Sierra - Tweeter and Woofer
Time to discuss the Sierra tweeter...
In order to realize our goal of reducing the negative acoustic effects caused by each loudspeaker component, the Sierra would require a special tweeter. In addition to my typical requirements (linear on- and off-axis response and excellent extension), I demanded an exceptionally clean spectral decay combined with very low distortion. Of course, our good friends at SEAS of Norway were once again up to the task.
SEAS engineers recommended a new tweeter currently under development that I could customize to suit Ascend’s needs. Of course, this new tweeter took a bit longer than expected, but the first samples finally arrived and the results were very impressive. This new tweeter has a few unique features. It contains an integrated slightly elliptical wave guide made of flexible and absorbent elastomer. The subtle shaping helps control the off-axis response and aids in the reduction of diffraction, while the elastomer material helps absorb stray high-frequency wavelengths. The wave guide insert also has the added benefit of covering the magnet assembly screws, thus eliminating the pesky reflections these cause.
The tweeter also contains an extremely wide integrated surround (the part of the tweeter that attaches the dome to the faceplate). This serves to better dampen the dome, thus reducing various resonances and break-up modes.
We added our own customizations to this already superb tweeter to further improve performance.
The final result is a tweeter with an extremely impressive spectral decay. Both harmonic and IM distortion are extremely low and the frequency response is smooth and linear both on- and off-axis. This tweeter is incredibly natural sounding, with a clear and detailed character that is crisp without ever being fatiguing. It literally oozes that magical “airy” sound that is so elusive yet critical to a high-end loudspeaker.
Tweeter Features:
- Fully manufactured by SEAS of Norway
- 26mm high-definition pre-coated fabric dome
- Fully integrated slightly elliptical wave guide made from elastomer to reduce diffraction and control off-axis response
- Integrated wide surround for reducing resonance and break-up modes
- Low viscosity magnetic fluid for improved power handling and damping
- Pole piece damping chamber to absorb back-wave reflections and lower the resonance frequency
- Exceptionally clean spectral decay and low distortion for greater detail and improved accuracy
And, last but not least... The woofer...
Why stop with exceptional accuracy? Why not improve accuracy while also offering a broader frequency range? Ascend loudspeakers have never been known for their bass response, but what if I could design a woofer that was capable of offering accurate and deep bass response while also being able to reproduce the delicacy of midrange frequencies?
I tested dozens of woofers; some had great mids, others great bass – none offered both. Like all of Ascend’s previous products, the woofers were fully designed by us. It would require good excursion while remaining linear so that mids can be reproduced with accuracy. Reducing intermodulation distortion and keeping harmonic distortion under control would be most critical to performance. I would need a heavier mass cone to reproduce deep bass yet the area of the cone would need to be small to reduce cone breakup and resonance at higher frequencies. Additionally, the woofer must have a low inductance motor so that transients are reproduced quickly and with great accuracy.
This woofer took years to get “just right”. It was a source of frustration for both me and the various vendors we had working on it. In the end, the final results speak for themselves… The combination of this custom designed woofer, low energy loss rigidity of the bamboo cabinet and the custom designed high-flow port tube provide an accurate bass response well into the low 40Hz range with exceptionally accurate transients. The accurate anechoic -3dB point of the Sierra is 44Hz. No bumps to provide added warmth, just accurate and exceptionally punchy bass, no bloat or muddiness. You can expect in-room response to be -3dB at about 40Hz, while still providing clean and detailed mids. I think the bass response from this speaker will surprise youIt is deeper and more dynamic than many “full range” floorstanders I have auditioned.
Woofer Features:
- 5.25” long-throw injection molded mineral-filled polypropylene woofer
- Cast aluminum frame for exceptional rigidity and reduced resonance
- Vented pole-piece and vented spider to reduce compression effects and increase compliance
- Full size copper shorting rings for substantially reduced distortion
- Low inductance motor for accurate transient reproduction and detailed mids. Half the inductance of any other woofer we measured!
Quasi-Anechoic On-Axis Frequency Response
Cumulative Spectral Decay -- Very Clean!
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Originally Posted by curtis
