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Chip Amps Amplifiers based on integrated circuits

Is this a good LM3886 Kit?
Is this a good LM3886 Kit?
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Old 15th September 2017, 03:23 AM   #21
dotneck335 is offline dotneck335  United States
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Originally Posted by Aatto View Post
I got this and i m happy with it, upgraded the coupling caps tho,huge different :
Audio LM3886 Amplifier Board DIY Kit for HiFi (With Speaker Protection)
WOW!! That sure is cheap! ( ~$16 for a complete board with two 3886s) It's hard to believe that the parts are real, though, given that 2 x LM3886 chips from Mouser would be ~ $13 alone. Were you able to measure it to verify performance?
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Old 15th September 2017, 03:36 AM   #22
Aatto is online now Aatto  United States
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yeah it's dirt cheap, they obviously do not use original parts, but they do buy in large QTYs so it would be much cheaper than buying 2 from digikey. besides based on seller notes they use pulled components from torn down units :
Click the image to open in full size.

well at least they are honest about it !.
keep in mind that replacing the original caps with Audyn did make a huge different.

I do not have any equipment to measure anything, but compare to my Yamaha amp ( my reference amp ) it has slightly warmer character which i like.

Last edited by Aatto; 15th September 2017 at 03:39 AM.
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Old 15th September 2017, 07:21 AM   #23
dotneck335 is offline dotneck335  United States
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Originally Posted by Aatto View Post
.....based on seller notes they use pulled components from torn down units
Yeah, sorta makes you wonder, though----torn down FROM WHAT? Why would you tear down a perfectly good unit? My guess is torn down from a unit that didn't meet specification.....
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Old 15th September 2017, 05:42 PM   #24
tomchr is offline tomchr  Canada
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Originally Posted by Aatto View Post
yeah it's dirt cheap, they obviously do not use original parts, but they do buy in large QTYs so it would be much cheaper than buying 2 from digikey.
You're still looking at $7.25 for two LM3886TF at QTY = 1000 on Digikey.

I simply don't get the idea of buying projects that include fake parts, even if you can swap all the components out with known good components. There's more to good circuit layout than connecting the dots.

Tom
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Modulus-686: 240W/8Ω @ <0.00025% THD. Modulus-86: 40W/8Ω @ 0.000054% THD. DG300B & Other Tube Circuits.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 15th September 2017, 06:57 PM   #25
Chris888 is offline Chris888  United Kingdom
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Do we actually know that any of these parts are fake?
1) whenever I've spec'd components, a decent purchasing person in a small- mid size electronics company has been able to get them for a fraction of the Mouser/RS/Farnell 100-off price.
2) These Chinese outfits seem to be able to sell things at a loss to generate USD/euro/GBP revenue?
3) Don't forget that they are playing games with duties/sales tax/tarrifs by selling under the threshold where the taxman takes an interest.
4) I think some of these things are designed to use up remainder stock from assembly houses. Somebody buys a few thousand chips left over at the end of a run and knocks them out as a kit?

I know there is fake stuff out there, but is it really worth the effort to fake a part that's a dollar at the factory gate?
Anyone ever seen a proven fake chip? from an ebay kit?

I dare say a few dies go out the back door from 'outsource' fabs but AIUI, most of these get passed off as 'second source' alternatives.

It's not like say memory chips where it's viable to re-badge slow stuff as fast stuff or whatever.

The other thing is, these kits are part of many people's learning curve. You don't understand good PCB layout until you've suffered bad PCB layout.
( I assume that's tre in audio as it is in other areas of electronics?)
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Old 15th September 2017, 11:16 PM   #26
Aatto is online now Aatto  United States
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Yeah, sorta makes you wonder, though----torn down FROM WHAT?
from returned or "not working" and outdated units, this is what we do at our company with computer parts, and you won't believe the stuff we receive as faulty or damaged ! sometimes even brand new working components.

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Originally Posted by tomchr View Post
You're still looking at $7.25 for two LM3886TF at QTY = 1000 on Digikey.
never said they are fake or not, neither takin anybody's side,.

Quote:
Originally Posted by Chris888 View Post
Do we actually know that any of these parts are fake?
1) whenever I've spec'd components, a decent purchasing person in a small- mid size electronics company has been able to get them for a fraction of the Mouser/RS/Farnell 100-off price.
2) These Chinese outfits seem to be able to sell things at a loss to generate USD/euro/GBP revenue?
3) Don't forget that they are playing games with duties/sales tax/tarrifs by selling under the threshold where the taxman takes an interest.
4) I think some of these things are designed to use up remainder stock from assembly houses. Somebody buys a few thousand chips left over at the end of a run and knocks them out as a kit?

I know there is fake stuff out there, but is it really worth the effort to fake a part that's a dollar at the factory gate?
Anyone ever seen a proven fake chip? from an ebay kit?

I dare say a few dies go out the back door from 'outsource' fabs but AIUI, most of these get passed off as 'second source' alternatives.

It's not like say memory chips where it's viable to re-badge slow stuff as fast stuff or whatever.

The other thing is, these kits are part of many people's learning curve. You don't understand good PCB layout until you've suffered bad PCB layout.
( I assume that's tre in audio as it is in other areas of electronics?)
couldn't agree more, people focus way too much on what's fake or what and i bet that if you do a blind test 90% wouldn't be able to tell.

i do not call myself audiophile or a pro or whatever, i just don't hear anything horribly wrong and i m happy with it !
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Old 15th September 2017, 11:18 PM   #27
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by Chris888 View Post
You don't understand good PCB layout until you've suffered bad PCB layout.
I'd say you don't understand good layout until you understand Ohm's Law and perhaps a little electromagnetic field theory and can apply those to your circuit. If you want the best performance, you'll need to have some experience with precision circuit design as well.

Tom
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Old 17th September 2017, 12:05 PM   #28
dotneck335 is offline dotneck335  United States
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Originally Posted by tomchr View Post
I simply don't get the idea of buying projects that include fake parts, even if you can swap all the components out with known good components. There's more to good circuit layout than connecting the dots.
Tom
Well, the idea is quite simple...If you are building a say, 4-channel amp (stereo bi amp), the eBay kits cost ~$32. If you go the neurochrome route, you're at $300 JUST FOR THE BARE BOARDS AND PLANS. Now, paying extra for a superior design is all well, and good. But an extra $260 (say the boards are $20 apiece) is HIGHWAY ROBBERY!! HALF that would be a steep price---maybe worth it.
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Old 17th September 2017, 12:18 PM   #29
scottjoplin is offline scottjoplin  Wales
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Originally Posted by miro1360 View Post
not good, additional opamps in signal way (servo and another one probably before LM4702 input) ... if you avoid these opamps, it can be good ... avoid I mean servo not used and another one jumpered if it is in signal way for LM4702
before you avoid servo, be sure your source have small DC offset ..
There's nothing wrong with using opamps like this
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Old 17th September 2017, 12:50 PM   #30
HatlessChimp is offline HatlessChimp
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How can I reduce the noise when nothing is playing. Im running line in with no potentiometer. I have all my cables earthed and have the heatsink between the toroidal and amp board. This is the amp I have LM3886 Power Amplifier Board Kit DC SERVO 5534 Independent op amp DIY Amplifier | eBay
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