Fascinating speakers. I've heard several people say they like them. Reminds me of the bird that shouldn't be able to fly but did anyway.
Here data and measurements on them:
hifigoteborg.se
https://hifigoteborg.se › pdfPDF
(can't copy in the pdf link, see attached picture,
www.hifigoteborg.se for how to google that pdf

)
"DAHLQUIST DQ-10 Phased Array
Translation graph below:
Speaker test results
Type:
Belongs to certificate no. 75110.88
Appendix 2 -H?
Belongs to certificate no. 75110.88
Appendix 2 -Hl
Frequency curves in reverberation rooms
Manufacturer: Dahlquist
DQ-10
Supplier: Nord PressAP
Nominal impedance: 8ohm
Signal voltage across the speaker: 2.7 V noise, 30 Hz bandwidth
Efficiency: 0.08%
Frequency curve, the 0 level * 50 dB rel. 1 pW
harmonic curve, 0-level * 30 dE rel. 1 pW
Scale: distance between each scale bar = 1 dB
The speaker was measured on the floor 15 cm from the wall
Loudspeaker tone control in max. mode (max. treble)"