Trinaural decoding equations for 3 speaker stereo matrix ?
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 14th March 2013, 08:58 AM #151 hajj   diyAudio Member     Join Date: Nov 2009 Thanks for the quick reply Elias. I now have more questions, what would the values of Rps & Cps have to be for 8ohm drivers? Or to be more general, what's the equation that dictate Rps & Cps? Furthermore, only one of my amps in my stable has a common ground at the speaker output, and it's the amp that sounds the least good. So, although I know that for most people, being able to derive trinaural audio for a single two channel amp is the better/easier/cheaper solution, in my specific case, a line-level circuit would be better suited. Just wondering if there is such a passive circuit (or an easy active one) available at the moment.
Elias
diyAudio Member

Join Date: May 2003
Location: Suomi
Quote:
 Originally Posted by hajj Thanks for the quick reply Elias. I now have more questions, what would the values of Rps & Cps have to be for 8ohm drivers? Or to be more general, what's the equation that dictate Rps & Cps? Furthermore, only one of my amps in my stable has a common ground at the speaker output, and it's the amp that sounds the least good. So, although I know that for most people, being able to derive trinaural audio for a single two channel amp is the better/easier/cheaper solution, in my specific case, a line-level circuit would be better suited. Just wondering if there is such a passive circuit (or an easy active one) available at the moment.

For 8 ohm drivers you may start experimenting with
Rps = 4.7 ohm
Cps = 4.7 uF

Roughly the function can be describes as:
With smaller values of resistor the center signal is attenuated more and side signals are boosted more.
With smaller values of capacitor the filtering action starts higher in frequency.

There is plenty of room for experimentations I believe, since every listening room is different including wall absorption, lateral dimensions and the listening distance.

Happy experimenting !

- Elias
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Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets

 15th March 2013, 02:21 PM #153 hajj   diyAudio Member     Join Date: Nov 2009 Got it, Thanks! Will try to start experimenting this weekend. Will do also do more reading and try to derive some line level circuit. Thanks again. Regards Nick
ro9397
diyAudio Member

Join Date: Jan 2007
Location: No. Utah
Quote:
 Originally Posted by KSTR That will remain to personal taste I guess. Some people are more sensitive to subtle tonal coulouring etc, others are more after the most realistic spatial impression. Trinaural is more something for the second group, one could say. Also it may depend on the genre and style of music you play.
Lynn Olson describes how proper 3-ch more accurately reproduces tonal qualities in the C Ch vs. stereo's phantom C. I absolutely agree. I am Trinaural user since 2007 and never prefer 2ch.

I often switch back to 2-ch and quickly adapt, thinking Trinaural is unnecessary. Immediately upon switching back to Trinaural I notice how inferior and how mucked up was the tonal color of stereo's phantom C. You have to really know the true currency to recognize the counterfeit.

For Trinaural I increased L/R spacing 62% (Golden Ratio) beyond Cardas' 4/5th specification. Trinaural has wider stage and images extend farther vs. stereo. Audience members appear 75' beyond side and front walls.
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James
"Television is the poor man's whiskey." Russel Baker

ro9397
diyAudio Member

Join Date: Jan 2007
Location: No. Utah
Quote:
 Originally Posted by KSTR http://www.diyaudio.com/forums/multi...ml#post2731346 Bongiorno's Trinaural is the same as Miles' Optimum Linear Matrix with k=0.5 and also one of Gerzon's TriField variants, if I gather up things correctly.
With all due respect, James never disclosed Trinaural "algebraic processing" so there's nothing to "gather".

I know only one living person who likely has access to the formula and he has every reason James did to keep it secret.

Trinaural released early 2000s for \$1500 and is now \$2500. With average discount I consider it decent value or better.
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James
"Television is the poor man's whiskey." Russel Baker

ro9397
diyAudio Member

Join Date: Jan 2007
Location: No. Utah
Quote:
 Originally Posted by markus76 ...in your personal priority list of what sound reproduction needs to be capable of. That list might not be the same for everybody. My priorities are certainly different. Your page says "center phantom image weak or non existent" for frequency band 1-20kHz. It doesn't say 6-20kHz!? The cutoff in the track I've used is 1.6kHz (not 1kHz as in your example), still I get a perfect phantom center. You skipped over my questions about room and speaker characteristics in your listening test.
Your C image may indeed be perfect, no sarcasm. My best references are Crump's last CES (two large Soundlab stats, Blowtorch, hot as a mutha JC1s) and Kimber's best ever IsoMic never again to be displayed, eight floor to ceiling stats (2 per corner), proprietary IsoMic 4.0 DSD, oodles of Pass class A amps.

My center image in stereo equals about the best I've heard. After switching to Trinaural it is immediately apparent that the stereo image that seemed "perfect" a minute prior, has extreme tonal aberrations. In stereo the saxophone sounded more like a plastic toy well played. In Trinaural the glory of the instrument is crystal clear and obvious.

It's as subtle as a 2x4 to the thigh.
__________________
James
"Television is the poor man's whiskey." Russel Baker

ro9397
diyAudio Member

Join Date: Jan 2007
Location: No. Utah
Quote:
 Originally Posted by Lynn Olson No question that 2-speaker stereo suffers from severe comb filtering for centered images - specifically, vocalists. I sometimes wonder if that's why some recordings have the vocalist a bit off-center. The comb filtering noticeably changes the timbral balance of the singer - but then again, just about all recordings have a final mastering on a 2-speaker playback system, and the EQ is intended for 2-speaker playback (with a secondary cross-check for single-driver lo-fi mono playback). Just guessing here, but I'd imagine that vocals sound a bit more direct and "up-front" on a symmetric 3-speaker playback system, due to the absence of comb filtering for the centered singers.
Last sentence: Bingo!

Lynn, are you ever wrong?

I'm 75 minute drive NE of Salt Lake City. Anyone who wants their "sacral" 2-ch paradigm destroyed is welcome!
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James
"Television is the poor man's whiskey." Russel Baker

Last edited by ro9397; 24th July 2013 at 08:49 PM.

Elias
diyAudio Member

Join Date: May 2003
Location: Suomi
Quote:
 Originally Posted by ro9397 With all due respect, James never disclosed Trinaural "algebraic processing" so there's nothing to "gather". I know only one living person who likely has access to the formula and he has every reason James did to keep it secret. Trinaural released early 2000s for \$1500 and is now \$2500. With average discount I consider it decent value or better.

I am also giving respect, but I cannot help noticing in Austria they are building DIY trinaural decoder
DIY Trinaural Decoder - HiFi Forum

I don't know how they are able to do it without knowing the matrix coefficients ?

However, it is very easy to measure the coefficients by test signal if one has access to the original Trinaural equipment. Afterall, it is said to be linear static matrix, right.
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets

Last edited by Elias; 24th July 2013 at 09:03 PM.

ro9397
diyAudio Member

Join Date: Jan 2007
Location: No. Utah
Quote:
 Originally Posted by markus76 The "clang" of cymbals is typically in the hundreds, even as low as 200Hz.
Excellent point.

The audible spectrum is 20-20kHz, while "middle" C is a mere 262 Hz! (1st fret of the 2nd highest string, 2nd string from the bottom, standard guitar tuning...listen to it next time you pass a guitar)

Notice how "piercing" high is that 1kHz test tone.
__________________
James
"Television is the poor man's whiskey." Russel Baker

ro9397
diyAudio Member

Join Date: Jan 2007
Location: No. Utah
Quote:
 Originally Posted by Elias I am also giving respect, but I cannot help noticing in Austria they are building DIY trinaural decoder DIY Trinaural Decoder - HiFi Forum I don't know how they are able to do it without knowing the matrix coefficients ? However, it is very easy to measure the coefficients by test signal if one has access to the original Trinaural equipment. Afterall, it is said to be linear static matrix, right.
Excellent! Thanks for posting that! Now that I read this, I remember it indeed crossed my mind years ago that all one must do is input signals and check what happens at the output. Moderator please delete my stupid post above!

If the math is so basic and easy, why do Japanese mass market receivers not employ it? All their multi channel synthetics sound like crap. I suppose it just reflects how dumb they are.

What is estimated parts cost to make DIY at least equal to the original in pure sound quality? Also, is it easy to adapt the math to the digital domain? Is it possible that Dolby Pro Logic II properly implemented with state of the art digital technology can create a new digital benchmark? If so, strange indeed! DAC makers take note! Time to add value!

Jim Smith said he thought Trinaural C Ch quality was inferior to the L/R. I had to admit, after he said this, I though I noticed a disparity in quality. All three of my speakers are identical highly refined 2-way stand mounts crossed in Trinaural @ 80 Hz. Elevating the C Ch speaker 1.75" (no other change) seemed to completely cure the disparity.
__________________
James
"Television is the poor man's whiskey." Russel Baker

Last edited by ro9397; 24th July 2013 at 09:20 PM.

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