Audio-visual electronics maker Tonic Industries' profit in the first half to September 30 climbed 20 per cent from a year earlier to $34.4 million. Turnover climbed 12 per cent to $1.08 billion. Chairman Simon Ling Siu-man said Tonic wanted to increase earnings by shifting to high-margin and high- technology goods. He said the company had sold 150,000 mini disc hi-fi systems during the period, turning a gross profit of up to 25 per cent. This compares with an overall average gross margin of less than 15 per cent. Tonic is now developing portable mini-disc players and systems, digital versatile disc (DVD) players and other home appliances, to be launched in the first half of next year. Mr Ling said the firm initially would make 5,000 DVD players per month. Tonic is also diversifying into digital satellite receivers, Internet set-top boxes and audio-visual consoles.