Does Optical work the same as Analog 5.1?

AC7 KN

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May 22, 2017
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First, Sorry for my bad English.
So Here's the story
I Have an A/V Receiver (Yamaha RX-V359) and there's a Multi Channel Input
To connect to Multi Channel Input, i must put 3 Cables (RCA to Aux) from My PC (AUX) to my Home Theater AV. First Cable is L and R, the Second Cable is Surround L and R, the last is Subwoofer & Center. Nah, i know that this is True 5.1 Sound because i Connect Each Cable to the right one (i mean my brain explain why this is True 5.1 because each cable connect to (1. L/R 2. Surr L/R 3. Center Sub). And how about Optical Cable? it's only 1 cable but is it really true 5.1 Channel and delivering each sound to the Center, Sub, Surr, And Front? My Motherboard also have an Optical Out. Now my A/V Receiver is too old, i want to buy the new one, but all A/V Receiver now are using Optical and Digital, Does Optical work the same as Analog?
 
what your receiver has is a 6ch analog input. this is the same as your pc, but the plug formats are different. pc uses 3.5mm which combines two channels while your receiver uses rca which carries one. yes, hooking up via 3x 3.5mm->2 rca will give you true surround.

as far as optical is concerned, it is capable of carrying 5.1 audio BUT not in all cases. the standard was developed to carry an uncompressed full quality 2.0 stereo signal and at the very worst this is what you will get. nowadays it can also carry a compressed dolby digital 6 channel (5.1) signal but only if both the source device (in this case your pc) and destination device (your receiver) supports this. many very old devices may not support 5.1 over optical but most fairly new devices do.

if you buy a brand new receiver, instead of using optical you might be using hdmi. hdmi is multi-channel and uncompressed for full quality audio. if you are using standard resolutions (1080, 4k, etc) you might even pass through the video from receiver to tv/monitor if its a 60hz signal.

if hdmi does not work for you (you use 100/144hz panels or some other reason) then you can still use optical for 5.1. does your motherbord onboard support this? i do not know, read your manual. at the very most to get it to work perfectly fine would require an inexpensive soundcard that does support 5.1 over optical.

3.5mm that you are using now is analog. this means that your pc acts like the dac (digital to analog converter) and processes the audio into an analog signal. from there it goes to an amplifier so that it may power speakers or headphones. your motherboard does have a small amplifier which is good for either very low power speakers or some easy to power headphones but thats it. in this case that fairly low level signal is sent to your receiver and boosted by the onboard amp to power your speakers.

hdmi or optical is a digital signal. while some processing may be done on your pc it is exported as a digital signal which goes to an external dac to be converted into an analog signal. in this case we are talking about your receiver. then, inside of your receiver is an amplifier to power the speakers or headphones.

which is a better method? its hard to say as both can be adequate. thing such as dac quality or emi interference can affect things. digital signals on optical/hdmi are not as easily influenced as analog signals though.

TLDR: no, they do not work in the same way but it is possible to carry 5.1 on optical provided certain conditions are met.
 

AC7 KN

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May 22, 2017
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oh... thank you for the explaination from your answer, i want to ask again :
1. can i convert from 3 Cables (RCA to Aux) (LR, Surr LR, SUB, Center) to 1 Optical Cable? is it possible? if it is possible, then i put the optical cable to my AV that has an Optical Input, is it still true surround? and what is the name of the converter if there's available?

2. I want to buy this : https://www.asus.com/us/Sound-Cards/Xonar_DGX/
Asus Xonar DGX has an optical out, if i connect my Asus Xonar DGX to my AV Receiver using Optical Cable, is it true 5.1 surround and much better than i connect my AV to Asus DGX SoundCard using analog (RCA to AUX) 3 Cables (LR, SL SR, Sub-Center)?

Edit : for question number 2, the AV Receiver is new type not the old one (because you already explain that old av receiver doesn't support 5.1 trough optical cable)
 

robert600

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I'm pretty sure that the answer to question2 is: yes ... you will get true 5.1 using only the optical cable and ... yes, better than using analogue. As an added bonus, it's easier to hook up lol.
 

AC7 KN

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May 22, 2017
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Okk, thank you so much guys for helping.
 
1. yes, there are 6ch analog to optical converters. no, i would not suggest using them unless you have no choice. it would be better to natively come out of your pc with optical or hdmi instead.

2. the xonar dgx should support 5.1 over optical as far as i know. it supports 'dts' which is the format for 5.1 compressed over optical. any new receiver should also support this. as far as digital being higher quality, that is not always true as analog in the right situations can also be high quality. modern receivers only connect up in 6ch with digital sources though so this means optical or hdmi. if at all possible i would highly recommend using hdmi instead of optical but if that is not an option then optical would work.

i run a home theater system myself with a pc. i route pc->receiver->tv via hdmi. you can also run pc->receiver via hdmi without piggybacking a monitor/tv and still get audio. the receiver would just show up as an extra monitor but without any display options only sound options.

 

AC7 KN

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May 22, 2017
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Oh i see, Thank you for the answer...
By the way last question please, i want to ask which one is the best, connect from my GPU (Nvidia GTX750ti) using HDMI to AV Receiver or Connect from ASUS Xonar DGX using Optical to AV ?
Because i read that GTX750Ti Support 3D Blu-ray, 3D Surround and i can configure the surround from control panel > hardware & Sound > sound > then i choose Nvidia HD Audio Output > Right Click > Configure Speakers > Then i Set it to 5.1

Sorry if the last question is little bit / slightly out from the main topic
 
hdmi is superior to optical. hdmi is uncompressed (full quality) while optical when used in 5.1 is compressed (slightly lowered quality). when in 2.0 stereo mode, optical is uncompressed. for stereo, they are equal. for 5.1 hdmi is better. will you hear the difference? maybe, maybe not depending on your ears. both are "good" options.

the only case where i suggest optical instead of hdmi would be if you do not want to run your monitor out of the receiver output (you use a strange resolution, run over 50/60hz [fps] signal, or just dont want to daisy chain, etc).

when connecting a receiver up to a pc, generally one of two things shows up in your 'audio devices' panel. A) the name of the receiver B) hdmi or nvidia. in my case, pioneer vsx-30 (my receiver) shows up. the only configuring you generally need to do on pc is set it to 5.1 in your sound options, the rest (equalizer, speaker delay, etc) is all set on the receiver.

i have not messed with 3d.

what resolution monitor are you using and is it a standard 60hz panel? what connectors are on the back of your video card?
 

AC7 KN

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May 22, 2017
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1920x1080 60hz, the connectors are DVI-I 24+5 pin (1x), HDMI (1x) , Display Port [DP] (1x) total = 3 outputs
i have a DP cable to HDMI Ver.1,4 cable, so i think i can connect my monitor to my computer using DP and the surround with HDMI
 
given that you are 1920x1080 60hz, you could just go pc->receiver->monitor as well without issue. of course given those connections you could do as you listed above and connect pc->monitor and pc->receiver separately as well.