Retro Hi-Fi Girl Friday - This one is for Thebes. http://itishifi.blogspot.com
Sunday, June 17, 2012
Emia Strain Gauge
It has been a long time in the coming but the first official Emia strain gauge phono supply is ready to be delivered. It holds true to its "drug through the hudson" brethren with a couple of new tricks.
The need for biasing has been done away with and it is now simply plug and play as you roll through tubes to find the "tone" you want. Also two switchable filter sections have been added to bring the riaa EQ closer to the ideal. The beauty of the way the filters are designed is that they are relay switched shunt filters so when they are in the off position there is no sonic penalty to be had.
The average panasonic gives about +- 2.5dB accuracy from 100hz to 10Khz and has rising response on either side of that. The first filter addresses the 100 -10K range and uses a permalloy inductor to bring things close to +-1dB. I was able to get it to +- .5dB but it reached the point where I felt the filter was killing the overall beauty of the strain gauge sound so I backed it off a bit to where I felt it listenable again. The other filter section is in place to tame the rising high frequency behavior and even though the plots are not that different, the results are quite audible. My preferences are for both filters to be out but others may feel differently so the option is there.
below are the plots I measured to show the three response curves of the various filters. (the filter robs about 3dB of overall gain and the plots are normalized to a 1Khz level)
For those who look at the measurements and don't read the above text...I want to be clear that I was able to get much better measured response (hell I could nail it) but the sound suffered so I backed off to get sound I would accept putting my name on. I still prefer the sound without filters and now you have an option of hearing both and deciding for yourself. Luckily in some circles junkies with differing tastes can still enjoy their high.