Analog vs Digital outputs

SACD format

Audio ADC/DAC resolution

Tone & warmth

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Analog vs Digital outputs back to menu

The question of which is better - analog or digital outputs is not an entirely simple one to answer. A lot depends upon the quality of the circuits and components inside the player itself. If your amplifier supports a digital input you should probably consider using it in addition to the analog connections.

The difference lies in the number of times a signal is processed and converted. Let's follow the signal from a CD disc to the speaker through each possible connection.

CD's Digital Audio is recorded in digital format. The CD player reads the digital information as carefully as it's jitter prevention will allow. This is then up sampled by better players offering 2x,4x or even 8x "oversampling". This means that for every 16bit "word" of data actually read from the CD there is added another 1,3 or 7 16bit "words" of data copied from the original sample. This has the subtle though useful effect in better CD players of shifting the harsh edge noise away from the actual information we want to hear. This in turn allows for more subtle filters to now be employed for waveform smoothing.

It is at this point, immediately prior to the D/A conversion process, that the digital output is tapped off and exits the chassis via Coax or Optical cable.

The analog output goes through the D/A conversion process in the DAC surprisingly enough! And then exits the chassis through the analog outputs.

Now that should be the end of the story, obviously the digital should be better right? wrong!

The amplifier or receiver that will be lending it's current to this signal has to handle the incoming signal. This step can easily bring a fine CD player to it's knees. The whole process has to end in an analog signal for the power amplification circuits to supply to the speakers. To make matters worse, along the way the signal must be in a digital format for the receiver to process into the sort of curve it's transformers need to produce the right sounds. Hmmmm. Looks as though the answer to this question is not a straightforward one.

 

- Audio ADC/DAC resolution back to menu

This refers to the actual number of samples the DAC or ADC can handle per second. All things being equal (jitter management etc) the higher the sampling resolution - the more musical. Back to that phrase "all things being equal", in the real world they're not equal. Chassis rigidity, Power Filtering and isolation, internal interconnect quality, component choices and pickup and transport differences ensure that the resolution is not the holy grail - though it's a mighty fine chalice to chase in general.

In order to convert an analog waveform into a digital bitstream it is necessary to slice the wave up into very very small instants of time and record the snapshot of sound. Play these digital snapshots back at the same speed they were captured and you can reconstruct an approximate to the original waveform. (Don't laugh about the "at the same speed" business - more than one classic CD has been laid down overly fast and therefore slightly off-key. One Miles Davis CD springs to mind as an example of a 44.1khz CD released directly from a 48khz studio master tape.)

Many inexpensive CD players and pc CDRoms feature lower resolution Audio DAC's with steep filter curves offering harsh sound. Better Audio CD players offer at least 96khz sampling resolution.

 

- Tone & warmth back to menu

The tone and warmth of a CD player is a very subjective measure, although fatter midrange tends to give a warmer sound and thinner midrange and bass generally a colder tinnier hollow sound. Also the cleanliness of the separation of instrumental and vocal components of a track add to the richness and depth effects best experienced with a very good CD player.

The output curves generated by the CD player are a direct result of the filters used on the data resolved by the ADC. There are the limiting factors - ADC resolution and filter quality.

These days digital filters are used regularly for their much higher flexibility and ease of reprogramming. Some analog valve hybrid CD players do exist - see Vincent among our products.

A final word on tone and warmth - CABLES. I know we keep going on about it, but cable quality can change a good sounding system into a superb system for very few dollars.

 

- SACD format back to menu

Originally designed by Sony Music for archiving studio master tapes and vinyl recordings to prevent deterioration, the format was found to be so successful and with so many advantages that a consumer variant was inevitable.

Super Audio CD uses a new and radically different technology called Direct Stream Digital (DSD) to convert music into a digital signal that can be stored on a disc. Compared to the traditional PCM method (the technology used for CD), DSD offers a much higher resolution by following more closely the original wave form of music. With a frequency response of over 100kHz and a dynamic range over 120dB across the audible frequency range - some 64 times higher resolution then CD - Super Audio CD offers music reproduction that reveals details you just can’t hear on a normal CD. A major plus is the extremely simple conversion from any recording sampling frequency to any output sampling frequency.

The Direct Stream Digital pulse train "looks" remarkably like the analog waveform it represents. More pulses point up as the wave goes positive and down as the wave goes negative.

What you hear is less background static or hiss, cleaner separation of instruments and vocals as well as an open and expansive soundstage.

SACD discs come in numerous types: SACD only, Hybrid CD/SACD and Stereo/Multi Channel SACD Hybrid discs.

In order to play SACD discs, you must have your SACD player connected to your amplifier using the 6 cables of the 5.1 external pre-out on the back of the player. These must be connected to the amplifier's external 5.1 or 7.1 pre-input. The amplifier must also have this external input assigned to the device in order to play.