The article is about reviewing a NAMEC BTL SCHEMATIC, a Power Amplifier Module from Indonesia made by audio Holic home brewer that their PCB are available at online market in this country.
The driver Kits are using Bridge Tied Load as the output to get optimal output results.
Contents
INFO NAMEC BTL SCHEMATIC PCB
The working voltage in this circuit uses a symmetrical voltage between 45VDC to 65 VDC.
With this voltage, it possible to make audio output 250 Watts at 8 Ohm up to 400 Watts at 4 Ohm load.
Note: You need to have total 4 pairs of C5200/A1943 transistors to make your goal are successfully.
You can purchase the PCB online shop such as MHL ELEKTRONIK.
PCBs appearance is look LIKE THIS LINK.
SCHEMATIC NAMEC BTL SCHEMATIC
This is a result of tracing down from that PCB:
From the schematic above you can see that the circuit is using the principle of passive BTL.
Passive BTL is a technique of changing the signal phase for the SPK- side by signaling from the SPK+ output to the second inverting power input via Resistor R29+R30.
Meanwhile, the second power on the input side goes to GROUND.
With a model like this, it is expected to achieve an output signal voltage of 2 x than usual.
The point is that if SPK+ is +45Vp against Ground, then SPK- is +45 but has a phase difference of 180 degrees.
So that at the SPK+ and SPK- points will produce voltages up to 90Vp-p.
Mathematically, if you use a supply voltage of 65VDC symmetrical and a 4 Ohm speaker load, then this series of kits will produce up to 760 Watts of power.
You need at least a total of 6 pairs of TOSHIBA 2SC5200 / 2SA1943 transistors for this circuit.
3 pairs for Power SPK+ and 3 pairs for Power both SPK-.
