First build component sourcing

J

JimmyS2

New member
Hi all!

Ive picked up a few boards to try building some pedals, only ever did a BYOC kit like 15 years ago. I think back then I tried a second pedal, it didn't work, and i decided not to worry about it anymore.

Anyway, last night I was going through the build docs and trying to put together an order from Tayda, I've done some research on component selection that helped a bit.

My question so far, is about selecting op amps. I'm building the Increment, a Barber Plus od, and it specifies "JRC072DB" which seems to be hard to find. Since I'm new, I don't know if there are obvious substitutions, or if any dual op amp will behave about the same. If I need to track the exact part down I will, ebay maybe?

If anyone has either some insight about what I can/should use, or where I might find it, that would be greatly appreciated!
 
It's just a TL072 made by Nishimbo/japan radio corp instead of TI. Mojo where it doesn't really need to be.

You could really use any dual op amp. The TL072 is cleaner, among other specs, over a 4558 or something like that, but almost aby dual will do
 
Here's one more question while im working my way through it.

The increment overdrive specifies a couple of "2D503B" diodes, which i couldn't find on tayda, and the BOM includes a link for them to PPCBs listing. This is handy, but again with a strangely hard to find component I wonder if it's actually necessary to have the exact thing, or if there are functionaly equivalent substitutions and I just don't know what I'm talking about yet.

If I'd gotten everything figured out ahead of time I could have just thrown those in with my order, i guess at least I've learned THAT so far.
 
There appears to be a little unicorn magic with those diodes and it's particular curve..... That being said you could also use some silicon diodes that are readily available as well with .68-.79 FV and be in the same territory of clipping...
 
Wow. I appreciate that, although I don't really know what I'm looking at yet. This is exactly the type of information I enjoy in other hobbies once I'm well down the rabbit hole. Hopefully I can get the first few builds working well and see how i feel, I do love a good graph/chart once I feel like I can get my head around it.

Thanks for the responses guys, very welcoming and helpful to a complete newcomer, I appreciate it.
 
To me it looks like the KD503A would be very close to the 2D503B, based on the graph. It's easier to see them if you click to disable a lot of the ones further away (so the beginning and end of the list). KD503A seems to be available in Europe at least, from a bulgarian webstore and a 100pcs lot from Ebay.

As for how big the difference would be if you just used 1N4148's instead... probably not very big. It's asymmetric so preferably you would switch them with something else if you want to keep the asymmetry, but to be honest in a lot of situations the clipping diodes don't make a huge difference in sound. There is some difference between big jumps (eg. something that clips a lot and something that clips a little), but as long as you're sort of in the ballpark it's quite hard to hear the differences, usually, in my experience.
 
To put this (exact component selection) in historical perspective, especially early on, some companies were very loose with selection. If they could get a good price on a part that was a bit off spec, then that run used that part. This is one reason why certain era pedals are more desired. Electro Harmonix was infamous for this.
 
Thats a good point, I'm sure for things that where in production a long time part availability for components probably shifted over time leaving the legends and lore of certain specific vintage things being superior for mysterious reasons.

While I'm sure substituting components is probably often totally fine and not even unlike the original, I guess I'm still just intending to learn. That way I only pull a quick part sub when I know it's ok, and I know the reason it's ok.
 
JimmyS2 said:
Wow. I appreciate that, although I don't really know what I'm looking at yet.
Click to expand...
Using that graph is easy. Scroll thru the list of diodes on the right side until you find the one you need, in this case the 2D503B. Then click it off and on again so you can find its curve on the graph, which will also turn off and on. Then find another diode with a similar curve in the same spot, or the closest one. Hover the cursor over the curve and it will pop up with a color coded detail, making it easy to identify them. If you click its curve it will turn off the diode in the list, and you can scroll thru until you see its name, which will be grayed out. Google search that one and see if it's available for sale somewhere. Repeat this until you find a diode that is similar and still available. Thomas is super, super cool for putting that together.

The curves represent how the diodes behave as they see voltage, but it's not important to understand that for this
 
jessenator said:
It's just a TL072 made by Nishimbo/japan radio corp instead of TI. Mojo where it doesn't really need to be.

You could really use any dual op amp. The TL072 is cleaner, among other specs, over a 4558 or something like that, but almost aby dual will do
Click to expand...
This is something i really wish i understood when i first started. I bought so many different op amps and transistors when i didn’t need to. And spent a chunk in shipping because of it.
 
Locrian99 said:
This is something i really wish i understood when i first started. I bought so many different op amps and transistors when i didn’t need to. And spent a chunk in shipping because of it.
Click to expand...
Hey, just sell a build with the mojo and mark it up 🤪 there's a market. Some poor 🤡 will eat it up.
 
jessenator said:
Hey, just sell a build with the mojo and mark it up 🤪 there's a market. Some poor 🤡 will eat it up.
Click to expand...
Ive got a boutique tube screamer build right now to repair with all mojo parts. Annoying part is ill have to replace any thing bad with “mojo” parts. Though my current bet is a solder joint, havent opened it up yet.
 
JimmyS2...

From what I've read, if you get the correct forward voltage for clipping it will sound as it should, regardless of diode type.


I like this vid:


For dirt-circuits op-amp choice is more open to swapping out compatible stuff (JRC4558/TL072/NE5532/etc...), but for a compressor or EQ circuit you may want to stick to low-noise op-amps.


Some circuits it does make a difference... I don't hear enough of a difference between a LM308 and a OP07 to worry about which is subjectively-better (especially in a band-mix), but I do know a lot of people hear distinct differences in a Rat with CA3130EZ, CA3140, LM301, and TL071 etc.



It's like cooking. You always (well almost always) want to use the best ingredients possible.

Why go to the effort of hand-making noodles if your pasta sauce is based on tinned tomato-paste and tinned-stewed-tomatoes?
NO! Since you hand-made the noodles from scratch, you're going to pick some tomatoes off the vine in your garden *(or source fresh vine-ripened tomatoes at the farmers'-market) and use fresh herbs, not dried flakes out of a jar... only fresh ingredients and simmered on low heat, not zapped in a microwave-oven...


Pick PCBs that are well laid out (no issues with power/signal cross-talk etc), and use trusted brands of components (needn't be expensive-mojo, just trusted known-good stuff)...

NOTA BENE! Use good jacks and switches. I bought second-rate power-jacks and had to replace them — a total PITA pulling the builds out of enclosures, de-soldering and re-soldering and reinstalling...

I also bought some audio-jacks that weren't second-rate, not third-rate nor fourth-rate... well, they weren't really jacks at all — just some malleable-metalbutter jack-shaped objects that didn't hold their shape.
 
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