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Our Flagship Center Speaker!

Combining exceptionally wide and linear dispersion, massive dynamics, high levels of detail and a smooth and musical presentation, the Sierra Horizon has been designed to transport you into the concert venue, recording studio or movie theater.

Equally adept at music and home theater, this speaker is extremely neutral and balanced, reproducing the source material accurately with the ability to convey emotion and life-like dynamics.

The perfect performance match to our Towers, use as a center or mains. Featuring our exclusive low resonance layered bamboo cabinet and either our NrT dome or custom RAAL true ribbon tweeter.


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Our goals for this loudspeaker were simple; create a center speaker that perfectly matches the performance of our Sierra Towers but in a compact and placement friendly cabinet. The driver components are identical to those found in the Sierra Towers and the crossover only requires two minor changes to compensate for the larger front baffle width. The dual front slot ports allow for maximum placement versatility and precisely match the low frequency tuning of the Towers.

Featuring our exclusive fully custom neodymium ring magnet dome tweeter built for us by SEAS, the NrT provides high frequency extension to 28kHz with exceptional transient response. It provides crisp and airy highs with effortless dynamics and many layers of detail.

For those seeking even higher levels of details and transparency combined with improved soundstage width and imaging, we offer a tweeter upgrade using our customized version of the best true ribbon tweeter on this planet, the RAAL 70-20xr utilizing an amorphous core transformer (as opposed to iron/ferrite core.)

The midrange driver is housed in its own dedicated critically damped sealed enclosure within the cabinet and is designed to reproduce the critical midrange response. By isolating the midrange from the rest of the drivers, intermodulation distortion is greatly reduced and detail and separation between individual instruments is greatly improved.

Dual 5 ¼” long throw woofers handle the low end but don’t let the small size fool you, these woofers provide exceptionally tight and accurate bass reproduction well into the mid 30Hz range. Bass and mid-bass response are well balanced with surprising punch. The woofers hit hard and dig deep when required, but due to low mass and low stored energy combined with very low inductance levels, they are also detailed and subtle when need be. They will not gloss over notes that large diameter higher mass woofers can often miss.

All this combined in our exclusive minimal resonance layered bamboo cabinet and the results speak for themselves… This is a loudspeaker that simply must be heard to describe.

Our flagship center and simply one of the highest performance center speakers available at any price – the Sierra Horizon.

Hand assembled, tested and packaged in the USA, we are so confident of the component and build quality of the Sierra Tower that we are backing it by a comprehensive 7 year parts & labor warranty.  Left / right pairs are matched by hand to within ± 1dB and we are including a printout of the actual production line response measurements of each speaker. We dare say it, but you simply can not find this type of quality control, care and pride from products that are fully assembled and tested in overseas manufacturing facilities.

At Ascend, it is all about performance and we have found a unique way to offer exceptional natural beauty that also offers documented performance improvements. Now you can have that renowned Ascend performance AND good looks, all in a product that represents the very best of what we have to offer while joining the growing trend towards environmental responsibility.

We thank you for your interest!



  • All Sierra Horizons are hand assembled, tested and packaged at our factory in Orange County, CA.
  • A serialized production line frequency response measurement is included with each speaker.
  • 7 year manufacturer's warranty + 30-day satisfaction guarantee.


  • Exclusive 3-ply vertically laminated bamboo cabinet construction dramatically reduces cabinet resonance for a cleaner, more detailed, and transparent performance.
  • Cabinet is a stunningly beautiful natural hardwood finish, there are no veneers and as such, no need to be concerned about peeling veneers or wraps or veneer cracks.
  • Cabinet is fully environmentally friendly as the bamboo we source is a completely renewable resource.

Bass Woofers:

  • Injection molded mineral-filled polypropylene cone provides excellent stiffness and superior self-damping.
  • Long-throw design for high power handling and extended bass.
  • Cast aluminum frame for a exceptional rigidity and reduced resonance.
  • Exceptionally large magnet system for improved damping and lifelike dynamics.
  • Pure copper shorting ring to reduce distortion, linearize magnetic flux, and dramatically reduce inductance.
  • Vented pole-piece and vented spider for enhanced air-flow and cooling, minimizing compression artifacts.

Midrange Woofer:

  • Injection molded mineral-filled polypropylene cone provides excellent stiffness and superior self-damping.
  • Extreme low mass design for improved transient reproduction and lower stored energy.
  • Underhung voice coil for exceptional linearity and lower distortion.
  • Large metal phase plug for improved dispersion and enhanced cooling.
  • Inverted surround eliminates edge resonance.
  • Pure copper shorting ring to reduce distortion, linearize magnetic flux, and dramatically reduce inductance.
  • Vented pole-piece and vented spider for enhanced air-flow and cooling, minimizing compression artifacts.

RAAL 70-20 Ribbon Tweeter:

  • Fully custom true ribbon tweeter manufactured by RAAL in Serbia to our specifications.
  • True ribbon tweeter has no voice coil, the pure aluminum ribbon is the only electrical conductor and the only moving part.
  • Extremely low moving mass design, typically less than 1/50th the mass of a dome tweeter, enabling near instantaneous acceleration / deceleration, and no stored energy all combined to provide near perfect transient reproduction.
  • Class-leading horizontal dispersion width provides a huge soundstage and precise imaging.
  • High powered neodymium magnets in a unique homogenous design (equal strength magnetic field throughout the entire ribbon area) provides lower distortion and less stress on the ribbon diaphragm.
  • Critically damped rear chamber to absorb the back wave of the ribbon diaphragm, improving frequency response linearity and overall transparency.
  • Amorphous core transformer as opposed to ferrite reduces saturation and compression for much improved micro-dynamics and detail.

NrT Dome Tweeter:

  • 26mm high-definition soft dome custom manufactured by SEAS of Norway and exclusive to Ascend Acoustics.
  • Integrated elastomer wave guide.
  • Axially magnetized neodymium ring magnet with large damping chamber dramatically lowers the resonant frequency and effectively eliminates back-wave radiation.
  • Underhung voice coil for reduced distortion and improved transient reproduction.
  • Wide surround and low-viscosity magnetic fluid for higher power handling and improved transients.


  • Large open topology with proper inductor spacing and orientation to reduce mutual inductance and saturation.
  • Heavy gauge pure copper traces to reduce resistance and provide higher power handling.
  • Featuring metallized polypropylene capacitors.
  • Air-core inductors in the direct signal path.



Typical In-Room Frequency Response 37Hz - 27kHz
Typical In-Room Sensitivity 93dB @ 2.83v / 1 meter
Nominal Impedance 8 ohms
Max Continuous Power* 300 watts
Max Short Term Peak Power* 500 watts
Cabinet Detail Exclusive V-LAM™ construction featuring 20mm thick vertically laminated bamboo, internally braced. Bass reflex via dual front slot ports
NrT Dome Tweeter Option 26mm high-definition soft dome tweeter w/integrated elastomer wave guide. Axially magnetized neodymium ring magnet with large damping chamber and fully underhung voice coil, wide surround and low-viscosity magnetic fluid cooling. Fully manufactured by SEAS of Norway and exclusive to Ascend Acoustics
RAAL 70-20xram Ribbon Option Custom made RAAL true ribbon tweeter featuring a 20mm wide pure aluminum ribbon with a total moving mass less than 1/100th of a gram, large rear damping chamber and Amorphous core transformer instead of ferrite
Midrange Woofer Low mass 5.25” mineral-filled polypropylene cone woofer featuring an underhung voice coil with neodymium magnet system, vented pole-piece, vented spider and aluminum phase plug, inverted surround
Woofer (2) Proprietary 5.25” long-throw mineral-filled polypropylene cone woofers. Features non-resonant cast aluminum frame, copper shorting rings, low-inductance motor assembly, vented pole-piece and vented spider
Connections (2) gold plated all metal 5 way binding posts
Anechoic Frequency Response 41Hz - 27kHz +/- 3dB
Anechoic Sensitivity 90dB @ 2.83v / 1 meter
Dimensions H x W x D** 11" x 23" x 12.5"
Speaker Weight (each) 42 pounds
Shipping Weight (each) 48 pounds
Minimum Recommended Power At Listening Position for Specific Speaker Distances
3 Feet or Less 1 watts minimum
9 Feet or Less 8 watts minimum
15 Feet or Less 23 watts minimum
21 Feet or More 45 watts minimum
     *Unclipped peaks      **Grille On



*All measurements taken using DRA Lab’s MLSSA system with RCAI, calibrated ACO Pacific 7012 ½” free field measurement microphone with associated pre-amp and power supply and an automated Outline turntable.

Full-range quasi-anechoic on-axis frequency response:
Horizon Frequency Response Graph

Horizontal and vertical off-axis graphs plus listening window:
Horizon Off-Axis Graph
Listening window is the averaged response of 5 separate measurements, on-axis, +/- 15 degrees horizontal and +/- 15 degrees vertical. Note: due to the measurement technique, the response below 200Hz is invalid, as represented by the above and below horizontal green bars.

45 degrees off-axis horizontally is within +/- 6dB of on-axis up to 8 kHz, which is about the best there is in a horizontally configured center speaker. The horizontal listening window is +/- 45 degrees, which translates to nearly 20 feet wide (10 feet to left of center, 10 feet to right) at only 10 feet back from the speaker, which is remarkable.

Vertical response is extremely symmetrical, considering this is not a vertically symmetrical driver array, with a +/- 20 degree vertical listening window. This translates to a vertical listening window of ~7.25 feet at 10 feet back, approx 3.5 feet above listener and 3.5 feet below listener. This means the speaker won't sound different if you are sitting or standing and offers great placement flexibility (above or below the TV), while also not being too wide such that floor and ceiling reflections are causing problems.

Polar Response:
Horizon Polar Response
5 degree increments from 0 degs to a full 90 degs off-axis. Note how the critical midrange response remains linear and consistent with uniformly decreasing spl as frequency increases. Also note the lack of tweeter bloom as far off-axis as 45 degrees. Horizontal off-axis shows zero evidence of comb filtering (lobing) at any off-axis angle. This represents an exceptional off-axis response.

Impedance and electrical phase:
Horizon Bode Plot
Note the extremely clean impedance response (free from wrinkles which would represent various forms of resonances) and linear phase with minimal phase angles. The mild phase angles ensure that this speaker is an easy load for even basic receivers.

Energy Time Curve:
Horizon ETC Graph
This measurement is a good indication of overall transient accuracy and stored energy. The graph displays the decay time of a full range impulse. The impulse occurs at approx 2.8ms and decreases uniformly to the noise floor (-45db) by 4.4ms. This represents a decay time of 1.6ms, which is superb. Large diameter woofer cones, woofers and tweeters with poorly designed motor systems and/or heavy mass and poorly constructed cabinets will often contribute to far greater decay times which damage transient accuracy, coherency and overall resolution.

Cumulative Spectral Decay:
Horizon CSD Graph
This measurement is similar to the energy time curve but displays a 3 dimensional view such that we can examine the decay time with reference to frequency. It is an exceptional tool to reveal transient accuracy and indicate various problem areas with respect to resonance and stored energy. The CSD of the Sierra Horizon is exceptionally clean with good uniformity.



A high-performance center speaker is critical to any home theater system, it is the single most important speaker for this type of system.  The performance of our Horizon is well known, offering remarkable dialogue intelligibility from low volume levels to reference level volumes, even when sitting far off-axis. The Horizon offers best-in-class off-axis horizontal dispersion, while providing a smooth and detailed presentation with stunning dynamics.

Suitable for use as a center with any of our left/right speakers, and much like our Towers, the Horizon is a true end-game speaker, finding better center channel performance, regardless of price, would be most challenging.


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