This is my first posting on this forum. I apologize if this is the wrong place. My friend is trying the experiment where corn starch is placed on a speaker at low frequencies and forms strange shapes. There are videos on youtube but I cannot add links yet. It's for our physics class as a final project (yeah, it's a great final). She's having trouble getting it to work though. She's using a 25W guitar amp with a frequency generated by a laptop. The signal runs from the labtop straight into the regular guitar input. The amp works with a guitar, but at the very low frequencies she's trying to use to get the fluid to become more viscous there is no noticeable effect. My theory is that the signal from the laptop is meant for a speaker alone, and not an amplifier then a speaker. Is this true? Could adjusting the gain on the amp help? Any ideas on how to get this to work? Thanks for reading. May the gravitational force be with you.