Table of Contents
Advertisement
Section 15
Distortion Problems
Let me say this now. There is no such thing as a BAD
distortion—merely a distortion which you don't like or isn't
the sound you were looking for. That's not to say that it isn't
part of the sound you are looking for. As we saw with the
preamps, what effects you mix together can greatly change
the sound. Distortion is the same. Please, NO MORE—
'There are NO GOOD distortions on the GT-3/5'. My
answer is
1.
Learn to use your GT-3/5
2.
Learn to use your equipment,
3.
Learn how to set it all up properly
4.
Take the time to play around, and seek out the
sound you want.
Secondly, 'The distortions all sound too harsh'. Gibberish.
Anyone who says this probably hasn't got the speaker sim
on when they should have. On the GT-3, you need a preamp
ON to get the speaker simulator working. And that brings
me to my third point. 'The preamp distortions aren't as harsh
and sound more natural'. Poppycock. I would suggest that
this is because the GT-3/5 has been set to 'Line
(Headphones)' and the OD/DS is being used without a
preamp. Again, as I said before, on the GT-3 - No
PREAMP—No Speaker Sim. Make sure you do use a
speaker simulator when you are using full range speakers –
particularly when using headphones. It is quite easy to see
how the GT-3/5 could be criticised given these scenarios.
Please take the time to learn how to use the unit effectively.
Understand what is on when and off when.
Right then folks, with that off my chest let's take a look at
the OD/DS effect on the GT-3/5.
GT-3/5 OD/DS
First let's take a quick look at the basic controls. Many of
these will be familiar. If you are used to pedals like the Boss
MT-2 Metal Zone you may be thinking that the pedal is
provides more controls than the GT-3/5. This is not
necessary true. "OK Barry, so what about the MT-2's
parametric tone controls?". Well, quite simply the GT-3/5
already has more than this available on the EQ section.
Anyway, the GT-3/5 does supply some basic tone controls
with the OD/DS. Let's take a quick look at these basic
controls then:
Bass
This is a low pass shelving filter, providing boost
and cut to roughly 50-700Hz. With roughly
slightly more boost than cut available. The largest
boost/cut is available around 60-70Hz.
Treble
© Copyright 2000-2002 Barry S. Pearce et al.
Overdrive/Distortion
This is a high pass shelving filter, providing boost
and cut to roughly the 500Hz-22kHz region. With
the largest boost/cut available around about 5kHz.
Again slightly more boost than cut is available.
Drive
Use this to control the amount of distortion.
Level
Use this to level match the output.
It should be remembered that just like the preamps, the
distortions carry with them their own frequency response,
and that the figures above for Bass and Treble are rough
guidelines.
Now I've not really given the Drive control much of a
description here so before we move on I would like to say a
bit more about it.
Distortion is traditionally formed by clipping a preamp.
This is done by driving it too hard, not so much driving the
input too hard but generating a enough gain within the
preamp for it to clip internally.
Picture a threshold above which, everything clips. If the
threshold is real high then no clipping will occur, therefore
no distortion. As the threshold is lowered more and more of
the signal level exceeds the threshold and is clipped, thus
providing more distortion.
However, the threshold for clipping is seldom adjustable
and instead a varying amount of gain is used to control how
much clipping occurs. Small amounts of gain against a fixed
threshold will provide small amounts of distortion, large
amounts of gain produces large amounts of distortion, as
more of the signal exceeds the threshold and clips.
As a quick aside, different preamps (tube/solid state)
behave differently in this clipping and thus we have
different types of distortions. For instance a tube will clip
more softly than a transistor, adding add even order
harmonics, whereas solid state add odd order harmonics.
Even order harmonics sound better- kinda like 3rds and 5ths
rd
versus flat 3
or #7's in chords. When you start looking at
digital systems the end result will not be so obvious as the
clipping is now dependent on the software algorithm, which
ultimately is derived from a processing model. For
simplicity's sake we will look on the GT-3/5 distortions
from a traditional point of view rather than a software point
of view. This is quite a sensible approach, after all the
software is typically just an implementation of a model of
the traditional system.
Anyway, the change of gain in the preamp is effectively
what the Drive controls. It increases the gain, as the drive is
increased. Thus a low drive figure will give a lower
distortion than a higher one. OK so why do different
75
Advertisement
Table of Contents
