This review page is supported in part by the sponsors whose ad banners are displayed below
FirstWatt is all wrong if you chase bling face plates, milled-from-solid cases, hernia- inducing bragging rights and butch power ratings doubling into half an ohm. But if your needs coincide with one of the special-app models in this second catalogue from legendary amp designer Nelson Pass—he takes care of big power with Pass Labs—this brand is a treasure trove of very special finds. Having reviewed the lot, our archives tell the individual tales.
The arguably biggest blow to 'normal' users came when the model F5 was discontinued. It was applicable for the most conventional speakers relative to the other FirstWatt amps. As such it was the easiest entry into the range. Now the clouds have parted. Initially available only as a DIY project with immediate publication of the necessary schematic, 1.5 years later this 25/50wpc 8/4Ω push/pull stereo amp with Jensen input transformers for passive voltage gain, phase splitting and local feedback has gone into formal production. What's changed over the original DIY-only version? Just the output devices. They began as SemiSouth enhancement-mode power JFets whose electrical behaviour makes them more transistor triodes. (Nelson's proprietary SIT or static-induction transistors are an advanced form of the same kind).
DIY version F6 on Nelson's bench
Now they're International Rectifier FP240 Mosfets. By comparison those act closer to pentodes. As he describes in this PDF, Nelson feels they're ultimately more appropriate for this push/pull circuit. For $3'500, each outgoing amp is again hand-tuned by the master to hit the exact same THD curves as his reference unit. For all those who've cried salty tears over the F5's demise—occasionally used units still show up at RenoHifi—the launch of the F6 is cause for sweet celebration. Whilst DIYers continue to roll their own, those of us fit only for turn-key satisfaction now have their own access to the F6. Why that's good news is very simple. Having compared the DIY version against my SIT1 and SIT2 production amps at $10'000/pr and $5'000 respectively, I'd called it a very close stand-in on sound whilst rather upping power and lowering output impedance to do the happy into many conventional multi-way heavily crossover'd speakers.
So welcome what I personally consider to be the long-awaited successor to the well-liked FirstWatt F5. Its numerology certainly falls in line with this site too...