Coaxial designs offer the advantages of a single point source for a consistent acoustic center and a symmetrical dispersion pattern. But designing coaxial systems without acoustic anomalies has been extremely expensive—until now.
Solving the problems involved in coaxial designs requires massive amounts of DSP and subtle, sophisticated transducer design, which is why such systems have, in the past, been limited to very high-end systems with external processors.
However, Fulcrum Acoustic’s amazing, cutting-edge technology has allowed us to overcome the usual design problems of coaxial systems while taking advantage of coaxial’s unique properties. Thanks to custom transducers and TQ algorithms designed by Fulcrum’s Dave Gunness, Sceptre CoActual monitors deliver clarity and coherence that has previously only been available in ultra-high-end systems.
Multi-way, non-coaxial speaker designs have long been the way to go in speaker applications. But they suffer from the changing relationship between the listener and the speaker elements: When you move around in the coverage area, the sound is inconsistent. Even more troublesome, the crossover point between the drivers can sometimes be audible.
Coaxial systems solve this by having the drivers on the same axis, thus providing a single point source for a consistent acoustic center. This results in symmetry of response on both the horizontal and vertical axis, at any given angle. The crossover transition is seamless (inaudible) at all angles. (By “symmetry,” we mean that whatever response is observed at a given angle with respect to the axis, the same response will be observed at that angle in the opposite direction. The loudspeaker’s behavior is “mirrored” about its axis.)
Non-coaxial loudspeakers cannot exhibit this symmetry.
All of which is great for coaxials, in theory—yet very few companies have successfully marketed coaxial studio monitors, and only a few very expensive models are considered to be truly of professional caliber. That’s because coaxial designs are fiendishly difficult to get right. The challenges are complex and, to date, impossible to solve with acoustic design alone. Making it work at high sound-pressure levels is especially difficult.
Fortunately, a company called Fulcrum Acoustic developed a solution based on a sophisticated combination of driver design and signal processing that we’ll discuss in the section “The Magic of TQ™.” This eventually led to PreSonus Sceptre-series monitors (and also to PreSonus StudioLive™ AI-series PA speakers).
The Magic of TQ
Each Sceptre monitor contains a DSP chip that enables the use of Fulcrum Acoustic’s TQ algorithms. The result is speakers that deliver the full benefits of coaxial design.
Monitors You Can Customize
Sceptres provide extensive user-adjustable contour features that let you optimize the monitors for any mixing space.
In addition to making possible the Sceptre’s coaxial design, the monitor’s onboard DSP provides user-adjustable contour features for optimizing the monitors for your mixing space. This enables full integration into any studio environment.
The Acoustic Space Control
A four-position Acoustic Space switch controls a second-order shelving filter centered at 100 Hz, with four attenuation settings (no attenuation, -1.5 dB, -3 dB, and -6 dB) so that you can account for the boundary bass boost that occurs when the monitor is placed near a wall or corner. If you don’t want to roll off those lows, set it to 0 dB.
You also can adjust the Sceptre’s overall sound and response using its performance controls.
The Sceptre’s performance can be customized in several ways.
A sensitivity control that ranges from +4 dBu to -10 dBV helps you match the Sceptres to your mixer’s outputs.
The High-Frequency Driver Adjust switch adjusts the tweeter’s overall level to linear (0 dB), +1 dB, -1.5 dB, or -4 dB. This lets you control the balance between the tweeter’s output and that of the mid/low driver.
The High Pass switch rolls off the low frequencies below the specified frequency (60, 80, or 100 Hz) at a slope of -24 dB/octave. This control is important if you are using a subwoofer in conjunction with the Sceptre S6/S8 monitors; in that case, set it to the same frequency as the crossover to the subwoofer. If you're not using a subwoofer, you simply set the control to Flat.
Any loudspeaker is subject to an assortment of environmental and performance problems, and Sceptre monitors offer protection from most common of these. RF shielding protects against radio frequencies that could be induced into the signal and become audible. (If you’ve ever heard a radio broadcast unexpectedly coming out of a guitar amp, that’s the result of RF interference.)
Sceptre monitors also provide over-temperature protection to avoid heat-related issues and current-output limiting to prevent damage should there be a short circuit on the speaker terminals.
Finally, the power amplifiers have a “soft startup” so that you don’t get damaging pops in the speakers when you power them up.
Big Woof or Huge Woof
The Sceptre series includes two models with the same high/mid coaxial section. The S6 delivers far better bass response than you’d expect for its size. The S8’s bass response is downright stunning. The Sceptre S8 CoActual Studio Monitor combines an 8-inch low/mid-frequency driver and a 1-inch (25 mm), horn-loaded, high-frequency transducer into a single coaxial unit with aligned voice coils. The Sceptre S6 uses the same technology and design as the S8 but with a 6.5-inch low/mid-frequency driver. Both models have front-firing acoustic ports. The systems are biamplified: Each transducer is powered by a 90W RMS, Class D power amp with an internal heat sink. Each Sceptre has its own internal power supply with IEC connector and a power switch with on/off LED. All Sceptre-series monitors have a balanced XLR and ¼-inch TRS line-level inputs with A-taper level control. To this package of custom transducers, powerful DSP running custom software, and first-rate power amplification, add a rich set of acoustic adjustments and full speaker protection, and you have a new, affordable close-field monitoring standard for project studios and commercial facilities. As you expect from PreSonus, Sceptre studio monitors use top-quality components and construction quality fit for royalty—and they look regal, too!
|1- Balanced XLR|
|1- Balanced ¼” TRS|
|Frequency Response (-3 dB)||46 Hz - 20 kHz|
|Frequency Response (-10 dB)||38 Hz - 23 kHz|
|Crossover Frequency||2.4 kHz|
LF Amplifier Power (@ 4Ω)
HF Amplifier Power (@ 4Ω)
|Peak SPL (@ 1 meter)|
|LF Driver||8” glass-reinforced paper|
|HF Driver||1” diaphragm compression driver|
|Input Impedance||10 kΩ|
|Volume Range||A-type taper|
Flat, +1, -1.5, -4 dB
|Low Cut||Flat, 60, 80 Hz, 100 Hz|
|Acoustic Space||Flat, -1.5, -3, -6 dB|
|External mains fuse|
|100-120V ~50/60 Hz or 220-240V ~50/60 Hz|
|Vinyl-laminated, medium-density fiberboard|
|Width||11.4” (290 mm)|
|Depth||13.3” (338 mm)|
|Height||15.75” (400 mm)|
|Weight||24.25 lbs (11 kg)|
NOTE: As a commitment to constant improvement, PreSonus Audio Electronics, Inc., reserves the right to change any specification stated herein at any time, without notification.