Posted by SteveBrown [ 155.188.247.5 ] on February 02, 2007 at 11:54:26:
Just wanted to mention that I have a new preamp on the bench, well it has actually moved beyond the bench and into my system for a listen. Initial impressions are very good. This design uses a 5687 (1/2 per channel). The 5687 is biased (82ohm AN Tant) for 18ma and the plate load is a CCS. Pretty ordinary, but then the fun begins. This goes to a 3.3uf Obligato parafeed cap (cool looking copper jacket) and then to a Lundall LL1676 4:1 step down transformer. This gives me single ended or balanced output, lower output impedance, and loads of isolation from the rest of the system. The power supply is tube rectified (6CA4) and choke loaded and will soon be shunt regulated using a CCS on top of gas regulators. For volume control I'm using a step attenuator and the pre is silver wired throughout. If anyone is looking for a nice project, this has been pretty rewarding so far. As it cooks in, I'll add any meaningful comments about the sound. One thing I did notice right off is that there is great focus and depth. The bass is a bit different than before, it isn't as "thick" as my prior 6SN7 pre, but seems to have more punch. Strange. I'll investigate further.
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