Anyone know the decoding equations for Trinaural stereo matrix intended to be used with 3 speakers ?
Trinaural Processor
I cannot find any related patents for James Bongiorno (the supposed designer) nor for the company Spread Spectrum Technologies from Espacenet 😕 What no patent ?!?
- Elias
Trinaural Processor
I cannot find any related patents for James Bongiorno (the supposed designer) nor for the company Spread Spectrum Technologies from Espacenet 😕 What no patent ?!?
- Elias
The website states that it uses some kind of vector based approach. I have no idea how one could realise this using an analog system, but it might be similar to the methods outlined in this paper? But perhaps you're already familiar with that paper.
This is nothing more than a Dolby Prologic approach to creating three channels out of two. Depending on how fast the steering logic is, and how good the cross cancellation vectors are used, you are going to get a deep soundstage and more narrow lateral soundstage, or a deep and very wide soundstage. If this processor splits it processing based on frequency(like Prologic II does) the effect is quite good with stereo sources.
As the article says, you have to get use to listening to three channels, as opposed to two. The presentation can be pretty different based on how good the processing is.
As the article says, you have to get use to listening to three channels, as opposed to two. The presentation can be pretty different based on how good the processing is.
Trinaural Processor says:
"the Trinaural Processor is a linear analog device with no digital processing whatsoever"
and based on what internet search gives me it seems to be linear time invariant matrix.
Just lacking the coefficients...
I even read the Austrian thread DIY Trinaural Decoder
DIY Trinaural Decoder - HiFi Forum
but no decoder equations !! I don't know how they manage to do it without coefficients ?? Supernatural powers or thin mountain air ??
- Elias
When I read Jim Fosgate's patent on Dolby Prologic II, it sounds remarkably familar to this approach. His first implementation of DPL II was done entirely in the analog domain, and I have seen and heard it myself in his lab. This is probably why you cannot find any patent on this technology by James Bongiorno, it was already patented by Peter Schreiber or Jim Fosgate - and I am thinking more from the latter than from the former.
Lot's of guessing going on here.
It's said the device is linear thus there cannot be any steering logic.
- Elias
It's said the device is linear thus there cannot be any steering logic.
- Elias
You are right, lots of guessing. I am curious to find out how they can get more than 3db separation without some sort of logic steering.
It is well known optimum linear matrix provides 6dB electrical separation between the three front channels.
Is that 6dB between L & C (or R & C) or is that 6dB between L & R ?
And is that true when the level of L (or R) is the same as C?
http://www.diyaudio.com/forums/mult...y-pattern-stereo-speakers-30.html#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.
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 this approach you are reducing comb filtering for a correlated signal by 6dB, but then you also get comb filtering on uncorrelated signals. Is it worth it?KSTR said:
I ask this because I find comb filtering between the two speakers to be the major drawback of stereo reproduction: it makes me aware of the two loudspeakers and takes me out of the stereo illusion all the time, resulting in a diffuse phantom image...
I have never tried Trinaural, but if it adds some more comb filtering how can it produce a better illusion?
Now we are getting somewhere ! Does there exist a reference for this information ?
I don't remember Gerzon had a matrix with 0.5 ? Which particular one this could be ?
- Elias
I should have said three front speakers. There is only two channels, of course. But yes, between three speakers maximum separation is 6 dB, L <-> C and L <-> R.
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.
Trinaural makes a different sound field around your head and quite more a difference in the room sound, and, if only for this, it is different. In fact Tri positions and sizes different kinds of phantom sources in a slightly different way than 2 speakers, and this not always in a "better" way. But more often it does, for me.
Trinaural makes a different sound field around your head and quite more a difference in the room sound, and, if only for this, it is different. In fact Tri positions and sizes different kinds of phantom sources in a slightly different way than 2 speakers, and this not always in a "better" way. But more often it does, for me.
Uncorrelated signals cannot comb filter. If there is comb filtering then the signals are correlated to some degree.
It is worth it.
I've been listening a couple of weeks 3 speaker stereo matrix with coefficient of 0.5, the optimum matrix. I have three identical prototype speakers, and I'm doing extensive comparisons with standard 2 speaker stereo. I can change the configuration from the listening position by use of a switch so A/B comparison is immediate.
So far I've listened about 100 songs and there is no single song I prefer with 2 speaker over the 3 speakers. That should tell some direction already 😉
- Elias
The basic TriField equations are :
L' = 0.5[(sin(phi) + w)L + (sin(phi) - w)R],
R' correspondingly, and
C = sqrt(2)cos(phi)(L+R)
A certain selection of phi and w should yield the trinaural amplitude relationships but I haven't tried to solve the eq's
EDIT: Once I progress to try a 3-way full TriField matrix with the coeffs that Gerzon recommends, and with DSP linear phase, I'll know....
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It could be interesting. Is it known what order the low-high pass filters are in Trifield decoder ? I've allways assumed 1st order.
An uncorrelated L/R stereo signal split into 3 speakers following this matrix will result in correlated sound between speakers, as they all have sums or differences of L and R...
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