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· Cool Member
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Discussion Starter · #1 ·
MY HR22/100 is connected to my Samsung TV via HDMI cable. I've subsequently added a Vizio soundbar to the setup, currently connected to the TV audio-out via a simple stereo audio cable.

The soundbar has a jack for SP/DIF input. I'm not familiar with optical audio connections, so here is my question: Could I connect the soundbar directly to the HR22 with a SP/DIF cable, and would it really improve the sound? (The Vizio is capable of "pseudo-surround" output.)
 

· Broadcast Engineer
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RANorton said:
MY HR22/100 is connected to my Samsung TV via HDMI cable. I've subsequently added a Vizio soundbar to the setup, currently connected to the TV audio-out via a simple stereo audio cable.

The soundbar has a jack for SP/DIF input. I'm not familiar with optical audio connections, so here is my question: Could I connect the soundbar directly to the HR22 with a SP/DIF cable, and would it really improve the sound? (The Vizio is capable of "pseudo-surround" output.)
From nearly every channel, the audio is AC3, which means it is in a compressed digital form. To get it to analog, the audio is decoded to PCM, and converted to analog. When you use a digital out, it can be either DD, which is essentially the same as passing through AC3, or PCM from that same downconvert.

So the only difference between your analog connection and optical is a stage of D-to-A, which is pretty nondestructive. Not only that, the digital audio is D-to-A converted eventually anyway, by circuitry comparable to what is used inside the DVR to get it to analog. So there is no appreciable benefit of using optical out vs the analog audio outs.

The advantage of passing AC3 as DD (which analog can't do) would only be that you can get all 6 audio channels. But a sound bar (and correct me if I am mistaken) typically only uses stereo 2.0 anyway, and any surround mode is simulated from that.

Bottom line, there would be no advantage to using anything other than analog. Keeping it in digital form does not keep it from degrading, and does not impart it with any "betterness".
 

· Broadcast Engineer
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yep.

But I think for a sound bar to use 5.1 is probably not very effective. If you want a good result from 5.1 the best way to do that is with discrete channels and discrete speakers. A 5.1 SB would likely not be appreciably better than a 2.0 SB, I wouldn't think, and neither would be near as good as a conventional 5.1/7.1 setup.

I assume the original question was about sound quality. The advantage of 5.1 is not sound quality (the quality is the same, all else held equal), it is mostly about directionality, and the ability to create a more realistic sound field than conventional stereo can. The LFE and bass management does increase quality below 120 Hz a little bit, though, but that is mostly in reproducing those frequencies accurately compared to conventional 2.0 stereo where normal speakers have difficulty with those lower frequencies. But then sound bars very likely don't manage LFE, even if they do use 5.1, and they are usually not capable of subwoofer performance anyway.
 

· Registered
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Most sound bars do not decode DD, period. If you set your sat box to output DD, your sound bar will not work at all (if using the optical digital connection). It will actually produce an error (front panel leds have error patterns), in most cases.

The second problem if you try to use HDMI and the sound bar at the same time, you are most likely to get a horrendous echo, as there is a time difference between the two connections (hdmi vs. optical).

I know this, because I have a sound bar and regular tv audio and an Onkyo SR-605 home theater amp. Only one audio output can be used at a time, or you get a nasty echo, and of course, the DD noted above was also checked with three different people's sound bar setups and D* boxes.

BTW, I've been testing with the $98.00 Vizio sound bar.

I thought of using the sound bar as a center channel amp only, but I didn't have a low level center channel output, and didn't feel like building/buying an impedance transformer which would use the 8 ohm output and transform up to a higher impedance. I decided it wasn't worth the bother and ended up moving the sound bar to the upstairs bedroom on a 37" Sanyo, an the difference in audio clarity (dialogue) was dramatic.
 

· Cool Member
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Discussion Starter · #10 ·
"TomCat" said:
From nearly every channel, the audio is AC3, which means it is in a compressed digital form. To get it to analog, the audio is decoded to PCM, and converted to analog. When you use a digital out, it can be either DD, which is essentially the same as passing through AC3, or PCM from that same downconvert.

So the only difference between your analog connection and optical is a stage of D-to-A, which is pretty nondestructive. Not only that, the digital audio is D-to-A converted eventually anyway, by circuitry comparable to what is used inside the DVR to get it to analog. So there is no appreciable benefit of using optical out vs the analog audio outs.

The advantage of passing AC3 as DD (which analog can't do) would only be that you can get all 6 audio channels. But a sound bar (and correct me if I am mistaken) typically only uses stereo 2.0 anyway, and any surround mode is simulated from that.

Bottom line, there would be no advantage to using anything other than analog. Keeping it in digital form does not keep it from degrading, and does not impart it with any "betterness".
The Vizio soundbar does have a "Trusurround" feature, which is supposed to provide 2.1 surround sound. It also has an output for a subwoofer. I may give the TOSlink cable a try. Thanks for the feedback.
 

· Godfather
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Not sure which model you have, but according to the specs for this model

http://store.vizio.com/vsb200.html

The input only supports PCM digital. It's probably intended to be hooked up to the optical output of TVs, which generally only output stereo PCM (even if receiving 5.1 over HDMI). You could hook it up directly to your receiver, just be sure dolby digital is turned off.

Definitely should be better than the analog stereo connectors, which are prone to noise during quiet passages.
 

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djrobx said:
Not sure which model you have, but according to the specs for this model

http://store.vizio.com/vsb200.html

The input only supports PCM digital. It's probably intended to be hooked up to the optical output of TVs, which generally only output stereo PCM (even if receiving 5.1 over HDMI). You could hook it up directly to your receiver, just be sure dolby digital is turned off.

Definitely should be better than the analog stereo connectors, which are prone to noise during quiet passages.
Yes, that is the model I have and you have to go into the D* sat box menu and turn DD off, or you won't get any sound at all via the optical digital output of the sat box. The vsb200 does not support dolby digital input.
 
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