White Noise Active Power Supply

[ANDYLASER]

I have an active PSU kit that was purchased from White Noise Audio, some years ago. It has remained unused since being built. Hopefully someone else will have a use for it..

It was originally configured for +/- 30V @ 5A. It can easily be reconfigured ( +/- 15V up to +/- 100V) by changing a couple of power resistors. The PSU features built in soft start and over current protection (up to 10A).

It will be supplied with full documentation, including BOM, schematics & board layout.

These originally cost £125.

I would like £60 including UK postage and paypal fees.

Will post elsewhere at cost.





Schematic (large size)

Details from web site.

Conventional audio power supplies consist of a transformer, rectifier, and smoothing capacitors. The smoothing capacitors are the capacitative element of an RC low pass filter designed to attenuate the 100Hz ripple, or 'hum', produced by the rectifier/capacitor combination. The resistive element of the filter consists of the transformer secondary windings and the power supply wiring. This small resistive component means that the turnover frequency of the filter is much higher than desirable and consequently the ripple is not attenuated by as much as is desirable. The value of the resistive component can't be increased very much beyond 1-2Ω because the output voltage would drop to nearly zero as soon as any significant current was drawn from the supply. The capacitative element can be increased up to a point, but size, cost, and availability soon become a problem. Stabilized power supplies overcome this difficulty, but necessarily waste a considerable amount of power in the expensively heatsinked pass transistors, whilst the stabilization loop introduces high frequency triangular wave corruption onto the output voltage.

The rectifier bridge of the active power supply drives a high current active filter which delivers essentially ripple free power, without the power losses inherent in stabilized power supplies. The power active filter leads to an effective multi-thousand fold increase in the value of the RC filter resistive component; with a consequent massive reduction in ripple voltage and very low output impedance over a wide frequency range. You can't get this level of ripple reduction with a conventional power supply no matter how large, sophisticated, or expensive the smoothing capacitors. The sonic improvement extends across the audio spectrum but is most noticeable on bass peaks which are fast, tight, and free from the roughness associated with conventional power supplies.

The active power supply is soft start with built-in over current protection and can be configured for any output between ±15V ( for op-amps and pre-amps ) and ±100V ( for monster power amplifiers ) whilst the current limit can be set to any value between 0 and 10A. A conventional power supply is obtained if the pcb is not populated with the current limiting and power active filter components, whilst adding a few extra components in spaces provided on the pcb will give a simple stabilized supply. The rectifier bridge ( using discrete TO220 rectifier diodes ) is on the pcb and the input is fused; the only off-pcb component required is a transformer. As with a simple power supply, one for a pair of power amplifiers is adequate but one per power amplifier is optimum.

[ANDYLASER]

Bump for the weekend and a discount to £50
Need to shift this to pay for another more urgent project.

[ANDYLASER]

Time for a bump and a discount. How does £45 sound?

[peranders]

You could try Ebay

(A bit odd PSU I must say....)

[ANDYLASER]

Happy to take £40 for this.

[AlanElsdon]

Originally Posted by ANDYLASER

Happy to take £40 for this.

Go on - I will make you happy - do you have the documentation that WNA normally supplied?

How do you want payment - Paypal?

Alan
Alan