Single driver full range speakers

It is not easy to manufacture a single driver speaker to properly address the unique demands and challenges inherent in this topology. Prior to German Physiks, I tried Omega and Ohm at home. I listened to Liisong and MBL in my friends' systems. With the exception of MBL, the other ones had several shortcomings that I just couldn't see myself living with in the long term. German Physiks Unicorn changed my mind about single driver speakers though. Not only is it the best single driver speaker that I've owned, it is THE best speaker that I have owned to date regardless of design or price point.

absolutely is done.  My Ref3A DeCapo I speakers are two way and use no crossover, just a high pass cap on the tweeter.

the trick is to find a woofer that rolls off as a good match to where the tweeter begins to come in.

You could also make an effort to time-align woofer and tweeter if you are a diy builder.

I really like full-range speakers with lightweight and additional whizzer cones, but they lack the deep bass we are used to from “standard” speakers. There are back loaded horn designs that improve the bass somewhat, but they usually cause other problems. I have been working on this topic for almost 50 years and have tried and listened to many drivers and designs. 

In the end, I developed a completely different approach. A: The driver must have an electromagnet and B: There must also be a large diaphragm for the low frequencies. Perhaps the effort involved is too great for some, but listening to music with the Wolf von Langa London really gets under your skin and gives you boundless pleasure! At least take a look at the speaker; in the US, Colin King (Gestalt.Audio) may be able to arrange for you to listen to it. https://fieldcoilloudspeakers.com

"Full range single driver" (FRSD) is often an oxymoron. Because there is no crossover,  the midrange and a few octaves on either side might be the best you ever heard, but they are lacking at the extremes, necessitating a subwoofer, supertweeter or both. Many times these are simply cobbled together and levels, timbre, phase, etc., are often mismatched. An exception would be German Physiks and a few others that do employ only one driver and achieve phenomenal extension. Most do not.

Wilson Benesch uses a 2.5 way design that direct-couples their midrange driver to the amp. This 7 inch driver’s frequency response is approximately <100Hz - >5KHz, which some might regard as full range or close to it, practically speaking. They then use acoustic or first order crossovers to mate this driver with their proprietary tweeter and woofers to yield 30Hz to 30KHz. While a subwoofer will be needed to get to 20Hz, the seamless integration of their "FRSD" with their impeccably designed, constructed and matched high and low ends yields what I think many are trying to achieve, which is a lucid midrange with transparent extension to the extremes. 

I tried a single driver speaker and while it sounded great at lower volumes it just didn't do it for me after a while.   I admit I fell in love with their presentation of vocals and imaging,   they struggled with rock at even modest listening levels.  

I used them for about a year and I'm glad I tried a single driver speaker but in the end I was missing the sparkle and air a tweeter brings to the party so I sold them and bought a sealed acoustic suspension 2 way.  Never looked back.