F1 and J2 - anyone own both?

I'm currently listening to an F1 borrowed from a friend. It truly is magic - driving 16ohm compression drivers through large horns - covering 460hz-20khz. Active system with an arc-welder doing bass duties (old-school Crown - awesome)

Its got me sold on First Watt. I absolutely love it.

Given the zero-availability of the F1- and based on reading and advice, the J2 might be my option. However,here is no chance for me to hear one before I place an order.

Can anyone familiar with both make some general comparisons or comments to help me out? I would really appreciate it.

The F1 is SO quiet, black. With the horn sensitivity at 110db, that is important. J2 has two gain stages vs 1 etc.

I welcome your thoughts.

is DIY an option for you? - it's easy to make F1 , considering that there is no unobtanium parts at all

if you found F1 pushed all your buttons , there is no way that J2 will do the same , without pains - as you said , when dealing with sensitivity of drivers so high , everything is critical , and even more

why - even if you buy J2 made by FW , which is properly made , there is possibility that you'll have worse S/N ratio when connected and interconnected , simply because there is a ton of gain in J2 comparing to F1

also - J2 is 2nd harmonic dominant , while F1 you found so nice is either 3rd dominant or so-so (depending of fact who made it)

so , just go and build it ...... or build any of recent shenanigans of our Michael Rothacher (MoFo) - again - your in good place with your hysteric squawker , making an amp for that is more easy than hard

if needed , I believe you will find F1 pcbs on forum , or files to make your own

Dennis Hui

Paid Member
2002-08-27 7:19 pm
Toronto, Canada
Was the F1 you used a factory one or a DIY piece? Can you check with
the owner if it's the original mosfet version or whether it has the semisouth
jfet update.

If it is the mosfet version, then as the Mighty Zen Mod said, all parts are
readily available. Since it works so well for you, I suggest you try building
Thanks for the responses. It is great to know the DIY option exists for the F1 - certainly something I will look into.

The F1 I am borrowing is an original First Watt-built unit with mosfets. I listened to two albums last night - both live jazz recordings - not usually my thing - but the F1 was riveting. Scary real. Relaxing, then snap! a snare hit would make me leap out of my seat with a shot of adrenaline. Damn!

With the DIY thing acknowledged as a valid option, I'd still very much like to hear from people who have experience with both F1 and J2. My DSP can take care of a minor discrepancies, gain matching etc, but are these wildly different sounding amplifiers?

With thanks!