TREE

The output devices are MJL4281A (NPN) and MJL4302A (PNP), and feature high bandwidth, excellent SOA (safe operating area), high linearity and high gain. Driver transistors are MJE15034 (NPN) and MJE15035 (PNP). All devices are rated at 350V, with the power transistors having a 230W dissipation and the drivers are 50W. Having built a P68 using these transistors, I recommend them highly - the amplifier is most certainly at its very best with the high gain and linearity afforded by these devices. Note that there are a few minor changes to the circuit (shown below). High power amps are not too common as projects, since they are by their nature normally difficult to build, and are expensive. A small error during assembly means that you start again - this can get very costly. I recommend that you use the PCB for this amplifier, as it will save you much grief. This is not an amp for beginners working with Veroboard! The amplifier can be assembled by a reasonably experienced hobbyist in about ...

 Subwoofer Amplifier Circuit 30W  description:      This circuit with 30w output Power circuit. This Amplifier circuit is very suitable for use in subwoofer amplifier system based on IC SI1030G. Amplifier has 30W output with 8 ohm impedance. Supply voltage required minimum of 12 volts and a maximum of up to 22 volts DC.  Subwoofer Amplifier Circuit 30W  Circuit diagram:  Subwoofer Amplifier Circuit 30W   Subwoofer Amplifier Circuit 30W  Partlist: R1 = 100K R2 = 1R C1 = 2.2uF C2 = 100uF C3 = 47uF C4 = 100nF C5 = 10uF C6 = 47uF C7 = 100uF IC = SI1020GL , SI1030G

The crossover network is intended for use when an existing audio installation is to be extended by the addition of a subwoofer. Often, this additional loudspeaker is one that has been lying around for some time. If its frequency response extends down far enough, all is well and good, but a filter is then needed to cut off any frequencies above, say, 150 Hz. Often, a subwoofer network is an active filter, but here this would necessitate an additional power supply. The present network is a passive one, designed so that the speaker signal of the existing system can be used as the input signal. Crossover For Subwoofer Circuit diagram : -  Crossover Circuit Diagram For Subwoofer Since the bass information is present in both (stereo) loudspeakers, the signal for the sub woofer can simply be tapped from one of them. The network is a 1st order low-pass filter with variable input (P1) and presettable cut-off frequency (P2). The signal from the loudspeaker is applied to terminal ‘LSP’. Volta...