Leveling up on schematic reading

[SweetDan]

I'm not spending huge amounts of time on the DIY effect pedal stuff, but of the time I've spent with soldering iron in hand, I've probably spent 5x the time reading up on electronics theory.

I've known maybe since high school what the basic components (resistors, capacitors, etc.) were, what they did to an electrical current in isolation, and what their symbols were, so in that sense I could "read" a schematic. But until recently, I didn't understand how specific arrangements of components worked together to produce a certain sound effect.

I'm getting better, though. I've attempted to work my way through some electronics-theory reading material...that sucks! But when I find an explanatory article (like this one: https://www.coda-effects.com/2016/02/de ... everb.html), and then refer back to the theoretical stuff, it all starts to gel a bit more in my mind.

Anyway, nothing truly useful in this post, but that article I just linked is nice. (It does have a typo, I think...the author talks about transforming a "low impedance signal from the guitar into a low impedance signal..." I think he meant "high impedance" to low impedance. Also, better schematic here: https://www.dropbox.com/s/qsx1fy4ipr8ma ... c.pdf?dl=0)

[SweetDan]

The next reading list: http://aikenamps.com/index.php/white-papers

[JD01]

Let us know what you learn, Dan. I also vaguely understand the diagrams but it's what they mean with regard to sound is what baffles me

[vomitHatSteve]

I like the idea of reading this kind of stuff, but honestly, I would never get around to it if it's not in a physical book.

[Greg_L]

The next reading list: http://aikenamps.com/index.php/white-papers

Stuff like that was very useful when I was building my amp. You'll get a lot out of it.

[JD01]

The next reading list: http://aikenamps.com/index.php/white-papers

Stuff like that was very useful when I was building my amp. You'll get a lot out of it.

This is kind of a question to both of you really but I was thinking of it in the context of Greg's amp.

Are you just following the diagram? Or when you were building the amp would you have been in a position to have thought, "Ah, I want the amp to start to compress and overdrive at lower vol so I need to change the value of this component" or "I need to adjust this as I want slightly brighter cleans". So are you actually designing your circuit for what you want or just copying... not that I'm belittling just copying a diagram - its way more than what I could do! I just imagine its quite a big leap to go from copying a diagram to knowing what influence all the bits have on tone and altering them as you like.

[Greg_L]

This is kind of a question to both of you really but I was thinking of it in the context of Greg's amp.

Are you just following the diagram? Or when you were building the amp would you have been in a position to have thought, "Ah, I want the amp to start to compress and overdrive at lower vol so I need to change the value of this component" or "I need to adjust this as I want slightly brighter cleans". So are you actually designing your circuit for what you want or just copying... not that I'm belittling just copying a diagram - its way more than what I could do! I just imagine its quite a big leap to go from copying a diagram to knowing what influence all the bits have on tone and altering them as you like.

For me, when I was doing my Fender clone amp, it was a little of both. I wanted to stay true to the original 60s schematic because that's why the amp is what it is. But I changed a few things to suit my own needs and wants. I changed the negative feedback so it wouldn't break up so easily, I changed the output transformer so I could use multiple Marshall cabs with it, and I changed the screen resistance to get a little better spread between the plates and screen voltage, little stuff like that to let it still be what it is, but also make it more suitable for what I want to do with it.

For my Marshalls, the only mods I've done are gain mods or tone shaping, and that comes with tweaking component values. Put a cap over a resistor to shelf low end and bump the gain, alter plate resistance, stuff like that tweaks the tone and/or gain without redesigning the whole damn thing.

There's really not that much difference going on inside of two different amps. Fenders, Marshalls, Orange, Mesa, whatever, they all work the same way on the inside. Tube amps all do the same exact thing. How you choose the values of the components and how you arrange them is what really makes a Fender clean and a Mesa filthy. But the electricity still flows the same through both.

[JD01]

Cool... so you do know what changes to little values like that would have on tone then.

[Greg_L]

Cool... so you do know what changes to little values like that would have on tone then.

Yes, in some cases. If I wanted to get more gain from my JCM 800 without adding tubes I know what I could try and where to try it. If I want to roll off more low end or add more low end, I know what needs to get tweaked. But even still, it's trial and error. You can make an educated guess on capacitor or resistor values, but you still have to just try it and see.

[Greg_L]

Also....my amp still works great!!!

[SweetDan]

...Are you just following the diagram? ...are you actually designing your circuit for what you want or just copying... ...I just imagine its quite a big leap to go from copying a diagram to knowing what influence all the bits have on tone and altering them as you like.

It is a leap, but you have to take it in a series of tiny hops. (You may not have to, but I did/am.)

For me, it all started with exactly following diagrams. The rest is all a blur. The first tiny hop might have been to take a single part and understand what that component does in isolation. The next hop could have been to understand how any single other component connected to that first component would change the behavior of the first, how those two would interact, and how those two might affect the overall circuit. Other hops are noticing there are patterns that commonly appear in different types of circuits and effects.

The process for working through each hop has, for me, not been straightforward at all. Some things I've learned by watching videos. Other things I've learned by reading. I know a few electrical engineers, so some things I've learned by asking them questions. Very often, I'll be watching a video or reading a blog post and get into really thick, heavy electronics theory stuff, my eyes gloss over, and I feel at the time I don't get much out of it. But later I might be watching a different video (Uncle Doug's videos are especially good for this) or trying something out on a breadboard, and it clicks, and then I can go back and re-read the theoretical stuff and do much better understanding it.

As I see it, that process could go on for a really long time. I estimate I'd actually be ready to try something like a basic tube amp (think Fender Champ) from a kit (and probably following the schematic exactly) anywhere from a few months to a few years from now. After that I might be up for trying a tube amp that's a bit more complex or in which I try to tweak things. For now, effects pedals are a relatively cheap and safe way of going about this.

...I changed a few things to suit my own needs and wants...

Cool... so you do know what changes to little values like that would have on tone then.

The whole "customization" aspect of this is part of what motivates me too. The trouble is: 1) clearly understanding what I need/want, 2) understanding what in the existing circuit is helping or hindering those needs/wants, and 3) what to do about it -- what values of existing components could be tweaked, or whether or not components can be rearranged, or whether or not to add or remove more components.

As far as knowing what effect the changes have, the theory behind all of it helps me to know what's possible and what the expected outcome is (for example, you can calculate the cutoff frequency of a low-pass filter based off a resistor and capacitor's values). But I've also found that you can't always let the theory dictate exactly what values you should use; you sometimes have to try some stuff out first and judge the sound by ear. Also, the theory might work for the components in isolation, but as part of a larger circuit, there could be additional component interactions that don't neatly fit into the formula describing the smaller part's behavior.

It's kind of like mixing...actually, a whole lot like mixing. For example, maybe you "know" adding a compressor to a track should help achieve the sound you're after, but once you've added the compressor, you have to tweak the knobs (or try a different plugin, or try the compressor before/after some other effect, etc.). And you have to consider the changes in the context of the entire song -- does the compressor add so much weight to X that now you can't hear Y? -- stuff like that.

[WhiskeyJack]

You guys are bunch of wizards.

[SweetDan]

You guys are bunch of wizards.

With soldering irons for wands! lol

[JD01]

That's really interesting, Dan.
It's supposed be science but it sounds more like art...

[rayc]

I've learn a little through following Greg's amp build and from Uncle Doug's calm, clear explanations of stuff.

[SweetDan]

Helpful list of schematic symbols: https://www.rapidtables.com/electric/el ... mbols.html

[Greg_L]

Helpful list of schematic symbols: https://www.rapidtables.com/electric/el ... mbols.html

Good list....but how could they ignore this one?



or this one?

[Greg_L]

Whoa, that's big.



That's what she said.

[SweetDan]

Good list....but how could they ignore this one?...

Because, to have one of those, you also need one (or more) of these:



which also imply the presence of high voltages. Anything more than 9V is .... scary and stuff.

[Greg_L]

Because, to have one of those, you also need one (or more) of these:



which also imply the presence of high voltages. Anything more than 9V is .... scary and stuff.

Yeah but that one is on the list.