The NaO II RS is a premium quality Dipole Open Baffle speaker designed by John Kreskovsky of Music and Design, offering outstanding “top of the range” performance. The NaO II RS design attempts to maintain constant directivity in the form of dipole radiation above the Schroeder frequency, below the Schroeder frequency the NaO II RS panel is integrated with a unique, U-frame woofer system. For full technical information including Schroeder frequency details, specifications of the active and passive crossovers, and discussions on the design philosophy followed, please visit the Music and Design website here.
Please note that the kit offered here are driver sets only. For construction plans, PCB’s, MiniDSP details and general recommendations, you will need to visit the Music and Design website here where there is detailed background information and you can purchase Plan Set Packs, PCB’s etc.. Photographs of completed NaO II RS speakers are reproduced by kind permission of John Kreskovsky and are © Music and Design 2012.
The NaO II RS employs a reconfigured, damped U-frame woofer system, using two Peerless 10″ XXLS 835016 aluminum cone woofers and has dual 18 cm ScanSpeak Discover 18W/8545-00 midranges in a classic MTM arrangement with the legendary Seas T25CF002 E0011-06 Millennium Tweeter. A rear-mounted Seas 27TDFC H1189-06 Tweeter is incorporated for improved spectral balance at higher frequencies.
The design of the NaO II RS follows a hybrid approach, using an active crossover between the woofer and main panel and a passive crossover between the midrange and tweeter. The passive crossover is designed to primarily control the response of the midrange and tweeter through the crossover region. In this manner very little amplifier headroom is wasted in the passive crossover compared to a design where the necessary response equalization is performed in the passive circuits.
The hybrid approach results in a cost effective, bi-amplified system which has many of the benefits of a fully active system without employing additional channels of amplification. Further discussion of the Hybrid Design philosophy can be found in the Music and Design technical section and application to the original NaO II may be found under the NaO Website menu.
Fully Active and MiniDSP upgrade versions if preferred are also available on the Music and Design website here.
A narrow baffle design for the NaO II RS midrange/tweeter panel is implemented to achieve dipole radiation. The MTM format was chosen to allow a sufficiently narrow baffle to maintain dipole operation of the midrange drivers from the panel low frequency limit to the crossover point of 2.2 k Hz and provide sufficient radiating area for the targeted maximum SPL of the system. Above 2.2k Hz the NaO II RS employs front and rear tweeters. While the rear tweeter helps slightly in controlling the radiation pattern above the crossover point its primary function is to improve the spectral balance of the sound radiated to the rear of the speaker. This aids in achieving a more even spectral balance between the direct and reflected sound.
Contrary to other open baffle designs, the NaO II RS uses a unique,damped U-frame woofer system, which due to careful integration of the NaO II RS dipole midrange/tweeter panel with the damped U-frame acoustic resistance woofer results in a high performance, bi-amplified speaker system which: 1) achieves nearly ideal dipole radiation throughout the critical midrange, 2) has very uniform polar response over a wide listening window, and 3) provides great flexibility in coupling the system to the room.
The NaO II RS is 53″ tall, 12 1/2″ wide and 19″ deep at the base.
|4||18W/8545||18cm 42mm Carb SCA Denmark||SCAN-SPEAK||728.08$|
|4||269SWR51XXLSB||27cm 51mm Al 835016 Denmark||PEERLESS||906.55$|
|2||27TDFC06||26mm Text 10cm SEA Norway||SEAS PRESTIGE||110.95$|
|2||T25-002||26mm Sono 11cm SEA Norway||SEAS EXCEL||592.45$|