How to connect two seperate subs?

[WBFAir]

I recently decided to add a second sub of the exact make & model to my sound system.

Both subs are self powered and are receiving there signals via Monster Sub interconnects from the single sub out of my amp.

I used a standard RCA "Y" splitter and started listening and found that while both had the same and correct volume for the system, the old sub sounded fine but the second had more of a fuzzy sound.

For a bit I though I might have gotten a bum driver but then I disconnect the old sub, leaving the splitter in and the new one started working correctly.

Could someone maybe explain to me what might be wrong and what I can do about it? are the special splitters for this?

Thanks

[TwisterZ]

If you have preamp outputs for right & left use your Reciever setup to set the mains to large and no sub. Then connect your to subs to the right & left outputs using the crossover on the sub to keep the highs out. You may need to lower your crossover point depending on the low frequency capibility of your mains.