John go ahead & move this if it would be better in Accessories or whatever...
Member Ricmon owns two of Bongiorno’s SOA stereo amps; he twice requested this review, so here it is.
Bongiorno’s Trinaural Processor arrived early this decade at $1200 USD list & is now $2k. It is pure analog, stereo input/3.0 to 3.1 output. All inputs are SE; each of the four outputs have the following: SE standard polarity, SE inverted polarity, balanced XLR.
The bass output has variable level & is low-pass crossed w/ a fixed pole in the neighborhood of 80 Hz. A very transparent high-pass fixed-pole XO can be switched in/out for the main channels. The Trinaural is probably best described as a pure analog 3.1 version of Meridian’s Ambisonic DSP. I’ve not heard Ambisonic but the algebraic formulas appear to be similar (Trinaural being analog only; Ambisonic being digital). It is important to note that the center channel is not a simple summed mono & that all three front main channels are processed via Bongo’s proprietary algebraic formula.
As a brief sidebar, Stereophile did a pretty thorough article summarizing the well-researched long-known deficiencies of the stereo format & the advantages of a three channel system. Both the Trinaural & Ambisonic were mentioned & described to some extent.
The Trinaural was for a long time a Stereophile class-A recommended component; the reviewer was not anxious to return to stereo. Earlier in the history of Meridian’s Ambisonic processors, one was similarly raved about in Stereophile & also a class-A recommended component. A Meridian Ambisonic processor also won the CES Best of the High-End Award years ago. From all my reading Ambisonic is the only digital processing to up-convert a stereo input into a greater number of channels & unequivocally improve performance in every way. Meridian invented Meridian Lossless Packaging (MLP), licensed worldwide & one of the most successful commercial products of its kind.
I will never willingly choose to return to stereo after living w/ the performance upgrade of the Trinaural. Every audiophile performance parameter is hugely improved. I don’t want to elaborate on this because it’s boring to read. Just insert your most glowing review here. One thing I will specify is that playing certain vinyl, the stage & images fill the entire front half of the room, like you are swimming in it.
The best I’ve heard other than this Trinaural system (maybe just as impressive but not necessarily better) are these two systems heard a few years ago in Las Vegas: one was the TAD system at T.H.E. Show, Reference Ones (or their successor) a huge array of Pass amps & the 24k/192 hard drive master on which was originally recorded Boz Scaggs, My Funny Valentine recorded only w/ Boz singing & playing his gorgeous sounding grand piano in his home; processor was a 10-15 year old pro model whose name escapes me & was at the time regarded as still unsurpassed by Andrew Jones. The other system was Ray Kimber’s at CES, about $350k + total MSRP, ditto huge array of Pass amps, two floor to ceiling Sound Lab stats in each of four corners in a huge room playing Ray’s own original 4-ch Iso-Mic SACD recordings. (May have been the original hard drive masters. FYI this specific system, displayed several times in public, is now permanently retired because of the risk in damaging the stats. The recordings were made at Weber State University about 30 minutes south of me. All Iso-Mic are 4-ch discreet recordings that can of course be played back on any 2-ch system.)
A few notes about benefits not apparent unless you have lived w/ the Trinaural for some time. This goes against all intuition yet it is advertised by Bongo & it is the case in my personal experience: The L/R channels must obviously be identical but the center can be different. If any disparity exists the center performance must be better than the L/R, never vice versa. The center is dominant while the L & R are demoted to effects/ambience roles similar to other multi-channel formats. When auditioned w/ a huge floorstanding center speaker & L/R standmounts by the same speaker maker the performance was exemplary. Currently my L/R speakers have sloped baffles while the center has a vertical baffle & is a completely different brand, yet they sound coherent & blend perfectly. Yes, these “mismatched” speakers do have very similar musical presentations but they are still very different in overall architecture.
The ability to mismatch the front channels provides a huge cost-saving potential. You can put one more costly speaker in the center & two lower cost speakers at the L/R effects channels. There are most likely some mismatches that won’t work, but I can emphatically state that two speakers that look like they’d never work may indeed work (as is the case in my system).
That’s just the speaker angle. In my case the ultimate goal is three exactly matched bipolar clones of my French ASA Pro Monitors. I’m quite happy w/ my current amplification but I am also very familiar w/ the advantages of the best tube amps. I intend to audition a tube amp powering the center channel. If performance improves as expected, someone has graciously offered to make one custom 30W 845 tube monoblock to power my center channel.
Yes, I hear you saying that’s all nice but you’ve got the weirdest system in the world w/ absolutely no resale value so I’d never consider doing anything so dumb. That’s fine. Except that as mentioned above I have no interest in ever returning to the inferior performance of the best stereo, meaning I’m happy to commit to the permanent nature of the system. The coming speakers & the 845 amp are intended to be final purchases. I’ve heard enough of everything offered in the audio world to be convinced that nothing’s likely to be on the horizon to make me want to put the intended gear on the auction block.
Another advantage is that the variable bass output w/ HP & LP crossovers work perfectly w/ standmount speakers. One advantage of standmount speakers is that their smaller enclosure dimensions push the standing wave frequencies up higher where they can more efficiently be damped (damping materials inside speakers are ineffective below 200 Hz). Plus smaller speakers often have narrower baffles for improved stage/image performance.
An unintended consequence is that high-pass crossed standmounts work splendidly w/ a subwoofer system. The past year brought to my attention what I believe is the best subwoofer system philosophy extant in providing large-room (read commercial size) bass performance in a small (domestic) sized room & the most efficient method of flattening bass modes. So the whole system just happened to evolve into something that I think I can live w/ for a long, long time if not forever.
Finally, I’ve known for about 20 years that absolute polarity makes a worthwhile audible difference. The XLR balanced outputs offer the following potential. I made a box that accepts the Trinaural XLR balanced outputs; a 4PDT switch selects between normal or inverted polarity then outputs single-ended signals to the sub & three front amp channels. Even in a stereo-only system the Trinaural could function as a transparent high-quality polarity switcher w/ the addition of a simple outboard box. (Incidentally, my box was hard-wired.)
There are HT bypass inputs to integrate the 3.1 channels into a HT system.
That’s my story & I’m sticking to it! My 2 yen.