• QuadraphonicQuad welcomes you and encourages your participation! Treat all members with respect. Please keep all discussions civil, even when you have a strong opinion on a particular topic.

    Do not offer for free, offer for sale, offer for trade, or request copies or files of copyrighted material - no matter how rare or unavailable to the public they might be. We do not condone the illegal sharing of music. There are many places on the internet where you can participate in such transactions, but QuadraphonicQuad is not one of them. We are here to encourage and support new multichannel releases from those companies that still provide them and as such the distribution of illegal copies of recordings is counter-productive to that effort. Any posts of this sort will be deleted without notification.

    Please try to avoid discussions that pit one format against another. Hint for new users: make liberal use of the search facilities here at QuadraphonicQuad. Our message base is an incredibly rich resource of detailed information on virtually all topics pertaining to surround-sound. You will be surprised at what you can find with a little digging!

SQ Shadow Vector Soundfield Mapping

Help Support QuadraphonicQuad:

Sonik Wiz

1K Club - QQ Shooting Star
QQ Supporter
Joined
May 30, 2005
Messages
1,240
Location
Kansas City
While I was googling to look up patents under Lynn's name I ran across a page on GitHub by Markk Merzin. He claims to have a LADSPA plug in for doing SQ decoding with Shadow Vector enhancement. I can't tell much about it because it's in in command line & Linux. So perhaps someone smarter than I can suss it out.
I mean if this was for real certianly wouldn't quaddie's already know about it?
 
Last edited:

Owen Smith

300 Club - QQ All-Star
Joined
Apr 6, 2012
Messages
319
Location
UK
While I was googling to look up patents under Lynn's name I ran across a page on GitHub by Markk Merzin. He claims to have a LADSPA plug in for doing SQ decoding with Shadow Vector enhancement. I can't tell much about it because it's in in command line & Linux. So perhaps someone smarter than I can suss it out.
I mean if this was for real certianly wouldn't quaddie's already know about it?
I write C code for a living. I had a look at the code on github and it contains almost no comments explaining how it works. So good luck to anyone, including the author, working out what it does.
 
Last edited:

BJMarsh

Member
Joined
Jul 21, 2007
Messages
14
Yeah, I saw this about two weeks ago. Downloaded the source code and try to build it. I’m missing some header files and probably other stuff as well. I put it aside for now. Maybe get back to it in a while.
 

Lynn Olson

Active Member
Joined
Aug 29, 2010
Messages
93
Hi, Sonik Wiz, I only have three patents. The first is for Shadow Vector (assigned to Charles Wood and Cliff Moulton of Audionics), the second is for a three-dimensional mouse (assigned to Tektronix and not pursued by them, although cited in many later patents), and a digital storage-scope display that mimics phosphor trace brightness and decay over time (co-invented with Bob Bales and also assigned to Tektronix, and this one became the foundation of “digital phosphor” in modern scopes).

Although not credited with a patent, I consulted with one of the TATE principals around 1978 or so and devised a simple re-matrix that allowed them to use a professional QS decoder for a novel diamond-shaped matrix, with outputs of Screen Left, Screen Center, Screen Right, and Auditorium. I think you can guess who sold this matrix to Dolby after I returned to Oregon, none the wiser. I received a one-time payment of $500 and that was the last I heard of it until I saw a big-screen movie that used that matrix.

I also have an AES Journal Tech Note for a “Stereo-180 Microphone” around 1979. This used a pair of Limacon-pattern mikes at a critical spacing to generate wide-field stereo playback on normal stereo speakers, which was also compatible with QS playback.

The rest of my audio work was in loudspeakers. Immediately after the BBC/EMI tour in Europe in 1975, the Shadow Vector was shelved in favor of TATE DES, and I was recruited into loudspeaker design after Audionics’ designer high-tailed it out town with no forwarding address or phone number. I either taught myself or found another line of work. So, I taught myself, and a number of speakers followed. Almost nothing in loudspeakers is really patentable ... nearly all the patents that are issued are abuse of the patent office, with trivial variations of ideas that are decades old.

I was so disgusted by Audionics that I stayed out audio for nearly a decade. I didn’t get back in until the early Nineties, when the vacuum-tube triode revival began. That’s when I began writing for Positive Feedback magazine, Glass Audio, and Vacuum Tube Valley (brief stints as Tech Editor for the last two). The DIY projects I created were the Ariel and ME2 loudspeakers, and the Amity and Karna amplifiers. The notoriously long-delayed “Beyond the Ariel” high-efficiency loudspeaker was actually built by Gary Dahl in Washington State.

So I guess my career started with quadraphonics, followed by loudspeakers, then tech writing and network design, then more writing and self-taught amplifier design, with a brief foray into horns mentored by Bjørn Kolbrek, who I regard as one of the world’s premier horn designers. His doctoral thesis became the AH-425 Azurahorn, built in Perth, Australia, and a key component of the “Beyond” project. Bjørn is now at Celestion Loudspeakers in the UK, the last I heard, although he might have returned to his native country of Norway.

As you can tell, I enjoy working with international collaborators, which is why I’m so pleased to see the arrival of the Australian Surround Master and the development of the UK’s better-than-ever version of Shadow Vector. I’m bunkered down here in Colorado, which seems to be doing an OK job on CV19 so far. We have groceries delivered to the house, and plan to stay bunkered down until things are under control and it’s safe for an oldster like me to venture out. At least we have a magnificent view of the Rockies, and a pleasant bike-path to walk the doggie several times a day.

Doggo is sleeping right next to me now, curled in a little ball on her dog-bed, as I type this on my iPad in the dark. Looks like we’ve got another bright sparkling Spring day tomorrow, as we go into Week Eight of self-isolation.
 
Last edited:

jonmchugh

Active Member
Joined
May 5, 2019
Messages
56
Location
UK
While I was googling to look up patents under Lynn's name I ran across a page on GitHub by Markk Merzin. He claims to have a LADSPA plug in for doing SQ decoding with Shadow Vector enhancement. I can't tell much about it because it's in in command line & Linux. So perhaps someone smarter than I can suss it out.
I mean if this was for real certianly wouldn't quaddie's already know about it?
It pretty easy to build, Just needs the ladspa-sdk installed as well as the usual build tools.
Here is a SQ test tones decode using it.
 

Attachments

Sonik Wiz

1K Club - QQ Shooting Star
QQ Supporter
Joined
May 30, 2005
Messages
1,240
Location
Kansas City
It pretty easy to build, Just needs the ladspa-sdk installed as well as the usual build tools.
Here is a SQ test tones decode using it.
Well this is interesting. Owen pretty much dismissed software Shadow Vector, BJMarsh gave it a try & couldn't do anything with it and then you seem to have installed & using it already! The only I know less about than LINUX is golf. Can you give some insight as to how this actually functions? Is there any way to verify it truly follows Shadow Vector parameters & not some other form of high seperation SQ? As the author stated it might be able to be ported to Windows. Copuld you do that? And lastly I wonder if the maths involved would be helpful to Malcolm & his project.
 

jonmchugh

Active Member
Joined
May 5, 2019
Messages
56
Location
UK
I can hear no difference at all between decodes done with the shadow vector markmerz code and those done previously with the Auroran audition script.
However the markmerz code is something like 15 times faster! It can also be run in real-time live which some people might find interesting.
 

Sonik Wiz

1K Club - QQ Shooting Star
QQ Supporter
Joined
May 30, 2005
Messages
1,240
Location
Kansas City
Hi, Sonik Wiz, I only have three patents. The first is for Shadow Vector (assigned to Charles Wood and Cliff Moulton of Audionics), the second is for a three-dimensional mouse (assigned to Tektronix and not pursued by them, although cited in many later patents), and a digital storage-scope display that mimics phosphor trace brightness and decay over time (co-invented with Bob Bales and also assigned to Tektronix, and this one became the foundation of “digital phosphor” in modern scopes).

Although not credited with a patent, I consulted with one of the TATE principals around 1978 or so and devised a simple re-matrix that allowed them to use a professional QS decoder for a novel diamond-shaped matrix, with outputs of Screen Left, Screen Center, Screen Right, and Auditorium. I think you can guess who sold this matrix to Dolby after I returned to Oregon, none the wiser. I received a one-time payment of $500 and that was the last I heard of it until I saw a big-screen movie that used that matrix.

I also have an AES Journal Tech Note for a “Stereo-180 Microphone” around 1979. This used a pair of Limacon-pattern mikes at a critical spacing to generate wide-field stereo playback on normal stereo speakers, which was also compatible with QS playback.

The rest of my audio work was in loudspeakers. Immediately after the BBC/EMI tour in Europe in 1975, the Shadow Vector was shelved in favor of TATE DES, and I was recruited into loudspeaker design after Audionics’ designer high-tailed it out town with no forwarding address or phone number. I either taught myself or found another line of work. So, I taught myself, and a number of speakers followed. Almost nothing in loudspeakers is really patentable ... nearly all the patents that are issued are abuse of the patent office, with trivial variations of ideas that are decades old.

I was so disgusted by Audionics that I stayed out audio for nearly a decade. I didn’t get back in until the early Nineties, when the vacuum-tube triode revival began. That’s when I began writing for Positive Feedback magazine, Glass Audio, and Vacuum Tube Valley (brief stints as Tech Editor for the last two). The DIY projects I created were the Ariel and ME2 loudspeakers, and the Amity and Karna amplifiers. The notoriously long-delayed “Beyond the Ariel” high-efficiency loudspeaker was actually built by Gary Dahl in Washington State.

So I guess my career started with quadraphonics, followed by loudspeakers, then tech writing and network design, then more writing and self-taught amplifier design, with a brief foray into horns mentored by Bjørn Kolbrek, who I regard as one of the world’s premier horn designers. His doctoral thesis became the AH-425 Azurahorn, built in Perth, Australia, and a key component of the “Beyond” project. Bjørn is now at Celestion Loudspeakers in the UK, the last I heard, although he might have returned to his native country of Norway.

As you can tell, I enjoy working with international collaborators, which is why I’m so pleased to see the arrival of the Australian Surround Master and the development of the UK’s better-than-ever version of Shadow Vector. I’m bunkered down here in Colorado, which seems to be doing an OK job on CV19 so far. We have groceries delivered to the house, and plan to stay bunkered down until things are under control and it’s safe for an oldster like me to venture out. At least we have a magnificent view of the Rockies, and a pleasant bike-path to walk the doggie several times a day.

Doggo is sleeping right next to me now, curled in a little ball on her dog-bed, as I type this on my iPad in the dark. Looks like we’ve got another bright sparkling Spring day tomorrow, as we go into Week Eight of self-isolation.
Thank you for the extensive reply. I always know when I see a new post by you there will be some good meat to chew on.

I do have the Audionics patent you mentioned. I have, say, 18" if I stack them up of patents printed out going back to ~'74. I find it's a good way to find out how something works with out all the fluff of ad hype or dumbed down audio mag reviews.

So, with out going downstairs & double check, if IIRC the direction sensing was based on comparing front L/R, rear L/R & center front to center back. I understand each of those can have +- control voltages. Much has been said here about how the Shadow Vector does not favor directions; no speaker hugging effects it is both precise & full at the same time. So what I don't get is how that can be done using what seems to me limited direction sensing. Seems like it should also be sensed on the diagonals since SQ can do diagonal pans also? Or maybe an omni direction where all signals are summed & compared to the corner signals? And is what you did similar to Fosgates's servo feed back logic that also claimed to have accurate total power with no favoring of speaker feeds?
 

Owen Smith

300 Club - QQ All-Star
Joined
Apr 6, 2012
Messages
319
Location
UK
Well this is interesting. Owen pretty much dismissed software Shadow Vector, BJMarsh gave it a try & couldn't do anything with it and then you seem to have installed & using it already! The only I know less about than LINUX is golf. Can you give some insight as to how this actually functions? Is there any way to verify it truly follows Shadow Vector parameters & not some other form of high seperation SQ? As the author stated it might be able to be ported to Windows. Copuld you do that? And lastly I wonder if the maths involved would be helpful to Malcolm & his project.
I didn't dismiss it. All I said was if anyone needs to actually understand the code it will be hard work because it is almost completely uncommented. It's surprising how quickly you forget how code you've written yourself works, any more than two or three years (it varies by person) and knowledge of it just slips out of your brain.
 

jonmchugh

Active Member
Joined
May 5, 2019
Messages
56
Location
UK
Yes I look at code I wrote only last year and I'm like what the hell is this, can't make head nor tail of it.

markmerz's code I didn't even look at. Just cloned the github repo and typed make. error came up needs ladspa.h so installed ladspa-sdk and make again, produced the .so file, run the command in readme to use it. No coding knowledge needed really just an understaning of the linux build system.

Sorry I have no clue how to build code for Windows, Honestly cant understand why people use it.

Your welcome to send me some audio samples for me to decode if you want to hear for yourself.
 

Lynn Olson

Active Member
Joined
Aug 29, 2010
Messages
93
Thank you for the extensive reply. I always know when I see a new post by you there will be some good meat to chew on.

I do have the Audionics patent you mentioned. I have, say, 18" if I stack them up of patents printed out going back to ~'74. I find it's a good way to find out how something works with out all the fluff of ad hype or dumbed down audio mag reviews.

So, without going downstairs & double check, if IIRC the direction sensing was based on comparing front L/R, rear L/R & center front to center back. I understand each of those can have +- control voltages. Much has been said here about how the Shadow Vector does not favor directions; no speaker hugging effects it is both precise & full at the same time. So what I don't get is how that can be done using what seems to me limited direction sensing. Seems like it should also be sensed on the diagonals since SQ can do diagonal pans also? Or maybe an omni direction where all signals are summed & compared to the corner signals? And is what you did similar to Fosgates's servo feed back logic that also claimed to have accurate total power with no favoring of speaker feeds?
Here's a deep dive into the Shadow Vector directional sensing. There are 6 fullwave precision rectifiers (using op-amps as precision rectifiers) for each cardinal point of SQ ... LF, CF, RF, LB, CB, and RB. There's a bit of lowpass filtering for the output of each fullwave rectifier, followed by 3 differential amplifiers for LF/RF, CF/CB, and LB/RB. There's a single tight AGC loop with at least 40 dB dynamic range wrapped around the array of precision rectifiers, lowpass filters, and differential amplifiers. The logic only relaxes for low-level inputs that approach the noise floor of an LP, around -50 dB or lower.

Following that, the three bidirectional (+/-) control lines go through three identical nonlinear circuits (in practice, an array of resistors and diodes) that shape the control response so the variable-gain amplifiers track the Scheiber sphere precisely. The nonlinear shaping circuit was determined by connecting a pair of analog oscillators 1~5 Hz apart, which generates a spinning-phase signal that goes from LF to CF to RF to CB to LF again. By observing the output of LB and RB on one axis of the scope, and using the LF/RF control line on the other axis, the nonlinear circuit can be trimmed so the each of the back channels precisely follows the ideal SQ pan-locus. LF to CF to RF to CB to LF isn't a standard SQ pan (in fact it is an ideal QS pan), but it calibrates the response of each back channel exactly, so separation is maintained as the signal sweeps across the front, and then smoothly moves back to the default LB or RB position as the signal sweeps across the back quadrant. Just to check, the spinning LF/RF input signal can be re-matrixed into LB/RB, or CF/CB, to confirm the other axis of the decoders have symmetrical responses.

The array of variable-gain amplifiers needed 1% or better accuracy on the gain control. Cliff Moulton made the decision to use high frequency time-slicing on FET switches, and we spent several months chasing out DC offsets and LF bumps. It also made the prototype very susceptible to RFI, which ruined the East Coast debut of the product.

I'm not too sure where feedback would be useful in a system like this, unless there were errors in the gains of the variable-gain amplifiers. The AGC loop on the directional-sensing array can always be improved, of course, but tracking directionality down into the noise isn't a good idea with LP playback. You don't want each little tick and pop to be hard-localized; better to just ignore them. There's also room for improvement in the ballistics of the control lines, initial localizing transients need a faster response than slow sounds, or phase conflicts between instruments. The Shadow Vector mimicked the attack and decay response of Dolby systems, around 1~3 mSec for attack, and 20~50 mSec for release ... this was implemented in the lowpass filters for each of the control lines, with diodes and lowpass filters. In a multiband system, of course, the attack and release times have to be optimized for each band .. slow for LF, and fast for HF.

Shadow Vector has the same dynamic separation on a diagonal split as a pan on the L or R sides. The engineers at EMI were quite surprised to hear a clear side pan when they played the SQ master of "Rhymin' Simon"; apparently their CBS decoder couldn't do that. I think Malcolm could chime here: side pans and diagonal splits are excellent with Shadow Vector; the crudely built prototype had no problem at all with those pans.

I'm not sure what you mean by "limited direction sensing". All 3 axes of a Scheiber sphere are sensed and responded to, but there's no corner optimization because it was felt that would seriously degrade the spatial impression. As it was, the analog prototype, with no feedback, had a measured separation between 30 and 35 dB, which is about all that could be expect with a 6-pole phase shifter array. We didn't think chasing 40 dB or more was worthwhile, considering that normal stereo cartridge separation was around 30 to 35 dB with very careful adjustment (using an axial tilt circuit and a mono LP to calibrate it).

What baffles me is how TATE works. I'm mystified by the 6 control lines, which are presumably unidirectional, and maybe this lets them hard-optimize for the corners (this would follow CBS's lead on maximizing corner separation). I personally think hard corners and "detenting" (image compression) around the speaker are very objectionable, and it certainly doesn't sound better in quadraphonic than in stereo. In quad, I'd say it was worse, since the whole goal of quad, or surround in general, is to make all the speakers completely disappear, leaving the listener surrounded by nothing but sound. That's kind of the point; as soon as you localize the physical speaker, the illusion is destroyed. In stereo, you kind of expect the soundstage to be just that, a stage, with definite limits. In quad, there shouldn't be an impression of a stage, more like being there in the presence of the musicians, whether they are a frontal array or all around.

But CBS was using the big JBL studio monitors popular back them, and those have almost no ability to form a stable image (thanks to a primitive crossover and multiple unsuppressed peaks in the drivers). The folks at Audionics, including myself, were heavily influenced by British design, since we were the authorized importer of Radford amplifiers and speakers, and the Brits at that time were far ahead of the Americans in smoothness of response, crossover sophistication, and image quality. This was important in the design of Shadow Vector: the image quality, spaciousness, and stability had to be as good as stereo at its best. That was an unstated but real goal for the project.
 
Last edited:

sjcorne

2K Club - QQ Super Nova
Joined
Jan 1, 2010
Messages
2,753
Location
Southern NY
The engineers at EMI were quite surprised to hear a clear side pan when they played the SQ master of "Rhymin' Simon"; apparently their CBS decoder couldn't do that.
That's really interesting, as I have the quad-8 track of that title (which is the only way to hear the discrete 4-channel mix) and I don't believe there are any side-panned instruments. There are, however, some diagonal pans - most notably in the song "One Man's Ceiling Is Another Man's Floor", which begins with the grand piano stretching diagonally from front left to rear right. Maybe you're thinking of the first Paul Simon album? That one has a fairly unusual quad mix that even features use of the 'rear center' position - if you play the SQ LP in mono, the guitar solo in "Run That Body Down" will cancel.

The 'side center' location is very rarely used on the CBS quads, outside of some classical releases - the only example I can think of on a pop/rock album is the song "Train Kept A Rollin" on Aerosmith's Get Your Wings, which begins with the lead guitar suspended between front right and rear right.
 

Lynn Olson

Active Member
Joined
Aug 29, 2010
Messages
93
As I remember it, it was “Rhymin’ Simon” ... however, it could have been the EMI version. I don’t remember them using using a phonograph, so it might have been a 2-track master tape. Come to think of it, I’m pretty sure it was a professional format tape, since I don’t remember any surface noise or any calibration of the axial-tilt knobs. It was definitely a pan, though, since it was a big listening room, and you could hear the music walking along the wall.

Of course, this was a *long* time ago. What I remember was the reaction of the EMI quadraphonic design team. I had never heard the CBS Paramatrix before, but they had, and were used to it’s sound. The Shadow Vector took them and BBC professionals by surprise, which added to the sting when the whole project was shut down a few weeks later. But I can’t blame Audionics too much for that.

Wesley Ruggles, who was the son of a famous Hollywood director, had contacts in the film industry who could fund the conversion of the TATE system to silicon, but we didn’t. So that was the end of Shadow Vector until Malcolm came up with his digital version, some forty-plus years later.

My reaction to the further adventures of the Audionics Space & Time Composer was mixed. I had left under something of a cloud and had more or less washed my hands of all things audio. I had heard of the multiple failures of the National Semiconductor chipset, and my Tek friends considered National Semi to be an untrustworthy and at times dishonest vendor who promised but didn’t deliver. Tek had an in-house lab that could look at a chip with a scanning electron microscope and find exactly where the vendor had cut corners, but Audionics didn’t have that luxury ... nor the clout of one of the world’s leading instrument companies as well as a prime military contractor.

Audionics struggled for a year or more on the complex “band-aid” circuit to rescue the chipset so they could sell a few of the decoders. Jim Fosgate must have kept them afloat for at least several years, because there’s no way they could have made money on the Space & Time Composer after the National Semiconductor chipset debacle. As for the fate of the one Shadow Vector prototype, which was a bare-bones black box with a single volume knob on the front, good question.

As the result of the Audionics mass firing of my three best friends there (I had left for Tektronix several months before), I didn’t keep in touch with Charles Wood, the CEO who carried out the firings. I thought the mass firings sealed the doom of the company, because they got rid of the engineer who had designed their most successful and profitable product (the CC-2 amplifier), their marketer and show planner, and the front-office genius who was able to keep many financial balls in the air and many creditors at bay. What was left after the firings was a shell; Charles Wood, one repair technician, and two or three assembly people. That they lasted for another five years had to be due to the generosity of Jim Fosgate, who ran a very successful autosound company and was a big fan of surround sound.

That said, I’m still glad the Space & Time Composer got made under what had to be very difficult circumstances, and many surround-sound enthusiasts enjoy them to this day. Audionics certainly didn’t deserve the mistreatment they got from National Semiconductor.

So much of this came down to timing. Shadow Vector in 1975 was already facing a market with declining interest in quadraphonic, the TATE DES chipset had many additional years of delays thanks to National Semi’s lack of interest, as well as struggles with funding from the Hollywood investors, the failure of the chipset to do its job, and additional re-work to get the “band-aid” circuit working. That must have added six to eight years as Audionics struggled to stay in business.

Meanwhile, flashy, well-financed “boutique” companies like Krell and Wilson started to dominate the high-end industry, and the Big Two review magazines gradually squeezed the little guys out ... if you couldn’t pay for three months of full-page color ads, nope, no review for you. (Not joking about this. Both magazines had policies that demanded several months of full-color ads, as well as a dealer network of at least 10 dealers nationwide, before a product would even be considered for review. And a good review was by no means assured, since catty reviewers often wrote nasty reviews just to keep the little guys in their place. The high-end market was a real snakepit in the Eighties.)
 
Last edited:

boondocks

1K Club - QQ Shooting Star
Joined
Apr 19, 2006
Messages
1,301
Location
boondocks of NC Florida
(cut all but last paragraph)
..........
Meanwhile, flashy, well-financed “boutique” companies like Krell and Wilson started to dominate the high-end industry, and the Big Two review magazines gradually squeezed the little guys out ... if you couldn’t pay for three months of full-page color ads, nope, no review for you. (Not joking about this. Both magazines had policies that demanded several months of full-color ads, as well as a dealer network of at least 10 dealers nationwide, before a product would even be considered for review. And a good review was by no means assured, since catty reviewers often wrote nasty reviews just to keep the little guys in their place. The high-end market was a real snakepit in the Eighties.)
What do you think was the impetus behind wanting to screw the little guy? My memory is not supreme by any means, but I seem to remember in at least the mid point of the quad days, they (magazines) put everything including the kitchen sink in print eventually. Praise was heaped, so to speak.

EDIT: I was in the military for two of the quad years and we probably got different/different versions/ of magazines
 
Last edited:

sjcorne

2K Club - QQ Super Nova
Joined
Jan 1, 2010
Messages
2,753
Location
Southern NY
It was definitely a pan, though, since it was a big listening room, and you could hear the music walking along the wall.
I just gave the album a listen - at the end of the song "Take Me To The Mardi Gras", the New Orleans-style marching band walks around-the-room in a circle. The Tate does it quite well.
 

Lynn Olson

Active Member
Joined
Aug 29, 2010
Messages
93
What do you think was the impetus behind wanting to screw the little guy? My memory is not supreme by any means, but I seem to remember in at least the mid point of the quad days, they (magazines) put everything including the kitchen sink in print eventually. Praise was heaped, so to speak.

EDIT: I was in the military for two of the quad years and we probably got different/different versions/ of magazines
I sat on the editorial board of Positive Feedback magazine in the early Nineties and heard an appalling range of horror stories from the manufacturer's point of view. For some weird reason, the Big Two magazines saw themselves as the gatekeepers of the entire industry. (Which they were: they could bankrupt a new manufacturer with a single nasty review, and did so.)

Perhaps even worse, there was a small "charmed circle" that never, ever received a bad review. If you work in the industry, that's immediately suspicious, since there are plenty of expensive high-end products with obvious design defects that should never have been sold, never mind receiving a top review, year in, year out. The horrendous titanium-dome inverted tweeter used by Wilson for more than a decade is one example; I've measured that tweeter, and it was one of the worst ones ever made, with obnoxious peaks that are impossible to ignore. Or voltage regulators in Audio Research products that oscillated around 10 MHz, each with its own oscillation at a different frequency. But the "charmed circle" always got glowing reviews, even if the product under review was getting an "update" to fix a design defect in the previous version!

The Infinity speakers and Audio Research products were notorious for this ... charging the customer for an "update" to fix a previous defective version. One of the worst examples was an Audio Research power amp that shared a common cathode resistor for 4 output tubes; if one tube started to go a little off, it would run away, burn out the resistor, and maybe take another tube with it. The tubes were sold in matched sets by Audio Research at twice the market price, so you'd need to replace ALL FOUR tubes if one ran away.

The combination of the "charmed circle" and the open hostility to new manufacturers had a devastating impact on the US industry. When I said the industry was a snakepit, I meant it. Much worse than automotive reviewing, where the reviewers usually had a general idea how a car worked, and what technical features made it the car that it was. By contrast, the editors on the Big Two magazines openly bragged that their reviewering staff knew nothing of the technology, and based their reviews solely on listening.
 
Last edited:

fredblue

2K Club - QQ Super Nova
QQ Supporter
Joined
Mar 30, 2009
Messages
23,330
Location
London, England
I just gave the album a listen - at the end of the song "Take Me To The Mardi Gras", the New Orleans-style marching band walks around-the-room in a circle. The Tate does it quite well.
the Surround Master does alright with that pan too, was just giving it a spin earlier.. still wouldn't trade my Q8 though 😉
 

BJMarsh

Member
Joined
Jul 21, 2007
Messages
14
Yes I look at code I wrote only last year and I'm like what the hell is this, can't make head nor tail of it.

markmerz's code I didn't even look at. Just cloned the github repo and typed make. error came up needs ladspa.h so installed ladspa-sdk and make again, produced the .so file, run the command in readme to use it. No coding knowledge needed really just an understaning of the linux build system.

Sorry I have no clue how to build code for Windows, Honestly cant understand why people use it.

Your welcome to send me some audio samples for me to decode if you want to hear for yourself.
My problem building this is that I have a MacBook Pro. I have a spare Mac mini and would like to install Linux on it. What Linux are you using?
 

Lynn Olson

Active Member
Joined
Aug 29, 2010
Messages
93
I’ve been reflecting on the internals of the TATE and possibly the Surround Master as well. To the best of my understanding, they have an internal static SQ decoder, and additional signals are applied to the LF, RF, LB, and RB outputs. If no additional directional enhancement is needed, the signals applied to each output is zero, leaving only the static matrix.

So far so good. Unlike Shadow Vector, it is conceptually possible to make a TATE unit that is purely gain-riding. It all depends on *what* signals are applied to, say, LB, for example. If the TATE is running in pure gain-riding mode, then -LB will silence the output when the encoded input signal is LF. However, if the TATE is running as a purely variable-matrix decoder, then LB is steered to RF, which also silences it. But the two operations are quite different sonically; the first actually mutes LB, while the second leaves it wide open for any sonic content that is not directly panned into LF ... in particular, CF, LB, RB, and CB are only 3dB down while LB is temporarily steered into RF. This property is why a variable-matrix decoder preserves random-phase ambience, while a gain-riding decoder suppresses it.

But ... this is where I get very confused with the TATE patent, which descends into a morass of impenetrable matrix math, which I suspect was intentional on the part of drafters of the patent. It is far from clear what the TATE is doing. Is it a symmetric variable matrix? No way of telling. Does it favor the corners? No way of telling. Do it combine elements of gain-riding with a variable matrix? Again, no way of telling.

This is why I find the TATE patent so opaque. I’m not a dummy when it comes to dynamic decoders ... heck I hold one of the very few patents in the field ... and I was a technical writer for nine years at Tektronix, documenting some of the complex instruments ever made, including a weird development station that merged Motorola 68030 assembly language with an object-oriented Smalltalk development environment. Not to mention my first job documenting the 496 portable spectrum analyzer, complete with a field calibration procedure. So I can deal with complex and even deliberately opaque technical documents; I’ve done it for many years. But the TATE patent is completely beyond me.

So I don’t think it’s me. Granted, I can’t follow the code in these script-based software decoders either, so have no idea how they work. But I am genuinely curious how the TATE and the Surround Master work. The Shadow Vector is simply a 3D version of a variable matrix, but much faster and more accurate than the Sansui Vario-Matrix. (Brief digression: 1% gain precision and fast ballistics are needed to track the envelope of an attack transient, otherwise it is blurred into the other channels. This is where modern digital look-ahead is so useful, since the matrix can be steered *before* the transient, which relaxes the ballistics tracking requirement quite a bit.)

The TATE seems like a different animal. Maybe it corner-optimizes, maybe it doesn’t, and maybe it decides on its own how it wants to decode, based on an analysis of signal content, although that seems pretty fancy for late-Seventies analog computing.
 
Last edited:

BJMarsh

Member
Joined
Jul 21, 2007
Messages
14
Hey Folks, I wonder if someone could help me get an SQ channel test file so that I can test a decoder that I am working on. I think I have an issue with the decoder and I need a known good test file. Any help would be greatly appreciated.

Blaine
 
2
Top