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Chip Amps Amplifiers based on integrated circuits

Neurochrome LM3886DR Build
Neurochrome LM3886DR Build
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Old 16th September 2018, 11:25 PM   #421
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by ozenfant View Post
Ah, that I do not have. Any recommendations on how to approach that? I guess literal holes bored through the side would be one approach, or perhaps routing a channel on the inside that exits at the back?
If possible orient the heat sinks such that the fins are vertical. Then either let the heat sinks poke through the side of the chassis or drill a bunch of holes below the heat sink fins and above them for the air to flow through.

Tom
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Old 16th September 2018, 11:32 PM   #422
chrisb is offline chrisb  Canada
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Ideally I think you’d want to create a open air path for convection - usually with the fins of heat sinks oriented vertically. With high efficiency class D type amps such as Hypex modules, the thick extruded side panels of something like the DIY Audio store Slimlines work great, but amps like Toms, or the class A ACAs need either surface area exposed to free air, or some other creative heatsink /cooling mechanism with which to dissipate that thermal energy.

OK, I see Tom answered pretty much the same thing
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Old 20th November 2018, 08:56 PM   #423
TioFrancotirador is offline TioFrancotirador  Poland
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Guys,
I have really strange issue. I am running stereo lm3886DR with one smps -/+24V (2x60W/24V). On each lm3886dr board instead of two 1000uf caps I put two 3300uf/50V.
When I connect the amp to the 4R speaker I works perfect. Dc offest less thatn 2mV in both channels. I measured the voltage across the caps and it is either -24V or +24V. Everything is just fine. However after some time (5mins) one of the 3300uf cap in one channel get extremly hot! (the other channel does not have this issue). I checked polarity and it is ok. I replace the cap (thining it is maybe faulty one) but a ran into same issue. Then I just removed this cap and everything works fine ...
Any ideas what might have happend? Please help. It is really strange for me. Why this particular cap get so hot?
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Old 20th November 2018, 09:08 PM   #424
tomchr is offline tomchr  Canada
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One of your SMPSes may be oscillating due to the capacitive load. That would burn significant power in the cap, thereby heating it up.

Tom
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Old 20th November 2018, 09:55 PM   #425
TioFrancotirador is offline TioFrancotirador  Poland
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Originally Posted by tomchr View Post
One of your SMPSes may be oscillating due to the capacitive load. That would burn significant power in the cap, thereby heating it up.

Tom
Thanks Tom,

But is the increased capacitance the cause of oscilation? or one of the smps oscilates because of different reason (like low ESR of caps) and increased capacitance does not have anything to do with this?

Last edited by TioFrancotirador; 20th November 2018 at 10:07 PM.
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Old 21st November 2018, 04:31 AM   #426
tomchr is offline tomchr  Canada
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If you add capacitance, you'll change the feedback loop dynamics. Many SMPSes have a max specified additional cap.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 16th February 2019, 04:40 AM   #427
invaderzim is offline invaderzim  United States
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I still need to do a bit of tidying up inside and may add a divider between the power supply and the amp boards but here's my LM3886DR in a 2 bottle wine box.
Attached Images
File Type: jpg lm1.jpg (127.9 KB, 454 views)
File Type: jpg lm2.jpg (131.6 KB, 457 views)
File Type: jpg lm3.jpg (135.4 KB, 468 views)
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Old 16th February 2019, 04:17 PM   #428
tomchr is offline tomchr  Canada
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That's a pretty neat use of a wine box. Thanks for sharing.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
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Old 6th August 2020, 02:41 AM   #429
DaveFred is offline DaveFred  Canada
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Originally Posted by tomchr View Post
That would work. You could also use microphone cable. Use one conductor for the centre conductor, the other for the shield. Terminate the cable shield at one end (the transmitting end). That would be your standard "audiophile" interconnect cable setup. Just add directional arrows...
You'll probably get better performance if you use one conductor for the shield connection and connect the shield at both ends as that reduces the ground impedance. Of course then the cable won't be audiophile approved as it won't have the directional arrow.

The W2319 you link to above would make sense for the wiring inside the chassis. Use the centre conductor to carry the signal and the shield to carry the ground.

Tom
Would W2524 also work well for RCA to RK271 10K pot to LM3886DR amp?

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David.
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Old 6th August 2020, 04:51 AM   #430
tomchr is offline tomchr  Canada
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Sure.

TOm
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
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