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Simple Cheap Compact IC-based High Performance Amp 
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Apparently I was naive, and there are more/other caps involved. Almost no difference, possibly a negative difference:

Image

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One of those things that just has to be done :-)

Fred.

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Sun Mar 17, 2013 12:13 pm
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The IC is a Sanyo LA4192 device, data sheet here:

http://octopart.com/la4192-sanyo-2179025

THD is less than 1% from ~40Hz to ~15kHz
THD is less than 0.4% from ~80Hz to ~2kHz

It claims to be 2.3W per channel, however the power supply is higher voltage than recommended, so it's probably a bit more with the standard speaker loads.

I can't see any way to alter the clipping behaviour of it, so I'll give up and go back to doing more important things now :-)

Image


Attachments:
File comment: Datasheet for Sanyo LA4192 2.3W 2 Channel Amp IC
LA4192-Sanyo.pdf [355.12 KiB]
Downloaded 158 times

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Sun Mar 17, 2013 2:47 pm
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Tonight I got a bit impatient and soldered one of the 3 ICs that I have to a bit of perf-board. I'll get that up and running tomorrow just to see how it goes. With a TINY bit of luck, I'll get enough of a PCB design gifted to me in time to order some from China to arrive before my guest arrives. Hoping to show him the speakers with proper electronics, not those pictured above LOL... won't be the same if it's mono, though. Fingers tightly crossed here in the BCN FreeEMS central HQ.

EDIT:

Image

Image

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Sat Jun 01, 2013 4:22 am
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Andy's been busy and come up with a first cut layout, shown below! Yay! :-)

Image



Which is good, because I've been busy too, emitting smoke, and slamming the speakers into oblivion briefly. Fortunately the speaker survived the excursion (literally, all the way out!).

The smoke was from some insulation tape I had covering some current limiter resistors that I (wisely) put on the rails. Unsure why it's drawing current and doing bad things. It might be time for me to learn some Kicad and make some changes to Andy's work myself, rather than being a lousy beggar bastard. I'll put my ideas in the next post for review.

Fred.

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Sun Jun 02, 2013 9:15 pm
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First pass review notes:

  • R7 is BIG and may not fit there? Unsure if i gave measurements, but it's 16mm long in the body, plus a bit for leads, dia is 5mm.
  • Mounting holes are a bit small.
  • Mounting holes on heatsink side are too close to edge to screw into/onto a bracket easily.
  • Mounting holes are grounded, and should likely be only optionally grounded, or isolated permanently.
  • Speaker should really be grounded back to the central ground, not to the board. Doesn't hurt to have the hole, I guess, but I won't be using it, and it burns space.
  • C1, C15, C16 might be a bit close together? Have to check.
  • The trace under the U1 silkscreen letters should not T and should go to the pin directly.
  • The traces to/from the caps and inductor could be (much?) bigger, tapering at the end for IC connection.
  • The decouple caps should be closer to the IC pins.
  • Am I blind, or is the +ve signal trace not routed? Is that the red line across from the +ve power pin?
  • The input pin needs a matching ground, and the board needs a ground in from the supply. Currently there is enough, just labeled wrongly? The main ground for the board should probably come in between the +ve and -ve inputs.
  • It'd be nice if the input came in the front of the board rather than the side. Ditto the clip and control line.
  • I like the input topology.
  • The standby/mute circuit could be shuffled and come to the front of the board, and be more left too. This would give more room to move the decouple caps in close.
  • Good job keeping the three high-current traces away from everything else, and leaving a solid ground plane.

Man, that sounds so negative! :-/ It's only meant to be positive/constructive. One deal breaker in bold, though.

Fred.

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Sun Jun 02, 2013 9:39 pm
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One more, just noticed, the ground for the zobel network should be brought out for an independent return to the power supply. That's at the end of C10.

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Sun Jun 02, 2013 9:42 pm
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Why is it quiet and mono? Hmmm! Oh, that wire is touching that other wire, woops. Apparently the Sanyo LA4192 is pretty robust to shorts. FWIW = about nothing.

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Wed Jul 31, 2013 11:17 pm
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