Improving the amplifier
I have found some ways to increase the decoupling between the individual amplifiers and to even increase the decoupling between input and output stage of the individual amplifiers. This improves the dynamics of the amplifier.
Tuning the output impedance of the amplifier. There is room for some increase in output impedance. This further improves the distortion in the drivers.
I see possibilities to increase the output impedance to more than 250 kΩ, but that requires a change in active component which looses the capability to decouple input from the output stage.
The reason to go 4-way is to lower distortion even further and to increase further the dynamics.
The current system is already full range. But going 4-way increases the possible displacement in the bottom area’s of both current drivers. The idea is to add a midrange to higher the crossover frequency for the tweeter and to add a subwoofer to higher the crossover for the woofer. This lowers the distortion even more in all the drivers.
The biggest advantage however is the possibility with 4-way loudspeakers and an active crossover to parallel four amplifiers, which increases the output till 16 times the output power of one amplifier with only a four times increase in power demand for the power supply. So, four amplifiers capable of delivering (for example) 100 watt peak deliver in total an equivalent of 1600 watt peak power (four times the peak voltage and four time the peak current).
I am experimenting with the use of closed transmission lines. A closed transmission line gives the possibility to dampen the resonance in an acoustic way and improves the damping of sound in the enclosure.
Improving crossover and correction methods
This area involves software and algorithm development. This, with four goals in mind:
- To automate the design of the crossovers and the correction of the drivers.
- Phase linearization.
- To design non-linear transfer functions (compressors) to add distortion to achieve certain sound characteristics (like a tube amp).
- To develop a black box feed forward method for minimizing distortion in drivers.