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Puzzling connection problem, TV to m-DAC/pre-amp

Jonathan Tafler

Jonathan Tafler

Well-Known Member
The optical out of my Panasonic tv is broken. I wish to route the sound to my Audiolab m-DAC/pre-amp, which only has digital inputs. Taking advice on a previous thread I bodged the toslink connector into the socket with Blutac - this holds for a bit but because the angle is awkward, not very long. I am therefore trying another way - using the analogue out from the tv via a jack to female phono adaptor, then going via the phonos to a little analogue to digital converter, and out of there via either toslink or coaxial to the audiolab. I have connected it all up as described and I can see the connection is there as when I select the relevant input on the audiolab it shows a 20bit/48khz connection (if there is no good connection the display will say "unlocked"). However there is no sound coming through the speakers and no level showing going through the Audiolab. Can anyone guess from this information what simple schoolboy error I may be making? Because Panasonic customer support were worse than useless.
 
can you use a 3.5mm jack to 2 rca cable and plug the 3.5 mm into the headphone socket of the tv ? and rca into the dac ? we have done that with a set up
 
As you describe it, you cannot connect an 'analogue out' from the TV into a DAC. A DAC needs a digital signal (Toslink). The Analogue output is designed to go to an analogue input on something like an amplifier or, say, a soundbar.
 
JensenHealey said:
As you describe it, you cannot connect an 'analogue out' from the TV into a DAC. A DAC needs a digital signal (Toslink). The Analogue output is designed to go to an analogue input on something like an amplifier or, say, a soundbar.
Click to expand...

I am not connecting the analogue signal to a DAC but to an analogue to digital converter, and thence to the DAC/preamp. It is a convoluted way of doing things but all I could think of
 
Is it a line level output or does it have volume control? I would expect your ADC to send a digital output to the MDAC even if the output is silence.
 
Strictly Stereo said:
Is it a line level output or does it have volume control? I would expect your ADC to send a digital output to the MDAC even if the output is silence.
Click to expand...
What is puzzling is that the display on the mDAC shows the connection - which presumably it wouldn’t if no signal was being routed via the analogue out of the TV? Yet there is no level showing - again, if there were level but no sound it would be obvious that the problem was with power amp or speakers (although all other sources and inputs working fine). Maybe the ADC is faulty? I only just bought it. All the lights come on. Trying to think what else I can test it with.
 
Jonathan Tafler said:
Not line level - DAC/preamp with volume control.
Click to expand...

I was referring to the analogue output from the TV. As the output is a jack, it is probably intended for use with headphones and almost certainly has a volume control. If the headphone output is disabled or if volume is turned down very low or muted, this would account for the problem you are experiencing.

Jonathan Tafler said:
What is puzzling is that the display on the mDAC shows the connection - which presumably it wouldn’t if no signal was being routed via the analogue out of the TV?
Click to expand...

This is to be expected. The ADC almost certainly sends a continuous digital signal to the MDAC even when there is no signal to its analogue input.

Jonathan Tafler said:
Yet there is no level showing - again, if there were level but no sound it would be obvious that the problem was with power amp or speakers (although all other sources and inputs working fine). Maybe the ADC is faulty? I only just bought it. All the lights come on. Trying to think what else I can test it with.
Click to expand...

What model of Panasonic TV do you have? My Sony TV has a separate volume control for the headphone output buried in the menu. On my LG TV, I have to select the headphone output from a menu, which also disables the other outputs. I have no idea what options your TV's menu offers, but if you can tell me the model number, I can download the manual from Panasonic's website and take a look. My working theory/best guess is that either the output is disabled or the volume control for that output is turned down or muted altogether.
 
"..bodged the toslink connector into the socket with Blutac - this holds for a bit but because the angle is awkward, not very long..."

Could a stronger mechanical connection be made with some Sugru or Polymorph (aka modeler's plastic)..?
 
Strictly Stereo said:
I was referring to the analogue output from the TV. As the output is a jack, it is probably intended for use with headphones and almost certainly has a volume control. If the headphone output is disabled or if volume is turned down very low or muted, this would account for the problem you are experiencing.



This is to be expected. The ADC almost certainly sends a continuous digital signal to the MDAC even when there is no signal to its analogue input.



What model of Panasonic TV do you have? My Sony TV has a separate volume control for the headphone output buried in the menu. On my LG TV, I have to select the headphone output from a menu, which also disables the other outputs. I have no idea what options your TV's menu offers, but if you can tell me the model number, I can download the manual from Panasonic's website and take a look. My working theory/best guess is that either the output is disabled or the volume control for that output is turned down or muted altogether.
Click to expand...
Thank you. Will investigate further tonight. Not at home now. It is a Panasonic TX47AS802B. At the moment the out from the tele is the audio part of component out, havent tried headphone out as yet.
 
  • Do you have a bluray player that allows for the Audio return channel(ARC) of hdmi 1.4?, if so you can...
  • Activate ARC by connecting your bluray player to the hdmi output that supports ARC
  • Using the bluray player's (Oppo 103, for example) audio return input.
  • When you want to watch TV, you select the bluray input on the mdac.
  • Then the ARC input on the bluray player
  • Then you select the Hdmi, or TV tuner input of the TV.
 
Jonathan Tafler said:
At the moment the out from the tele is the audio part of component out, havent tried headphone out as yet.
Click to expand...

I think you'll get better results with a mini jack to twin RCA cable, either directly connected to an input on your amplifier, or via an ADC into the mdac. I connected an older TV with analogue outputs, and no digital outputs, this way, and it worked fine.
 
Jonathan Tafler said:
Thank you. Will investigate further tonight. Not at home now. It is a Panasonic TX47AS802B. At the moment the out from the tele is the audio part of component out, havent tried headphone out as yet.
Click to expand...

I use the headphone output from my Panasonic as a line input to my pre-amp. It is under Menu>>Sound>>Headphone volume.
 
Strictly Stereo said:
I was referring to the analogue output from the TV. As the output is a jack, it is probably intended for use with headphones and almost certainly has a volume control. If the headphone output is disabled or if volume is turned down very low or muted, this would account for the problem you are experiencing.



This is to be expected. The ADC almost certainly sends a continuous digital signal to the MDAC even when there is no signal to its analogue input.



What model of Panasonic TV do you have? My Sony TV has a separate volume control for the headphone output buried in the menu. On my LG TV, I have to select the headphone output from a menu, which also disables the other outputs. I have no idea what options your TV's menu offers, but if you can tell me the model number, I can download the manual from Panasonic's website and take a look. My working theory/best guess is that either the output is disabled or the volume control for that output is turned down or muted altogether.
Click to expand...
Thank you. Will investigate further tonight. It is a Panasonic TX47
Peter Stockwell said:
  • Do you have a bluray player that allows for the Audio return channel(ARC) of hdmi 1.4?, if so you can...
  • Activate ARC by connecting your bluray player to the hdmi output that supports ARC
  • Using the bluray player's (Oppo 103, for example) audio return input.
  • When you want to watch TV, you select the bluray input on the mdac.
  • Then the ARC input on the bluray player
  • Then you select the Hdmi, or TV tuner input of the TV.
Click to expand...
Thank you for that; looks like a plan. I do have a Blu-ray successfully connected to mDAC. What is against is that I am trying to make operation as simple as poss to placate my wife But I have bought a harmony remote recently so I should be able to programme that so it happens without having to think about it.
 
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