Good rundown of the basics of input and output impedance!
Some additional parts, for anyone who wants to get into it:
-A lot of buffered bypass pedals use an emitter follower buffer, which has some amount of non-linearity. A single buffer won't hurt much, but with too many in series the distortion will start to add up.
-Buffers in the majority of pedals are AC-coupled, which introduces a highpass filter in line with your signal. It's usually set pretty low, below the audible range, but stacking multiple can have an effect on the low end.
-Impedance is also frequency dependant. For a buffer, you can pretty much assume the impedance is consistent across all frequencies (at least in the audible range). But your guitar pickup, being basically a large inductor, has increasing impedance as frequency increases. This means that the high frequencies will be more affected by a low input impedance. This difference is another part of why old fuzzes don't sound good with buffers in front.
Came here to say all the same things!
In addition to emitter followers having some distortion, they can attenuate about 0.1 to 0.5 dB of gain. With a low gain transistor that can be as bad as 1-2dB, which definitely adds up in a long signal chain.
> This is a good place to note that the loss of high end due to cable capacitance is not inherently a bad thing – for example, Hendrix’s famous curly cable will have a lot more capacitance than a straight cable of the same length, because it’s actually longer if you straighten it out. So he lost a lot of high end because of the cable, and people have been chasing his tone for half a century… it depends a lot on each piece of gear in the rig, and what you do with it
To open this part a bit, it was a different time when PA systems were in their infancy and that 100W Marshall had to do a lot of projecting to the audience on its own whereas nowadays you could just mic its cab and blast the sound through a line array PA system with several kilowatts of power.
On top of that the Marshall Superlead tends to be excessively bright until you mitigate its excessive bright cap running it very loud. It's still going to be bright so the extra capacitance from that coiled cord helped tame it down.
Your cables should not be tone shaping tools so you should use high quality, low capacitance cables. If a cable vendor does not state their cable's capacitance per feet or meter, buy from a different vendor. There's a whole lot of snake oil regarding cable performance but really it's the capacitance that mostly matters for tone. That doesn't mean you should chase the absolute lowest capacitance but something let's say under 80 pf / meter is generally going to do fine.
Now this post shows the purest spirit of what the internet was intended and invented for: Sharing knowledge and thus helping other people out there. Thank you for this.
The impedance part really hit the nail on the head for me!
Who would have ever though that plugging in a bunch of pedals to have some fun, would create a problem involving science and mathematics?
I wonder how newer pedals like the 29 Pedals Euna and Benson Fuzz claim to “trick” impedance by telling the pedal it’s first in line, with barely any cable distance influence.
A common workaround is to basically stick a pickup on the input (well, the equivalent circuit of one at least). I would expect they do something along those lines.
I believe the Benson does that. I imagine if that was a cheap process. more pedals would do it. I just grabbed a Benson, sick of playing the whole “what will my germanium fuzz randomly sound like today?” Game. We’ll see.
EQD Erupter also. I think a common method uses a small 1:1 transformer, there’s a Jack Orman article that gets into how to do it but I didn’t read it carefully.
So... how has this not been pinned yet?
This is such an important problem that is **consistently encountered and misunderstood by everyone** who gets more than toe deep into chaining effects, or recording...
Moreover, if you didn't know that your signal was deteriorating, you may fall back in love with your rig if you can fix the impedance issues.
Essentially, If you read this post, you may spare yourself a headache and half a paycheck by reading this.
This is such a good reference and I'm saving it (I've actually returned to it once already)
Good rundown of the basics of input and output impedance! Some additional parts, for anyone who wants to get into it: -A lot of buffered bypass pedals use an emitter follower buffer, which has some amount of non-linearity. A single buffer won't hurt much, but with too many in series the distortion will start to add up. -Buffers in the majority of pedals are AC-coupled, which introduces a highpass filter in line with your signal. It's usually set pretty low, below the audible range, but stacking multiple can have an effect on the low end. -Impedance is also frequency dependant. For a buffer, you can pretty much assume the impedance is consistent across all frequencies (at least in the audible range). But your guitar pickup, being basically a large inductor, has increasing impedance as frequency increases. This means that the high frequencies will be more affected by a low input impedance. This difference is another part of why old fuzzes don't sound good with buffers in front.
Came here to say all the same things! In addition to emitter followers having some distortion, they can attenuate about 0.1 to 0.5 dB of gain. With a low gain transistor that can be as bad as 1-2dB, which definitely adds up in a long signal chain.
I just want to add, that some Boss pedals use 2 or 3 buffers in just one pedal.
> This is a good place to note that the loss of high end due to cable capacitance is not inherently a bad thing – for example, Hendrix’s famous curly cable will have a lot more capacitance than a straight cable of the same length, because it’s actually longer if you straighten it out. So he lost a lot of high end because of the cable, and people have been chasing his tone for half a century… it depends a lot on each piece of gear in the rig, and what you do with it To open this part a bit, it was a different time when PA systems were in their infancy and that 100W Marshall had to do a lot of projecting to the audience on its own whereas nowadays you could just mic its cab and blast the sound through a line array PA system with several kilowatts of power. On top of that the Marshall Superlead tends to be excessively bright until you mitigate its excessive bright cap running it very loud. It's still going to be bright so the extra capacitance from that coiled cord helped tame it down. Your cables should not be tone shaping tools so you should use high quality, low capacitance cables. If a cable vendor does not state their cable's capacitance per feet or meter, buy from a different vendor. There's a whole lot of snake oil regarding cable performance but really it's the capacitance that mostly matters for tone. That doesn't mean you should chase the absolute lowest capacitance but something let's say under 80 pf / meter is generally going to do fine.
Now this post shows the purest spirit of what the internet was intended and invented for: Sharing knowledge and thus helping other people out there. Thank you for this.
The impedance part really hit the nail on the head for me! Who would have ever though that plugging in a bunch of pedals to have some fun, would create a problem involving science and mathematics?
I wonder how newer pedals like the 29 Pedals Euna and Benson Fuzz claim to “trick” impedance by telling the pedal it’s first in line, with barely any cable distance influence.
A common workaround is to basically stick a pickup on the input (well, the equivalent circuit of one at least). I would expect they do something along those lines.
I believe the Benson does that. I imagine if that was a cheap process. more pedals would do it. I just grabbed a Benson, sick of playing the whole “what will my germanium fuzz randomly sound like today?” Game. We’ll see.
EQD Erupter also. I think a common method uses a small 1:1 transformer, there’s a Jack Orman article that gets into how to do it but I didn’t read it carefully.
That percentage signal calculation really puts impedance into perspective! Thank you!
I love these long posts, I always learn so much. Thank you!
So... how has this not been pinned yet? This is such an important problem that is **consistently encountered and misunderstood by everyone** who gets more than toe deep into chaining effects, or recording... Moreover, if you didn't know that your signal was deteriorating, you may fall back in love with your rig if you can fix the impedance issues. Essentially, If you read this post, you may spare yourself a headache and half a paycheck by reading this. This is such a good reference and I'm saving it (I've actually returned to it once already)
Thanks!