Hands on: Sounds better

The Hardware mailbag has been buzzing with comments following our recent columns on getting serious quality audio from PCs. High-end audio often divides opinions, with passionate followers balanced by those who believe there’s little in it.

As an audio fanatic myself, I’m pleased to report the majority of our readership belong to the former category.

Not everyone is convinced by the often esoteric techniques and equipment involved though, so we’ll start with an enquiry following my experience with a Logitech Squeezebox I modified to deliver superior quality through its digital output.

It’s all noughts and ones
Retired electronics engineer and PCW reader Peter Hinch was puzzled how such modifications could improve the delivery of what is essentially a stream of zeros and ones.

Peter wrote: “It strikes me the entire signal chain, starting from a WAV file and ending in an S/PDIF data stream is a lossless, digital process. It would be a reasonably straightforward task to design a box that took the S/PDIF data stream, decoded the biphase mark signal and output a WAV file.

"I appreciate S/PDIF can cause harmonic distortion if afflicted with significant clock jitter, but high-end audio amplifiers have circuitry to correct this; besides, since the Squeezebox doubtless buffers data received from the network, I would expect it to employ a good-quality, constant frequency crystal controlled clock for its S/PDIF encoder.

“If I am correct in my assessment of how the Squeezebox works, it makes no more sense to modify it than to use gold-plated Cat 6 network cables or special ‘audio grade’ hard disks or CPU in the server. The entire system chain from WAV file to the input terminal of the audio amplifier should be lossless.”

This is a valid point. CD transports have the added difficulty of physically reading the data from a disc, but purely electronic delivery systems such as the Squeezebox have the potential to be perfect.

As Peter points out, so long as the original file is lossless and doesn’t involve decoding errors, then the data should pass from the server through the device to the digital to analogue converter without any loss in quality.

Connectors and cables play a big role though, as do power sources for various components. Who better to explain it than Wayne Waananen of the Bolder Cable Company, who designed and implemented the modification performed on my own Squeezebox.

Wayne said: “The RCA output connector of the standard Squeezebox is not designed to S/PDIF specifications ­ it doesn’t have 75ohm impedance.