Lau Wai Pan’s solar-powered preamp: His best design so far

The big box at the bottom houses the solar panels which power the preamp (the black box with two knobs). The others are the DC-AC inverter and cooling fan.

By Lam Seng Fatt

When audiophile, electrical engineer, tinkerer and inventor Lau Wai Pan came to my house with an assortment of components (see, I was wondering first of all how I could fix all the stuff together to get it to work and secondly, how it would sound with a solar-powered power supply.

I must say that the solar-powered power supply is a novel and original concept. After googling around, I found that there are some audiophiles who live in remote off-grid areas who have solar panels on their rooftops to power their homes including their hi-fi systems. There are also audiophiles who have set up solar panels due to their areas being commonly affected by power outages or who believe in greening the world with renewable energy. But these power delivery systems entail solar panels on the roof either sending power to the grid or charging batteries which are then connected to an inverter to convert from DC to AC to power the house. Lau’s invention features solar panels lining the sides inside a metal box which has two car headlight bulbs lighting up the system.

This contraption powers a preamp which has a battery-powered gain stage and a solar-powered tube output stage. Lau uses a pair of 5670W tubes for the output stage.

First of all, I have to say that Lau’s solar-powered preamp system is bulky and has many boxes. It has very low WAF (Wife Acceptance Factor) and that is a very important factor to take into account (as all of us would sigh and grudgingly agree). But bear in mind that the review system is a beta model and Lau is fully aware that it needs some refinement and better WAF.

But in terms of sound quality, this is Lau’s best design so far. I have reviewed two of his preamp designs (see and and after listening to this solar-powered design (with no name yet) I can state that Lau likes a smooth sound with no hardness, no shrill treble and no brightness.

The solar-powered preamp functioned very well but the power supply generated some heat as Lau uses halogen bulbs. I have seen LED car headlight bulbs in the market, but Lau said LED light bulbs cannot be used as they flicker and the wavelength of the light is not right.

The car headlight halogen bulbs create some heat.
The beta design allows too much light to leak out. Lau said the sealing to stop light leakage can be improved with no issues.

With the solar power supply, the noise floor is very low. This results in a lot of micro details popping out.

Remarkably, the sound stage is wide and especially deep, and the pace is quite fast. Images are not as well outlined and etched out as some of the high-end preamps in the market, but if you like a smooth sound with rounded-off leading edges and a bass that could be tighter (remember the output stage uses tubes), then this solar-powered preamp is for you. Of course, you need a very patient and forgiving wife.

For more details, call Lau Wai Pan at 012-5121787.

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