I just finished putting an F2J together. I used a modushop 3U/400 steel chassis. The transformer is an Antek AS-3218 and the bias current is about 2.7A per channel. Part subs were minimal (BC560C instead of ZTX550, R6=10k). I did not test the jfets before hand for gate leakage so I kept R6 relatively low. The trimmers for the channels were adjusted to minimize distortion at about 4W output into 8 ohms @1K Hz.
The PCBs were a generous gift from Twitchie.
Thank you Papa for sharing this design with us Greedy Boyz.
The PCBs were a generous gift from Twitchie.
Thank you Papa for sharing this design with us Greedy Boyz.
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I've only tried it with test speakers since I finished the amp adjustments earlier today. I'll probably hook them up to the Zu's later today.
Of course. We are self proclaimed god damn sissienezzezzzzzzzz.F2J is for weaklingsesssss
Everyone else is just insecure…always having to strut around waving all their watts in the air 😉
My neighbour thought it wass a 200 watt amp at first listen…
Hello guys, changing the subject: I am thinking about experimenting by adding some ribbon tweeters on top of my full rangers, so a new two channels of F2 (kind of) would be nice, but I do not want to burn another 130W or so... so I was wondering about lowering the current, using some "smaller" MOSFETs, much much smaller output caps (so they could form a HP filter with the tweeter impedance), smaller radiators 🙂 Has anyone done something like that before? 
EDIT: and because it's a current source amp using the same amp with the ribbon... not sure if Mr. Kirchhoff would be on my side...
EDIT: and because it's a current source amp using the same amp with the ribbon... not sure if Mr. Kirchhoff would be on my side...
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why separate amp for tweet helpers?
isn't approx. 1uF in series , connected in parallel with FR, just enough?
of course, if you feel as building another small amp, I have no objection
isn't approx. 1uF in series , connected in parallel with FR, just enough?
of course, if you feel as building another small amp, I have no objection
Hi ZM, with the voltage amp... no issue, but with CS I am stealing the current from the FR, and that's where my doubts are coming from.
Dennis - On your 3U/400 steel chassis - how's the thermal performance on those heat sinks? It's certainly not apples to, but I'm in progress of collecting parts for an F6 and would like to consider the 3U/400 instead of a 4U chassis. Thanks