Lack of bass in NHT 3.3.

Also be sure to replace the deteriorated foam strip on the front baffle if it's rotted out. It plays an important part of the sound. 

you probably have a room null under 100hz somewhere. i have one at 45 and 75hz. every room is different, you will need to change your listening position or move the speakers. which is why ones that have strict placements are so troublesome.

There butt old but worth the effort. 
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I agree with the node suggestion above. I have NHT T6 towers (pretty much the 3.3's replacement) and the bass is not powerful unless you are in certain spots in the room. Being that they are tower speakers, they don't offer the placement flexibility of a monitor and separate sub - you're kind of stuck with what you get. I did add several standalone subs in the room to help balance things out. The woofers are only going to get down into the mid 20's before they start rolling off, so subs will be useful anyway to get the very bottom frequencies.

Hi , I know this is an old thread but thought I would join in , I live in Fort Worth and am a NHT 3.3 owner, I bought mine in the early 90's.  My speakers are in a large room, maybe 16 by 26 with 10 ft ceilings and my pair will play without noticeable distortion or compression to Rock concert levels, and that includes the Bass frequencies as well.  I've never found their limits , they can play loud enough to make me have to leave the room .... and that's loud. I think I remember Ken Kantor the designer saying that they were designed to be able to play at 115 or 120 db. I'm also in agreement that it's important they have lots of clean power to make them really get up and boogie. I don't do it often but once in a while, Boston goes into the cd player and they Rock! The 3.3's have the best Bass I have heard in a speaker system without a subwoofer, I love my pair, they sound great playing any type of music. You would be welcome to come by for a listen to compare them to yours.

Best regards,
Dean