The use of an active filter (ASP) multiplies the amplifiers. The advantage is that this facilitates the amplifiers’ work, because they deal with a smaller frequency range and different power. Now, we use home theater amplifiers, such as the ATI6012 12 times 60W, ATI1806 6 times 180W, or ATOLL AV500 5 times 100W. But the problem is that in the same box, all have the same power, they do not distinguish between tweeter, medium and bass. I find it damaging to use the same technology for powers as different as 30W for the tweeter and 400W for the bass. So it is much better to use amps that offer ranges of powers that correspond. However, there is no company offer the mix of amps with different powers. The possibility of mixing good stereo amps exists, but the price will take the lift! So I decided to create my own amplifiers which correspond to the needs of the LX521. In addition, I have integrated the active filter (ASP) in the same box to avoid too many connectors.
These amplifiers were developed and built in the same artisanal spirit as the LX521. For the box, I have partners who use powerful machines such as laser cuts and CNCs to provide me the basic parts. Then I assemble everything. Each pair is unique, and can be personalised.
The electronic part gave me the most satisfaction. This is the field I know the best.
For amplifiers of the tweeter and midrange, I use push-pull design, polarized in class A and it stays in class A up to 2 amperes. This is sufficient for a normal use of the LX521. These 2 amplifiers have the same design, which provides the same sound signature. I just use a lower voltage for the tweeter. All transistors are paired, allowing for high stability and symmetry. My goal is to have a signal as direct as possible, no capacitor on the passage of sound, they can amplify DC current. Moreover, I did not want to use electronic compensations for thermal drifts. The control of temperature is totally separated. I use a fan per amplifier to control the temperature with the precision to 0.1 C°. These fans have large diameters (12cm), are very quiet and they rotate at a very low speed. No noise is heard during operation. Stability is the key word. All power supplies are also stabilized and have their own toroidal transformers (4 per box). The variations of the main power supply do not affect these amplifiers. Despite the fans, the heat sinks are large in size, which creates thermal inertia and offers more stability. The final stages and their drivers are installed on the heat sinks, once again to guarantee a great stability. The electrolytic capacitors (Epcos), with a total value of 544'000 uF per box, that are distributed between the tweeter and the medium, are of very good quality and have very long life. The addition of capacitors of MKP technologies with high values (up to 100 uF per capacitor) allows very high speed and clarity of sound.
For the bass, I use a 400W class D amplifier from Hypex. They are powered by a 1200W switching power supply.
It took me a lot of time to arrange coherently all these different elements, i.e. class A, linear power supply, class D, digital power supply, fans, capacitors of 544'000 uF, four toroidal transformers, and big heat sinks, in a box. I call those big boxes "Transducers".
With a total weight of 29 kg per piece, these "Transducers" try to fully use the enormous potential of the LX521.
Each piece is unique and may be painted at your choice. If desired, your name can also be engraved together with the serial number.