OK, Tony you missed me. I see the connections of which you speak and that if you cascode the VAS, you must also cascode the predriver as it sets the operating point of the VAS cascode.
Perhaps Professor Leach was referring to the predriver, driver and power stage collectively as the output stage (all three stages of the triple Darlington).
What Jens's circuit allows is connecting just a standard Low TIM style output stage to the cascoded predriver/driver stage. As in low TIM, you take the drive from either side of R51 (J1J5 and J1J8), feedback connects to J1J6//J1J7. Is there any reason that would not work?
Perhaps Professor Leach was referring to the predriver, driver and power stage collectively as the output stage (all three stages of the triple Darlington).
What Jens's circuit allows is connecting just a standard Low TIM style output stage to the cascoded predriver/driver stage. As in low TIM, you take the drive from either side of R51 (J1J5 and J1J8), feedback connects to J1J6//J1J7. Is there any reason that would not work?
I figured with new front end options folks would choose the output stage they preferred. Doesn't seem like too many have bothered.
Please update the wiki to reflect YOUR choice of output board style
Of course we're not in a terrible rush as design isn't finished and we haven't tested a prototype yet.
Please update the wiki to reflect YOUR choice of output board style
Of course we're not in a terrible rush as design isn't finished and we haven't tested a prototype yet.
output devices
The header in the wiki suggest FETS as output device:
"The options are:
Standard Leach - just like a detached version of the last buy. Positions for 5 N channel and 5 P channel devices
Super Leach - Jens' version of the super leach output with 4 complimentary pairs of cascoded devices - 8 n channel and 8 P chanel, 16 total devices."
Maybe simply NPN and PNP will clear this.
Regards, Loek
The header in the wiki suggest FETS as output device:
"The options are:
Standard Leach - just like a detached version of the last buy. Positions for 5 N channel and 5 P channel devices
Super Leach - Jens' version of the super leach output with 4 complimentary pairs of cascoded devices - 8 n channel and 8 P chanel, 16 total devices."
Maybe simply NPN and PNP will clear this.
Regards, Loek
Everything is still up in the air a bit. Jens was working towards a separable board, but with multiple output board options we're probably looking at separate boards. We'll see when Jens gets another "play day".
Rough guess on the size of the boards: front end 4.25"x5", 10 device output 4.25" x 5.5", 16 device output 4.25" x 8.5", 4 device cascode tweeter output 4.25" x 3"
We've got enough interest that a few people backing out isn't going to impact the buy (assuming it happens) Don't sweat it Norm.
Rough guess on the size of the boards: front end 4.25"x5", 10 device output 4.25" x 5.5", 16 device output 4.25" x 8.5", 4 device cascode tweeter output 4.25" x 3"
We've got enough interest that a few people backing out isn't going to impact the buy (assuming it happens) Don't sweat it Norm.
Rob, I think the forum rules suggest that we keep it here. I made an announcement thread for the AF4 buy in the Loudspeakers forum pointing to the GB thread and it was promptly moved to the GB section.
Hopefuly members have figured out that checking out the group buy section is a good idea. If we keep enough activity here, it will pop up on the main page for many.
Hopefuly members have figured out that checking out the group buy section is a good idea. If we keep enough activity here, it will pop up on the main page for many.
Jens, Where does the small diode pcb connect to this board. I believe this design is going to be quite popular. This layout with a separate frontend board opens up a lot of possibilites to the constructor in terms of output design. Are we getting closer to having some boards produced? You have to be just a little bit anxious to build one yourself by now. Nice picture again.
One small question on the 10 transitor amplifier quite a few of us have built. Why did you propose the change to it with the feedback? The boards I built up sound quite good like you originally designed them. Tad
One small question on the 10 transitor amplifier quite a few of us have built. Why did you propose the change to it with the feedback? The boards I built up sound quite good like you originally designed them. Tad