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Request 1 : could you make it one stereo board by copying the mono design twice on a larger board (possibly scored) ? It is more easy to drill, mount, wire etc. It will be powered with one power supply in most cases anyway.
Request 2: could you incorporate a DC speaker protection circuit with a relay ? It would let the board stand out of the crowd. Maybe overcautious but one learns after having used the Tripath chips
Request 3: a board complete with power supply would be fantastic. A pi filter (2 large caps with a coil in between) and rectifier. SMPS are cheap and there is one guarantee: they will die one day. The YJ board sounds and measures OK with a transformer based power supply like that.
1. I could leave two boards not separated if anyone wanted to order a pair that way. To separate you could use a heavy duty tile (not ceramic) cutter or a bandsaw with a 0.050" thick cut.(similar to hacksaw blade thickness) No problem.
2. Most DC speaker protection circuits I have seen are not for BTL outputs. (Maybe I haven't been looking too hard.) Not everyone would want my version and I would probably not want theirs. Too many flavours for that out there. Beside that, the 3116/8 has DC detect/shutdown. So I respectfully decline this suggestion.
3. Integrated power supply. Again too many flavours and (IMHO) if done correctly would more than double the size of the board. Not this time.
And thank both of you for helping me learn something:
Just never though that film caps came in SMT.
Digi-Key has some. I might even try some:
Some Digi-Key film caps
The input caps now have a footprint for 0805 and 1210. (1206 will still fit)
Anything larger will have to extend off of the board. (or vertical)
hajj: got it, 4 boards.
Later,
Doug
Here is some discussion on the power-up mute circuit:
http://www.diyaudio.com/forums/class-d/237086-tpa3116d2-amp-306.html
Post 3054-3059
Hi Dug,
1. PCB manufacturers can do something they call "score" which is that they already cut the board slightly (at both sides) so that they can be separated easily by hand. Please check on that. It would make a tidy build for stereo builders. Just imagine 2 separate boards with wiring, a separate power supply and then imagine one board with all stuff on it. Modular thinking is old fashioned by now.
2. OK, there are protection circuits around that can protect BTL amps but they use one relay per channel. I never trust unprotected amplifiers. Must be because of burnt woofers in the past
Have you ever used Tripath TA2020 ? 3. Too bad. There are not too many flavors. 4 Diodes in TO220 or DO201, 2 x 4700 µF snap in caps in parallel with 1 µF X7R 1210 and a coil in between. No wiring necessary, no hassle, reliable, no safety ground issues as with SMPS. Sounds good too. You could ask the potential builders if they like such an option. Just think of your nicely designed board accompanied by some hardwired "thrown together" power supply. The mounting hardware for mounting caps costs more than board space
4. Good that you found the film caps, 1210 would be the preferred size I guess. Please add the pads for Wima MKS2 in 2.5 mm pitch as the pads can be combined with the 1210 pads. Costs nothing and leaves some choice for the builders. No one will regret using film caps at the inputs.
5. Please don't underestimate a GB. People have wishes (some will even demand things like they are customers) and you won't be able to please everyone. Some ideas might be good however. Picture people that will build your amp while they haven't build SMD stuff. We did some GB's on a DAC and experienced the variety in experience. Also the safety issue. The less wiring the better. For some reason many will save on mains rated stuff (a fuse !) so we added such stuff on the board. If I would design another DAC now I would make one PCB with everything on it and even RCA connectors soldered straight to the PCB. Even using Molex KK connectors is too much for many as they don't have the crimping tool.
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Hi Dug,
1. PCB manufacturers can do something they call "score" which is that they already cut the board slightly (at both sides) so that they can be separated easily by hand. Please check on that. It would make a tidy build for stereo builders. Just imagine 2 separate boards with wiring, a separate power supply and then imagine one board with all stuff on it. Modular thinking is old fashioned by now.
2. OK, there are protection circuits around that can protect BTL amps but they use one relay per channel. I never trust unprotected amplifiers. Must be because of burnt woofers in the past
3. Too bad. There are not too many flavors. 4 Diodes in TO220 or DO201, 2 x 4700 µF snap in caps in parallel with 1 µF X7R 1210 and a coil in between. No wiring necessary, no hassle, reliable, no safety ground issues as with SMPS. Sounds good too. You could ask the potential builders if they like such an option. Just think of your nicely designed board accompanied by some hardwired "thrown together" power supply. The mounting hardware for mounting caps costs more than board space
4. Good that you found the film caps, 1210 would be the preferred size I guess. Please add the pads for Wima MKS2 in 2.5 mm pitch as the pads can be combined with the 1210 pads. Costs nothing and leaves some choice for the builders. No one will regret using film caps at the inputs.
5. Please don't underestimate a GB. People have wishes (some will even demand things like they are customers) and you won't be able to please everyone. Some ideas might be good however. Picture people that will build your amp while they haven't build SMD stuff. We did some GB's on a DAC and experienced the variety in experience. Also the safety issue. The less wiring the better. For some reason many will save on mains rated stuff (a fuse !) so we added such stuff on the board. If I would design another DAC now I would make one PCB with everything on it and even RCA connectors soldered straight to the PCB. Even using Molex KK connectors is too much for many as they don't have the crimping tool.
1. Boards are not going to be scored. My offer for physically paired boards still stands. If anyone wants them this way please let me know.
2. Have not used 2020. Maybe I will offer my version of a protection board for BTL amplifiers on another GB...another unique board.
3. There is already room for two caps on board that have a footprint good for
4700uF. Just add a external bridge and you have your "power supply on board". Not enough for "full power" IMHO so some external caps are required if using 60HZ full wave rectified source for power in stead of a SMPS.
I took a look at other recent GB amp boards and came up with a list (by no means complete) of boards with the bridge or separate diodes on them: 4 no 1 yes.
4. 2.5mm (0.1") I might be able to do that. It would mean (IMHO) a compromise on the ground plane under the input caps.
5. I have requests for 30 boards now...maybe some will back out maybe there will be more requests. That is the nature and risk (mine) of a GB.
I have incorporated a few changes that I have accepted. You are correct when you say that all cannot be pleased. All will not be pleased (or even interested) or I would be selling to all of the 310,307 members. Wouldn't that be something.
Keep offering suggestions...I may not utilize them but I do consider them.
Still a little over 2 weeks until design freeze and board purchase.
Bye for now
Doug
Pads for volume control by means of an Alps RK27 (or the smaller version) and a few input switching micro relays would be nice too. There is not a point in making everything separate as it will be needed anyway, or not ?Again less wiring which always is a show stopper for many DIY people.
A small input buffer can be beneficial. My blue YJ boards all benefit from low impedance sources as they have way less noise then.
A small input buffer can be beneficial. My blue YJ boards all benefit from low impedance sources as they have way less noise then.
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I would weigh against any addition except the bare necessities, something that fits the approach that was taken for the Subbu DAC (where a power on LED was considered the highest luxury the board would have)
A volume pot (with an option to bypass it) might be a good addition as most people would need it.
A LP filter on the other hand is something I consider to be surperfluous especially that there are so many different designs and topologies that are far from being universal and this is before considering the extra compelxity and cost that comes with it
A volume pot (with an option to bypass it) might be a good addition as most people would need it.
A LP filter on the other hand is something I consider to be surperfluous especially that there are so many different designs and topologies that are far from being universal and this is before considering the extra compelxity and cost that comes with it
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