The Argos design is a compact 5" two way bookshelf using the Faital Pro 5FE120 and the Beston RT002A ribbon tweeter. This small bookshelf speaker is capable of more output then its size would suggest and exhibits excellent dispersion characteristics with a good directivity match at the crossover resulting in a wide sound stage and solid imaging. I actually purchased a pair of each driver over a year ago to start working on the design but only got around to it just recently. Background: I'd been itching to try a ribbon design for a while and decided to go ahead and start with a simple two way bookshelf design. The only real goal for this design was was good price/performance ratio, as with most of my designs I like to stay with more value oriented drivers so that the final design is accessible to those who are on a budget. I started looking for a ribbon tweeter to use and the Beston RT002A caught my attention for it's ability to be crossed fairly low for a ribbon (2500Hz). I also liked the implementation on a shallow waveguide which I suspected would give much better control of horizontal directivity then flat surface mounted ribbons. With the tweeter selected I moved onto the woofer. I knew I wanted to stay in the 5 - 5.25" range in order to prevent too much beaming at the crossover. I've had my eye on on the Faital Pro 5FE120 for a number of years as it checks nearly all the boxes, very good sensitivity for a 5" woofer, decent xmax, high power handling, nice flat frequency response free of major cone breakup and has low inductance with a shorting ring in the motor as well. The only downside is it's bass extension is somewhat limited, a trade off for the above average sensitivity the little 5" midbass gives. The result: A speaker very impressive for it's size. The high power handling and xmax on the 5FE120 means you will be hard pressed to find it's limits on regular AVR power when crossed to a subwoofer. I find the woofer handles itself well when pushed hard, I noticed no modulation of the midrange even under very bass heavy content being pushed to and perhaps a little beyond xmax. These won't wow anyone with their bass extension as it falls off hard below 60hz but it is enough to provide decent kick in smaller rooms with most music when used without a subwoofer. That said a subwoofer is recommended if you want full range extension. The RT002A doesn't have the best distortion performance I have seen from a tweeter, most inexpensive ribbons don't seem to do well distortion wise but I don't find it too objectionable. Most of the harmonics are pushed up above the vocal range which gives the highs a slight sense of false detail, again I don't find causes any listening fatigue the same way distortion that lands in in the vocal range does. Dynamics and transparency however are great and it seems to give a quicker attack then many cheap domes do which tend to get nasally and compress when pushed hard loosing their detail and separation. I found the sound stage to be excellent, the very wide and even off axis response helping there, imaging good as well. Overall I'd consider these to definitely be a step above my Nexus TM design in terms of output capability, dynamics and clarity while maintaining roughly the same footprint and cabinet size. Measurements: I ended up with a fairly flat and even response which I felt worked and sounded best in this design. There is slight rise at the top octave which could not be pulled down without using another notch filter, however it is not problematic in normal listening. The waveguide of the RT002A shows excellent horizontal directivity control maintaining near constant directivity down the the crossover where it transitions fairly smoothly to that of the the 5FE120. The woofer response does narrow some in the 2khz range which I believe is due to some diffraction from the cabinet rather then beaming from the driver as the woofer widened back up to match the tweeter at the 3kHz range. Besides that slightly narrowing the horizontal dispersion is roughly 140 degrees (+-70 degrees). -New full measurement set for the Argos MT here- Crossover: 2022 update - I have revamped the crossover for this speaker like I have for several of my other designs after updating my measurement process and jigs. The previous measurement method I was using had limited resolution which was masking a peak in the midrange. For the updated crossover I have completely revamped the low-pass network on the woofer. It is now 3rd order with the the RC acting as a broad contour filter of the upper midrange while the parallel LCR filter in series with the driver acts as a notch of the ~950hz peak which had been previously masked. The tweeter still uses a 3rd order filter with a series resistor for padding but the crossover point has been shifted upwards to 3kHz which takes some strain off the ribbon and actually results in a smoother directivity transition between the drivers. Crossover Schematic and Parts List: Note: If using the PCB a 5w 20 Ohm resistor is required for R3 this will have to be purchased elsewhere as Parts Express does not carry one otherwise the 15 Ohm (015-15) they carry could be used instead and results in just slightly more output near 950hz. If you are not using the PCB you can use the 10w 20 Ohm resistor (016-20). I also forgot to add the 1-7/8" x 5-5/8" flared port tube (260-476). The total cost for the above is ~$130. Optional Crossover PCBs for this design can be found here. VituixCAD simulated response: Cabinet Design: The enclosure is 6.5" wide x 10.5" high x 8.5" deep. I used a 3/4" baffle and 1/2" for the rest. Internal volume is approximately 0.2cuft. I placed a pair of cross braces centered between the drivers going front to back and side to side. This cabinet uses the 1-7/8" x 5-5/8" flared port from parts express which results in a tuning of ~65hz. The port is placed on the back and is centered behind the tweeter. Cabinet damping should be light fill or lining of the top half surrounding the port tube but staying behind it. I also lined the walls on either side of and behind the woofer. The crossover is placed on the bottom of the cabinet pushed to the back.