Everything looks wonderful to me, I can't think of anything to make it better.
The LM3875 and LM3886 seem like pretty similar chips to me. With you doing your new LM3886 boards it seems redundant tohave an LM3875 board available as well. Perhaps you should pick the better of the two chips and simply focus on that, unless there is a big difference between them that I don't understand. I just don't think it makes sense to have two choices available that are so similar.
The LM3875 and LM3886 seem like pretty similar chips to me. With you doing your new LM3886 boards it seems redundant tohave an LM3875 board available as well. Perhaps you should pick the better of the two chips and simply focus on that, unless there is a big difference between them that I don't understand. I just don't think it makes sense to have two choices available that are so similar.
m0tion said:
My plan is to get another batch of the standard LM3875 boards made with the small modifications made, and a new batch of boards made with the LM3886 and the snubber setup, and I will compare the two. With the board pinouts being the same for hooking up connections, the LM3875 boards will work together well with the rectifier board on the LM3886 pcb, so I can also try the new power supply setup with the LM3875.
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Brian
Brian, is the LM3886 board the same size as the rev B LM3885 board? Just wondering if it will fit in one of Peter's chassis without modification. The PS board isn't the same, of course, but I think it should still fit in the chassis, just need to drill new mounting holes. Looks very nice to my untrained eye, can't wait to see/hear the final product.
sbolin said:
I am going to handle the new LM3886 boards first, and then once I get the order placed and finalized, I will work on getting the LM3875 rev.3 boards done. The changes are quite minor for the rev.3 boards compared to the rev.2 boards, so I would like to see how the LM3886 boards work out first, and possibly build more features into the LM3875 rev.3 pcb set based on this. I still have about 50 rev.2 boards available, and I will take orders for them again soon.
In the end, there will be 3 pcb sets offered, each with 2 amp boards and 2 rectifier boards:
- LM3875
- LM3886
- LM4780
Let me know if you have any more questions.
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Brian
Thanks for the quick replies, Brian.
If possible, I would like the rev C board to have the 'standard' PS (like the current rev B board). In the LM3886 thread you mentioned that the LM3886 would be where the new ideas and experiments take place, and I think that is a good idea. I like that board, but for the LM3875 think a simple design is best.
And yes, I'm with homer09...any time tables?
If possible, I would like the rev C board to have the 'standard' PS (like the current rev B board). In the LM3886 thread you mentioned that the LM3886 would be where the new ideas and experiments take place, and I think that is a good idea. I like that board, but for the LM3875 think a simple design is best.
And yes, I'm with homer09...any time tables?
sbolin, i side with you on the time tables, but i would like to see the snubbered power supply for the rev3 boards of the lm3875. and i think im far from being alone on that one. the complexity of the snubber isnt much greater either, only larger caps and extra pair of resistors... 
but anyway, correct me if im wrong brian, you're planning on desiging a rectifier board capable of a snubbered or normal supply right (up to the builder's preference)?
but anyway, correct me if im wrong brian, you're planning on desiging a rectifier board capable of a snubbered or normal supply right (up to the builder's preference)?
homer09 said:
sbolin said:
The form factor of the LM3875 board will not change, and it will be compatible with new power supply board on the LM3886 set.
As for time frames, if people are interested in the LM3886 boards, I will order them Friday and start taking pre-orders for them.
As for the LM3875 boards, I will sell the remainder of my rev.2 inventory starting within a week, and work on ordering the boards for that after I get the LM3886 boards ordered.
All boards are ordered with a 2 week leadtime.
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Brian
homer09 said:sbolin, i side with you on the time tables, but i would like to see the snubbered power supply for the rev3 boards of the lm3875. and i think im far from being alone on that one. the complexity of the snubber isnt much greater either, only larger caps and extra pair of resistors...
but anyway, correct me if im wrong brian, you're planning on desiging a rectifier board capable of a snubbered or normal supply right (up to the builder's preference)?
To get the LM3875 with the new snubber power supply, you will have to order the LM3886 pcb set to get the power supply boards to go with the LM3875 amp boards. The snubber power supply boards will be compatible with all previous LM3875 amp boards, so if you already have a built amp, you should be able to swap the power supply boards, and swap the 1500uF caps for a 100uF/0.1uF combination (pads are there for it, see screenshot above in this thread).
The reason that the snubber supply boards won't be included with the LM3875 set is the extra board size, and extra components. If it is determined that this is clearly a better solution, then the board for the LM3875 can be redone again in the future for this, or a stand-alone snubber supply board can be offered, but I would like to take this one step at a time and see how the setup works with the LM3886 boards.
If you are interested in the LM3886 boards with the new snubber power supply, please indicate your interest in the Wiki that I created:
http://www.diyaudio.com/wiki/index.php?page=chipamp+lm3886+interest+survey
as I will reference this when placing my order for pcbs.
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Brian
homer09 said:sbolin, i side with you on the time tables, but i would like to see the snubbered power supply for the rev3 boards of the lm3875. and i think im far from being alone on that one. the complexity of the snubber isnt much greater either, only larger caps and extra pair of resistors...
but anyway, correct me if im wrong brian, you're planning on desiging a rectifier board capable of a snubbered or normal supply right (up to the builder's preference)?
I know adding the snubber isn't that complex, it is actually the size I am more concerned with. I can snubber the current PS board if I want AND have a small board. The PS board for the LM3886 is big whether I snubber it or not, that was all I was getting at. Of course, the boards are cheap, so I may end up ordering the rev B board along with the rev C kit...
if that actually works. Or maybe just order one of the remaining rev B kits and one of the LM3886 kits, just to try it. Sheesh, I still have a LM4780 kit I haven't finished, maybe I better finish that first!
sbolin said:
I know adding the snubber isn't that complex, it is actually the size I am more concerned with. I can snubber the current PS board if I want AND have a small board. The PS board for the LM3886 is big whether I snubber it or not, that was all I was getting at. Of course, the boards are cheap, so I may end up ordering the rev B board along with the rev C kit...
I will make it more clear when I get everything together. Now, my main focus is getting the LM3886 boards together.
btw: I put up a new LM4780 schematic that makes it clear what component values are which:
http://www.chipamp.com/lm4780.pdf
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Brian
there's probably an obvious reason why this isnt a good idea, but here goes anyway....
i was thinking, instead of always having PCBs made with 2 amp channels and 2 rectifiers, why not make PCBs with only rectifiers and PCBs with only amp channels? what i mean is, for example, you would order a set of PCBs which have 2x LM3886 channels and 2x LM3875 channels (no rectifiers). Then another set with 2x standard rectifiers and 2x snubbered rectifiers.
Since everything is scored, you could then easily mix and match. And now, a much larger number of possibilities become available (ex. dual mono snubbered LM3886, stereo standard LM3875, etc)
when ordering from Brian, one would have the following variables:
(LM3875 | LM3886) + (dual mono | stereo) + (snubber | standard) + (PCB only | stand. comp | premium comp.)
Or if larger PCBs are better for pricing (when Brian has them made), combine the two sets above (4 channels, 4 rectifiers). If smaller PCBs are better for pricing, separate everything... the possibilities are endless.
just a thought that could possibly better accommodate everyone.
. i guess, the remaining question is: does it accommodate Brian better?
i was thinking, instead of always having PCBs made with 2 amp channels and 2 rectifiers, why not make PCBs with only rectifiers and PCBs with only amp channels? what i mean is, for example, you would order a set of PCBs which have 2x LM3886 channels and 2x LM3875 channels (no rectifiers). Then another set with 2x standard rectifiers and 2x snubbered rectifiers.
Since everything is scored, you could then easily mix and match. And now, a much larger number of possibilities become available (ex. dual mono snubbered LM3886, stereo standard LM3875, etc)
when ordering from Brian, one would have the following variables:
(LM3875 | LM3886) + (dual mono | stereo) + (snubber | standard) + (PCB only | stand. comp | premium comp.)
Or if larger PCBs are better for pricing (when Brian has them made), combine the two sets above (4 channels, 4 rectifiers). If smaller PCBs are better for pricing, separate everything... the possibilities are endless.
just a thought that could possibly better accommodate everyone.
. i guess, the remaining question is: does it accommodate Brian better?
homer09 said:there's probably an obvious reason why this isnt a good idea, but here goes anyway....
i was thinking, instead of always having PCBs made with 2 amp channels and 2 rectifiers, why not make PCBs with only rectifiers and PCBs with only amp channels? what i mean is, for example, you would order a set of PCBs which have 2x LM3886 channels and 2x LM3875 channels (no rectifiers). Then another set with 2x standard rectifiers and 2x snubbered rectifiers.
Since everything is scored, you could then easily mix and match. And now, a much larger number of possibilities become available (ex. dual mono snubbered LM3886, stereo standard LM3875, etc)
when ordering from Brian, one would have the following variables:
(LM3875 | LM3886) + (dual mono | stereo) + (snubber | standard) + (PCB only | stand. comp | premium comp.)
Or if larger PCBs are better for pricing (when Brian has them made), combine the two sets above (4 channels, 4 rectifiers). If smaller PCBs are better for pricing, separate everything... the possibilities are endless.
just a thought that could possibly better accommodate everyone.
For me, it is much easier having 3 complete boards on hand, than having to worry about mixing and matching 5 different boards. But, I can consider this for the future, after I get the initial boards done and shipped out.
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Brian
Brain, im guessing you should split up the boards and split up the components into little bags (snubber rectifier comp., LM3875 amp comp. etc). A bit in the same way you do now. Then it would just be joining the baggies and PCBs in the right quantities for each order.
but then again, easier said than done. im not the one who's going to have to do this...
and everyone already appreciates your efforts Brian
but then again, easier said than done. im not the one who's going to have to do this...
and everyone already appreciates your efforts Brian
Here is what I am currently looking at for the rev.3 boards. It is similar to the new LM3886 board, which followed a similar form from the LM4780 board.
The only other modification that I am looking to do to this board is add more spots for decoupling caps for a setup similar to the snubber setup on the LM3875 board. This way, it can be implemented with the new power supply board in the same fashion as the LM3886 board.
Let me know if you have any comments. I am going to try to finalize the layout soon, and order more pcbs. I ordered the pcbs for the LM4780 boards yesterday and am accepting pre-orders again for them on the website.
--
Brian
The only other modification that I am looking to do to this board is add more spots for decoupling caps for a setup similar to the snubber setup on the LM3875 board. This way, it can be implemented with the new power supply board in the same fashion as the LM3886 board.
Let me know if you have any comments. I am going to try to finalize the layout soon, and order more pcbs. I ordered the pcbs for the LM4780 boards yesterday and am accepting pre-orders again for them on the website.
--
Brian
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