11/09/2008

Never Connected publish a 'white paper' that tells all.

With the imminent launch of our new AT2000 integrated amplifier, at the London Heathrow Sound and Vision show, 19th-21st September (Syndicate room 9), it was good timing to receive a 'white paper' from Richard at Never Connected. It outlines the design and development process that has produced the amazing Mk 2 power supply for audio applications we are using in the AT2000. So, for those of you who are interested in the technical details and inner workings of the products they own, or are thinking of owning, please read on:

WHITE PAPER

Never-Connected, Generation 2. September 2008

The Never Connected Isolating Power Supply for high quality Audio use was originally developed over 5 years ago and is now incorporated under license in equipment manufactured by Astin Trew, ECS, Mitchel and Trichord Research.

Built on this initial success with many thousands of satisfied Never-Connected users, we have now developed a totally new and improved version of Never-Connected known as version 2.

The role of the power supply in producing high quality natural sound is absolutely fundamental, rather like the foundations of a house.

The use of simple low cost linear or switch mode power supplies always compromises sound quality, a fact which in our experience no amount of clever circuit design, sophisticated regulator circuits, fancy cables, or filters can correct for.

This is down to the fundamental fact that all power supplies either let through high levels of mains borne interference or worse still in the case of switch mode power supplies actually produce this noise.

Whilst filters can prove effective in removing this noise, in our experience they also tend to have an adverse effect on the source impedance of the power supply producing a sound spectrum with un-natural tonal balance.

The Patented Never-Connected supply overcomes this using a sophisticated switching system to ensure that at no time is there a direct connection between the incoming mains and the connected load thus breaking the conduction path for mains borne noise and interference.

As a specialist in the development of Power Supplies for Audio use we are able to justify spending far more time and money in the development of the power supply than most manufacturers who are often under time and cost constraints to produce complete new product designs on a regular basis, often resulting in the use of refined versions of standard power supply designs.

Building on our extensive experience in the use of Never-Connected v1 in a very wide range of applications we looked at every element and function of the existing Never-Connected design in detail.

We came to the conclusion that the design could be improved in many areas. In the first instance, we took several new design iterations and evaluated each by measurement and extensive listening tests, utilising a wide range of different equipment.

At an early stage it became clear that the design of the output regulator and switching circuits played a critical part in achieving optimum sound quality, in the case of the output regulator it was clear that the use of even the highest quality integrated circuit type regulators was a major compromise when compared to discrete circuit designs; especially when the supply was used to feed a 2 channel load where output stability and uniform source impedance are required over a wide frequency range 20hz to 40Khz (2 channels, operating at 20khz, 180 degrees out of phase).

On this basis a discrete regulator design was developed and optimised, in all listening tests we ensured that for best results all secondary regulators were removed from the equipment to give us a clear window on the sonic effects of the new regulator design.

Once circuit design was optimised the development and fine tuning of board layout was undertaken along with further optimisation of circuit design. Having got to this stage comprehensive listening tests were undertaken to firstly establish which components effected the subjective sound quality, this was then followed by further listening tests to select the best possible component.

This was a fascinating process, at every stage of this exhaustive process small but meaningful gains in sound quality were achieved.

The cumulative effect when finally compared to a high end commercial power supply and the original Never-Connected design is a significant lift in sound quality, with a clearly lower noise floor, improved dynamic resolution (macro and micro), truly natural tonal balance and excellent tonal colour, combined with unforced detail, and greatly improved sense of depth width and focus.

Further evaluation of N-C v2 was then undertaken in a wide range of equipment to establish the relative benefits of its use in various different circuit locations.

The greatest levels of improvement were achieved when N-C v2 was used to power the analogue line level stages in source components, eg pre-amplifier stages, CD players. The input and low level drive stages in power amplifiers also show substantial gains in sound quality.

In the case of a high end digital to analogue converter using N-C v2 to feed the analogue stages, if the local regulators (x4 decoupled high performance IC type regulators) were put back in circuit, a clear and definite compromise in sound quality occurred.

When used to power digital stages the benefits of using N-C v2 were again clearly audible and definitely worthwhile.

Whilst the supply can be adapted to work with Power Amplifier output stages, the improvements here were not as great as those achieved on the line level stages with their greater susceptibility to noise and interference.


If you found this interesting, you may well now wish to go and have a listen to the AT2000 to understand what impact the N.C. power supplies can have on an already good amplifier design!