Thursday, May 19, 2011

kit set amp for old Sony speakers

So there were 2 VERY OLD, DUSTY (at least 1" thick beneath the cover!!) and UNAPPRECIATED Sony speakers that one day magically appeared in our T902 club hauZ. Seems that somebody conveniently let this GOOD SPEAKERS rot in an isolated corner, get kick around and UNLOVED.

Upon close inspection, the speakers are still usable. Well, at least the leads to the + and - terminal are still intact and no sign of corrosion from the moisture yet. To make these bad boys start to sing angelic tunes AGAIN, I need something to amplify the audio signal from iPod, laptop, android phones etc (not necessary be mine laaaaa). By plainly hooking the other exposed end of the mini stereo jack to the speaker’s 2 terminal won’t yield any sound. Better luck if the speakers are hooked up to a 2kHz function generator.

I need an AMP as cheap as possible. There is no luck finding the original Sony ones. Obviously, it was dumped because of the spoilt amp and hifi system. Try making one amplifying circuit from components from the lab, e.g some TIP31C, R&C ? Too time consuming and the amplified signal produced may only yield <1W from these big ASS speakers. We need something that can yield 8W from the circuit. A quick look at the store, no such IC’s readily available..... Some shopping is seriously needed at your friendly Sim Lim Tower......... After some browsing at the kit set’s section, I came across a 8W amplifying circuit kit set complete with good quality PCB with routes thick enough to pass high current, BIG heat sink and the best part, it is only s$17.50. After laying my paws on it, I hurried back to office can’t wait to start work on it.

The I/O parts are not supplied in the package, just few pieces of measly bare copper connector. I modified the inputs to a 3.5mm Stereo jack for the convenience's sake of plug to a laptop/android/iPod etc. As if it is going to be the headphone, albeit a BIG one. As for the power jack, it is done using a DC power jack with the +ve leads in the inner ring. DO NOT SOLDER or CONNECT inversely ! Outputs, I used some screw down terminal blocks meant for PCB. Too bad the PCB is designed for the above mentioned copper. I got to cut the terminal blocks to half to use it. Make sure to stick some tape on the components side, this is to prevent the components from falling out of place when soldering.

Fire up the soldering gun and start soldering......

Next up, I need a power supply that can supply 12V DC for 1A. My unloved HP charger can only go up to 6v and 200mA. I quick dive into my pile of junk and tadahhhhh... I found a dc wall adapter that satisfy the requirement. Lesson learnt, do not discard the old parts. It may come handy some day. I also added my VU meter which i made many years for practising my soldering skill. Now we got LED light indicators on the sound

Hook up the dc adapter, stereo jack to laptop and speakers to the amp circuit. Enjoy!
On a side note, the boys hook up this set to their home made projector and now we got a poor man’s cinema complete with “dolby digital surround” (speakers on the floor facing wall and reflectors to create the effects)!

What's neXt? Tube Amplifiers ???? teeeheeeheeeee