Ref Four ? Audiophile Acoustics for the Audio Elite Our Reference series have always been about that little extra, the added experience that is hard to pinpoint, but that makes the sound more sophisticated and refined. Making the heritage appear clearly, over-sized products can be applied in a wide range of configurations, even those not intended at first. We have always taken great pride in meticulous R D to provide premium products, but it has also been a misconception that B2 Audio products might not have been designed with SQ as a cornerstone. The Ref Four is a statement to show the contrary. It took numerous prototypes and revisions to ensure it would be catering to the purists and audio elite. The Reference project has taken almost 2 years to come to a working design that meets our expectations. The profile of the amplifier is more conservative, but that can?t be said for what?s inside. No compromise This amplifier is provided without compromise, focusing on dynamics, headroom, and overall sound quality. Renown component manufacturers such as Mcap, Nichicon, Burr Brown, IR have been used to fulfill the stringent component level specifications required for this project. There will always be comparisons to certain brands, but looking at the unique aspects of the Ref Four: *A heatsink with better heat dispersion, meaning you don?t need fans in the amp. *Mcap capacitors and burr brown op amps coupled with the finest caps from Nichicon. The cost increase of these compared to no name can easily be 150 times more per unit. *High precision hand mounted and matched mosfets from International Rectifier, where others use ordinary cheaper Philips screws, we use Allen head, as it not only looks nicer, but it also allows for better mounting. *Custom specced power supply cover. This may appear that it is for looks only, but there is again a huge cost related to it, as it needs to have a particular surface area allowing the torroid not to overheat, and offers a slight added performance feature as well. *Class AB to Class A bias mode. Meaning you can drive the amplifier in a full open mosfet configuration to achieve a different sound reproduction that can increase the overall High Fidelity. *1 ohm stereo option. Due to all the upgrades to the amplifier, the Ref Four is able to run at 1 ohm stereo, this is actually where the amplifier really comes alive and impresses. It was nearly a day night scenario. Not saying we weren?t impressed by 4 ohm, but there was such a huge difference from 4 ohms to 1 ohm that was nearly unbelievable. Product Manual Power Output 12V 1% THD 14.4V 1% THD Power @ 4 ?: 4 x 75 w 4 x 125 w Power @ 2 ?: 4 x 135 w 4 x 225 w Power @ 1 ?: 4 x 190 w 4 x 325 w Frequency Response: 10 Hz ~ 30 KHz Signal to Noise Ratio: 95 dB Input Sensitivity: 8 ~ 0.1 V Crossover: 24 dB / Oct Low Pass Crossover: 40 Hz ~ 4KHz ? 24dB High Pass Crossover: 40 Hz ~ 4KHz ? 24dB Bias Class AB Class A: Yes Damping Factor: 300 Power Terminal Gauge: 4 GA x1 Fuse Rating: 120 A Operational voltage: 11 V ~ 15 V Dimensions: 15.35 x 8.6 x 2.6? / 390 x 219.5 x 65 mm