These speakers certainly catch the eye with their distinctive Pioneer branding, reminiscent of car audio systems rather than home speakers. Having spent considerable time evaluating the Pioneer SP-BS21-LR, this review delves into a comprehensive assessment of their performance, addressing earlier impressions and providing a detailed analysis. Despite initial reservations, these speakers continue to be a recommended option for some, warranting a thorough examination.
Visual Examination
Removing the speaker grills proved to be an unexpectedly challenging task, requiring tools typically reserved for more unconventional situations. This immediately raised questions about what design choices lay beneath the surface.
The aesthetic appeal of the grills seems to come at a significant acoustic cost. From a performance perspective, these grills are far from ideal. If Andrew Jones, the designer, had been consulted on grill implementation, a stronger emphasis on acoustic transparency would likely have been prioritized.
With the grills removed, the visual presentation shifts dramatically, revealing a less refined aesthetic. While sound quality generally takes precedence over visual appeal in audio equipment, the exposed drivers present a somewhat unattractive appearance. The combination of a square frame driver within a circular housing and a plastic waveguide tweeter projects a budget-oriented image. It becomes clear why the grills were employed in the first place – to conceal these less visually appealing elements. However, the acoustic compromise introduced by the grills is substantial, forcing a choice between compromised sound and an unappealing visual.
Driver Components
The tweeter is a notable 1-inch textile dome design, integrated within a plastic waveguide. This waveguide aims to control the tweeter’s dispersion characteristics to match those of the woofer. While this directivity matching is a design element often associated with Andrew Jones’ speaker designs, its practical benefit is debatable. The intention is to create a more cohesive soundstage, making the tweeter sound as though its output originates from the woofer’s location.
Visually, the woofer cone appears somewhat undersized relative to the tweeter’s prominent waveguide. This might be a consequence of utilizing readily available, off-the-shelf components to meet budget constraints. The woofer’s appearance is reminiscent of drivers found in certain Aura speakers or even larger soundbars, suggesting a focus on cost-effectiveness.
The woofer assembly incorporates a substantial plastic ring housing, which seems more like an afterthought in design than a deliberate aesthetic choice. Despite this, the driver features a reasonably sized magnet and a quality spider, indicating a focus on core performance within the budget category. The components suggest a capable driver for speakers at this price point.
The rear panel includes a bass reflex port and gold-colored binding posts, which add a touch of perceived quality. Notably, Andrew Jones’ signature is prominently displayed on the back panel, highlighting his design involvement.
Setup Configuration
In a desktop listening environment, despite their size, the SP-BS21-LR speakers necessitate stands to elevate the tweeters to ear level for optimal soundstaging. Using improvised, non-vibrating risers effectively achieves the desired tweeter height.
Initial Uncorrected Sound Impressions
Straight out of the box, the immediate sonic characteristics are “boomy” and “inefficient.”
However, they possess positive attributes when used with content lacking deep bass and at moderate listening volumes. In such scenarios, the waveguide design contributes to good imaging, creating a sharp and focused, albeit somewhat detached, soundstage.
The rear port is a potential source of sonic issues. Attempting to mitigate boominess through port stuffing or speaker placement adjustments proves ineffective. Even when positioned away from walls and room boundaries, the low-frequency response retains a boomy quality, more akin to a budget 2.1 system’s subwoofer than a refined bookshelf speaker.
Frequency Response Measurements
Frequency response measurements, taken with tight windowing to minimize reflections and without smoothing, reveal a significant deviation of ±5dB across the audible spectrum above 1kHz.
Contrary to initial subjective impressions of boominess, the measurements indicate a more accurate description would be “muted treble.” This lack of high-frequency output also explains the perceived inefficiency. A nearly 10dB dip in output at 5kHz, relative to the woofer’s mid-range level, is audibly substantial and contributes to the speaker’s muffled character.
DSP Correction Implementation
The implemented DSP correction strategy focuses on subtractive equalization. This approach involves attenuating frequencies above the lowest point in the frequency response to achieve a flatter overall response. In the case of the SP-BS21-LR, significant cuts were required to restore a discernible treble presence. Additionally, a bass boost was applied below the port tuning frequency to enhance low-end extension. This bass adjustment was largely done subjectively by ear due to limitations in accurately measuring bass response in the current testing environment. The resulting corrected response aims for a more balanced sound, though it still necessitates placement away from walls, especially in desktop setups.
Corrected Sound Impressions
Recent amplifier changes are relevant to evaluating the corrected SP-BS21-LR’s performance. Following the demise of a JVC 1024vbk amplifier, a switch was made to a Muse M50, a compact amplifier rated at approximately 30 watts per channel (WPC). A separate review of the Muse M50 is forthcoming. While the M50 is sonically neutral, it lacks the power reserves of the larger JVC.
Amplifier power becomes critical post-correction because the DSP adjustments for the Pioneer BS21-LR dramatically reduce their efficiency. Substantial amplifier power is now needed to achieve higher listening levels. The 30WPC Muse M50 struggles to drive the speakers to even moderate volumes on a desktop, reaching around 85dB before audible distortion emerges. This distortion seems to originate from both the amplifier clipping and potentially stress on the tweeter, manifesting as smeared high frequencies and listening fatigue. A more powerful amplifier may yield improvements, but the speakers’ 80WPC power rating suggests a risk of damage if driven too hard in pursuit of spirited listening levels.
Final Verdict
In their uncorrected state, the Pioneer BS-21’s sonic performance is subpar. The issues are not typical of cheap, crossover-less speakers (which often exhibit ringing resonances), but rather stem from a tonally imbalanced and boomy sound profile. It appears the passive crossover network heavily attenuates higher frequencies, creating substantial deficiencies in the treble range.
Listeners who primarily listen at or below 85dB might find the corrected sound acceptable. However, even with DSP correction, these speakers present significant compromises. Ultimately, these speakers are not recommended, whether used with or without correction. They are frustratingly flawed, and the extensive DSP correction required diminishes overall performance to a point where they are not a worthwhile investment.
For those who already own the BS-21s, removing the grills and applying DSP correction as provided is recommended to experience their potential, albeit limited. If dissatisfaction persists, selling the BS-21s and upgrading to alternatives like the Micca MB42x or Pioneer BS-22 is strongly advised.
Click here to download the DSP correction file for Pioneer SP-BS21-LR speakers.
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Further Reading
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