I build mine.I find fraws in most designs.15-18 inch drivers in a sealed box.Mid Q design seem to work fine in the HT arena.Amps must be 800-1000 watts,with a real ampere output current in mind.Cabinets have to be at least two inches thick of MDF.Heavy on the bracing too.I tend to use two in my system, it takes the edge off of the other driver and always seems to give me the headroom I need.It needs to play clean up to 110-115db to get that,"I'm not even working feeling" when playing around 80-85db.Nothing is worse than a sub running out of steam at around 85-90db.I cross mine over at 65hz.That's where my sats. rolloff.Room modes suck.You have to get a parametric to keep out the bumps or all you will hear is the bumps.I have been building them for about thirty years now and seem to out grow them every five years.My neww ones will be using Adire drivers(tumults) and Adcom GFA 555mkII's in mono.Wish me luck.
What's you opinion?
Yes, your opinion does matter. What do you honestly think about subwoofers? What makes a good subwoofer? Are we or is the market tainted by big boomy, mushy woofers and car boom boxes? Does anyone really know what a good sub should sound like and how it should perform? Who makes a truly quality product? Is quality being measured by sound or physical characteristics or both? Maybe some other criteria I did not mention? Tell me what is your ideal subwoofer? Create it. Is it a sub or a subwoofer system? The floor is open.