Thursday, 13 August 2015

Project X

I've been interested in how things work for quite sometime which in the old days was fairly straight forward in that often you could see just by looking at all the key bits and that often was connected with audio equipment as getting good sound has always mattered to me.
Sometimes I'd buy either a full kit to assemble or boards with all the main components mounted on to just wire up and a few bits to make say a radio unit or an amplifier for not much money.
Sometimes it was worth it just for the learning experience alone.
As a good number of you know in recent years because of my acquired difficulties with my hands, that whole avenue has been denied me simply cos I can't solder and screw things together anymore. That really hacks me off big time.
I've bought something more or less ready done to experiment a bit with though and it is this.
It's a SA 36A Pro 'amplifier' ready assembled from board similar to what can be bought part done with a power unit.
The first and in many ways intriguing aspect to it is it uses a special low power integrated circuit to produce approximately 25 watts per channel made by TI Instruments, the TPA3118D2DAP, which is a Class D high efficiency one that a number of people are raving about for its sound..
I won't bore the pants off of you by explain all about Class D as there's a good entry on Wikipedia explaining all but it's why such a small cheap board can equal the output of a more conventional amplifier of a similar power using less electricity and getting less hot.

The front panel shows just how small it is and  also why  I put parenthesise around the word amplifier as while it has a volume control, it does lack an input selector which at a later stage of this project I intend to tackle.

This is the actual board as fitted with the integrated circuit the small black object in the centre and you'll also see how careful design has removed the need for trailing wiring from back to front.

This is the back panel of the SA 36, original version which only accepted 12 volts dc input, the 36A Pro accepts up to 24 volts for higher output via black switched mode (transformerless) power unit that is supplied.
There are binding posts to connect 4 to 8 ohm loud speakers to, left and right line input and that 2.5mm inner, 5.5 outer socket for the power unit.

The supplied power unit is 12 volts but only 2 amp maximum which I feel is a bit restricting so I've ordered a 60 watt max, 5 amp one to use with it as if the amplifier draw more than the supplied power unit can give it's protection circuits are more likely to need to kick in and some have found the quality of these units is compromised  by the rather basic supplied units, that are not the manufacturers own. 

That unit also has a fused UK mains lead where as the supplied unit is a unfused continental 2 pin one with a basic unfused adapter which I wasn't happy about on safety grounds as serious conditions could develop before your mains circuit tripped, knocking off the power.
I'm interested in two things, the first being just how good is this chip? and secondly as advocate of getting good sound into peoples lives, can budget hifi equipment by non mainstream manufactures provide a way in for people who end up with so-so all in one music systems to enjoy more of their music.

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