# Will switching to Dolby Digital output make a huge difference?



## jnelaine (Dec 31, 2001)

My current audio receiver doesn't have a digital audio input, so I had to hook my HR10-250 up to my receiver using a regular stereo signal. I can still get 5.1 surround sound because Dolby Surround can be encoded over a stereo signal and then decoded using Dolby Pro Logic on the receiver. My question, and I assume the answer is a resounding "yes", is: Will I notice a huge difference if I upgrade my receiver and speakers so they can accept a digital audio input and then switch my HR10-250 over to output Dolby Digital?

Is there anyone out there who had to use Dolby Surround over a stereo connection and then was able to upgrade their system to Dolby Digital output? If so, did it make a dramatic difference in 5.1 surround sound quality?

Thanks!
Jay


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## phox_mulder (Feb 23, 2006)

You can't get 5.1 through stereo connections, 5.1 is Dolby Digital and only available through digital connections.

You can get Dolby Pro Logic surround through stereo connections though.
It isn't 6 seperate sound channels, only 2 (hence the two wires),
and it is very analog.

Yes, DD5.1 is much better than Pro Logic, when properly utilized.

phox


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## Luke M (Nov 5, 2002)

jnelaine said:


> Is there anyone out there who had to use Dolby Surround over a stereo connection and then was able to upgrade their system to Dolby Digital output? If so, did it make a dramatic difference in 5.1 surround sound quality?


Yes, there's really no comparison. Dolby Surround is a rather lame attempt to synthesize a little bit of surround effect from two channels. Dolby Digital is discrete multichannel, a completely different thing.


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## Pictor Guy (Apr 6, 2003)

Dolby Pro Logic is not the same as 5.1 audio. I've had my kids switch my receiver to Prologic a few times and I immediately noticed something was wrong. If you pick up a newer receiver to get 5.1 audio you may want to seek something that also supports LPCM, TrueHD, and/or DTS-MA as these will sound even better than DD 5.1 and will future proof your investment.


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## phox_mulder (Feb 23, 2006)

Although, the first time I heard Pro Logic surround in a home environment, I was very wowed. (I think it was Star Wars, the original movie)

Even more so the first time I heard DD5.1 used to it's potential.

I haven't yet yeard DD7.1, I might have witnessed DTS, but I only have the 6 cheap speakers, so the effect was minimalized.


phox


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## Pictor Guy (Apr 6, 2003)

phox_mulder said:


> I haven't yet yeard DD7.1, I might have witnessed DTS, but I only have the 6 cheap speakers, so the effect was minimalized.
> 
> phox


I don't notice much of a difference between DD and DTS (all things being equal). But good LPCM is night and day over either DD or DTS. Unfortunately you need a HDM that supports it and I have only seen/heard it used by a few studios on Blu-Ray. And LPCM isn't supported by Toslink due to the higher that the optical connection just wasn't designed to handle.


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## jnelaine (Dec 31, 2001)

Thanks, this is exactly what I wanted to hear! Before I drop $800 to $1K on a new audio system, I wanted to make sure I'm going to hear a big difference over my current "simulated" 5.1 HTIB system. I guess I was naive to think that when I purchased a "5.1 surround system" a few years back that it would actually allow me to get real 5.1 surround from an external source. I was fooled by the Dolby Pro Logic stuff! The only way I can get real 5.1 surround right now is if I use the built-in DVD player (and I don't watch many movies). I'd much rather be able to get real 5.1 from my TiVo.

I think I'm either going to get the Onkyo HT-SP908 all-in-one HTIB system or get the Onkyo TX-SR705 receiver and buy the speakers separately. Does anyone have a recommendation for a relatively inexpensive set of 5.1 (or 7.1) speakers?

Thanks!


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## phox_mulder (Feb 23, 2006)

jnelaine said:


> Thanks, this is exactly what I wanted to hear! Before I drop $800 to $1K on a new audio system,


I think mine was $300 with speakers.

No fancy HDMI or Component Video switching, no upscaling, no fancy bells or whistles.

It had an Optical Digital input and a Coaxial Digital input and that's all I cared about at the time.
My DVD player has Coaxial, and my R10 has Optical and those were the only DD5.1 components I had at the time.

I really need to look into something with the bells and whistles now since I have many more components outputing digital audio along with HDMI and component video, and will most likely be getting more in the near future.

phox


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## boneskrw (Jan 28, 2006)

A $300 5.1 DD setup can't hold a candle to Dolby Surround with a good system---one that has substantial speakers and a reasonable receiver--like stated above $800-$1000. Those packaged $250-$350 5.1 DD systems are horrible. Your car speakers sound better than they do.


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## phox_mulder (Feb 23, 2006)

boneskrw said:


> Those packaged $250-$350 5.1 DD systems are horrible. Your car speakers sound better than they do.


I don't know, I have the stock Dodge stereo and speakers in my truck.
But, it is the Infiniti system.

phox


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## jerryj (Mar 7, 2004)

phox_mulder said:


> You can't get 5.1 through stereo connections, 5.1 is Dolby Digital and only available through digital connections.
> 
> You can get Dolby Pro Logic surround through stereo connections though.
> It isn't 6 seperate sound channels, only 2 (hence the two wires),
> ...


Actually, Dolby Surround uses 2 channels but manages to create 4 channels using a matrix system. They derive a center channel by adding the left and right channels. A single rear channel is derived using the difference between the left and right channels. I always thought the 4 channel surround was remarkedly good considering how they got it. But I agree, there is really no comparision; DD5.1 is much better. 6 true channels and much higher fidelity.
Jerry


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## jnelaine (Dec 31, 2001)

jerryj said:


> Actually, Dolby Surround uses 2 channels but manages to create 4 channels using a matrix system. They derive a center channel by adding the left and right channels. A single rear channel is derived using the difference between the left and right channels. I always thought the 4 channel surround was remarkedly good considering how they got it. But I agree, there is really no comparision; DD5.1 is much better. 6 true channels and much higher fidelity.
> Jerry


Thanks Jerry, that's the way I understand it too. But as long as true 5.1 Dolby Digital makes a BIG difference over 4-channel encoding, I'm willing to make the jump.


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## TyroneShoes (Sep 6, 2004)

boneskrw said:


> A $300 5.1 DD setup can't hold a candle to Dolby Surround with a good system---one that has substantial speakers and a reasonable receiver--like stated above $800-$1000. Those packaged $250-$350 5.1 DD systems are horrible. Your car speakers sound better than they do.


I could not agree more. I find it incredibly ironic that many folks insist on 5.1 as a delivery system and then use a sub-standard amp/speaker system to deliver it to their ears. The difference in quality between a quality system and "5.1 in a box" systems is huge, and significantly more different than the relatively minute differences in quality between Dolby Pro Logic IIX (an analog system) and DD 5.1 (digital delivery of signals that were mostly once analog anyway) 95% of the time.

But there are a lot of fake connoisseurs out there that insist on what they incorrectly perceive as being what will give them quality as opposed to knowing what will or actually being able to hear the difference. The 95% number refers to the fact that only 5% of audio you will listen to is DD implemented well and/or not derived from a 2-channel source anyway. IOW, it might be important to get that U2 3D concert in 5.1, but probably not that reissue of "Bladerunner" or reruns of "Angel" on TNT.

Also, proper equalization of the signal in the playback environment is nearly impossible for digital signals, and very easily done for analog ones. Most digital equalizers in modern AVRs are lacking and have 3 to 5 channels, while most analog equalizers have 12 to 30. The ability to tailor the sound for the environment that you may give up to get the sound in 5.1 can easily detract from the final product much more than the benefits you might derive from using PL IIX, which has actually MORE derived channels with 25+ dB of separation (usually considered completely adequate) and limited surround freq response (based on the fact that reflected sounds are band-limited in nature anyway) and is uncompressed, than a compressed 5-channel full-freq 60 dB separation digital system such as 5.1. That's especially true if using cheap or inadequate speakers. At least in PL IIx or an analog system you can equalize mid-level speakers to sound pretty OK, which is much more difficult when using DD 5.1.

IOW, 5% of the time DD will wow you on a good system a bit more than PL IIx, but 95% of the time PL IIx will outperform DD in day-to-day listening on a good system set up properly, and the differences between those delivery systems are typically not that great. I would recommend setting up a good system with most of the money in the speakers, and using PL IIx for the bulk of the listening, switching to DD only when it will make a difference, which is actually not all that often.

If your 5.1 system is using any speakers with only 1 element (other than sub), or your sub cutoff is higher than 80 Hz, or if the speakers are not optimally placed and equalized, you can be assured that you are giving up a lot of quality, a lot more than would be gained than by using 5.1 DD in lieu of PL IIx on a proper system. Putting a full-frequency 5-channel signal into speakers that can't properly handle full-frequency sound kind of defeats the whole purpose (you need a minimum of high-quality bookshelf speakers with two elements and crossovers in each). That's like buying primo weed and cutting it with oregano (not that I have any idea what that's really like ).


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## TyroneShoes (Sep 6, 2004)

jnelaine said:


> Thanks Jerry, that's the way I understand it too. But as long as true 5.1 Dolby Digital makes a BIG difference over 4-channel encoding, I'm willing to make the jump.


In practice there are probably not any 4-channel _encoded_ systems in use (Quad died in the 70's). Most audio _decoded_ by a 4-channel system such as original Dolby Pro Logic is _encoded_ as either 1 or 2 channels to begin with. Generally, the difference we actually have control over at playback is in locally decoding either 5-channel digital encoding (DD) vs. 1 or 2-channel analog encoding (mono or stereo).

Characterizing it as such would be an indicator that you may not have researched this subject enough quite yet to the level of understanding that would lead to your making a truly informed decision. That's not a knock, as not being well-informed is not in any way disgraceful (I don't feel bad because I don't know the difference between a MRI and a CAT scan, for instance), but it might be a wake-up call, and is meant only to help guide you.

And again, most of the time and on suboptimal systems, the difference between 2-channel encoding and 5-channel encoding will likely not be BIG, as you put it.


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## Luke M (Nov 5, 2002)

TyroneShoes,

I can understand (and would support) an argument favoring a quality 2-channel system over a crappy surround system. But I'm baffled by your enthusiasm for an antiquated matrix surround system that never really worked. It's not as though Dolby Digital is some esoteric, high-end feature.


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## TyroneShoes (Sep 6, 2004)

jerryj said:


> Actually, Dolby Surround uses 2 channels but manages to create 4 channels using a matrix system. They derive a center channel by adding the left and right channels. A single rear channel is derived using the difference between the left and right channels. I always thought the 4 channel surround was remarkedly good considering how they got it. But I agree, there is really no comparision; DD5.1 is much better. 6 true channels and much higher fidelity.
> Jerry


Actually, 5.1 channels and higher fidelity in only 2 of those 5.1 channels, if there.

Dolby surround is only 3 channels derived from 2 stereo channels, L, R, and L-R (which constitutes the "rear" channel). It is truly nowhere near as good as 5.1, but AVRs with Dolby surround have not been on the market for well over 15 years, as Pro Logic and PL IIx have long-ago replaced it.

But Dolby Pro Logic and PL IIx are very-effective 5.1 and 7.1 delivery systems derived from 2 channels with performance very close to 5.1 DD and outperforming it in many instances. The separation is much better than Dolby surround using a center speaker (25-30 dB compared to 3 dB) due to steering logic, making the sound-field recreation effect nearly as good as 5.1, especially poorly-implemented 5.1 (lots of that out there) or 5.1 that came from an original 2-channel source.

And we have to define "fidelity". The reason Pro Logic can get away with band limiting in the rear and surround channels is due to the fact that sounds from these azimuths are band-limited in nature in most cases, meaning that replacing band-limited surround channels with full-frequency surround channels (as 5.1 does) is really not as effective as one might hope, in the interests of "fidelity". Full-range channels can't improve band-limited source audio. The front and center channels of PL IIxx have equal "fidelity" to 5.1 even when well-implemented.

The advantages of 5.1 vs PL IIx are increased separation (but increasing separation from 25 dB to 60 dB is like going from 20/22 vision to 20/20 vision) and full-frequency surround channels (which typically do not contain full-frequency source audio). Technically, on paper, it's an improvement. Effectively, well, maybe not so much.

The advantages of PL IIx over 5.1? It works on any stereo audio source, can be implemented and equalized easily in the listening environment, has more surround channels enabling less localization of surround audio (a good thing) and it is not compressed.

Dolby Surround is truly inferior to 5.1. Dolby PL IIx, maybe not so inferior, and it's also not very often when it actually is. I know we'd all like to believe the hype that 5.1 DD is a great invention and a great improvement over existing decoding systems. Unfortunately, what we want to believe is sometimes less than perfect, and less than a significant improvement. Such is the case with DD 5.1 in the real world of consumer listening environments, which in my opinion is only incrementally better than well-implemented PL IIx and only some of the time.


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## TyroneShoes (Sep 6, 2004)

Luke M said:


> TyroneShoes,
> 
> I can understand (and would support) an argument favoring a quality 2-channel system over a crappy surround system. But I'm baffled by your enthusiasm for an antiquated matrix surround system that never really worked. It's not as though Dolby Digital is some esoteric, high-end feature.


I think what you may be baffled by is the BS of industry hype. You simply may be surprised by having it revealed to you, rather than baffled by that. By "esoteric" (definition: intended for a small number of consumers) I guess you mean not mainstream. Well, DD is becoming mainstream, but it still comprises a small fraction of audio for video available to any consumers. I'm sure those who sell it intend all of us to buy it.

It's not that I have enthusiasm for systems other than DD, it's that there is no reason to have enthusiasm for DD as if it were some magic improvement over what exists already. It isn't. It's marginally better, and only so in a small number of instances.

"Antiquated" would imply that newer systems had significant advantages or made significant improvements over existing systems. That would make "antiquated" a completely improper characterization, as the improvements in DD 5.1 are neither highly-advantageous by comparison nor significantly-improved over PL IIx. Dolby Surround is antiquated, that I agree with. PL IIx is not, then by definition.

The matrix derivation approach was originally highly flawed due to low separation. Steering logic greatly improved that, and while original steering was sluggish with ineffective separation, modern-day steering is flawless. PL IIx adds 4 unique surround channels (which masks rear localization much more effectively than 2 surround channels) and implements steering perfectly. The matrix system has always "worked". It just originally didn't work all that well, and was improved in many generations to work now really well in modern implementation.

Once DD is implemented better and more regularly, it will become more significant, but still not significantly better in any degree, than PL IIx which still outperforms it in many everyday instances and settings.

Using a DD 5.1 setup to listen to most available audio is not unlike using a HD display to watch mostly-SD video in 2003. And when DD is available, the difference between it and PL IIx is like weak HD vs. excellent SD. IOW, not really so much of an improvement as typical HD over typical SD is.

I think the obvious lack of blind listening comparisons by the industry of 5.1 vs PL IIx are a testament to the tiny difference that would be borne out, and are conspicuous by their absence. IOW, the industry never made that comparison because they knew it would not be perceived as significant, while pure hype can be, and has been.


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## Luke M (Nov 5, 2002)

TyroneShoes,

From my perspective you have it backwards. Dolby Surround and similar systems are the "industry hype" that should be ignored. I tried them out in the pre-DVD days and discovered that they don't work. The only point to them today is enhancing 2-channel content. They are in no way competing with discrete multichannel.


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## jnelaine (Dec 31, 2001)

TyroneShoes said:


> In practice there are probably not any 4-channel _encoded_ systems in use... Characterizing it as such would be an indicator that you may not have researched this subject enough quite yet to the level of understanding that would lead to your making a truly informed decision.


I appreciate your help, but yes, I do understand that the sound is delivered over two channels and then decoded by Dolby Pro Logic into four channels. You misinterpreted my statement.


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## jnelaine (Dec 31, 2001)

TyroneShoes - I'm a little confused about Dolby Surround vs Dolby Pro Logic II and which one I'm actually using (or if I'm using both). You seem to say that Dolby Surround sucks but Dolby Pro Logic II is great. Isn't Dolby Surround the encoding method and Dolby Pro Logic II the decoding method? (http://www.dolby.com/consumer/technology/prologic_II.html)

When I bring up the TiVo guide on non-HD channels, many movies are listed as "Dolby Surround". My receiver has a Dolby Pro Logic II button (but not IIx) and I can hit it anytime, even if I'm not watching a Dolby Surround encoded program. But I'm not impressed AT ALL with the sound (I know, a lot of that has to do with my speakers)

So, if Dolby Surround blows but Dolby Pro Logic II is fine, which one am I using? I thought I was using both.

Sorry, I'm a newbie to this stuff, but I just want to make sure that moving to a digital audio connection and Dolby Digital instead of my current stereo connection is going to make a big enough difference to warrant spending close to $1K.

Thanks


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## boneskrw (Jan 28, 2006)

My point was that an "antiquated" system of Dolby Surround or better yet, Pro Logic II, using quality speakers and amps is superior to the "box" systems that sell for around $250-$350. So many people can't wait to get rid of those "big, ugly" speakers and replace with the pinteks that sound like table radios with a subwoofer that doesn't do as well as those "big, ugly" speakers did. 

Then, there's the Bose system that, for around $1,500, you can buy a Dolby Digital system that doesn't put out ANY sound below 40 Hz. That pretty much takes the thrill out of many movies that have so much info between 20 and 40 Hz.


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## jerryj (Mar 7, 2004)

At the risk of getting too technical, you have to appreciate the historical development of sound reproduction. Just as stereo was a major improvement over the previous monaural systems, Dolby Surround was a big advance in the home reproduction of MOVIE soundtracks. Many movie soundtracks only had two optical sound channels, but the studios encoded surround sound information into the two tracks so that theaters could easily retrieve the extra channels. Dolby realized that the early Beta and later VHS movie tapes (remember these?) being marketed as 2 channel stereo, in fact contained 4 channel information and Dolby surround was a very easy way to retrieve the extra channels in a home system. And it sounded much better than 2 channel stereo even though the real channel had limited fidelity. Pro Logic was an advanced way of processing the channels with improved results. But there is only so much you can do with only two independent channels of information. DD5.1 provides 6 independent channels, 5 at full fidelity. Most movies made in the last 10 years do use these channels and the improvement in sound reproduction is significant. 
Jerry


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## TyroneShoes (Sep 6, 2004)

jnelaine said:


> TyroneShoes - I'm a little confused about Dolby Surround vs Dolby Pro Logic II and which one I'm actually using (or if I'm using both). You seem to say that Dolby Surround sucks but Dolby Pro Logic II is great. Isn't Dolby Surround the encoding method and Dolby Pro Logic II the decoding method?...
> 
> ...Sorry, I'm a newbie to this stuff, but I just want to make sure that moving to a digital audio connection and Dolby Digital instead of my current stereo connection is going to make a big enough difference to warrant spending close to $1K.
> 
> Thanks


The Dolby site has tons of info that can clear this up for you. All of these algorithms are double-ended, meaning an encode on the software end and a decode on the home theatre end (if you can really consider analog stereo a form of encoding, which it technically is not, yet can be decoded by some of these systems).

And yes, the basic matrix system of Dolby Surround is the same method for extracting multiple channels as is used in PL IIx, just done much more primitively. Dolby Surround creates C by simply adding L+R, and creates LS and RS by simply subtracting L-R (RS then = LS). That gives separation that is not very good, and only 3 dB from L to C or R to C. Pro Logic measures the relative level difference between L and R, and multiplies it by an equation that makes something panned L or R not appear at all in C, and uses similar steering logic for surround channels. In later incarnations such as PL IIx, the steering is much more sophisticated, and there are four unique surround channels, LS, RS, LB, and RB. The end result is much-greater separation and much better surround non-localization, both rivaling garden-variety 5.1, without the drawbacks of fewer channels and limited software.

Original DS wasn't very impressive at all, but the current day incarnation, PL IIx 7.1 is surprisingly impressive. DD 5.1 has the potential to beat the pants off of either, but is rarely implemented well-enough to make it significantly better than PL IIx. It can be, it just rarely is.

Much of the anecdotal enthusiasm for the "mindblowing difference" folks hear when hearing 5.1 for the first time is due to the increase in quality level of the system itself (which is usually also a new experience), and not really due to the 5.1 algorithm. Even good 5.1 doesn't collapse significantly when PL IIx is switched in on a good 5.1 system unless the software was mastered extraordinarily well. That is an experiment anyone with a good system can try -- tune in "Bones" or "Criminal Minds" or any other 5.1-delivered network fare first in 5.1, and then drop to PL IIx. You might not even hear the difference.

That is why I recommend putting most of your dough in the speakers, because it is difficult to reproduce full-range audio for 5.1 with cheap speakers, and difficult to re-equalize them for 5.1 (much simpler with analog). You can also get a very good AVR that does both for $300, such as the JVC digital amps (D401 and D701 are two examples of 7 channels at 90 or 105 wrms each plus all bells and whistles, both outstanding). That way you can use 5.1 when the software warrants it, and PL IIx for everything else that comes at you as 2.0 audio.

But 1K is not really enough for the AVR + 7 speakers + powered sub, I'm afraid. Be prepared to double that if you really want to take full advantage of either PL IIx or 5.1 (and there are a lot of elitist snobs snickering at anything less than 5K, but screw 'em).


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## jnelaine (Dec 31, 2001)

Thank you so much for taking the time to help me out and leaving very informative posts! It's quite informative!

So, it sounds like you're saying that the fact that I only have a stereo input on my receiver and am using Dolby Pro Logic II isn't really holding me back very much. Moving to a new receiver with a digital input and Dolby Digital isn't that important. What is key is the speakers.

Interesting. Everything I've read agrees that speakers are the most important, but most people also think that moving to Dolby Digital is also very important. And, in fact, when I watch a DVD (which is built into my receiver, so I can get full Dolby Digital), I get MUCH better surround sound over my speakers than I do when watching the same HD movie on HBO. So, I've got to believe that Dolby Digital is making a pretty big difference.

In the end I think I'm sticking with my plan of getting either the Onkyo 605 or 705 receiver with the 7.1 speakers that come in their 908 HIB. People seem to agree that those speakers are adequate, and I guess I can use either Dolby Pro Logic IIx or Dolby Digital, so all will be good.


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## joed32 (Jul 9, 2005)

Sounds like a plan.


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