When you mention the Ambisonics website and their decoder in the same breath, I'm guessing you're referring to
Cantares and its
SSP-1 Surround Sound Processor/Decoder. I've not heard the decoder and have had no contacts with the company, so I cannot speak with any authority about its performance. I'll have to defer to the
Audio Media review of the Cantares decoder.
The review does not have a great deal to say about its SQ and QS performance. Nevertheless, we can probably assume that these are simple decoders which come no where near to matching the capabilities of the Fosgate Research Tate II or the Sansui Vario-Matrix units. If you were to buy it, it would be for the UHJ capabilities. And for that it is pretty expensive. Even the professional version of Minim's AD-10 Ambisonic decoder, built of hand-picked components, retailed for only $1000 in the mid-'80s. The standard version of the AD-10 went for $500 and the scaled-down AD-7 cost a mere $250. And I cannot imagine that the sales volume was that high for these units.
What impressed me about Ambisonics is the common sense of the approach. Quad systems from the '70s and latter day digital surround systems contain speaker feeds. That is, they encode signals meant to go to a particular speaker. If the arrangement of your speakers is not ideal for these feeds, you get a less than ideal presentation. Ambisonic recordings contain an omnidirectional signal and multiple directional signals. On the front of the Ambisonic decoder, you specify the layout pattern of your speakers. The decoder then creates speakers feeds that are ideal for your layout.
Probably Ambisonics failed to catch on because it did not come from a marketing behemoth like Dolby Labs. Capitalism, contrary to the opinions from some quarters, does not always bring us the best products, only adequate ones. Also, I think potential customers probably assumed that it could only produce ambience recordings. Nothing could be further from the truth. It can reproduce any sort of dazzling, swirling pan-pot effects you could desire. Regretably, I know of no commercial Ambisonic recordings that showed off this capability; if you're aware of any, let me know. However, I have heard live Ambisonic recordings, made with the Calrec Soundfield microphone, that provided the best surround imaging I've ever heard. I could distinguish the reactions of individual audience members beside and around me. Their location was specific and rock-solid, and this was from a UHJ-encoded LP. I never had that experience with SQ or QS, and I just haven't listened to live digital surround recordings. However, the digital recordings suffer from the same deficiency as SQ and QS, relying on pair-wise mixing to produce speaker feeds, and, as I stated in a previous post, pair-wise mixing does not work for side and rear images.
For those who want a quick Ambisonic tutorial and links to other Ambisonic information sites, feel free to visit the
UHJ Ambisonic Encoding page at my site.
Larry