SDA vs. Sonic Holography

**TroyD** · 08-19-2002 01:16 PM

I was wondering if anyone out there could lay out for me what the difference between SDA and Sonic Holography are. I mean I realize that SDA is passive and that SH is incorporated into the preamp. What I am getting at is (and I am VERY uneducated here) is that to the uneducated observer (me) it seems to be two different ways of achieving the same thing.

I'm hoping that some of the more knowledgeable folk, ahem, madmax, raife1, Ken Swauger might be able to break it down for a brother....

BDT

**RuSsMaN** · 08-19-2002 01:24 PM

Lexicon touched on crosstalk cancellation also. They may all do it differently, but they are essentially achiveing (or going after) the same thing. Wave field synthesis, Ambisonics?

Am I talking out of my cornhole, or did Polk actually 'pay off' Carver to use and market the SDA technology? I remember hearing/reading something about that some time ago....

Cheers,
Russ

**hoosier21** · 08-19-2002 01:30 PM

I am uneducated about the Carver Sonic Holography, but I believe it does the same as the Polk SDA. Adding out of phase information to the mix, creating a wider soundstage and such.
The cool thing to me about the SDA is that if is isn't IN the music, the SDA doesn't create the wider soundfield (passive). Where as the Carver will create SH on any music.

I have been told the Carver SH is less forgiving on listening position, literally moving your head a couple inches will destroy the effect. Polk's SDA effect is more forgiving.

**TroyD** · 08-19-2002 01:35 PM

to touch on what Russ said, according to George Grand one of the things that Carver liked to stress (he was a Carver salesman at the time) is that Polk Audio paid Carver to avoid a court battle over the technology.

BDT

**Aaron** · 08-19-2002 01:38 PM

The cool thing to me about the SDA is that if is isn't IN the music, the SDA doesn't create the wider soundfield (passive). Where as the Carver will create SH on any music.

This was my experience. When I demoed the SRS-1.2's I really didn't notice anything out of the ordinary in terms of imaging. A few times, though, I noticed a diffinite improvement. It never sounded unnatural. With SH, the instant you hit that button the soundstage expands. Sometimes it sounds OK, but overall I think it sounds fake and contrived. There will be times when I'm listening to it, and I'll hear something that I know just sounds totally wrong. I'd liken the SH to a glorified DSP mode on your surround sound receiver. So yeah, you could say I'm not a big fan.

Aaron

**TroyD** · 08-19-2002 01:50 PM

Aaron, you not a fan of SH or SDA?? I never would have guessed......

I've never heard SDA and my experience with SH really isn't enough to make a judgement.

BDT

**gidrah** · 08-19-2002 03:54 PM

I snagged a SH a few months back. I haven't heard SDA in years and can't give an honest opinion on the sound differences.

The SH was $60.00. SDA starts around $400 and I already own 10Bs.
You can record the SH into music. You can't do this with SDA. I've gotta try it sometime.
You can turn the SH off.
The stand alone SH is an extra component in the loop, thus more plugs, cables, distortion and noise compared to SDA.

If I remember correctly from my audio prepubescence. There was no copyright infringement or anything it was just easier and probably cheaper to just cut Bob a check. I could be wrong though. I missed George talking about this subject.

**Aaron** · 08-19-2002 04:49 PM

Aaron, you not a fan of SH or SDA??

Actually, what I said was that SH sucks, and I don't have a problem with SDA. I don't think SDA speakers are very good, but I don't have a problem with the technology, unlike SH.

Aaron

**wangotango68** · 08-19-2002 06:14 PM

our local radio station used to have carver weekends,they would hook up a sonic holographic generator to there gear and gave instructions on setting up your speakers. they have not done that in about 10 years.

scott

**TroyD** · 08-19-2002 07:32 PM

I just remembered some of the things we discussed this weekend at George's regarding Sonic Holography. The strong points do seem to be:

It's switchable. Don't like what you hear, hit the switch.
It's recordable. Tape or any recording medium can be "processed" and will yield holographic effects when played on non-holographic/SDA ystems.

As for "working better" with some music and not others, both SDA and the Sonic Hologram Generator are TOTALLY DEPENDANT on the amount of difference between the left and right audio signal. No difference (mono)? Nothing for either system to work with, thusly, neither system yields effects from mono sources. It doesn't work better with some music than others. If it does, it's because there's a much greater amount of stereo separation (in db) contained in the source that is yielding the greater effects. Dolby Surround and Dolby Pro-Logic worked the same way.

As for the drawbacks, there's just the sweetspot. What are you doing getting up and walking around anyway? You shouldn't "trivialize" the music by doing anything other than LISTENING TO IT. If you do, don't complain about the system, cause the system works, as long as YOU work within the framework too. Who cares if your friends get as much sweetspot as you?

Yeah, those are some of the things we talked about.

**Paul Connor** · 08-19-2002 08:02 PM

This thread is rather fascinating to me because I use both SDA and SH. Carver and 1.2's. I have never understood the similarities between the two having no technical expertise. However, I can say that I do not use the SH feature of my Carver preamp all of the time simply because with certain recordings the music really becomes overdone. Does the soundstage open up? Yes, and with certain recordings, it really enhances the music. The problem is changing the preamp setting for everything you listen to. Should you have to "tweak" everything you listen to? In my opinion, one thing is certain with SDA-in order to fully experience the 1.2's you must be sitting in the sweet spot. When you move out of it, you lose the intended effect. Is this a bad thing? I'm not sure.

I would love to hear more on this subject. Thanks for a great thread Troy.

Paul

**TroyD** · 08-19-2002 10:42 PM

I'm big, I'm dumb, and my name is Troy, and even I know that George would tell you not to send a hologrammed signal downstream to SDA type speakers.

You can tweak all you like. Either disconnect the SDA cable, or shut off the hologram. You must have some real space sounds going on there.

BDT

**Paul Connor** · 08-20-2002 12:04 AM

What is happening when you use the SH feature with the SDA?

**Frank Z** · 08-20-2002 12:50 AM

I had a pair of SDA-2b's and a Carver Sonic Hologram Generator about ten years ago and they complimented each other very nicely. As a matter of fact there was an article in Sterwo Review back then that stated that combining these two systems actually improved the effect. I believe that the article was written by Julian Hirsch. If you know anything about him or have ever read his reviews you'll understand why people would buy equipment sight unseen based soley on his reviews.

**TroyD** · 08-20-2002 06:24 AM

Julian "I Never Met a Piece of Equipment I Didn't Like" Hirsch? The man has yet to give a product a bad review.

Check with the Polk "gods" first. You don't want to sent a "processed" signal to the SDA's. They are trying to extract a cancellation signal from a pure stereo source. The hologrammed signal already contains the cancellation transmissions.

BDT

**RuSsMaN** · 08-20-2002 07:25 AM

Did Troy stay at a Holiday Inn Express last night?

Cheers,
Russ

**nascarmann** · 08-20-2002 08:24 AM

Did Troy stay at a Holiday Inn Express last night?

**TroyD** · 08-20-2002 08:25 AM

Jeezuz....did someone slip me some of Dan's special tea last night or what?

BDT

**madmax** · 08-20-2002 08:26 AM

I used to use a carver preamp that had sh with my SDA's. I thought the sound of the two together was grossly exagerated. It was cool for 10 minutes but after that it just seemed annoying. I think it would be ok with non-sda speakers but I never gave it a good try.
madmax

**nascarmann** · 08-20-2002 08:33 AM

I've had no experience with the sonic hallucinations, but with it and SDA would seem to be overkill....

**SDA SRS 1.2** · 08-20-2002 07:35 PM

My Carver C-16 Preamp has the SH and I agree that the SH combined with the SDA effect is not something I would prefer to listen to - tends to sound dull in this mode and the "sweet spot" is so narrow, blinking your eyes seems to destroy it. The C-16 has a "Blend" knob which adjusts the (L+R) and (L-R) imaging - I found that this feature compliments the SDA effect well, keeping the knob in about the 10 o'clock position towards (L-R).

**madmax** · 08-22-2002 06:20 AM

I wonder if there is a way to vary the SDA effect? Most songs have the right amount but some have way too much. Maybe a potentiometer on the SDA cable or something?
madmax

**mhw58** · 08-22-2002 02:25 PM

Which songs do you feel have too much SDA affect? I'm
having the opposite feeling, I'm wishing more songs
had more of an affect. Maybe I'm not listening to the
right songs.
Mike

**TroyD** · 01-05-2003 01:09 PM

Hey,

I thought I'd ressurect this post since I got my C-1 and I've spent a good bit of time setting up 'The Shane' for optimal SH benefit.

VERY COOL. I found that SH is very exacting in terms of setup. The more care you take in setup, the greater the effect. The sweet spot is VERY narrow but since I'm the only one there, no biggie.

Just thought I'd share.

BDT

**HBombToo** · 01-05-2003 05:31 PM

Originally posted by SDA SRS 1.2
The C-16 has a "Blend" knob which adjusts the (L+R) and (L-R) imaging - I found that this feature compliments the SDA effect well, keeping the knob in about the 10 o'clock position towards (L-R).

Polk RTA 8t's with the CM 1090 was good for me untill HT.

Huh???

**George Grand** · 01-06-2003 07:06 AM

I have only been experimenting with the hologram since 1988. I will submit a report on my findings when my research is complete.

George Grand (of the Jersey Grand's)

**TroyD** · 01-06-2003 09:20 AM

Heh, heh....

I'm just amazed at how an inch or two can make such a remarkable difference. I think that maybe some of the folks who don't like SH may not have listened to it properly set up.

BDT

**gidrah** · 01-10-2003 10:52 AM

AGREED! I've tried my SH on a couple of different speakers and find that the SH benefit is best revealed when the speakers are located differently than in standard 2-ch form. Some more drastic than others, some in some out, some right on. I'm sure that any SDA enthusiast would come across the same thing when disconnecting their interconnect.

**Bob_Richards** · 12-01-2012 06:15 PM

I've been researching, designing and building audio signal processors and speaker systems since the 60's, and have been very interested in the "sonic-holography" thing since Carver first came up with his version. In the early 80's I got hold of the schematics for the Carver circuit, built one, re-optimized it, and still use that with my tri-amp'd open baffle tower speakers that I built.

I'm presently in the middle of a project that uses the Polk method of inter-aural cancellation, which I've never actually heard, but read reviews about and understand well on paper. The word on the street is that the Polk method isn't as picky about exactly where your head is located. What I'm building is a stereo holographic "soundbar", which will have a center speaker (like the current Polk soundbars), so the criticism about the Carver hologram having a "phasey" sounding center image shouldn't be a problem. The main difference between my soundbar and the Polks (that I know of) is that mine will be acoustically flat from 30HZ - 20kHZ. Two 6.5 inch side firing woofers actively EQ'd, are in the 16 inch deep (8 inch high by 39 inch long) box, which my 42 inch HD TV will sit on top of.

Carver vs. Polk:
Both methods attempt to cancel the inter-aural crosstalk that occurs during playback.

Below about 1kHZ, our ear-brain mechanism determines sound image location primarily by timing or phase comparisons, rather than amplitude comparisons above about 1kHZ. The crosstalk needs to happen only once, in order for our ear-brain mechanism to be able to interpret it (usually during the recording process). When crosstalk happens a second time during playback, as it will in the vast majority of the systems out there, our brain cannot use the info, so imaging is only good in the upper midrange. With inter-aural cancellation, imaging info can be wideband, and in my opinion, way more fun with most recordings. Theoretically, we should only cancel this crosstalk up to 1kHZ, but processing above that frequency seems to be more fun even though it's arguably less fidelity, so I think that's the norm. I've researched this obsessively for years and could talk about it for hours, but this is the very short story.

**treitz3** · 12-01-2012 06:31 PM

Hello, Bob. Even though this thread is almost a decade old? Please allow me to answer Troy's question....which he already knows the answer to by now. Carver did well with the SH but at the end of the day, Polk did it better. Less loss on the lower frequencies, less image smearing and a better overall performance with the recreation of the recording. I say this as I am a good friend of Bob and also with having extensive knowledge of the efforts by the Polk corporation.

Tom

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SDA vs. Sonic Holography

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