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?
Bob, no reason for that not to work......as i said, you can get rid of T12A and T22A and jumper their ce and you are go....😀
Bob - Just to confirm what is on the wiki site: Is the 8 device cascode output listed meant to be the same as the original Leach Amp (8 transistors total per channel)? I have seen Jens' schematic using 8 pairs (16 outputs). Regards, ---HK
nope - I meant to say 8 complimentary pairs. I'll fix that. anything cascoded is a super leach.
The original Leach output Jens is offering is 10 devices (5 pairs)
The original Leach output Jens is offering is 10 devices (5 pairs)
BobEllis said:
- bump -
Bob, it appears that the wiki still hasn't been updated by many of those who had likely signed up for the 10 transistor PCB prior to the edit. Safe to assume that the quantity should be the same as that of the Front End boards?
- Rob
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.
We just have to read thru 10 pages to find the difference...
-or you could make a small summary at the wiki-page?
Arne K
-or you could make a small summary at the wiki-page?
Arne K
Sure Arne, I'll do a blurb.
I thought the headers were fairly descriptive 😉 Standard Leach 10 O/P device, 16 device cascoded Super leach style or (possibly) a 4 device cascoded low power stage.
I thought the headers were fairly descriptive 😉 Standard Leach 10 O/P device, 16 device cascoded Super leach style or (possibly) a 4 device cascoded low power stage.
Please humor me, but I can be thick ...
When I looked at the WIKI it was obvious to me to what the output columns meant. I signed up (I hope!) for 2 plus 4 boards. However the 'Front End' column made no sense to me. What is that first column about?
Best Regards,
Carl Huff
When I looked at the WIKI it was obvious to me to what the output columns meant. I signed up (I hope!) for 2 plus 4 boards. However the 'Front End' column made no sense to me. What is that first column about?
Best Regards,
Carl Huff
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
Sorry, built too many Pass amps and nursing the flu. 🙄
It now reads:
Carl, Assuming that you want to build 6 amps you'll need 6 front end boards, too. I made the change for you.
It now reads:
Carl, Assuming that you want to build 6 amps you'll need 6 front end boards, too. I made the change for you.
What is the size of the boards going to be? How about physical layout?
are they going to be attached, with perforations, or completely separate? Dimensions?
Sorry if it was posted and I missed it. I just want to see if this will work with the sinks I have in mind before I update the wiki.
are they going to be attached, with perforations, or completely separate? Dimensions?
Sorry if it was posted and I missed it. I just want to see if this will work with the sinks I have in mind before I update the wiki.
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.
Posted to solid state?
Is there a discussion of this wiki anywhere in the solid state forum?
I don't recall how I found this thread, but I'm sure it was just by chance. Additional interest in the group buy could be had with a little 'advertising' (I'm assuming Group Buy posting only)
- Rob
Is there a discussion of this wiki anywhere in the solid state forum?
I don't recall how I found this thread, but I'm sure it was just by chance. Additional interest in the group buy could be had with a little 'advertising' (I'm assuming Group Buy posting only)
- Rob
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