1DIFFSYM2QC TYPE S220 Watts Class AB amplifier
Product Overview：
Class A/B amplifiers are known for providing warm and full bass. The 1DIFFSYM2QC amplifier is particularly impressive, offering a huge soundstage, accurate vocals, and detailed highs. The overall sound is well-balanced across the audio range, with no overpowering bass or shrillness in the upper register. With a THD of just 0.02% at 1 Watt and 1kHz, 4 Ohms, this amplifier is truly exceptional and unique. It's built like a tank and is sure to impress. We highly recommend purchasing a speaker delay and protection circuit to ensure optimal performance and protection for your equipment.
Dimensions
143mm * 130mm . Allowing for creation of a multichannel amplifier and or active speaker system.
Power Source
Unregulated +/-40VDC to MAX +/-60VDC, checkout our power supply module.
Mounting
You will need a suitable heatsink with at least 0.6 C/W dissipation and mounting kit. The module has holes for mounting. M3 screws and standoffs would be suitable for attachment.
Details
The amplifier should reach full power at line level voltages. You may use a preamplifier of your choice.
1. Connect the output transistors to a suitable heatsink using thermal pads, washers and screws 2. Ensure short circuit protection fast blow 6.3A are fitted on the board
3. Short the input with a jumper for initial power up and bias testing.
4. R24 is a 25 turn trimmer, center it at 12 turns. You can use a voltmeter to set this trimmer to maximum resistance between its pins before powering the board
5. Before attaching power,let the main power supply discharge by itself before connecting its leads to the board.
6. While power supply is powered down and discharged naturally connect the ground lead of the power supply first, then the negative lead and finally the positive lead
7. Use a multimeter to measure the voltage between speaker ground and speaker out terminals. This should preferably be less than 50mV.
8. For bias adjustment measure the voltage across R11 with a multimeter and adjust R24 until the voltage across R11 reads between 10mV to 20mV. Bias the output devices at 100mA (20mV) for better performance THD will be around 0.02%
WHERE More elaborate testing is required
Power the board from dual DC lab supplies limited at 300mA at -/+ 20VDC
1. Use a function generator to apply 20Hz, 1kHz and 20kHz sine waves of 0.2V to the signal
and GND terminals of the PCB.
2. Using an oscilloscope between the speaker GND and SPEAKER, observe the resulting
signal. There should be no ringing or oscillation.
Although fitted with series input resistors, do not accidentally use unreasonably high waveforms as those of other power amplifiers or mains AC at the input as you risk damaging the input stage. Public address systems and touring gear where such mistakes can happen are usually outfitted with input stage clamping diodes.
Have fun and let us know what you think.
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