how will a pedal change impedence?

[fishfartz]

say for instance you wanted to run guitar>amp (pre & power) then >pedal>speakers......

 

 

this would be a recipe for disaster for the load needed, correct?

[DIYethic]

Originally posted by fishfartz say for instance you wanted to run guitar>amp (pre & power) then >pedal>speakers...... this would be a recipe for disaster for the load needed, correct?

 

 

does it ever.

 

you see, most pedals have an input impedance of (usually, not including fuzzes or other special cases) around 1M or two (1 MILLION ohms or more). speakers have impedances of only 4, 8, or 16 ohms, and amps are designed to drive these impedances (your amp doesn't expect any kind of huge resistance). this could possibly fry your pedal, and will definitly blow out your amp (used to seeing only low impedances).

 

 

 

so don't do it. unless, of course, the manual tells you to, like talkboxes.

[Narcosynthesis]

You are missing one slightly important thing...

a pedal is used to a tiny signal from a pickup, and hence is only designed to cope with little signals mW at most (a rough guess)

an amps power stage (depending on the amp) usually goes from 20W upwards, often in excess of 50/100W, not good for a pedal designed with parts to cope with 1/4 or 1/2W at best...

So ignoring the pedal changing impedances, the second you play anything (or even static noise from the amp) you say goodbye to the pedals, and quite possibly goodbye to your amps output stage

One exception being things like talkboxes, which are in effect a speaker themselves (they use a smaller driver to direct the sound up a tube into your mouth instead of out the cab)

David

[DIYethic]

Originally posted by Narcosynthesis You are missing one slightly important thing... a pedal is used to a tiny signal from a pickup, and hence is only designed to cope with little signals mW at most (a rough guess) an amps power stage (depending on the amp) usually goes from 20W upwards, often in excess of 50/100W, not good for a pedal designed with parts to cope with 1/4 or 1/2W at best... So ignoring the pedal changing impedances, the second you play anything (or even static noise from the amp) you say goodbye to the pedals, and quite possibly goodbye to your amps output stage One exception being things like talkboxes, which are in effect a speaker themselves (they use a smaller driver to direct the sound up a tube into your mouth instead of out the cab) David

thanks

[zachary vex]

pedals can convert impedances at guitar level. somewhere around 1 million ohms in, converted to 10k ohms or less out... which can help drive a long cable line or help signals get through other pedals more intact, but to convert impedances at speaker level, you'd need large custom-made power transformers.

[fishfartz]

cool thanks guys -


i thought it would be a big no-no


but i had such plans to take over the world

[Howard Davis]

Originally posted by fishfartz say for instance you wanted to run guitar>amp (pre & power) then >pedal>speakers...... this would be a recipe for disaster for the load needed, correct?

 

 

Yes.

The pedal is designed to go BEFORE the amp and before the amp ONLY. You will not harm the amp by putting the pedal after it, but may blow the input stage of the pedal. Also, the pedal alone cannot possibly deliver enough power to the speaker to produce anything more than a barely audible and distorted sound.

 

Guitar pedal design engineering, repairs, and custom mods:

http://howard.davis2.home.att.net/