Sunday, August 13, 2017

Mimic - "Carbon" phono MM preamp

 After building and selling a number of Mimic MM  and MM\MC phono preamps, all based on Oddwatt's great design, I have here a Carbon film resistor version. All other builds use metal film 1/2W resistors. Carbon film 1W resistors have been used in a few of my tube power amps and the sound is rich and mellow. Here 1/4W fine carbon film resistors are used.

To make this build even more different with MKT caps I have also used Polypropylene and Russian Mil. PIO caps. The large red caps in the image above are 4uf PIO snubbed with 220nF polies. The usual OPA2134 chip and mil. spec. socket are used. Silver plated fine wire wrap wire is used for the short hookups. PS and amp exist on a 5cm square of vero-board. WBT silver solder holds it all together.

I had hoped this preamp would run from a single 9V battery but in the end two 9V batteries were required. This should provide 100hours of play between battery changes. A battery test point is at the front and an earth lug on the side. Initial test show good promise with a rich and warm sound from (at this point) limited listening. Interestingly on a short A/B test it sounded similar to my LM833 based two stage MM  preamp. Both have great warmth. 

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