The applications can be used on case of music and musical instruments as well.
We can take the example of a guitar which has a separate sound processing unit.
The sound processing units can either be digital or analog. Nowadays, we see
that the processing units which are digital are almost as good as the ones which
are analog. This is achieved by simulating the sounds using tube modeling oscillators.
Though, it has its own drawbacks such as it is very fragile and cannot be kept
under varying current (Somasundara et al., 2006)
and voltage. It has been taken into consideration that a multi-effects processor
cannot be directly embedded (OHara et al.,
2008) into a particular instrument due to several constraints such as weight,
change in density of the wood, size of the processor as a whole and the sound
Many musicians prefer to use stomp boxes to control their pedals as they strongly
believe that multi-effects pedals are not as good as analog pedals. After viewing
multiple pedals and effects a conclusion can be reached that the noise gate
pedal is the most optimal one to embed into the guitar or any stringed instrument.
The chip to be embedded (Sunkam Ramanujam and Lin, 2009)
will not be too large. It can be used as a substitute for an equalizer or even
a better than a substitute as it can cut off noise levels to infinity rather
than just minimizing the levels of a particular decibel (dB) level.
The effects pedals were first experimented in the 1940s and were commercially
brought out in the year 1948. A trem troll effects unit was released which simulated
the tremolo arm. This was done by passing the signals that were produced from
the guitar to effects area which had a water-based electrolytic fluid. A much
more portable version of these effects zones were created in 1962 more popularly
known as stomp boxes. These were more favored but then again with advancement
in times we can use the basic concept of the technology to modify it for our
needs. It is said that the circuits cannot be changed and placed anywhere but
with experimentation it has been found that the stomp boxes can be placed differently
to obtain different sounds (Abdullah and Green, 2011)
given the fact that the parameters are changed accordingly.
It can be implemented on the guitar or any musical instrument by embedding
the circuitry inside the instrument and placing a knob for controlling the threshold
levels that is, it is able to control the amount below which the levels need
to be cut off. The threshold levels can be controlled using one knob only if
we use a pull and rotate concept (Peiravi, 2008). That
is the same concept as the coil tap. The coil tap is something that is used
to change the humbuckers to pickups and vice versa which are solenoids (Lee,
2006). The coil tap has been diagrammatically shown in Fig.
What actually happens is that the knob can be raised to a certain level in
order to use it to control the threshold levels. The knob can be placed near
the volume control and tone control knobs. It will be easy to access and control
while playing. We notice that the noise gate is able to cut of dB levels that
are below a certain level (Manikandan and Madheswaran, 2007).
What if we want to set it in between two points? For this we cannot use a computerized
system to decide what the noise levels that should be cut out are. The reason
behind is that at times we like some unwanted sounds and are able to use it
to our advantage. If we allowed this to be fully computerized then we would
not be able to control the sounds that we want. Instead of installing an onboard
equalizer like we do in acoustic guitars we can install a noise gate system
which will comprise of a chip which will be soldered to the pickups and humbuckers
so that the output sound is controlled (Nadhim, 2006).
At the same time we are not going to compromise on the sound that is there.
So what we are going to do is that we are going to use an analog signal and
give it as an output as well.
Another such idea that can be implemented is that the coil tap can be used
to cut off two different ranges of noise levels. That is one above a particular
level and another below a particular level. An advantage of this is that different
kinds of sounds can be produced when combined with different kinds of effects.
|| The coil tap concept
CONSTRUCTION OF A NOISE GATE
The noise gate can be put in the top to control the sounds that are being brought
in. The noise gate will have a knob to control the amount to which a sound has
to be reduced. The levels can be between minus infinity to plus infinity. The
noise gate will be an analog circuit so that it can preserve the sounds (Tlelo-Cuautle
et al., 2010). Once it is passed to a digital circuit it must be
maintained in that form to prevent unwanted loss of signals.
Along with the noise gate there will be a pre programmed chip with a display
which will show the amount to which the threshold levels (Jia
et al., 2000) are being set at. The other two parameters such as
the attack and the decay levels are assumed to be preset. The values maybe defined
to suit the other circuits that are to be placed ahead. The Attack and Decay
levels (McIntire et al., 2012) set will also be
displayed on the LCD and they can be modified with a knob for each. The display
has been illustrated in Fig. 2. In the general circuitry of
a noise gate pedal all three parameters are there and can easily be modified.
As for the problem of the power supply for the noise gate effect we can use
a 9 V alkaline battery and set it up. In case the user wants to use a light
instrument then it is possible to connect the noise gate circuit with an active
pickup which will be having a battery supply in it. In case of passive pickups
then the weight can put under the noise gate circuit. Since, we do not have
a battery as it is under the pickups the weight is hence just been relocated
and no excess weight has been added or removed. Another factor that must be
taken into consideration is that the circuits have to be placed in blocks to
prevent unnecessary loss in signals. That is all the analog circuits must be
kept together and all the Digital circuits together. The battery will be connected
to the noise gate board and the pickups if any and then they would soldered
to the output line. This has been shown below with the aid of a diagram in Fig.
3. Many a time we notice that people use this pedal at the end of their
circuit as they believe that it may land up compromising the original tonal
signal that are produced with the help of the wood and other basic hardware.
This is not true. The tone can be preserved and yet a desirable result can be
obtained if the three major parameters are set correctly.
|| The display of the noise gate
|| The circuitry from the noise gate to the power source and
|| The architecture and the circuitry
ARCHITECTURE AND CIRCUIT
The architecture and the circuitry are not very complex and have been illustrated
and explained in the figures. The Noise gate pedal is connected to the 9 V battery
which is the source of its power. The battery will have to be replaced from
time to time depending on its usage. Other than this the connections between
the display and the board is also present in Simplified Noise Gate Circuit.
The circuit as we see is highly simplified and the knob that we can control
is at the input. The values can be modified by turning it thereby changing the
values in the threshold box. The active switch is where the coil tap becomes
functional as we can input another value for the threshold. The architecture
and the circuitry have been depicted in Fig. 4.
I would like to thank my professor Dr. N. Sairam for giving me insight and
guiding me through the course of this paper. He has also given me inspiration
to venture into a topic that is not very much written about.