Diving into the world of quadraphonic sound has been an interesting journey, marked by experimenting with various SQ decoders. My exploration so far includes both standalone units and those integrated into vintage receivers. Among the decoders I’ve tested are the Lafayette SQ-L and SQ-W external decoders, and the built-in decoders found in my Pioneer QX-9900 and a Sanyo DCX-3450K. While the Pioneer QX-949A isn’t explicitly part of this initial comparison, understanding the nuances of these decoders provides valuable context for appreciating the technology present in classic quadraphonic receivers like the Pioneer QX-949A.
Sanyo DCX-3450K: A Disappointing Start in Quad Decoding
Unfortunately, my experience with the Sanyo DCX-3450K’s decoder was quite underwhelming. Using Sly Stone’s Greatest Hits, a familiar SQ album with both vinyl and Q8 versions allowing for clear channel placement expectations, revealed significant issues. The Sanyo struggled with accurate channel assignment, placing instruments incorrectly, such as drums in the front channels when they were intended for the rear left. Vocals, meant to be centered in the front, were also misplaced in the rear. Strangely, the QS decoding on the Sanyo was surprisingly competent.
Pioneer QX-9900: Exploring Pioneer’s Approach to Quadraphonic Decoding
Moving on to the Pioneer QX-9900, a receiver from a brand renowned for its audio quality and potentially related in lineage to the sought-after Pioneer QX-949A, the decoding performance was a mixed bag. Despite being labeled as a non-logic decoder, some sources suggest it incorporates front-to-back logic. Regardless, the channel separation was noticeable, though far from discrete, likely due to blend resistors in the design. A peculiar issue was its tendency to center rear left and right channel information in the front center, at equal volume. While QS decoding was acceptable, like the Sanyo, it lacked the ability to steer sounds distinctly into each corner. Testing with The Grass Roots’ “Let’s Live for Today,” the discrete channel panning of “1…2…3…4” was not reproduced accurately on the QX-9900. This experience provides a glimpse into the era of quadraphonic technology that the Pioneer QX-949A also belongs to, highlighting the decoding limitations of the time.
Lafayette SQ Decoders: Contrasting Approaches to Matrix Decoding
Comparing the two Lafayette decoders I owned, the SQ-L and the SQ-W, brought further insights. Controversially, I found the SQ-L to be the more consistent decoder. It avoided the front-center channel overload with rear information seen in the Pioneer QX-9900. However, it wasn’t highly discrete either. The SQ-L effectively separated front and back channels but lacked distinct left-right separation in the rear channels and couldn’t precisely locate all four corners with test tones.
The Lafayette SQ-W, advertised as a full logic decoder, excelled in QS decoding. It nearly perfectly placed the “1-2-3-4” callouts from The Grass Roots into distinct corners with minimal bleed-through. Its QS section was truly impressive. In SQ mode, the SQ-W could locate corners well with test tones and cleanly decode the intro of Chase’s “Open Up Wide.” However, once the full music track began, the soundstage became less defined and instruments blurred together. While excellent at center-front localization, keeping vocals firmly in place, front-to-back separation was good but less pronounced than the SQ-L. Rear drums would have a noticeable ghost presence in the front channels (around 25%), and vice-versa, excluding center-positioned vocals. Front left-to-right and rear left-to-right separation were decent but not exceptional. For instance, a tambourine intended for the back left in a discrete mix would be louder in the back left in SQ but still audible in the back right – roughly a 60/40 distribution.
The Vintage SQ Decoder Dilemma: Discrete Still Reigns Supreme
Through these experiences, I’ve remained unconvinced by SQ matrix decoding. Even advanced software-based scripts, far superior to vintage hardware decoders, don’t match the clarity of discrete quadraphonic formats. While receivers like the Pioneer QX-949A offered quadraphonic capabilities and were highly regarded in their time, understanding the limitations of the era’s SQ decoding technology is crucial for modern listeners seeking the best quadraphonic audio experience. The journey highlights the inherent compromises of matrixed quadraphonic systems compared to the precision of discrete multi-channel sound.
