Does a subwoofer amplifer exist?

I am in the process of building a sealed subwoofer and I am in the middle of searching for an appropriate subwoofer amplifier. I would prefer not to get a subwoofer plate. I have searched for a subwoofer amplifer with a built in crossover, but so far I have not been successful.

Does such a thing exist?
Check HSU.
I thought a subwoofer plate was just a term used to describe what you are looking for, an amplifier with a crosover built in. What are you looking for that a plate amp doesn't provide? A conventional case?
Visit the Hsu Research website and check out Hsu's 500A (500 watt) subwoofer
amp. I believe that the owner's manual is available as a download. I'm using one
to power the second voice coils on my Gallo Reference 3 speakers and like it a
lot. Cost me $749 direct from Hsu. Many crossover modules are available. This
is a really serious subwoofer amp.
If you really can't find a stand alone amplifier for your sub, take a look at the ones that manufacturers send with their subs. For example, I know that Velodyne used to have a model that came with an external amplifier. You can sometimes find them for sale on ebay, more so than on audiogon. Also, you could use a regular two channel amplifier in bridge mode, and buy the Paradigm X-30 crossover to go with it?
Gallo just released their Reference SA. (

It can be used to set:
boost (through an eq function & stereo volume)
hsu,nht,dbx,m&k,all 4 of these manufacturers make subwoofer amps for passive subs.

Thanks, good references.
If you decide to build your own sub, rather than buy one, then you might want to look at Outlaw Audio's M2200 monoblock amp, which sells direct (via Internet) for $325. For more info, go to this link:

You may also want to consider just buying Outlaw Audio's powered subwoofer, which was designed for them by Hsu. It sells for $579, and has gotten some excellent reviews.
Wow, these amps aren't cheap. Why are they so much more expensive than a subwoofer amp plate? The Outlaw amp has a good price; however, I would still need to get a crossover, possibly the Paradigm unit I see on Audiogon on ocassion.