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Old 28th October 2011, 12:02 PM   #11
hates ground loops
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Same here, the boards look exceptionally well made, can't wait to populate them and fire them up.

RN55D resistors can be used, but the leads have to be bent to make them fit. I can post pictures if wanted.

How do we proceed from here? Should we open a new thread for our builds or do we post our findings here?
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Old 28th October 2011, 01:28 PM   #12
JL889 is offline JL889  United States
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Originally Posted by Rodeodave View Post
Same here, the boards look exceptionally well made, can't wait to populate them and fire them up.

RN55D resistors can be used, but the leads have to be bent to make them fit. I can post pictures if wanted.

How do we proceed from here? Should we open a new thread for our builds or do we post our findings here?
Wow, that made some good time for international shipping. I think i'll make a thread for each board so its neatly organized. I'll try to have that up by the end of the day.
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Old 28th October 2011, 02:33 PM   #13
potepuh is offline potepuh  Slovenia
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hi

I am interested for:
Chipamp 4780 Board 1
Chipamp 4780 Board 1
Chipamp 3886 Mono Board
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Old 30th October 2011, 09:58 PM   #14
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Here's a sneak-peek of my LM4780 stereo build.

Diodes are BYV29-500, big caps are Panasonic TSUP 10000uF 50v, small caps are Nichicon Muse 100uF 50V, small bypass caps are 1uF 63V WIMA. The resistors are CMF55 1% MF, except for the 10k muting resistor which is a compact MF. The values are 15k to GND, 221R to the + input, 20k and 1k in the FB path. The snubber resistor is a 2R7 1W MF resistor, and the snubber caps are 100nF film caps.

Soldering was straight forward, and other than bending the resistors' legs so that they fit, there were no real issues. It's noteworthy that the through-holes of the pcb don't have that bridge/cross type eyelet (don't know the name), so a lot of heat is transferred away from the soldering iron. Thus a fairly strong iron is best, I have a basic 50W Weller and managed to have the solder flow nicely.

I'll likely fire it up tomorrow, we'll see how that goes...


Edit: I have accidentally been sent two selector boards (and unfortunately no RK27 board). I don't plan on using them, so if someone wants to test one (or both) PM me.
Attached Images
File Type: jpg top.jpg (303.6 KB, 197 views)
File Type: jpg detail.jpg (307.5 KB, 191 views)
File Type: jpg caps.jpg (293.2 KB, 184 views)
File Type: jpg bend.jpg (327.2 KB, 179 views)
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Last edited by Rodeodave; 30th October 2011 at 10:01 PM.
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Old 31st October 2011, 11:50 AM   #15
UrSv is offline UrSv  Sweden
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Also received my boards. Really nice boards. Thanks!

Still haven't figured out if the LM4780 Boarda (1) is parallel or bridged. One or the other I suppose since there is only one input. Or have I missed something?
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Old 31st October 2011, 02:07 PM   #16
jackrak is offline jackrak  United States
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Did I miss the BOMs for the boards? I have been looking to see what I need to order, but have not seen an official schematic (for any of the builds).
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Old 31st October 2011, 02:20 PM   #17
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No, you haven't missed the BOM, it's not out yet. There are some schematics in the datasheet, and countless are floating around in the internet. Since the LM4780 is simply two LM3886s on one chip, I have populated the stereo board with parts/values I have had very good experiences with my earlier LM3886 builds.
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Old 31st October 2011, 02:32 PM   #18
JL889 is offline JL889  United States
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Hey guys,
Sorry its been a busy weekend. Brian should have the BOM in the next few days.
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Old 31st October 2011, 02:33 PM   #19
JL889 is offline JL889  United States
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Quote:
Originally Posted by Rodeodave View Post
Here's a sneak-peek of my LM4780 stereo build.

Diodes are BYV29-500, big caps are Panasonic TSUP 10000uF 50v, small caps are Nichicon Muse 100uF 50V, small bypass caps are 1uF 63V WIMA. The resistors are CMF55 1% MF, except for the 10k muting resistor which is a compact MF. The values are 15k to GND, 221R to the + input, 20k and 1k in the FB path. The snubber resistor is a 2R7 1W MF resistor, and the snubber caps are 100nF film caps.

Soldering was straight forward, and other than bending the resistors' legs so that they fit, there were no real issues. It's noteworthy that the through-holes of the pcb don't have that bridge/cross type eyelet (don't know the name), so a lot of heat is transferred away from the soldering iron. Thus a fairly strong iron is best, I have a basic 50W Weller and managed to have the solder flow nicely.

I'll likely fire it up tomorrow, we'll see how that goes...


Edit: I have accidentally been sent two selector boards (and unfortunately no RK27 board). I don't plan on using them, so if someone wants to test one (or both) PM me.
Looks Great!
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Old 31st October 2011, 03:06 PM   #20
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Alright, I just hooked the amp up to my speakers (nothing too special, Dual CL173 3-ways, rated 4 Ohm, rebuilt crossover), and it's sounding marvelous!
I'm looking forward to adding a second pair of 10mF caps to the PSU, maybe it will have an impact on the already good bass performance, we'll see.

The transformer is a (conservatively rated) 180VA EI-type with dual secondaries, and it puts out 22V AC for each secondary. After rectification and filtering I have pretty much exactly +/-28V DC. The amp is DC coupled for now, and both channels have a DC offset of 60mV, which is perfectly fine.

And yes, that's a clamp holding the chip against the heatsink...
Attached Images
File Type: jpg full.jpg (333.6 KB, 154 views)
File Type: jpg clamp.jpg (349.4 KB, 101 views)
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