At long last, the B4 design is complete and the first production run of PC boards is off being fabricated. Delivery of first units is scheduled for January 2012.

The B2 is a perfect solution for those of you who want to get the most from a system which is bi-amped using the passive crossover networks on loudspeakers. This approach has become a popular way of achieving better performance by sharing the load between two amplifiers. With identical amplifiers on low and high frequencies, it gives better performance by reducing the intermodulation distortion between the two ranges.

Of greater interest, this approach allows use of different amplifiers on the lower and upper frequencies, playing to the relative strengths between different types of amplifiers. For example, you might easily choose to use a beefy solid state amplifier on the bottom end for woofer control coupled with a sweet little tube amplifier on the midrange and top end.

In either case, you will find that you need to be able to adjust the relative levels of the upper and lower amplifiers. This is obvious when the amplifiers have different gain figures, but it is not so obvious when the amplifiers have identical gain. It is nevertheless true that improvements can usually be had

Often an impedance buffer is useful, given that many sources have a high output impedance and have difficulty driving paralleled amplifier inputs. The B2 isolates the source impedance and independently drives the separate amplifier inputs, so they don’t interact.

The B2 has a pair of inputs, one for each channel, and two outputs for each channel. One of these outputs has a fixed level, and the other one has level adjustment through knobs on the front panel.

The input impedance of the B2 is 100 Kohm, and the output impedance is 100 ohms. The bandwidth is 1.5 Hz to 500 Khz.

Discrete single-stage Class A Jfet buffer circuits operated without feedback achieve distortion figures less than .001% at 1 volt outputs.

More information will be posted when the owner’s manual is complete.