Impedance question gtr pickups >>> gtr amps

[Blast9]

Can someone clear this up please:

As I understand it, gtr amps have high impedance inputs around 1 meg ohm ---- Correct?

I assume that passive pickups are high impedance.

I also assume that pedals are also generally high impedance nowadays.

I assume therefore that signal degradation is minimised because the impedance is more or less the same throughout the chain.

What I can't understand is low impedance active pickups:

At which point is the impedance changed back to "high", so that the amp is being fed the correct signal?

I always understood that lo impedance circuits enabled the gtr signal to drive long chains of FX properly, but if pedals generally have hi impedance inputs, surely there's a mis-match?

I think I'm missing something

[foldback]

Here are some "Rule of thumb" to help you through.

Guitar amps have high impedance inputs. (100K to 1Meg)

Passive electric guitars have high impedance outputs (6K to 10K)

Active guitar pickups have relatively low impedance outputs (100)

Effect pedals have relatively low impedance outputs (100)

Active solid state devices have relatively low impedance outputs (100)

You don't want to "match" output to input impedance with these devices. A 10K output feeding a 10K input would be bad. This is the reason that passive transformer direct boxes load down Fender P-basses and sound dull, it's not that the direct box or transformer is bad, it's that the input impedance of the transformer is loadiing down the pickups which usually results in a severe loss of high frequency response.

Ideally, you want the "load" to be 10-times the source impedance to prevent distortion caused by loading down the source.

A passive electric guitar with a 10K output goes into a 100K input nicely (100K is 10-times 10K). If the 100K input is even higher in circuit impedance, all the better, that means less work for the pickups to drive the load.

Most active devices have on the order of 100-ohms actual output circuit impedance and will not be loaded down by any guitar amp input.

Most studio gadgetry has input impedances of 1000 ohms or more. This means you could plug virtually any active device in and not have the frequency response get degraded by loading problems (signal level and gain matching will still be an issue tho).

For years, Tascam showed the output impedance of semi-pro gear as 10K ohms unbalanced and they showed the input impedance on devices as 10K to somewhere around 40K (very confusing when I knew nothing about circuit design). Later I acquired schematics of Tascam products and discovered that the opamp outputs were the same as everyone else which led me to ask "why do they state the output to be 10K when it's really down around 100 ohms?". Deane Jensen answered the question for me with "Tascam assumes you're stupid and is trying to build in some margin for error without asking you what you want".

Hope that all makes sense.

[Blast9]

AHH I see now! Thank you

So with pedals, they also have a high(er) impedance input, but the output is lower impedance.

I assume they don't have xformers in pedals to do this... How is it achieved?

Cheers