Thursday, March 18, 2010

The ugly, the bad and the good.

I spent much of the day playing with measurements and chasing ugly things. Since it kills me to pull down the system to go to the bench to make measurements, I simply take the lazy approach and bring the measurements to the system.  This way while I am contemplating the meaning of life, I can have music to help me think.

The ugly part comes in when  you look at the mess of wires I create when attempting this task.
OK, I'll admit that isn't really that bad compared to my earlier works so I guess that means I am growing as an individual.  The goal for the day was to chase down some noise, compare the output and frequency response of a few cartridges and try to peer inside a sealed up Tannoy crossover.

The Good part is that all of the above has been made reasonably easy and affordable with the slew of audio measurement software and hardware out there.  I'll be the first to admit, I do not have Audio Precision quality or even Tek bandwidth but my humble measurement suite gets me the information I need.

The most important thing to me is to be able to capture and save the data.  I have a  data capture device that samples at 1mhz.  It has the ability to oversample to give (according to nyquest) 5mhz bandwidth which gives an acceptable live look at a 10K square wave.  It also has FFT capability as well as the ability to measure various aspects of the waveform.  The trace on the above picture is actual music and is something you will not ever see on anything other than a storage scope.  This is really important to me since I feel much of what we are looking for has to do with dynamics and to me,  using a 100mhz scope to view a static signal is like watching paint dry.

This is the little beast that does it all.  It comes from usb-instruments and costs about $200.  I find the datalogger function really helpful and they even have a higher sampling rate unit that only has a single channel for about the same price.  I guess you need to pick your battles first, then choose your tools.

In reading back I have covered the Good and the Ugly,  In order to make this post complete, I will leave you with the bad.... and when I say BAD, I mean sorta kinda really mis-behavin'

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