Beginners Guide to LTSpice for Guitar Pedal Builders, Part 3: Measuring Impedances

In this series we will go over using LTSpice for things more commonly used for guitar pedal builders. In this video, we will add a hard clipping section to our previous circuit and observe its waveform. After this (5:32), we will measure input and output impedance of a circuit in LTSpice.
* Correction. The voltage should read 0.994V on the image with the RAT pedal.
Download LTSpice here:
www.analog.com...
LTWiki:
ltwiki.org
LTSpice Parts, including op-amps:
github.com/eri...
LTSpice Playlist:
• Beginners Guide to LTS...

[@bertrandmajorik6589]

Classical music over a distortion design, NICE!!!!

[@EDGARDOUX1701]

Would like to see this on fuzz and other effects. Great work! Thank you

[@chotnt]

You are my savior

[@TomLeg]

At 2:33 and on, when you switch the the Pro Co RAT, you update the impedances of the voltage divider, but you leave the voltage across Z2 as only 0.45 V instead of updating it to 0.994V.

[@erikvincent5846]

Crap... now, do I reload or not

[@ChungasRevenge]

Thx! Great videos on LT Spice

[@Andrewfendrew]

thanks

[@warrensharp6681]

4:09 is the greatest edit in cinema history (yes, cinema).

[@fredimachadonet]

Pretty cool! Thank you!

[@leonardomeszaros6088]

Love it

[@kaistutz7067]

Now that I think about it, the whole thing with diode clipping is not very clear to me. From an electronics engineering perspective, could you explain sometime in the future which characteristics of diodes are important for the distortion effect. And, in which configuration they are commonly used. Maybe with minimum working examples in LTspice. That would help a lot for my understanding of the whole topic, and maybe others, too. :)

[@ViktoRxCZxSepultura]

Thank you for nice video. But I am not sure about the 10n capacitor. Capacitor of such a small capacity (foil or ceramic) will have series impedance in order of fraction of one Ohm. Its reactance will be approx. 15 kOhm at 1 kHz and that is exactly what you obtained. To set its serial resistance to absurdly high value is not a solution because such a capacitor does not exists. Because of RF jamming a capacitor with few pF should be utilized. My opinion.

[@pascalmerschaudio]

can it be the guitar is plugged in on the false port on the fuzz ? ;)

[@8Junio76]

This’s the sh*t. Thank you.

[@rodrigoreguera8577]

i've tested a circuit i found on internet and it was very interesting to see the outpot vs input curve. I would like to ask, if i'm interested in going deep on designing pedals, which books do you recommend to learn the theory?

[@kaistutz7067]

Great, thanks! Maybe I missed something but why do you model up to 1 MHz? I would think that everything beyond 20 kHz is not important since it is outside the human hearing. Looking forward to the next video in the series!

[@erikvincent5846]

Nope, didn't miss anything. You could do less than 1MHz. That's my day job kicking in. I do work with electronics where I need to see the sweeps that high, so basically, it was just force of habit.

[@kaistutz7067]

@@erikvincent5846 Nice, thank you Erik. BTW, I want to express again how great your LTSpice tutorials are. They gave me an easy access to something that seemed too complicated for me to deal with. By now, I already created several circuits from my DIY pedals to model different pots in tone controls etc. Thanks again for the great work!

[@alexm66]

9:14 the 10nF capacitor has an impedance of 15,915.5 Ohm (~16K) at 1KHz, which MUST affect the input impedance that much because it's in parallel with the ~5M input impedance. Watching your videos I always thought you at least knew the basics of electronics, disappointed, but keep on the good work.

[@erikvincent5846]

I realized that after I recorded it, but didn't want to redo it. I probably should do a reboot on these.

[@jayr292]

@@erikvincent5846so should i still do the equivalent resistance thing?

[@SilentThunder1969]

A bit late maybe, but why start at 1kHz? Most of the frequency's coming from a guitar are much lower, so why not start at i.e. 100Hz? Great video nonetheless.

[@erikvincent5846]

It just seems to be the "industry standard". A lot of guitar rhythm is under that frequency, but leads, solos, and resonant harmonics of chords do go up into that range often.

[@SilentThunder1969]

@@erikvincent5846 I understand this is "what the industry defines", but (especially) in "our" field the lower frequency's matter. For reference, to play a note above 1kHz on a standard tuned guitar, you'd be playing a c6 which is the 20th fret on the high e string. And yes, i also know that (resonant) harmonics play an almost vital role in the tone department. But that's just me wondering why ;) Thanks for your answer.

[@erikvincent5846]

@@SilentThunder1969 No worries. I think another reason that a lot use 1 KHz is that input impedance is frequency dependent. A lot of pedals have great impedances at around the 100 Hz mark that by 600 or so Hz are terrible. Namely due to input filter capacitors that go to ground on the input line. Tone Benders are a great example of that.

[@SilentThunder1969]

@@erikvincent5846 Thanks again for your answer. From what I know and have learned so far, is that around 600Hz is where most of the "tone" is. So if you're playing solo's from about the 7th fret up, bad filtering would probably kill your sound before it reaches the amplifier or other pedals.

[@erikvincent5846]

@@SilentThunder1969 This is true. There are some things in a mix, though, that some people (not saying myself) care about that go over the 1 KHz mark. For example, "pick attack", as in the sound of the pick colliding with a string, is at around 1.2 to 1.4 KHz. Some people want that stuff in their mixes. Myself, I try to cut it out of a mix, but that's an example of nuance frequency grabs.

[@wayahedia9989]

Not sure how seriously I should take this video because the Strat is strung left handed.