[LAU] checking passive input frequencies on non Hi-Z connection

Fons Adriaensen fons at linuxaudio.org
Sat May 27 09:39:37 UTC 2017

On Sat, May 27, 2017 at 07:28:08AM +0200, Ralf Mardorf wrote:

> usually those inputs are just designed to fit the impedance,

which is really all that is required. Anything else (EQ, non-
linearity) can be done later in software. 

There are different ways to provide a high-Z input. Provided
no signal attenuation is involved things should be OK. 

> they are
> not designed to sound good. Such an input does replace an impedance
> converter, such as a DI box or a workaround using a stomp box, but never
> ever those inputs are able to replace a good guitar tube pre-amp.

Quality varies, but guitar preamps are not designed to 'perfect'
(in a technical sense) either. Most will not have a flat response,
add distortion, etc., all that to make the guitar 'sound good'. 
Whatever specific frequency response a real guitar preamp will
provide (e.g. due to input capacitance combined with the inductance
of the pickup resulting in some resonance) can be had by classic
EQ as well.

> I might be wrong, but AFAIK those inputs are only provided by pro-sumer
> interfaces and not by professional interfaces, so don't expect
> first-class input amplifiers at all.

Pros will just use a DI-box. Combined with a normal mic preamp 
that will provide exactly the same result as a typical high-Z
input - a clean sound without any guitar-specific processing.



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