• Item: Chip based phono preamp  
  • Type: retro-thermionic - "Mimic - Custom"  
  • Posted: 3 May 2021  
  • Builder: mwhouston  
  • Country: Australia  
  • Comments: 0  

Chip based MM phono stage

Yet another chip (OPA2134) based phono stage. Most parts were on hand and in this build I used Russian PIO 4uf (snubbed) caps on the output. Metal film resistors here where in other builds I have used carbon. Other caps are a mix of MKT - for accuracy - and Polyester. Once more there is no PCB but a very small piece of vero-board. Differential PS in on board and two 9V batteries power the unit. Silver plated hookup wire (wire wrap) and WBT silver based solder is used. With quality batteries 50 hours of play can be expected.

The metal enclosure is deadened in the lid and under the bottom with bituminized heavy Al. This adds weight to an otherwise light metal (Al and steel) enclosure and also dampens any resonances. There is an earthing point and an external battery test point. The overall sound is very neural and dynamics are outstanding. The preamp is dead quiet with good gain. Simple and over-achieving.


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