Stuff you wanted to know but were afraid to ask

[giovanni]

I still don't quite understand phrases "it loads the pickups down" or "(thing) loads (previous thing in chain)". What does that mean, exactly?

That’s pretty technical. Loading refers to how much current the next stage absorbs. Or to be more precise, how low the input impedance is. For guitar pickups you usually want the first stage to absorb as little current as possible otherwise the sound gets dark. Intuitively you can imagine that a passive pickup cannot provide a lot of current to the next stage because it is, well, passive. The technical explanation is more complicated and has to do with impedance mismatch and the frequency domain but I find that the intuitive one is pretty decent.

 

[HamishR]

Indie rock was what happened when you couldn't stand Def Lepers or Bon Jovi and wanted to listen to the Pixies instead. It was kinda like punk again except with weirder music. But of course the label is, indeed, meaningless these days. "Indie" comes from independent, as in "not on a major label". Again, meaningless these days. Just as "punk" no longer has any meaning. What passes for punk these days is nothing like the original. It has become its own corporate genre and I'm not sure how modern punk is any different from modern anything else!

Indie is the term people use these days when they used to say alternative. But the genre thing is pretty meaningless. It's a kind of lazy shortcut to indicate which kind of noise we like. It's not great but what else do we have?

 

[mhshizz]

That’s pretty technical. Loading refers to how much current the next stage absorbs. Or to be more precise, how low the input impedance is. For guitar pickups you usually want the first stage to absorb as little current as possible otherwise the sound gets dark. Intuitively you can imagine that a passive pickup cannot provide a lot of current to the next stage because it is, well, passive. The technical explanation is more complicated and has to do with impedance mismatch and the frequency domain but I find that the intuitive one is pretty decent.

So when something is "loaded down" it's not being allowed to pass along as much current as it otherwise could?

 

[giovanni]

So when something is "loaded down" it's not being allowed to pass along as much current as it otherwise could?

I think it means we are trying to absorb too much current from it, affecting high frequencies (the energy we are trying to absorb is not there and comes off the high frequencies first).

 

[benny_profane]

So when something is "loaded down" it's not being allowed to pass along as much current as it otherwise could?

What's all this Impedance Stuff About?

I'll keep the math to a bare minimum, but you can't describe impedance without a little math. When I was in college, the professor in an introductory course on circuit theory shared this anecdote: "As part of their oral exam, PhD electrical engineering students were asked to define the term...

forum.pedalpcb.com

 

[spi]

I found this post helpful in understanding buffering and loading:
Buffers, impedance and other internet lore – Mr. Black (mrblackpedals.com)

 

[Harry Klippton]

What is a zendrive?

 

[mhshizz]

I think it means we are trying to absorb too much current from it, affecting high frequencies (the energy we are trying to absorb is not there and comes off the high frequencies first).

What's all this Impedance Stuff About?

I'll keep the math to a bare minimum, but you can't describe impedance without a little math. When I was in college, the professor in an introductory course on circuit theory shared this anecdote: "As part of their oral exam, PhD electrical engineering students were asked to define the term...

forum.pedalpcb.com

I found this post helpful in understanding buffering and loading:
Buffers, impedance and other internet lore – Mr. Black (mrblackpedals.com)

I truly appreciate all your efforts. Chuck's post seems to be above my head technically, while Mr Black's article features a painfully juvenile writing style and analogies I can't quite parse.

It seems this is a "me" problem, so I'll just go back to telling myself to not worry about and trust that people I respect behind the projects I like know what they're doing.

 

[swyse]

I was just thinking about something I always wondered but never was able to find out and remembered this thread. I wanted to use a CA3130EZ in a rat style circuit, do I need to protect the input like one does with a standalone mosfet? Do I just use the standard Zener to ground at the input? Also wondered If I have a mosfet after different amplifier in the middle of a circuit, do I need the Zener there too?

 

[andare]

I truly appreciate all your efforts. Chuck's post seems to be above my technically, while Mr Black's article features a painfully juvenile writing style and analogies I can't quite parse.

It seems this is a "me" problem, so I'll just go back to telling myself to not worry about and trust that people I respect behind the projects I like know what they're doing.

I'm with you, stuck between technical jargon above my pay grade and confusing metaphors.

A Fuzz Face cleans up because it has low impedance and therefore it loads the pickups?
Whereas a Tone Bender Mk2 has a buffer, i.e. the 1st transistor stage, so it doesn't clean up?

Or maybe I should just keep building by numbers and play my guitars...

 

[giovanni]

I think any gain pedal “cleans up” if you turn the volume down, in the sense that the sound gets cleaner because the overall gain is being reduced. The thing with the fuzz face is that when you do that, you are dramatically changing the relation between your pickup’s output impedance and the pedal’s input impedance, which ends up really affecting the sound in ways that people love. It’s a bit of a happy accident: the impedance mismatch is notoriously a “bug” not a feature (it goes against any EE 101 design practice) but it seems to work well in this case. Buffered pedals (or really any pedal with a high input impedance) don’t do that because even if you roll the guitar volume down, the pedal will not “load” the pickup; the pedal’s input impedance is still high enough to handle the changing impedance due to the volume roll off on the guitar side.
It’s hard to understand this stuff without knowing the math because I don’t think there are really good equivalents in the mechanical world or in any other every day experience that could help with understanding. I could come up with some metaphors but they will most likely all fall short.

 

[spi]

I could come up with some metaphors but they will most likely all fall short.

High impedance input: peeing into a toilet, you're going to make the water yellow.
Low impedance input: peeing off a cliff, you're not going to make the water yellow.
Yellow is your highs.

That metaphor sounded better before I wrote it down.

 

[benny_profane]

@spi make sure you’re drinking enough water.

 

[andare]

High impedance input: peeing into a toilet, you're going to make the water yellow.
Low impedance input: peeing off a cliff, you're not going to make the water yellow.
Yellow is your highs.

That metaphor sounded better before I wrote it down.

No I get it now. The ocean is low impedance so you need a lot of pee to make it yellow.
The ocean loads your peen much more than a toilet. Eventually you fall off the cliff and you shatter on the shore. Then the garbage collectors pick up your pieces aka "cleanup."

 

[giovanni]

I often think about it in terms of water pressure. If your pipe gets wider, you will lose pressure. That’s what a pedal with low input impedance does: it’s a wider pipe than what you have before and thus your guitar signal loses high end (pressure in this analogy). On the other hand, a pedal with high input impedance is analog to a very narrow pipe so even if the one before is already pretty narrow, you won’t lose pressure. If we want to make the metaphor a bit more accurate, when it comes to electrical signal we have different pipes for different frequencies, and high end pipes are affected more than low end ones… am I making any sense?

 

[Pauleo1214]

Why are some transistors in TO-92 format and TO-18? Are all TO-92's silicon? Are some TO-18s silicon?

 

[mhshizz]

Am I crazy or was there a Product Requests subforum that has recently disappeared? Reading through the thread containing sort of an origin story of what became the Hen's Tooth was fascinating. Or am I gaslighting or Mandela effecting myself?

 

[Bricksnbeatles]

Am I crazy or was there a Product Requests subforum that has recently disappeared? Reading through the thread containing sort of an origin story of what became the Hen's Tooth was fascinating. Or am I gaslighting or Mandela effecting myself?

https://forum.pedalpcb.com/forums/wishlist/

 

[mhshizz]

https://forum.pedalpcb.com/forums/wishlist/

Thanks. Not sure why it wasn't showing up in my list of forums before but it is now. #embarassing

 

[Feral Feline]

I had one (a question) but forgot it, so here's another one I came up with...

Most PullDownResistors are 1M or 2M2, but I've got a shipload of 6M2 — is this too high of a PDR value, how will it affect the rest of the circuit?

I read somewhere once that a PDR could be anywhere from 1M to 10M, but I can't find that reference again and whoever said it may have been full of bunk.

Sorry, I've been too lazy to do the math on input impedance etc...

Can I use my 6M2 stash for PDRs?