HF-Character:
The knob HF-CHARACTER is divided into two control ranges. When twisted clockwise from the center position, it works just like a tube power amp’s presence knob. PRESENCE generates soft, glossy top-end frequencies while rolling off harsher-sounding frequencies found at the low end of the high frequency range. This yields a sonic image very similar to that of a "soft" tweeter. The effect is particularly prominent in the high-end response of basses sporting active circuitry. If your instrument is equipped with passive pickups (or its strings are very old), you may find that this effect is hardly audible because there are few high-range frequencies in the instrument’s signal. When twisted counterclockwise from the center position, it works just like a normal TREBLE knob, affecting the lower end of the high-range frequency spectrum. In contrast to the PRESENCE function, dialing into the TREBLE control range yields a wiry kind of sound that you
might expect from a bass combo that is not loaded with an HF horn. Frequencies lying above the TREBLE control range’s center frequency are dampened, which emphasizes the character of this voicing control. Pushing the PUNCH button clearly
enhances the HF-CHARACTER
knob’s effect.The illustration shows the curves for PRESENCE (top curve) and
TREBLE (bottom curve) at extreme HF-CHARACTER knob settings.
The figure shows the harmonic overtone spectrum generated for a fundamental tone of 500 hertz.
Serving to harness distortion is an intelligent compressor that grants you precision control over tube saturation. It keeps your string attack up front without undesirable spikes in volume, while avoiding all the pitfalls of conventional compressors. This circuit does not mask attack, generate pumping sounds, or any other sonic side effects. But it does deliver truckloads of sustain, making your instrument easier and more fun to play.
3.2 Handling:
Tube Growl:
The TUBE GROWL knob is a particularly handy feature, allowing you dial in natural compression and tube effects: This tool puts at your fingertips the means to control the compressor parameters threshold, ratio, make-up gain, and attack and release, as well as tube saturation levels.
TM
Quantum -combo Manual
Low Mid:
Turning this knob up boosts a broad range of frequencies neighbo- ring the center frequency of 400 HZ (up to +12 dB), adding presence and punch to the bass signal. This parallel circuit does not squawk; even high settings do not elicit the annoying honk that serial EQs are infamous for. By backing off lower frequencies, you can dial in sounds similar to Jaco’s trademark woody tone. Note that this con- trol is like a notch filter – its slope is very steep, ranging all the way down to -25 dB. By carefully dampening select frequencies, you can dial in punchy sounds with a distinct hi-fi flavor.
The figure above shows the LOW MID | The figure above shows the HIGH MID |
EQ’s curve when boosting (top curve) | EQ’s curve when boosting (top curve) |
and cutting (bottom curve) frequencies. | and cutting (bottom curve) frequencies. |
High Mid:
This knob works along the same lines, boosting frequencies in a broad band and cutting them in a narrow band. This EQ’s center frequency on amps loaded with 10" speakers is 850 hertz; on amps loaded with 1x 12" and 1x 15", the center frequency is 1.2 kHz. The figure above shows the HIGH MID EQ’s curve when boosting (top curve) and cutting (bottom curve) frequencies.
3. Tube Growl
3.1 Tube Saturation & Compression
More than merely a means to determine saturation levels, the TUBE GROWL knob is a complex circuit that controls peaks like a tube preamp does, converting the energy of spikes into overtones rather than allowing it to dissipate. TUBE GROWL is comparable to a string that generates a fundamental frequency and a series of harmonics generated by half the string, a third, a quarter and so forth. The relative levels of harmonics are decisive in shaping tone, so it takes the right mix to please the human ear.
