I am looking for a subwoofer for a specific purpose for an experiment. It needs to be able to reproduce (cleanly) a continuous 19Hz tone at a faily good level. 100Watts or higher RMS. The problem is that frequency is below what I can hear. Presumably it is below what any of us can hear, so I can't simply listen to it and see if it's doing what it should be. Given the experts on this forum, I thought that someone might be able to suggest a speaker that would be up for this task. I don't care about ANY other specs for my purposes. Only that particular frequency. Obviously, I would like to find the most cost-effective alternative that does the job well. Thank you for your help.