[sdiy] New to sdiy but w/ some knowledge

[Andre Majorel]

On 2017-05-26 18:49 -0500, Quincas Moreira wrote:

> 3: line level = +/- 2v.

Marvellously concise. The longer answer :

-10 dBV, the "consumer" line level reference, is 316 mVRMS or
+/-447 mV or 894 mVPP.

+4 dBu, the "professional" line level reference, is 1.23 VRMS or
+/-1.74 V or 3.47 VPP.

These days, lots of nominally +4 dBu equipment can take (and
especially dish out) much higher levels, often beyond +/-15 V.

> Instrument level is high impedance, very low voltages (same as
> mic/electric guitar).

Two things maybe worth adding :

"Instrument level" is a misleading name in that the only
instruments whose output fits that description are electric
guitars and basses. Other instruments have been designed to
mimick them so they could be plugged into guitar amps but a
synth output is more likely to be line level.

The output amplitude of electric guitars and basses covers a
very wide range. At one extreme, softly picking the high string
of a guitar with single-coil pickups might give you millivolts.
At the other, the output of a bass can exceed +/-1 V when
playing hard on the low string. So gain is good to have but it
better be adjustable.

-- 
André Majorel http://www.teaser.fr/~amajorel/