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Old 21st April 2011, 04:17 PM   #1
6L6 is offline 6L6  United States
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Default Point-to-Point LM3886

I was perusing the local electronics surplus store and saw that they had a handful of LM3886 in the bins, and thought it might be fun to wire up a pair and see how they do.

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Here they are, on a heatsink used as an assembly jig.
Wires are;

Red/Green = (V+) and (V-)
Blue/Black = Speaker (+) and (-)
Orange = input twisted pair
Ground to PSU not wired.


Starting with this article as a reference -- Mick Feuerbacher Audio Projects --

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I began to wire the chips up. It's a very nice layout, but I realized, a bit too late, that when it's all done, it really is expecting to have the input RCA very close and at the right of the assembly... Hence why this one has the grounds going out that way.


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So I thought that a more vertical arrangement might yield a more compact layout, and it did. Luckily, I was able to use one of the capacitor's leads as the ground. Neat! These have the output Zobel. There is no input cap as wired, I will probably attach those to the potentiometer.

The caps are glued together with a bit of silicone, not hot glue. If small film bypasses are necessary, there is room to attach them to the electrolytics.

I have yet to build a powersupply, so these are untested.
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Last edited by 6L6; 21st April 2011 at 04:19 PM.
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Old 21st April 2011, 04:43 PM   #2
johnr66 is offline johnr66  United States
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Looks good (Note that didn't check against the schematic), but I have a couple suggestions: Wire the signal grounds so their ground doesn't have to travel through the output return ground. I would add a couple film caps across the PSU rails. Put a thermal insulator between the big caps and the heat sink so they don't get too warm.

If you tinker around, I'm just curious at what PS voltage these chips turn on. The TDA2050 will work with a +/- 2 volt supply at a few milliwatts of output, of course.

Last edited by johnr66; 21st April 2011 at 04:47 PM.
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Old 21st April 2011, 04:49 PM   #3
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I like it. If that doesn't shout "DIY audio" I don't know what does.
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Old 21st April 2011, 05:05 PM   #4
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nice!
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Old 21st April 2011, 05:39 PM   #5
LAJ is offline LAJ  United States
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Default I did something like that except...

I made a small PC board with round pads (one for each pin) surface mount style. All the components are mounted on the circuit board with only 1 wire going to each pin of the LM3886.
That way if 1 blows up its not such a nightmare to change.
I was pleasantly surprised when it didn't feedback from stray coupling.
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Old 21st May 2011, 09:10 PM   #6
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I do this

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อัพเดทหน่อย
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Old 22nd May 2011, 01:44 AM   #7
6L6 is offline 6L6  United States
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tigersilver - Very Nice!!!!

Do you have a schematic of the way you wired the chip?
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Old 22nd May 2011, 02:31 AM   #8
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^
Oh ... Thank you very much.

I'm coppy this schematic

Click the image to open in full size.

Modified set of the new power supply.

Modified set of schematic chipamp.

Rin Rl cut out
Cs 470uf.
Rm 22k.
Cm 220uf.
Cz 0.47uf.

CS//0.1 uF (wima).
for balance of electric (+ -)
----
I want to use accessory to a minimum,
I'm try removing the 0.1 uF (wima) out,
Result from the electric not balance.

Last edited by tigersilver; 22nd May 2011 at 02:49 AM.
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Old 22nd May 2011, 10:43 PM   #9
bbm3 is offline bbm3  United States
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Nice work 6L6,
I'll be interested to hear your impressions of the LM3886 once you power it up and have a listen.

Cheers,
-BB
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Old 22nd May 2011, 10:51 PM   #10
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