Coaxial vs RCA in audio

[Audiophile Heretic]

Any particular reason you are trying to stir up someone that hasn't posted for a few months, by responding to a post from 3 months ago ?
Surely you have something better to do on a Saturday afternoon.

I don't get a chance to read AH very often, I didn't look at the date, it was just something I hadn't read before, I didn't see any replies that I thought addressed the original question, ...and I am trying to avoid mowing the lawn.

 

[Audiophile Heretic]

Surely you have something better to do.

I guess I will go mow the lawn now.

 

[TLS Guy]

I don't believe that the spec for analog RCA is 50 ohm. Justify your claim. There is no spec for analog audio cable characteristic impedance. The wavelengths of analog audio signals on cable are between 9 and 9,000 miles.

I agree with your statement about error correction compensating for reflections on cable that is not the correct impedance. Don't digital audio devices also attempt to interpolate values if error correction is exceeded?

Since I last checked IEC 60958-3 spec has been somewhat revised.

The spec for audio cables is 45 ohms with an upper limit of 75 ohms. For digital RCA cables which should be colored orange is now 88 to 132 ohms. Apparently cables at the higher end of this spec, are actually prefered. As an example Belden RCA digital cables have an impedance of 110 ohms.

Their analog cables are 45 ohm.

 

[lovinthehd]

I don't get a chance to read AH very often, I didn't look at the date, it was just something I hadn't read before, I didn't see any replies that I thought addressed the original question, ...and I am trying to avoid mowing the lawn.

Part of the confusion is the OP (chrisanderson) hasn't been back for almost two months. Then IvanFerdinand hijacked the thread for his question which has been answered a coupla times.

 

[highfigh]

The sampling rate and bit depth of the digital audio signal carried by the digital audio cable is determined by the digital data stored on the media, not the specs of the DAC in your media player. The DAC in your media player does not process the signal carried on the digital audio cable. I have not heard of any media players that upscale the digital audio signal. I don't believe you can hear a difference between digital audio cables because they don't change the data that they transfer. The DAC that decodes the data to analog audio determines the sound quality. The DAC converting the digital data to analog audio can over-sample and interpolate to produce additional samples to reduce the need for analog filtering. There is where you may hear a difference between the DAC internal to your CD media player and the DAC external to your CD media player.

Now that I think about it, I do own an optical disk media player that will convert SACD DSD to PCM of selected sample rates to drive external DACs that are not capable of decoding DSD audio on HDMI. I consider this a downgrade of the original digital data signal, but I doubt I can reliably hear the difference.

Here's a post about whether 75 Ohm cable is important and as shown, it came from Belden, posted by Speedskater-

From an old Belden e-mail.
75 Ohms is important for coax cables longer than say about 30 feet (10 meters)
For coax cables 10 feet (3 meters) or shorter. Then cables with impedances from 50 Ohms to 125 Ohms are OK.
Note that almost any reasonable coax cable will have a impedance in the 50 Ohms to 125 Ohm range.

Kevin

 

[highfigh]

I apologize for some less than cordial remarks of some of the Audioholics members who have replied to your original post. I know that Internet forums are filled with trolls waiting to pounce, but that doesn't mean it is acceptable.

Is that the reason you gave me a dumb rating?

 

[Ivan Ferdinand]

Tha

You have a USB input. This accepts a digital signal from a source (computer? Phone?) to the K7
You have an optical input. This accepts a digital signal from a source to the K7
You have a coaxial electrical input labeled "coax". This accepts a digital signal from a source to the K7
You have two coaxial electrical inputs colored red and white and labeled "in". These accept single-channel (each) analog signals from a source.
You have two coaxial electrical inputs colored red and white and labeled "out". These provide single-channel (each) analog signals to send to something else (like an AVR).

The digital inputs are interchangeable (there may be some nuance around protocols on USB, but the two others have identical data simply sent over different physical media. These are what you should be using. They use the DAC on your K7 to convert to analog.

The analog inputs are there mostly as legacy. You use them if there's something in your chain with no available digital out. I suppose you could use them if you needed to bypass the K7's DAC for some reason, but no reason comes to mind.

Thank you for your explanation.
I have another qusstion about DAC/AMP combo. So in dac amp combo, if i connect dac amp combo to my pc or maybe cd player via digital connections like usb/coax/optical, and i connect my headphone to the headphone out, how it can make a sound? Doesn't a sound should come from an analog cable? Usb/coax/optical are digital. What happen here?

 

[Ivan Ferdinand]

Tha

Thank you for your explaination.
I have another qusstion about DAC/AMP combo. So in dac amp combo, if i connect dac amp combo to my pc or maybe cd player via digital connections like usb/coax/optical, and i connect my headphone to the headphone out, how it can make a sound? Doesn't a sound should come from an analog cable? Usb/coax/optical are digital. What happen here?

@Audiophile Heretic

 

[lovinthehd]

Tha

Thank you for your explanation.
I have another qusstion about DAC/AMP combo. So in dac amp combo, if i connect dac amp combo to my pc or maybe cd player via digital connections like usb/coax/optical, and i connect my headphone to the headphone out, how it can make a sound? Doesn't a sound should come from an analog cable? Usb/coax/optical are digital. What happen here?

Because the DAC works (digital to analog conversion), at least most headphones use an analog out, what does yours use?

 

[TLS Guy]

@Audiophile Heretic

Oh, for Heaven's sake please stop being so obtuse.

DAC means Digital Audio Converter.

So your DAC/ headphone amp, can receive a digital signal convert it to analog and amplify it for your headphones

 

[JerryLove]

Tha

Thank you for your explanation.
I have another qusstion about DAC/AMP combo. So in dac amp combo, if i connect dac amp combo to my pc or maybe cd player via digital connections like usb/coax/optical, and i connect my headphone to the headphone out, how it can make a sound? Doesn't a sound should come from an analog cable? Usb/coax/optical are digital. What happen here?

• CD source is digital data. It's read by the transport.
• It's then transmitted over the digital cable to your headphone amp.
• The DAC in your headphone amp converts the digital signal to an analog signal (that's what DACs do).
• Your amp (which has pre-amp and amp secrtions) then amplifies that to the signal strength suggested by your volume knob and sends the analog signal to the headphone jack.

Replace "CD" with "Computer" and it's the same steps.