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Maplin 150 Watt Mosfet Audio Amplifier
I was searching the internet on audio power amps and it looks like there are a few who has build the maplin 150 watt mosfet audio amplifier so i thought i'll join the bandwagon seeing that i have a bit of spare time and put up my build on this particular audio amplifier.
Back in 1985 i decided i wanted to build my own audio amplifier because i was fed-up listening to crap sounds from amplifiers that was on the market back then unless you could afford the esoteric hi-end amplifiers. Listening to these amplifiers gave me mental fatigue in the most disturbing manner,you come home put an LP on then swicth off after 2 mins because it sounds so crap. I don't pretend to have Golden Ears but i'm not far off! The amplifiers in those days where mainly bipolar or class B output. I wanted something a bit different. Maplins magazine where advertising their 150 watt mosfet audio amps modules with excellent frequency response, great sound and virtually bomb proof for £22. So i bombed down to Maplins in Hammersmith bought two modules and a 35+35 volt toroidal transformer.
Another maplin 150 watt mosfet audio amplifier build.
I bought a 19" system enclosure, put it altogether, set the quiescent current to
60 milliamps, sat back and listened and i was well chuffed. There are no high
quality components in this design and the sound is what i expected, clean,
smooth, warm, silky treble,............. it may not be everyone's cup of tea but i'm
over the moon.
You will notice two toroidal transformers in the photo,over the years the original "the one on the top" became faulty, it was producing a lot of mains hum so i replaced it and now there's not a murmur. You will also notice an extra amplifier module and its associated psu,that was for the sub-woofer. I added this at a later date but have now dispensed with it because it slightly degrades the sound but nothing to write home about. If this mosfet amplifier sounds good ,could i inprove on it! I thought about it and decided to take all the ceramic capacitors out and replace them with polystyrene ones,these are very small and high quality,they only cost a few pence more. A friend was with me at the time and he's a audiophile-nut. So after putting it all back together again we listened and yes we both agreed it sounded sweeter, there's no doubt about it!!
This is my main mosfet amplifier that is still in use today. Its feb 2011 and it has never let me down after all these years in use, its stood the test of time.
Preamplifier
In 1992 i decided to build a audio preamplifier to go with my mosfet amp. I built one from a published design namely Elektor Electronics magazine it offers very good signal handling qualities and low noise useing NE5534s. This also has stood the test of time.
Megafet Amplifier Module