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How do you ensure you are using only an external DAC with your TV and headphones?

post #1 of 9
Thread Starter 

Hello

I have a pretty good DAC and headphone amplifier coming from China which still has a while before they arrive.

 

Consequently I am now thinking on how to use them once they arrive. I know I wish to use them with my television to watch music videos with my headphones. My question now is how do I ensure I am using only my superior external DAC and not the DAC's within my television. Will using the optical audio out in 2 channel PCM mode as the provider of my audio ensure I am only using my better external DAC and not my internal one or not? If not are there probably TV settings that will allow me to do this? I have an LG television model LG 42LK450 and the people who answer telephone questions at LG about it do not know what I am talking about when I asked about the TVs DAC's. So is it probably possible to ensure you are only using an external DAC and not an internal one the seating the purpose of using a better quality external DAC?

post #2 of 9
Quote:
Originally Posted by bbmiller View Post
 

Hello

I have a pretty good DAC and headphone amplifier coming from China which still has a while before they arrive.

 

Consequently I am now thinking on how to use them once they arrive. I know I wish to use them with my television to watch music videos with my headphones. My question now is how do I ensure I am using only my superior external DAC and not the DAC's within my television. Will using the optical audio out in 2 channel PCM mode as the provider of my audio ensure I am only using my better external DAC and not my internal one or not? If not are there probably TV settings that will allow me to do this? I have an LG television model LG 42LK450 and the people who answer telephone questions at LG about it do not know what I am talking about when I asked about the TVs DAC's. So is it probably possible to ensure you are only using an external DAC and not an internal one the seating the purpose of using a better quality external DAC?


Optical out will work if you've got a digital source. You can always forgo connecting the audio to the tv and plug your cable box/ dvd player/ computer/ ect... directly to your DAC if the appropriate connection is available.

 

Cheers


Edited by ab initio - 3/26/14 at 12:55am
post #3 of 9
Thread Starter 

On more television oriented www.avsforum.com I ask this very similar question.

 

Setting the optical audio out to PCM to bypass all internal DAC's? 

And got this reply.

 

"It is very unlikely that the computer or TV would perform a 'digital to analog to digital' conversion when converting the input bitstream to stereo PCM.
The only thing that might compromise the integrity of the original source's digital audio is the conversion process from compressed multi-channel audio to stereo PCM (which will be an all digital process, but could color the source depending on how the processing chain is implemented)"

 

I would like to ask here on these Head-fi forums the same thing I asked there in response to that reply.  

 

 How the processing chain is implemented. Is there any threads or forums or places on the web you know of devoted to how the conversion process is implemented? I mean the conversion process for example from 5.1 Dolby to two channel stereo appropriate for headphones.


Edited by bbmiller - 3/26/14 at 9:09am
post #4 of 9
Quote:
Originally Posted by bbmiller View Post
 

On more television oriented www.avsforum.com I ask this very similar question.

 

Setting the optical audio out to PCM to bypass all internal DAC's? 

And got this reply.

 

"It is very unlikely that the computer or TV would perform a 'digital to analog to digital' conversion when converting the input bitstream to stereo PCM.
The only thing that might compromise the integrity of the original source's digital audio is the conversion process from compressed multi-channel audio to stereo PCM (which will be an all digital process, but could color the source depending on how the processing chain is implemented)"

 

I would like to ask here on these Head-fi forums the same thing.  How the processing chain is implemented. Is there any threads or forums or places on the web you know of devoted to how the conversion process is implemented? I mean the conversion process for example from 5.1 Dolby to two channel stereo appropriate for headphones.

To help you find out, it would be helpful if you could share what DSP chips are in the devices along the way from source to speaker.

 

Cheers

post #5 of 9
Thread Starter 
Quote:
Originally Posted by ab initio View Post
 
Quote:
Originally Posted by bbmiller View Post
 

On more television oriented www.avsforum.com I ask this very similar question.

 

Setting the optical audio out to PCM to bypass all internal DAC's? 

And got this reply.

 

"It is very unlikely that the computer or TV would perform a 'digital to analog to digital' conversion when converting the input bitstream to stereo PCM.
The only thing that might compromise the integrity of the original source's digital audio is the conversion process from compressed multi-channel audio to stereo PCM (which will be an all digital process, but could color the source depending on how the processing chain is implemented)"

 

I would like to ask here on these Head-fi forums the same thing.  How the processing chain is implemented. Is there any threads or forums or places on the web you know of devoted to how the conversion process is implemented? I mean the conversion process for example from 5.1 Dolby to two channel stereo appropriate for headphones.

To help you find out, it would be helpful if you could share what DSP chips are in the devices along the way from source to speaker.

 

Cheers

I assume you mean by DSP digital signal processor. And by source I would assume you mean the original audio codec’s? However the audio signal is arranged in the original audio codec’s? So I would also assume that this processing could take place in either my computer or television or maybe both assuming different ways playing video and audio files.

 

So is this DSP chips used discoverable for either a computer or television? How would you take it crack at discovering it for your personal equipment?

post #6 of 9
Quote:
Originally Posted by bbmiller View Post
 

Hello

I have a pretty good DAC and headphone amplifier coming from China which still has a while before they arrive.

 

Consequently I am now thinking on how to use them once they arrive. I know I wish to use them with my television to watch music videos with my headphones. My question now is how do I ensure I am using only my superior external DAC and not the DAC's within my television. Will using the optical audio out in 2 channel PCM mode as the provider of my audio ensure I am only using my better external DAC and not my internal one or not? If not are there probably TV settings that will allow me to do this? I have an LG television model LG 42LK450 and the people who answer telephone questions at LG about it do not know what I am talking about when I asked about the TVs DAC's. So is it probably possible to ensure you are only using an external DAC and not an internal one the seating the purpose of using a better quality external DAC?

 

Normally the TV digital out, S/PDIF or optical, is connected to the external DAC. The audio from the DAC goes to the headphone amplifier. You plug the headphones into the amplifier, you turn down the TV speakers using the remote. You may have to fiddle with the outputs in the menu.

 

That's how you're sure you're listening to the DAC, it's the only input to the headamp.

 

Now you can take your DAC output and switch it to an integrated or preamp, or you can treat the headphone amplifier as a preamp and use it to drive a power amplifier.

 

Is that what you're asking?

 

w

post #7 of 9
What that reply means is, if you are using a digital out e.g. optical out, it will not be using the TV's internal DAC because it is still digital (hasn't been converted to analog yet). It is extremely unlikely that it is converting to analog then back to digital again.

It converts the digital 5.1 signal to 2.0 via a digital process (I.e. a DSP). This isn't particularly relevant because it happens before the DAC.
post #8 of 9
Thread Starter 
Quote:
Originally Posted by higbvuyb View Post

It converts the digital 5.1 signal to 2.0 via a digital process (I.e. a DSP). This isn't particularly relevant because it happens before the DAC.

 (I.e. a DSP). This isn't particularly relevant, (I.e. a DSP). This isn't particularly relevant, (I.e. a DSP). This isn't particularly relevant.

 

OK well I am truly having trouble figuring out why this is not particularly, particularly significant, but it appears that you must be right cause on these Head-Fi forums there isn’t coming up on the DSP like there is on both headphone amps and DAC’s so apparently the community agrees with you but why? Can or cannot this conversion process take place with goodness or badness? Is it just because few people are using Dolby sound 5.1 & 7.1 sound as an original source? It seems to me it is fairly common to find music videos with only have that kind of sound duplex as the original sound source. So is there just never, never any goodness or badness in those conversions?


Edited by bbmiller - 3/27/14 at 12:44pm
post #9 of 9
Quote:
Originally Posted by bbmiller View Post
 

 (I.e. a DSP). This isn't particularly relevant, (I.e. a DSP). This isn't particularly relevant, (I.e. a DSP). This isn't particularly relevant.

 

OK well I am truly having trouble figuring out why this is not particularly, particularly significant, but it appears that you must be right cause on these Head-Fi forums there isn’t coming up on the DSP like there is on both headphone amps and DAC’s so apparently the community agrees with you but why? Can or cannot this conversion process take place with goodness or badness? Is it just because few people are using Dolby sound 5.1 & 7.1 sound as an original source? It seems to me it is fairly common to find music videos with only have that kind of sound duplex as the original sound source. So is there just never, never any goodness or badness in those conversions?

 

that was confusing...?

 

most DAC's will convert everything to 2 channel....this is great if you are going to use headphones or dedicated 2.1 speakers, but kind of silly if you want to receive 5.1 sound.  you can get a 5.1 DAC (surround processor) or even better IMO a cheap AVR (which will take HDMI), or else you'll have to use a soundcard DAC that uses DSP processing to get 5.1

 

if you are asking about the TV DAC, using digital by definition is bypassing that DAC and therefore the conversion will be done using your external DAC.  i've never heard of any unit that converts audio before the digital output channel, and least of all a modern TV where they assume you will be plugging in a soundbar or something (which have internal DAC's)

 

not only that, but i'd be surprised to find out that there was an inferior DAC in the TV to begin with (if it's reasonably modern), although i have no idea about what DSP they use to downmix to the headphone output (do TV's have headphone outputs?  mine doesn't)

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