Easy and work project

Let's test your subwoofer low-frequency respond. Each frequency duration is 3 second long so you can here different clearly. Frequencies start from 1Hz to 300Hz. You may not hear 1 -10 Hz sine wave frequencies because human hearing limitation but modern amplifier can amplify this low-frequency band, sometimes if you play these low-frequencies loud enough your body can feel it. You also can not hear 11 - 19 Hz (some golden ears human may hear 18 - 19 Hz) but your room will be shaking if you play these frequencies band loud enough. 20 - 30 Hz frequencies range are audible if you have a big speaker, good headphone or subwoofer, a small speaker may not produce these low frequencies or sound decrease so much but you can feel it when you touch the speaker. A good desktop external speaker low-frequency cut-off around 80 - 100 Hz but a normal laptop built-in loudspeakers low-frequency cut-off around 150 Hz. Below video will come in handy when you work out side but forgot your g

When I brought lepy LP-A6fm from my local store(Thailand) for under 10 $.  I though it's a good low-cost amp and I've found that this amp not bad at all. The bad thing I hate LP-A6fm is the amp have big pop noise when connecting to the power supply to the amplifier and the amplifier doesn't have any on/off switch. I thought the problem may come from JRC 4558 op-amp that doesn't have soft on/off function so I decided to change JRC 4558 to ne5532 op amp for low pop noise and change some capacitors for sound quality improvement. Yeah! Let's start. List of component: 1 x ne5532 opamp and 8 pins ic socket (for JRC 4558 op amp replacement, sound improve much). 3 x capacitor 100 uf muse FW(FG are better) for op amp power supply replacement and for main amp replacement 4 x 10 uf Elna Ccerafine or Silmic II electrolytic capacitors for the mellower sound. 1 mks 0.1 uf Wima capacitor(not see in the video because it attaches to preamp power supply under PCB board. 2 x

Advantage: 1 Wide supply voltage from 10 to 22 volts so you can use battery power. 2 Use only 8 parts to make jobs done. 3 High bandwidth 100khz 4 Low distortion no more than 3% at 2 watts (not 10% thd at full power like commercial amplifier spec ) Lm380n is old but still good sounding ic if you can eliminate oscillation and power supply ripple. The ic is very easy to build and you don't have to attach heatsink for normal operation. 2.5 watts power is enough to drive small 8 ohms loudspeaker for your little amplifier project. This wiring diagram is very stable and low oscillate noise even your hand near volume control. The cost of lm380n around 1$ R1 is 2 kilo-ohms resistor ( See how to read resistor color code here ) Beware!!!! Capacitor C1,C3,C4,C5 is electrolytic capacitor so you must check polarity or the capacitor especially C3 will explode,that may cause severe injured,so you must know what you do. See this ic sound test video.