VMPS uses first order networks and in-phase drivers because that emulates live music best. Material used as standard is first rate (Erse “Super Q”, Solen, Bennic, Axon, Vishay), and absolute best capacitors from Auricaps and TRT are offered as option at additional cost. We build passive crossovers to very tight tolerances. For us that means four decimal places, or 1/2000th of 1%. Each crossover is trimmed to exact value, no tolerances. This means, for example, 1.600uF, not 1.6uF. You only get repeatability with high levels of precision.We laugh at the tolerances (5%, 1%) even the best competitors use. All connections are soldered point to point, no printed board is used. This solution does not look very good, but sounds much better.
Our “Super Q” Erse coils are superior to any aircore, since their DCR is about 35% of an equivalent gauge aircore of the same value. It has nothing to do with cost, the Erse’s aren’t cheap either. DCR is the most important characteristic of a series inductor as long as it does not saturate or suffer from hysteresis. The very large laminar core of the Erse’s eliminates both problems and sound just wonderful, which is why we use them.
Crossover includes two L-pads for level adjustment of midrange panels and tweeter. We use them instead of fixed resistors because L-pads allow a 1/20th of 1dB change in level to be effected by the user. Often such a change is all that is needed to tame hot trebles or a forward midrange. A fixed value does not allow the user to adapt the music to his tastes. Also, resistors are not made with sufficient tolerances to give us the precision we feel necessary for level changes. You can’t get this level of precision with a stepped attenuator or a resistor network. In fact even 1% tolerance Vishays (which we use elsewhere in the xover) do not permit this level of precision, which can be very important when you switch equipment or IC’s/speaker wire.
Binding posts we use are selected because they have been proven best for a number of years and are best suited for accepting spades. They are solid brass/gold plated, with 6mm shafts, solid metal nut that can be tightened with a nut driver. There is no hole through the center of the shaft (for the bare wire) which weakens the shaft and causes breakage.
