[Milehighguy]

I enjoyed reading about the old carver C-9 as I used to use one a lot, and still have it in storage. However, the explaination about how it works, taken from wikipedia, was not even close.
Bob Carver's explaination doesn't involve the doppler effect. In short, he says that the brain is confused when the left ear hears both the right and left channels, and likewise when the right ear hears both channels. He  wants the right ear to only hear the right channel and the left only the left. To do this, he puts sound from the right channel into the left channel, at a lower level, out of phase, and delayed by a few microseconds. When this right channel out of phase sound hits the left ear, it cancels out the sound from the right channel that has gone around the head from the right side and arrived at the left ear at a lower level and slightly delayed a few milliseconds from having moved around the head. This process is also done for both channels, resulting in each ear primarily only hearing the sound from the side the ear is at. This gives better spatial cues to the ears, resulting in a better sound stage.
Polk audio tried to accomplish the same effect with their "SDA" speakers which had extra drivers on each side that produced a cancellation signal from the opposite channel by way of a speaker cable that went between the speakers.
In other words, Polk did acoustically what Carver had done electrically.

[Tweaker]

Carver's C-9 was designed to eliminate interaural crosstalk distortion which results from stereo playback creating two extra sound arrivals, as you mentioned, four total as opposed to only one per ear when listening live. I've got a C-9 in the closet and the only reason it's there is it has a noisy channel and I have not got around to having it fixed.
It never seemed to get much respect like it was some sort of gimmick but I found the results extraordinary. It did have a narrow sweet spot as far as imaging but it wasn't just imaging that it improved on. I could always hear much more of the space or reverberant field of the recording environment with the C-9 engaged and more detail, and that was obvious no matter where I was listening from. With some recordings I did prefer the C-9 out of the loop, but more often than not I liked what it did. It was fun to listen to music through it that had extreme left or right channel only information, which is quite rare in recordings. Led Zep's "Whole Lotta Love" was a good one. The "ah,ah,ah" part with the guitar would travel back and forth several feet to the sides and above the speakers. Another is "1983... (A Merman I Should Turn to Be)" from Electric Ladyland where the guitar would seemingly travel in a circle around the back of your head starting from the right speaker and then back to the left.
Gotta get that thing fixed.

[satfrat]

I have the Holographic circuitry on my Sunfire Theater Grand 4 processor and I simply love it. It does in fact narrow up the imaging when in stereo mode while at the same time throwing out a huge projected sound stage that'll make me feel like I have my rear channel speakers on. I don't use it much to as I do infact use my rear speakers most of the time, but it is quite the entertaining novelty. 

Cheers,
Robin

[Affordable$$Audio]

Hi Guys:
I appreciate your input regarding the Sonic Holography effect of the C-9. When I was writing up the piece I searched the Internet high and low for Bob Carvers explanation, but couldn't find it.  I settled on the Wikipedia because it does use similar capabilities to the Doppler effect.  I wish I would have had MileHighGuy's explanation, as it is outstanding. 

The key is that the Carver C-9 is a fun item and with the right type of music can give off an fascinating listening experience.

[dwk]

The topic of cross-talk cancellation has surfaced around here a couple times recently. It's the basis of ambiophonic approach to playback - search on that for more discussion. The web site at www.ambiophonics.org has various implementations you can try out, although these are all optimized for a 20 degree listening arc rather than the conventional 60 degree setup that the Carver unit was likely designed for.

Having played with some of the ambiophonic implementations, I certainly agree that on the right material it can be spectacular.

[Milehighguy]

Thanks for the compliment on my explaination.
The quality of the holographic effect is dependent on several factors. It works better with speakers that have a decent soundstaging ability to start with, and it works better when there are minimal sidewall reflections.
The best results I ever heard happened when I took some speakerlab das-7 speakers and moved them outdoors for a party. Those are large floorstanding speakers with 10 and 12 inch woofers and a 6 inch mid and 1 inch tweeter, and they image quite well. I had them a couple of feet from a mobile home with no other reflective surfaces, out in the country. The rest of the system was not exceptional, with generic cables and a proton amp. The soundstage was amazing. The illusion that the band was laid out in front of you was absolute, with perfect pinpoint imaging. I've never heard a better, more convincing soundstage, even at the 4 RMAF's that I've been to. People who were at the party still talk about it years later.
So to anyone who owns this or a similar device, my advice is to take it outside!
I still have the speakers and the c-9, and I plan on going outside with them when the weather permits.  aa

[miklorsmith]

The newer TacT preamp software includes a similar crosstalk cancellation feature.  It was firing up about the same time I got out, so no comments on how it works.  I think they said it works best farfield with the speakers quite close together.  I haven't seen any commentary about it anywhere, maybe it's not ready for prime time.  It is a cool idea though, always good to hear about new ideas.

[dorokusai]

That is a solid and simple example of Polk SDA, thanks Milehighguy.

I've heard both over time, certainly the Polk version old and new, and they both have "drawbacks". For the Carver Sonic Holography, the soundstage is not as large as the SDA idea and placement is usually an issue with the loudspeaker. This can narrow the soundfield pretty noticeably or widen it too much, which again, is quite odd.

In the early version of SDA, with dimensional tweeters as well as midrange, the soundstage could be a little strange, with sounds occuring quite unnaturally on the edges of your listening enviroment. The dimensional tweeter was eventually dropped as it was decided that most of the SDA effect was limited to the midrange portion of the sound spectrum.

Both are really cool to experience and you should at least experience them in your travels. The Carver Amazing is a wonderful speaker to own and play with and the SH circuit can be used on just about anything. The same goes for the vintage Polk SDA line and it can be found pretty easily, in a variety of models and size.

I'm a Polkie but a huge planar lover with no expectations that Polk will do that design. Oh well, I guess I'll have to make do with something else huh?

Mark

[TONEPUB]

Some of the headphone amplifiers are doing this now too...
(i think)  The Meier I heard was very good.

[dorokusai]

Isn't that the crossfeed thing? I believe Headroom offers that circuit.....perhaps others, not sure.

Mark