Diode subs help

[stevie1556]

Just wondering if anyone can help me out. As a few of my recent threads have shown, I've recently got into SMD circuits, but part sourcing can be a massive problem. I've been studying data sheets recently to find part numbers in SMD, but apart from that, I'm not 100% sure on what to look for on them.

However, I've stumbled upon a problem that I'm hoping someone can help with. I'm trying to do a layout for a circuit and it uses a 1N34a diode. As far as I can tell, they don't come in SMD form, but is there another diode, which is preferably silicon, that I can sub it with? The reason why I want to sub it for a silicon diode, is because they generally also come in SMD.

[RobA]

It depends on what circuit you are going to be using them in to determine which diode is going to work best. But to match the forward voltage drop, you can use a Schottky, something like the BAT41 or BAT46 which are available in MiniMELF packages. But, if you are wanting to use them for clipping, they aren't going to sound the same as a Ge diode.

[pickdropper]

Yep, Rob hit it on the head.  Bat 41s have the closest Fv to the 1n34a, but there will be slight differences.  BAT46 are a bit closer to 1n270s.  Both sound good in their own right.

There are no rules against a hybrid layout.  You can still use Ge clippers if that's what you want in there.

[stevie1556]

Many thanks for the replies!

It's for a OCD layout. Always wanted to try out the pedal and see what all the fuss is about, and thought now would be a good time as I'm currently converting my whole pedal board into SMD.

For the placement of the diode, I'm not 100% sure it's part of the clipping section, although I'm sure it is. I'm going to make a start on the layout tonight, I'll see how it's going before I make a final decision on the diode. Ideally, I want it to sound as close to the proper one as possible.

[blackedition]

i've had a similar question, but more general.  i don't even know how one knows which diodes are suitable substitutes for each other?  for example, i don't know why certain diodes are drop-in replacement/alternatives in the mudbunny manual...  don't want to derail the thread, just saying, i feel your diode pain   hope you get an answer!

[RobA]

If you really want to know what the OCD sounds like, then you could just use the through hole 1n34a for that part and do the rest SMD. That's a perfectly fine solution and the BAT41 is going to sound a bit different. Well, at least it does to my ears. I've tried both the BAT41 and the 1n34a in that position. In a somewhat useless description, I thought the BAT41 was a bit buzzy compared to the 1n34a. That said, the clipping on those is dominated by the body diodes of the 2n7000's and D1 just gives it a bit of asymmetric clipping. The BAT41 would be close.

[RobA]

i've had a similar question, but more general.  i don't even know how one knows which diodes are suitable substitutes for each other?  for example, i don't know why certain diodes are drop-in replacement/alternatives in the mudbunny manual...  don't want to derail the thread, just saying, i feel your diode pain   hope you get an answer!

That's a big question in a general setting. It really does depend on what the diode is doing. For the Mudbunny in particular, that's half the fun of that circuit, anything goes as far as the clipping diodes are concerned. Almost anything will sound good and everything sounds different.