Hi All :-)


2007-10-16 10:52 pm

I've been getting back into HiFi recently after a good few years away. I'm slowly putting together a decent system but need to do it for as little cash as possible:bawling: . Here my technical and DIY skills plus lots of free time are major assets :D

At one time I hoped to start an esoteric amplifier manufacturing company and borrowed a friends system which included Albarry monoblock amplifiers. To start I built a good regulated power supply and constructed star earthed versions of all the best published phono amplifiers. My goal was to see if I could work out what it was that made the difference between an amplifier with apparently good measured performance and top of the range esoteric amplifiers. I'm very much a scientist and sceptically suspected the main difference was just marketing. I found that at least one of the public domain circuits I used was rated by my 'golden eared' friend as better than the original but due to other factors never pursued the project any further.
Never the less I learnt a lot. I think the biggest shock I had was from simply placing an oscilloscope across the output of an amplifier playing music normally. On a scope clipping is very easy to see as the waveforms have an impenetrable floor and ceiling at a little less than the amplifiers power supply voltages. But what's surprising is that clipping is visible way before you can hear any hint of the well known sound of clipping distortion. This lead my to theorise that a lot of the subtle deficiency's of lesser amplifiers are a consequence of clipping before it become audible in the obvious way that results with extreme clipping. This seems to be a recognised issue as a lot of esoteric amplifiers use very conservative measures of their amplifiers output. One 60W amplifier I know has power supply voltages that suggest it is 'really' a 200W amplifier. Indeed it would produce 200W if driven by a sine wave rather than a real audio signal.
Another approach I took was to reverse engineer the Albarry amplifiers. It takes a lot of time and effort to laboriously trace out the connections between all the components on a printed circuit board but again I felt I learnt something from the result as the design in general didn't seem to vary much from standard ones, although I couldn't judge the subtle issue of how the exact choice of component values affected its working. It was very handy when I needed to fix a fault too!

Right now I'm working on my first speaker repair and will be posting a description in the appropriate forum looking for advice as I need to get this right first time :cannotbe: