best 4.5" midrange drivers under $1K

yeah it's 4in afterall..i cant go bigger cause dont wanna to rework much on enclosure and my listening space is limited if not small

The cone may be 4" but have you looked at the specifications for the voice coil. It probably uses a 26 MM diameter overhung voice coil - a diameter no bigger than most dome tweeters. These tend to get hot as the small surface area and long coil in a short gap and which means that heat dissipation can be a challenge. The metal phase plug is intended to help cool the pole piece but it is the voice coil that will get the hottest.

What struck me was the low distortion of the

Tangband W4-1337SA ($55)- click on harmonic distortion

It seems the be even lower than the ATC unit.

Tangband seems interesting, especially the price

anyone has any experience using it? How does it sound aside from its spec?

Cdc,

It all depends at what level the test is conducted and even the units are different. Shinobiwan's test was equivalent to 96 db spl at 1 meter without an infinite baffle (so the low end distortion rises as you go below 600 Hz as the driver loses the baffle assistance or half space 6db boost to the lower frequencies).

Tangband test appears to be done at what looks like 96dB at 1/2 meter or equivalent to 90 db spl at 1 Meter with an infinte baffle.

If you only need modest SPL's then the Tangband is great option but I doubt it can go much above the level at which it was tested. (Of course you could use two in Appolito config to gain some SPL!)

SPL level requirement is the key parameter that governs whether a cheap driver will be good enough or not.

Audioism,

In simple terms the ATC unit was tested at 6 db higher SPL and yet the THD is about 10 db SPL lower - and it can probably play even much louder cleanly. Furthermore, if you look more carefully you will see that 3rd order harmonic distortion is about 20 db SPL lower on the ATC unit. At the end of the day there is no free lunch - the Tangband is excellent but you can only expect so much at $55 (my guess is your Seas Excel is probably a much better driver).