Sonic Holography

[Juergen]

Most of my gear is Carver. My CT-7 Preamp has a Sonic Holography switch. I think I understand the basic principle of it. It certainly makes a big difference on certain recordings. How does it compare to other "X-Feed" devices? Is it the same thing? I just got a new pair of SennHD600s and am waiting for my X-CanV2 to arrive. Should Sonic Holography work with Headphones (in principle)? I know there is alot of discussion about crossfeed around here. I guess I am just wondering if I would benefit from such a device with my current setup.

 

[joelongwood]

I have a Carver Receiver with Sonic Holography. The only way to describe what it does to headphone listening is STRANGE! I don't like it at all........but you can give it a shot.

 

[Juergen]

I agree. I listened to it for a bit expecting to get that same sound I got the first time I listened to it through my speakers. I was disappointed. Later I listened through my speakers and I was smiling once again. I don't think the principles apply to headphones. I'm surprised Bob Carver enabled it through the headphone jack.

 

[eric343]

What exactly is it supposed to do?

 

[Abuhannibal]

It is more like the opposite of crossfeed - I think it basically sends a reduced-level out-of-phase signal for each channel to the opposite channel, thus giving a sense of increased separation and less crosstalk between channels.


I haven't tried it with headphones but expect that it would not be desirable.

-- Bob

 

[scm2741]

Bob's comments are correct. Sonic holography was an attempt to reduce crosstalk between speakers by generating an out-of-phase signal across speakers that would cause some cancellation of cross-talk as the wave-front from each speaker radiated out into the room. Since the wave-fronts on headphones do not have physical contact with each other the circuit would not work as designed. Whether or not you like the "effect" through headphones would be up to you.

-Scott

 

[finallyfree]

Well, 2 1/2 years later for this response.

I have a Carver CT-17 with Sonic Holography and to my brain it makes a good difference in the sound stage. It's much wider. With the holography on and rolling the balance to left and right you can hear the cancelling signal from the other channel. If I keep the balance in the center I hear good stuff. As a matter of fact I very seldom listen to my Perreaux head amp any more.

Maybe Carver used a newer version of the holography in the ct-17?

 

[drarthurwells]

Crosstalk between speakers is interaural distortion - a type of phase distortion. It smears the tones - sound image becomes a muddy blob instead of a focused 3-D image in a space.

Headphones eliminate this - that is why the sound is clearer with more focused imagery with headphones. However, headphones reduce ambient sound you get from speakers (from wall and other surface reflections that constitute phase distortion from delayed sound). When properly controlled by good speaker placement, this ambient sound can add desireable depth and tone richness to the sound.

Some headphone amps induce interaural distortion in a crossfeed feature.

Again this hurts focused imagery. However, the smeared tones do give a sense of expanded soundstage. To me this is a bad tradeoff. Give me a pure clean tone over a distorted one anyday.

 

[edstrelow]

I hadn't realized that the Sonic Holography is set up to do what the Polk SDA speakers do. The Polks actually use separate sets of speakers to generate signals to cancel the cross-talk, also called phantom channels. Essentially 4signals are sent to the human listener by stereo loudspeakers, each ear gets its appropriate left or and right channel signal but also then gets a delayed right and left signal respectively, essentially 4 channels of sound from a 2-channel signal. It amazes me that so few persons, even with a keen interest in sound reproduction, are aware of the essentially artifactual nature of stereo speaker reproduction.

I wouldn't expect such processing to work with headphones, since the cancellation signals would have nothing to cancel and would in effect constitute distortion.

I have never heard the Carver set-up but the Polk system is quite effective. However it has been some years since these were made, for various reasons including cost, since each speaker is essentially a double speaker. You can still find them on Ebay but they seem to hold their value well. Also more commercial interest has shifted to video surround sound, although the Polks work fine with such systems.

Headphones of course do not generate phantom channels since the appropriate signals go exclusively to the appropriate ear and that is at least part of the reason for the ability of even cheap phones to sound so good. Certainly they have no ambience from the listening room, however, they are able to better present the ambient sound in the recording, which is what you really want.