I tought it would be a good idea for my first real post here to contribute with a review, so here it is:

TangBand W4-1337 and W4-1320 FullRanger

To me a mid should be able to reproduce the frequency range of the human voice or very close, so I wanted a mid that was able to go from 200Hz or lower up to 6kHz or higher. That is why I ended up looking for 4" fullrangers to use as mids a few years ago, when I was looking for a nice set of affordable DIY-drivers.

While making my selection out of a few types (MarkAudio, CSS, TangBand...), I found this pair of used titanium-coned TangBand W4-1337SA's.

Off course, I wanted to have an impression of what they sounded like, so I hooked them up to my oldskool, but very neutral sounding 1976 Technics SA-5460 home-audio amplifier. Just free in the air, no box or baffle...
My conclusions:
- A detail level all the way to the top I would never have expected from a single 4" driver with no tweeter!
- No audible break-up nodes at the top, as you might expect from a metal-cone driver of this size!
- A very neutral and realistic sound
- Although lacking a baffle or box, they didn't sound "thin" at all! I even dare to say the low-end response made me thinking of a 5.5" midwoofer, but the beautiful higher-mid and top-end response with no audible break-up nodes didn't match this thought.

A few years later, my girlfriend Xenia decided she wanted a pair of TangBand 4" fullrangers for herself too, but she thought a bamboo-cone might fit her expectations even better, while being a little bit cheaper...
So we ordered a pair of W4-1320's and we connected one of them to this very same Technics SA-5460 amplifier, also free in the air with no box or baffle.
Since it was brand new, we played some various music on it at low level for a few hours before really testing it.
While doing this, we were under the impression that the sound was quite good, but off course, this was at low volume level, so it was time for the test:
- We were under the impression that this driver actually wanted to start breaking up at the top end, but the bamboo-cone dampened this, resulting in a lack of detail on the top.
- The driver sounded a bit more "full" compared to the titanium-coned 1337, but unfortunately, the level of detail in the midrange was also quite a bit below the one of the 1337's. Especially when listening to female voices, we were under the impression there was a woolen blanket over the speakers.
- The sound feels more "ambient" than the sound of the 1337's, which tend to have more of a "studio"-sound.

Well, we ended up sending the W4-1320's back and ordering a pair of W4-1337's instead... (Thank you Henkjan from Juoiga.nl to let us do this!)
This doesn't mean the W4-1320's are terrible drivers. We actually tried the combination of 1 W4-1337 and 1 W4-1320 and when the balance between these two is right, you get all the detail from the W4-1337, but the W4-1320 brings more fullness and ambience to the mix!
To use as a mid in a frontstage, the W4-1337 is a very good candidate and hard to beat for its price. Do not consider using the W4-1320 for this.
However, in combination with W4-1337's in the front, the W4-1320's are a very good candidate for ambient rear-fill!
For diy-home-audio enthousiast: an MTMW setup with both a W4-1337 and a W4-1320 as mids would be very very nice!