Creating a Realistic Bass With Logic's Sculpture
Sculpture is a unique instrument to Logic in that it is something called a 'component modeling synth'. Where Logic's other synths are the more standard FM and additive synth types, Sculpture tries to make a virtual model of an actual acoustic instrument which mimics that instrument's physical properties.
In this and a following tutorial, we will look at how this unusual synth operates and how we can manipulate its parameters to create a realistic electric bass sound.
The Sculpture interface.
First, some basic background information is a good place to start as Sculpture has some rather unique parameters that require some explanation. In order of signal flow, they are:
- String Section: Here you can set the properties of the string you will be modeling. The central pad allows for material selection (steel, nylon, etc.), while the surrounding sliders from left to right control media loss (emulates string dampening from the outside environment), resolution (determines maximum number of harmonics) and tension modulation (sets a momentary detuning of the string).
Detail of Sculpture's string section.
- Object Section: Here you can set up to three parameters to affect the string. At least one object must be activated for any sound to occur as, just like in real life, a string that is not affected by an outside force does not make any sound. The main portion of this section is the drop down menu that allows for 15 different types of either excitation, disturbing or dampening to be performed on the string. The large knobs set the strength of the action being performed, the timber slider changes between dull and bright sounds and the variation slider, which is another timbre parameter, whose effect changes based on the object type selected in the drop down menu (a comprehensive list can be found in the Logic Studio Instruments manual, pg. 334-337). Finally, the gate mode buttons select when the action is performed on the string.
- Pickup Section: This section emulates the pickups of an electric guitar or bass. The three large sliders control where the respective objects effect the string. The two pickup position sliders determine where the virtual pickups are placed along the string. The invert button inverts the phase of pickup B which can either thicken or thin the overall sound depending on the relationship with pickup A. Additionally, there are two controls to the right of the ADSR under the 'Spread' heading. The key spread sets the amount of panning by MIDI note number (i.e. the further up or down the keyboard you play, the further left or right the sound will be panned), and the pickup spread does what it says and spreads the pickups across the stereo field.
Detail of the object and pickup sections.
- ADSR Section: This section operates as one would expect; with standard ADSR controls. However,
the attack is somewhat unique in how it works. There are two sliders for attack: the lower slider determines the attack at maximum velocity while the lower determines the attack at minimum velocity. Furthermore, when both are set to 0 and a note is triggered while the string is still vibrating, it is reset. If anything other than 0 is set and a note is triggered while the string is vibrating, the occurring vibration acts on the new note as well which creates a unique and more organic sound
- Filter section: This is the most standard section of Sculpture and acts as one would expect.
- Waveshape section: This is a rather standard waveshape distortion unit. The controls are fairly self explanatory as well.
- Delay section: This is fairly basic as well. However the groove pad in the upper left is a pretty unique feature and is an intuitive way of creating stereo swing/groove times by simply moving the central puck around the XY axis.
Detail of Sculpture's delay.
- Body EQ Section: This area of Sculpture can act as a basic 3-band EQ or as a complex frequency spectrum shaper. The rounded rectangular button just below the knobs is a disclosure menu which allows you to choose between the basic EQ and a number of real instrument body EQ models. Depending on what you select, the knobs will have different functions. In basic EQ mode, the knobs are straight forward. In body EQ mode, the knobs and slider change and shift various characteristics of the model. The best way to learn how these act is to simply play around with them.
Detail of the body EQ.
- Limiter Section: Here you can set the output level as well as the limiter type. Mono acts on the summed signal of all voices, polyphonic acts on each voice independently and both, rather obviously, combines both types.
- Modulation Section: The modulation section allows for numerous standard and unique modulation sources to control pretty much every parameter of the sculpture interface.
Sculpture's extensive modulation section.
- Global Section: This section determines the global behavior of Sculpture.
Creating the Bass
Since we are trying to model an electric bass, we need to think about how an actual electric bass operates and then dial in those physical attributes into the respective parameters of Sculpture.
The first thing to think about is string type. In the string section XY table you can see options between wood, glass, nylon and steel. An electric bass obviously uses steel strings, so moving the puck to somewhere in the lower left of the table is what we want to do here.
In this section it is also important to make sure the 'media loss' slider at the left is turned low if not off as high values will make your sound cut off unnaturally short.
The next thing to think about is how the string is going to be played. Here, I have turned on Object 1 and selected 'Pick' from the drop down menu which mimics a fingered or plucked excitation of the string.
Moving on to the pickup section, the green line (you can right click it to activate string animation) represents the string. The orange oval under the number 1 represents the action of Object 1 (the plucking of the string) and has varying levels of opacity depending on the 'strength' dialed in. The object has a stronger effect on the string the closer to the middle and has a less pronounced effect off to the side. This makes sense as playing a string close to a pressed down fret will vibrate far less than one played towards the more open region.
The A and B sliders represent the pickups (electromagnetic fields which capture the string's vibrations). The pickups create more bass around the middle of the string and become more overtone rich the further to the side you place them. This mimics the real world in that the more open portion of the string will give a smoother and more powerful sound while the edges will create more harmonics. To create a bass with a single pickup, you simply need to place them in the exact same position (and make sure the 'invert' button is not turned on).
Finally, for our basic sound we want to have little to no attack and a very short release as well. I like to put just a bit of attack on in order to trigger the string while it is still vibrating as discussed in the ADSR section above. I just dial the release to taste, but always keep it short.
After going back and playing around with some of the settings, I've moved the string more to the nylon side of things, kept the media loss low, cranked up the object strength, randomly adjusted the timbre and variation settings to taste and locked both pickups and the object sliders to the lowest side of the string. I've turned everything else off and upped the number of voices to 16 in the upper right.
The final adjustments.
The bass thus far.
In the next tutorial we'll look some of the other sections of Sculpture in order to make our bass sound more varied, expressive and natural.