Speed drop after changing router to modem

[leekwangyaw]

I,m a singtel 10mbps user and my router is 2wire 2700hgv-2. A few days ago my router spoiled so I bought a new one but this time I changed to linksys AM300 ADSL+2 modem because I'm the only user here so I don't need a router. After I changed to it then I found that the download speed seems to drop so I runned a speedtest and the result was terrible. My previous result was around 5600-6000kbps but now only have around 1800-1900kbps.
What is the reason?
http://www.speedtest.net/result/426542275.png (http://www.speedtest.net)