Germanium OCD

[jeffwhitfield]

The only caveat here would be this: Many of us don’t compare them to the originals.

It’s fine to say your Klone blows away a real Klon if you have AB’d them. Hell, it’s fine to say you THINK your Klone blows away a real Klon even if you haven’t. As long as we are all on the same page about the subjective nature of tone, we can say whatever we want about DIY vs. the real thing.

Now, I’m not a mojo guy so I wouldn’t want to be misconstrued as being such, but there have been times when I’ve kept the commercial version of a pedal because, try as I may, that cheaper version I built didn’t sound the same.

You are right in the theoretical sense though: There’s nothing magical about circuit building and oftentimes there is only a thin layer of bullshit between that $200 pedal and the one you make in your basement for $40.

True, true. I think the only way to really know how one DIY pedal stacks up against an original is to use a spectrometer and measure the frequency response and such. Even then, there are elements that can't really be measured.

And you're right about the "thin layer of bullshit". That's definitely the case with lower priced pedals. But with something like a Klon or a KoT, that thin layer quickly turns into a thicker one in no time flat. The thing I argue is that with most guitar sounds you don't necessarily hear them much by themselves. They're usually mixed in with other things. At that point, can you really discern a real Klon from a well designed Klone? Or a real KoT from a good copy? I tend to think not.

The differences are largely subjective. I think we tend to hear things that aren't really there. Or, at the very least, get peace of mind knowing that we have an original as opposed to a copy...which in our mind is somehow inferior to the original. One is not really better than the other. It's all in the (err) "ear of the beholder".

 

[Lewage]

Then the "earliest OCDs" had the one germanium diode in series with one of the 2n7000s, so it's probably safe to assume the Germanium OCD did this twice.

You could do this with an ADHD board, solder a germanium diode to the two tied-together legs of the 2n7000 and put that into the right pads of Q2 and Q3.

I am building 2 of these and figure its worth messing around with tho see if it really makes a difference. Are you saying that connecting the ge diode from leg 1 to 3 of the 2n7000 will accomplish this?

 

[SillyOctpuss]

There's a thread and some schematics on the germanium OCD at freestompboxes. I'm out at the minute but will have a look for the thread when I get home later

 

[Chuck D. Bones]

I would imagine that it’s using the Ge diode to block the body diode of the clipping MOSFET. Some iterations of the OCD don’t include a blocking diode and have the clipping arranged such that the body diode conducts before the gate junction of the MOSFET.

Some of the OCD schematics I've seen have a Ge diode in series with one of the MOSFETs, other schematics have no series diode. When there is a series diode, it's pointing the same direction as the body diode, therefore it's not blocking anything. I posted some MOSFET diode curves here.

 

[Barry]

I think I have one of these laying around, I'll open it up and snap a photo if anyone is interested

 

[Robert]

Definitely would be interested.

 

[Barry]

Definitely would be interested.

Ok, I'll dig it out

 

[Feral Feline]

I am building 2 of these and figure its worth messing around with tho see if it really makes a difference. Are you saying that connecting the ge diode from leg 1 to 3 of the 2n7000 will accomplish this?

You may be already aware of the following, but for the aid of those unfamiliar...

Some background info:

Mosfet Body Diodes - AMZ-FX Guitar Effects Blog

Mosfets are 4-terminal devices with a gate that controls the conduction of the drain to source channel. The body (or substrate) of the typical n-channel enhancement mosfet is a P-type material with the drain and source formed from N-type materials. The oxide layer insulates the metal gate...

www.muzique.com

Applying the knowledge:

AMZ - Guitar Effects & diode clipping

How to use mosfet transistors and zener diodes for clipping in guitar fx pedals.

www.muzique.com

Diagram from the latter AMZ site above.

 

[Barry]

OCD GE

 

[Barry]

 

[Barry]

Robert, I can send it down if you want

 

[Chuck D. Bones]

Those Ge diodes have a single green band, yes? That would make them Д9Ж (D9J). They're hard-wired to the MOSFETs (Q2 & Q3). The diodes, MOSFETs and wires are glued down as a strain relief. 'Cuz clear goop would just be silly.

Sure are a lotta extra parts on that board compared to an OCD or Alpha Drive.

 

[Robert]

Sure are a lotta extra parts on that board compared to an OCD or Alpha Drive.

That's the newest version of the OCD with "Enhanced Bypass".

https://docs.pedalpcb.com/project/archived/ADHD.v2.pdf

 

[Robert]

Robert, I can send it down if you want

Do you see a cut trace anywhere around where those germanium diodes connect to the SMD transistors?

EDIT: Nevermind, I think I see it in your second pic, right above C4.

Looks like he just added a germanium diode in series with each MOSFET clipper.

Then the "earliest OCDs" had the one germanium diode in series with one of the 2n7000s, so it's probably safe to assume the Germanium OCD did this twice.

I believe you are correct. Although I didn't realize this was built on the V2, I thought the Ge version was older than that.

 

[Chuck D. Bones]

I wonder if there is a market for carbon comp resistors in SMD packages?

 

[benny_profane]

This board looks so hacky.

 

[Robert]

This board looks so hacky.

They haven't always been so bad...

Oh wait... yes, yes they have. But to be fair.... this one doesn't oscillate.

 

[K Pedals]

Those Ge diodes have a single green band, yes? That would make them Д9Ж (D9J). They're hard-wired to the MOSFETs (Q2 & Q3). The diodes, MOSFETs and wires are glued down as a strain relief. 'Cuz clear goop would just be silly.

Sure are a lotta extra parts on that board compared to an OCD or Alpha Drive.

There are some German and Japanese 1N314’s that have a sing green band as well… these look more like one of those to me.?.?

 

[SillyOctpuss]

They look a lot like the green band unizen 1n34a. I have some I can take a picture of later if it would help?

@Barry is this the limited edition candy Red germanium OCD from around 2 or 3 years ago?

I thought the germanium ocds only used one germanium diode with one of the mosfets but your pedal has one for each. Maybe that's the difference between the customer shop red one and the older units? The newer one is a V2 with a germanium diode on each mosfet

 

[Barry]

They look a lot like the green band unizen 1n34a. I have some I can take a picture of later if it would help?

@Barry is this the limited edition candy Red germanium OCD from around 2 or 3 years ago?

I thought the germanium ocds only used one germanium diode with one of the mosfets but your pedal has one for each. Maybe that's the difference between the customer shop red one and the older units? The newer one is a V2 with a germanium diode on each mosfet

Mine is green