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Subject: Re: Equalising "Problem"
From: Fred Maxwell (rockbox_at_anti-spam.org)
Date: 2004-03-12


Gerrit Van Vranken wrote:

Although this is somewhat off-topic, it does address the issue of
whether the EQ and signal processing should be done during the recording
of the MP3 or whether it should be done by the firmware of the player.
I maintain that a recording should be accurate and that the player, in
this case, an Archos with Rockbox, should have adjustments to correct
for problems with the output circuitry, headphones, listener hearing,
etc. It's also why I don't see the need for a by-track EQ.

> True, However Mixing, reverb (and other effects) and EQ are all required for
> this to occur. Record a Piano with an accoustic bass and don't EQ it.
> Unless you pan them hard, you won't be able to find them.

I can listen to a symphony orchestra recorded with two mics (left &
right) and pick out the position of the individual instruments. I don't
need artificially induced distortion of the frequency spectrum or mixes
in which the sounds are all mixed (or panned if you prefer) to one
channel or the other.

> Panning (what I
> assume you mean by "mixing") is the horizontal position of a sound.

No, I mean mixing -- as in what you do on a mixing console. Many stereo
mixers have a left and right slider with no pan control. I generally
reserve the word "panning" to refer to actively varying the left/right
placement of a track while the recording is in progress. For example,
the mono recording of a jet passing from left to right via panning.

> EQ creates a vertical position

EQ (usually done via DSP) can mimic the frequency shaping done by the
complex shape of human ears and can make it appear that sounds are
coming from above or below the listener's ear level. But how often are
you called on to make a piano sound like it's 5 meters above the heads
of the rest of the orchestra?

> and effects usually create the z axis.

The Z axis is normally created via mixing and eq. Want to make an
instrument sound further away? Reduce the level at the mixer and roll
off the high frequencies. To bring it closer, increase the level and
boost the high frequencies. Effects such as reverb and delay can make
it sound like the recording was done in a more spacious and/or
acoustically live environment, but it does not place instruments in the
Z axis.

> Not a SPECIFIC listener's system, but when you mix, you listen to your
> result on all different types of systems to make sure it does sound OK on
> everything. You can't eq for a high end system either. I'd be pissed if I
> bought a CD that I couldn't listen to in my car.

The best recordings are mixed and EQ'd for accuracy when played on the
finest systems. If you boost the bass at 20hz to make it sound better
in a car, you cause someone with a high-end system to think that there
is an earthquake underway. If you pan the sounds hard left and right to
make up for the lack of physical separation on boom-boxes, you get the
"ping-pong" effect when played on a high-end system.

You'd be pissed if the sound was substandard in your car? Imagine how I
would feel if I put the thing in my high-end stereo at home and heard
harsh, boosted treble and exaggerated bass because the recording was
compromised by an EQ and mix influenced by cars and boom boxes.

Regards,
   Fred Maxwell

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