HDMI vs. Optical cable

Shaishav_Udani

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I recently bought Yamaha RXV-4A receiver along with Yamaha floor speakers NSF-51 and center and surround speakers NS-P150.

When I connect my my phone to the receiver using bluetooth the sound quality is much better and louder, but when I'm connect my receiver to my smart TV using optical cable the sound is much low. Is it that I need to connect my TV using HDMI cable?

What could be the reason for difference in the sound quality via bluetooth and optical cable?
 

venkatcr

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You are confusing issues and products here. In one, you are connecting your phone to the receiver through Bluetooth. In two, you are connecting your TV to the receiver using Toslink. (Optical cable is also called Toslink).

Secondly getting lower volume does not mean lower quality. It is just that the gain(*) provided by the sending device through a transmission path is higher or lower. If you play some music or audio on the TV and increase the volume on your receiver, you will find the sound to be as good or even better than Bluetooth. Toslink is one of the highest forms of carrying audio signals, even 7.1. At the same time, it may need a higher amplification at the receiving end simply because the gain it provides is lower.

Toslink vs HDMI - in terms of technology HDMI also carries video and is a simpler connection. Whether you use Toslink of HDMI depends upon what your usage is. If the sound is generated in the TV and you want to amplify that using the receiver, Toslink will deliver a purer carrier path. If the receiver is the source of the sound and video, then using HDMI will be better.

(*) Gain can be understood in simple terms. Gain is amount of 'audio voltage' created at the source level and transmitted through a cable or wireless system. At the receiving end, a higher gain will sound louder when the amplification is not altered. Gain is the loudness BEFORE any kind of processing. The term gain comes from microphones where gain was used to decided at what dB level a recording was stored.

Don't confuse low volume with quality of sound.

Cheers
 

lightgamer

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You are mostly correct except this part.
Secondly getting lower volume does not mean lower quality. It is just that the gain(*) provided by the sending device through a transmission path is higher or lower. If you play some music or audio on the TV and increase the volume on your receiver, you will find the sound to be as good or even better than Bluetooth. Toslink is one of the highest forms of carrying audio signals, even 7.1. At the same time, it may need a higher amplification at the receiving end simply because the gain it provides is lower.
Optical or HDMI don't have any gain since they bitstream the audio (unless you're using PCM, but that's a topic for another day). Audio is then decoded completely at your receiver end. Optical cable can't even transmit voltage since it's done via light. In a digital audio signal, your receiver gets the exact source file audio itself, without any kind of alteration done to it.

However, Bluetooth is not a lossless codec(over transmission) and hence processes the file to SBC/AAC/AptX/LDAC or the upcoming LC3 codec. His files are likely sounding different because of the gain likely applied during the codec conversion on the Bluetooth end.
 

Shaishav_Udani

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You are confusing issues and products here. In one, you are connecting your phone to the receiver through Bluetooth. In two, you are connecting your TV to the receiver using Toslink. (Optical cable is also called Toslink).

Secondly getting lower volume does not mean lower quality. It is just that the gain(*) provided by the sending device through a transmission path is higher or lower. If you play some music or audio on the TV and increase the volume on your receiver, you will find the sound to be as good or even better than Bluetooth. Toslink is one of the highest forms of carrying audio signals, even 7.1. At the same time, it may need a higher amplification at the receiving end simply because the gain it provides is lower.

Toslink vs HDMI - in terms of technology HDMI also carries video and is a simpler connection. Whether you use Toslink of HDMI depends upon what your usage is. If the sound is generated in the TV and you want to amplify that using the receiver, Toslink will deliver a purer carrier path. If the receiver is the source of the sound and video, then using HDMI will be better.

(*) Gain can be understood in simple terms. Gain is amount of 'audio voltage' created at the source level and transmitted through a cable or wireless system. At the receiving end, a higher gain will sound louder when the amplification is not altered. Gain is the loudness BEFORE any kind of processing. The term gain comes from microphones where gain was used to decided at what dB level a recording was stored.

Don't confuse low volume with quality of sound.

Cheers
Thank you so much for your prompt response. I'm new to this world so sorry if I'm didn't put my question clearly. My confusion is that when I play music from my phone (through Youtube) when connected to the receiver using bluetooth, the music plays very loud and good; but when I play same music (through Youtube) but this time through my smart TV using optical cable / Toslink, the sound quality is very low.

Also can you guide how do you think my current setup is - I'm having Yamaha RXV-4A receiver, Yamaha NSF51 floor speakers, Yamaha NS-P150 and Yamaha SW300? what should be next update?
 

venkatcr

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Thanks, lightgamer. What I was attempting to do was to simplify the process for the OP's understanding. When I said 'audio voltage' I purposely used quotes to signify that the recorded gain was being transmitted as is, without any modification.

And, Shaishav, to expand on what lightgamer said, both Toslink and HDMI are carriers of digital media. All conversion including DAC and amplification is done at the receiving end.

Some receivers have a feature where you can set the level of each input. If your receiver has that feature, set it in such as a way that both the Toslink and Bluetooth work at the same rough amplitude.

Cheers
 

Shaishav_Udani

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You are mostly correct except this part.

Optical or HDMI don't have any gain since they bitstream the audio (unless you're using PCM, but that's a topic for another day). Audio is then decoded completely at your receiver end. Optical cable can't even transmit voltage since it's done via light. In a digital audio signal, your receiver gets the exact source file audio itself, without any kind of alteration done to it.

However, Bluetooth is not a lossless codec(over transmission) and hence processes the file to SBC/AAC/AptX/LDAC or the upcoming LC3 codec. His files are likely sounding different because of the gain likely applied during the codec conversion on the Bluetooth end.
Thank you for your comments.. one more question:)

Also can you guide how do you think my current setup is - I'm having Yamaha RXV-4A receiver, Yamaha NSF51 floor speakers, Yamaha NS-P150 and Yamaha SW300? what should be next update?
 

lightgamer

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Thank you for your comments.. one more question:)

Also can you guide how do you think my current setup is - I'm having Yamaha RXV-4A receiver, Yamaha NSF51 floor speakers, Yamaha NS-P150 and Yamaha SW300? what should be next update?
I'm not an expert on the audio hardware side. Someone more experienced will be able to guide you better.

About your volume level thing, just increase the volume a bit when connecting to TV. That should do it.
 

venkatcr

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Also can you guide how do you think my current setup is - I'm having Yamaha RXV-4A receiver, Yamaha NSF51 floor speakers, Yamaha NS-P150 and Yamaha SW300? what should be next update?

Your setup sounds good. The most important thing is to enjoy it. Dont think about upgrade for at least 5 years from the day you bought this system.
 

venkatcr

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Thank you so much for your prompt response. I'm new to this world so sorry if I'm didn't put my question clearly. My confusion is that when I play music from my phone (through Youtube) when connected to the receiver using bluetooth, the music plays very loud and good; but when I play same music (through Youtube) but this time through my smart TV using optical cable / Toslink, the sound quality is very low.
Again, you are confusing loudness with quality. What you do is as follows:

1. First play from your phone.
2. Second play from your TV. In this increase the volume on your receiver till you hear the music at the same volume.

If at the same 'loudness' you can hear a audible difference in the sound quality (cracks, jitter, background noise, inaudible voices, etc) then (only then) you have something to worry about. As I said before, Toslink is purer than Bluetooth.
 

neoonwheels

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You are mostly correct except this part.

Optical or HDMI don't have any gain since they bitstream the audio (unless you're using PCM, but that's a topic for another day). Audio is then decoded completely at your receiver end. Optical cable can't even transmit voltage since it's done via light. In a digital audio signal, your receiver gets the exact source file audio itself, without any kind of alteration done to it.

However, Bluetooth is not a lossless codec(over transmission) and hence processes the file to SBC/AAC/AptX/LDAC or the upcoming LC3 codec. His files are likely sounding different because of the gain likely applied during the codec conversion on the Bluetooth end.

Just 1 question.. Guess when you set the audio to DD in TV and feed DTS signal to it, I suppose it converts DTS to DD steam. I tried this using media player of TV and I could see AVR detecting the stream as DD rather than DTS. So TV also plays a part of decoding and encoding (Conversion) the formats? Is there any chance of improving quality during such conversions?
 

lightgamer

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Just 1 question.. Guess when you set the audio to DD in TV and feed DTS signal to it, I suppose it converts DTS to DD steam. I tried this using media player of TV and I could see AVR detecting the stream as DD rather than DTS. So TV also plays a part of decoding and encoding (Conversion) the formats? Is there any chance of improving quality during such conversions?
You can set the TV to pass-through the signal instead of transcoding. Though the TV won't be able to pass-through the audio in case the stream is of higher bitrate than ARC can handle. So if you have a 5.1 or 7.1 TRUE HD/DTS HD signal, the TV will only pass it as a 2.1 channel without conversion since ARC can't handle TRUE HD.
 

OM_2K19

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I recently bought Yamaha RXV-4A receiver along with Yamaha floor speakers NSF-51 and center and surround speakers NS-P150.

When I connect my my phone to the receiver using bluetooth the sound quality is much better and louder, but when I'm connect my receiver to my smart TV using optical cable the sound is much low. Is it that I need to connect my TV using HDMI cable?

What could be the reason for difference in the sound quality via bluetooth and optical cable?

  1. Optical Cables are equipped to pass lossless Stereo. For stereo content, it’s as good as HDMI. In simple words, Optical Cables do not increase or decrease audio quality. They transmit (bitstream) what's already there.
  2. Depending on the way Bluetooth is implemented by the Manufacturer, there can be a loss of quality. The LDAC codec, developed by Sony has the highest resolution audio available over Bluetooth (Apple has its own Codec). LDAC streams audio at up 990 Kbps at 24 bits/96 kHz.
In your case, it will be interesting to find what content you are playing and how you are playing on your phone and TV. At the end of the day, it should be an Apple-to-Apple comparison.
 
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