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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th September 2017, 01:40 PM   #21
doctormord is offline doctormord  Germany
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I'm using these with my own boards as well.

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Old 8th September 2017, 04:55 PM   #22
robinlawrie is offline robinlawrie  United Kingdom
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ok i have ordered two of those amps.

thanks a lot for the advice and help.

looking at the board layout sent earlier, it seems that just adding a couple of horizontal wires from the solder pads on the top of the board, 1cm or so in length, with the supplied caps attached to them (i.e shifting the caps to the top face, and laterally, diagonally away from the inductors.) should allow them to be fitted, assuming the heatsink is removed.

if it appears this wont work i will look at purchasing the suggested alternatives.
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Old 8th September 2017, 05:00 PM   #23
doctormord is offline doctormord  Germany
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If you're only doing 2xBTL Stereo, you could remove C21/C34/C42/C56 and move L3/L4 to the right - then the caps will fit without wires.
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Old 8th September 2017, 05:28 PM   #24
robinlawrie is offline robinlawrie  United Kingdom
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now tht is an *extremely* helpful idea!

i must admit im surprised you can remove *all* those big capacitors.. none of them are needed for stereo operation?

that would also have the effect of reducing the overall height to the point where i might not even need to place the big caps on the front face... (consider ill be removing the heatsink, all the bulky connectors for power and output and soldering to the board.)

the tallest elements in this case would be the inductors.
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Old 8th September 2017, 05:34 PM   #25
irribeo is offline irribeo  Netherlands
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A nice dutch composite 3886 amp was made into same cabinet. Heatpipes to use the heatsink But you might be able to mount standard evm boards with heatsink against topplate and cut holes in bottom for fat caps, you'll need holes for airflow in bottom anyway I guess..
http://zelfbouwaudio.nl/forum/downlo...9472&mode=view
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Old 8th September 2017, 06:00 PM   #26
robinlawrie is offline robinlawrie  United Kingdom
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well i dont know about custom heatpipes, no idea how youd even get them made!

but i intend to mount a custom aluminium plate to chip, which will be bolted to side heatsink. given the low heat output of these chips, im sure it will be sufficient.

i intend to direct all heat to the outside of the case this way.. i will be doing the same for the psu, removing heatsink and connecting to case with an aluminium bracket.

(although that will be connected to the top or side plate of the case on the opposite side to the amps. i think that should be sufficient.

i believe the case has some small vents top and bottom, which should take care of any residual heat.


thats a nice amp by the way

Last edited by robinlawrie; 8th September 2017 at 06:02 PM.
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Old 8th September 2017, 06:14 PM   #27
doctormord is offline doctormord  Germany
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Quote:
Originally Posted by robinlawrie View Post
now tht is an *extremely* helpful idea!

i must admit im surprised you can remove *all* those big capacitors.. none of them are needed for stereo operation?
These 4 capacitors are for SE operation only (4 channel mode).
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Old 8th September 2017, 06:25 PM   #28
robinlawrie is offline robinlawrie  United Kingdom
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ah even better.. so if i decide to use both of them PBTL in future, i still can even without those caps. i cant imagine ever needing to use this as an 8 channel amp. Converting to a stereo one is a vague possibility at some point though.
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Old 8th September 2017, 08:08 PM   #29
robinlawrie is offline robinlawrie  United Kingdom
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something is a bit screwy with that pcb layout you sent doctormord... im doing the amp case layout in 3d, and ive cropped it to the edges, mapped it onto a plane with the dimensions given for the pcb in the design document, and the caps are all oval shaped.. the only sensible explanation i can see is that the pcb dimensions are wrong. the only alternative is the drawing was done with the caps drawn as ellipses not circles.. hardly likely. according to the design doc it should be 140mm x 120mm.

what do you think?
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Old 8th September 2017, 08:20 PM   #30
robinlawrie is offline robinlawrie  United Kingdom
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going by the diameter of the larger capacitors given in the BOM, assuming the circles on the pcb layout match the size of the caps, i can scale it in my 3d software until the circles in the schematic are round, and the right size.. that gives me a pcb size of 150 x 115

is that correct?
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