[B]Regulated front end[/B]
Bob, Since you mentioned the regulated front end feature I was wondering if anyone had built this amp with the regulated supply. If so could that person elaborate on how things turned out.
What would be the specifications for regulating this layout in terms of power required for running the front end. During assemble of my boards I had noticed where Jens had provided the option coming off of the fuse blocks to leave out the resistor and supply regulated power. Nice touch Jens, it is almost as if you had done this once or twice before. Tad
PS. I just finished powering up a set of boards. Not sparks or smoke ---- oofta. Total no load current draw was .028 amps at 50 volts dc. I have not connected caps yet to bring voltage to +or- 70 volts.
Bob, Since you mentioned the regulated front end feature I was wondering if anyone had built this amp with the regulated supply. If so could that person elaborate on how things turned out.
What would be the specifications for regulating this layout in terms of power required for running the front end. During assemble of my boards I had noticed where Jens had provided the option coming off of the fuse blocks to leave out the resistor and supply regulated power. Nice touch Jens, it is almost as if you had done this once or twice before. Tad
PS. I just finished powering up a set of boards. Not sparks or smoke ---- oofta. Total no load current draw was .028 amps at 50 volts dc. I have not connected caps yet to bring voltage to +or- 70 volts.
peranders said:Good, I see that you have fixed the feedbackSmart to move the output instead. Are you sure that the magnetic coupling not will interfere with the driver circuits? All in all, it looks very nice, a fine job indeed.
Hi Per,
The original design was designed with this in mind, I wanted to seperate the power section from the small signal part of the design.... I'm not sure what will happen with the new layout, I think we will have to make a prototype and test before we do the GB.
\\\Jens
I'd be concerned about the inductor being so close to the low level stages, where it might couple magnetically.
Also, the Zobel should ideally be placed as close to the speaker posts as possible to keep RF picked up by speaker wire out of the chassis. I have been considering a separate board for the inductor and Zobel that contains only these components on design I'm working on, and providing alternative Zobel arrangements, like the ones suggested by Cherry and Thiele, for ones choosing.
Taking these components off the main board would provide more room, and reduce RF on the antenna line from the speaker posts to the boards output. On the design I'm working on, this Zobel board will have holes properly spaced to mount directly on the speaker posts, for both mounting and for direct electrical connection between the PC traces and the posts.
Also, the Zobel should ideally be placed as close to the speaker posts as possible to keep RF picked up by speaker wire out of the chassis. I have been considering a separate board for the inductor and Zobel that contains only these components on design I'm working on, and providing alternative Zobel arrangements, like the ones suggested by Cherry and Thiele, for ones choosing.
Taking these components off the main board would provide more room, and reduce RF on the antenna line from the speaker posts to the boards output. On the design I'm working on, this Zobel board will have holes properly spaced to mount directly on the speaker posts, for both mounting and for direct electrical connection between the PC traces and the posts.
AndrewT said:
But that would still not eliminate the real estate required on the main board if one chooses not to install these elements there, or not at all, as some advocate. Not to mention the much greater real estate required for other Zobel options. Besides, you know what a PITA it is to mount the Thiele/Zobel network on the speaker posts. Using a PC board mounting directly on the posts would make it much easier, and help keep capacitor leads short.
I'm not saying that Leach's original layout was perfect, but there doesn't seem to be a coupling issue with them. (Listening only, not hypersenstive measurement equipment) The Leach boards have the resistor//inductor closer to the front end than this verison of Jens' layout.
The half inch that could be saved doesn't make or break me.
The half inch that could be saved doesn't make or break me.
pooge said:
On my first design I wanted the end with the output to face the back of the amp, placing the zobel network only a few centimeters from the speaker terminals.....
So what should this be??
1) Original type layout with a long feedback loop, onboard zobel network.
2) New layout with shorter feedback trace, onboard zobel
3) External zobel..... long or short feedback??
\\\Jens
Jens and all,
I don't mean to be disruptive about this process, or sound critical of Jens' design.
I started a design process to please myself for my design criteria for these boards, with lessons learned. In the meantime, a group buy was done on the old design, which took a lot of potential customers away from a buy I was anticipating. There still seemed to be enough interest in more boards, so I intended to continue with my design. Jens told me he was not interested in being involved in this any more. Now there is involvement again, and it is doubtful that two more GB could be accomplished at this time. I'm kinda stuck about what to do. Any changes to Jens' design, or my design, should be prototyped to see how well they do. That takes time. That's not something I'd want to do if there is no hope for a GB.
I don't mean to be disruptive about this process, or sound critical of Jens' design.
I started a design process to please myself for my design criteria for these boards, with lessons learned. In the meantime, a group buy was done on the old design, which took a lot of potential customers away from a buy I was anticipating. There still seemed to be enough interest in more boards, so I intended to continue with my design. Jens told me he was not interested in being involved in this any more. Now there is involvement again, and it is doubtful that two more GB could be accomplished at this time. I'm kinda stuck about what to do. Any changes to Jens' design, or my design, should be prototyped to see how well they do. That takes time. That's not something I'd want to do if there is no hope for a GB.
pooge, where can I see your design?
I am in for GB, 4 pcs, and if you guys do not make it until end of January I will have to make my own boards.
Jens' last board is great, in my opinion it is much better than original one. I understand that you want to design "ultimate" leach clone but 80% of builders wont be able to get all that fancy parts.
My suggestion is:
-check price for 52 boards GB (if it matters I can talk some people to buy boards)
-find good price for capacitors
-find good price for output transistors
Like it or not.
Zeljko M
I am in for GB, 4 pcs, and if you guys do not make it until end of January I will have to make my own boards.
Jens' last board is great, in my opinion it is much better than original one. I understand that you want to design "ultimate" leach clone but 80% of builders wont be able to get all that fancy parts.
My suggestion is:
-check price for 52 boards GB (if it matters I can talk some people to buy boards)
-find good price for capacitors
-find good price for output transistors
Like it or not.
Zeljko M
After constructing several of Jens Leach Clone boards the only major concern was routing the signal input all the way to the front without crossing or coming into close proximity to the power supply leads or the transformer housing. I know that any design that has the signal input in the middle or at the rear of the amp is hard to design in. It would if possible make proper signal routing easier. Also, If the signal in could accomadate a screw type terminal assembly would be easier.
I personally like most if not all of the solderable components on the pcb. It makes for a neater less cluttered chassis.
What ever design is chosen I am still in for a GB. Tad
I use the word easier because as I get older I find that my magnifier lens gets stronger and my hands get less steady. Soldering these small components can be challenging if you want a nice clean finished unit.
I personally like most if not all of the solderable components on the pcb. It makes for a neater less cluttered chassis.
What ever design is chosen I am still in for a GB. Tad
I use the word easier because as I get older I find that my magnifier lens gets stronger and my hands get less steady. Soldering these small components can be challenging if you want a nice clean finished unit.