APEX LCR O speaker kit
The APEX LCR can be used as a center channel, as a right or left, or for the sides or rears: it is a very versatile speaker kit. It uses modified SDX7 woofers matched with the RA104.5 ribbon tweeter (the OW4 tweeter is optional), with the drivers placed in a WMTW configuration and mirror-imaged.
What to expect: the bass is very tight, not boomy, with in-room response below 24 Hz; the midrange and the higher frequencies are very well balanced, with great off-axis response. Crossover points are 550 Hz and 2000 Hz. The kit is for one speaker.
Frequency range
15 Hz – 40 kHz · log scaleThe kit includes
- 2 × SDX7 XBL² drivers (modified cone treatment)
- 1 × RA104.5 ribbon tweeter
- 1 × FR125S treated midrange driver (modified cone treatment)
- Solen (Mundorf) capacitors, 16 gauge air core inductors, metal oxide resistors
- Terminal cup with custom terminal posts
- Teflon silver wire, screws, damping material
- Cardas lead-free silver solder
- Cabinet construction plans, plus a CD with complete construction photos of the cabinets, the crossover layout plans with photos of assembled crossovers, and veneering and finishing information
Recommended cabinet
- Rear ported cabinet tuned to 26 Hz: 28" wide × 11.25" tall × 15.25" deep
- Sealed cabinet: 28" wide × 11.25" tall × 12.5" deep
Measured
Responses were taken at 1 meter: within ±2.5 dB from 200 Hz to 20 kHz.
Impedance: an easy 6 ohm load; the impedance plot of the ported cabinet shows the tuning at 24 Hz. The sealed cabinet was measured as well.
Off-axis horizontal measurements were taken at 15, 30 and 45 degrees, and unsmoothed spectral decay was measured with the complete crossover (the same parts sold in the kits) for the tweeter, the midrange and the woofer.
Used vertically as a monitor, place the tweeter towards the center of the room for the best imaging.