the MPB EgoDeath. Both are germanium clippers.

Also an update to my Filtertron Tele. I installed a Bigsby B5. Fixing to update my build thread next.

No, none that I have seen. I've lifted one in the past replacing components and thought I was screwed... soldered the part back and it was fine. I'm getting no reading on the right leg of the pot *facing the knob*

I recently had a couple faulty pots from a single order, so I'm wondering if this is the same deal. I'm going to replace it and see where that gets me. All my values are correct, there are no solder bridges, everything has been reflowed multiple times... so I'm kinda stumped...

 

[MichaelW]

Ok I think you guessed right. I tested the gain pot with a meter on the left leg to center I'm getting the proper ramp-up from zero to 500k... on the right leg to center, the meter reads for a split second and then nothing... turning the pot up or down produces nothing on the meter... I compared it to the adjacent volume pot, which ramps up and down on both legs...
Would I be safe to assume this is the issue... and would make sense why I'm not getting a big difference in gain unless fully cranked (zero resistance)?

Oh ya, there's something wrong with that pot the way you're describing the behavior. A bad gain pot would also explain why it sounds like mostly clean signal. If you checked the demo I did above you can hear that the OCD is a very compressed overdrive and far from "transparent". It's pretty "thick" from the git go.