Instrument impedance

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sorin

New member
Joined
Mar 7, 2005
Messages
3
Location
NJ
does anyone know what the impedance difference between a DI and a line output is. For example to get a proper impedance match between a microphone preamp (load) and an microphone or instrument (source) you should have a 10 to 1 impedance ratio between the load and the source.

What are typical output impedances for DI instruments like a electric guitar with an active or passive pickup.

What are typical otput impedances for instruments like a synth that have line outputs.

thanks
Sorin
 
I'm probably a bit off, but here are some common figures I've come across over the years:

passive guitar: 1Meg ohm, more or less
active guitar: 250k or less
synth: 250k or less, often closer to 100k

whereas,

microphone output: between 50 and 300 ohms, normally 200
line output: 600ohm (old school), 50ohm (new school)
line input: varies quite a bit. minimum 2k, maximum 50k??, nominal 10k. Often 600 on old school, impedance matching gear.

The 1:10 thing is for impedance bridging aka voltage transfer. theory says input impedance is at least 10times higher than source so as not to load it down and to make sure at least 90% of voltage drop across the input, rather than the source.

In orlder gear where both line input and output are 600ohm they were shooting for impedance matching aka power transfer.
 

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