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Chip Amps Amplifiers based on integrated circuits

XY LM3886 Kit Review & Measurements
XY LM3886 Kit Review & Measurements
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Old 10th July 2016, 12:20 AM   #11
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by Davey View Post
No, he doesn't. Tom is free to sell his product(s) at whatever price point(s) he establishes. You, as a possible customer, are free to evaluate and decide not to purchase if you so choose.

I also don't have any problem with objective comparisons of competing products. It happens all the time.
Exactly!

Quote:
Originally Posted by nycavsr2000 View Post
For a fully built board you are paying for the soldering, cleaning AND testing! Tom guarantees that the built board matches the prototype!
Absolutely correct. Any assembled amplifier board that you order from me gets checked out on the Audio Precision APx525 to ensure that it performs well before I ship it. That's part of what you pay for.

Quote:
Originally Posted by billshurv View Post
I also think having some objective measurements is a good thing. Few of us can afford 20k+ on an audio tester let alone have time to learn how to drive the beast properly (a fool with a tool is still a fool after all). The fact that Tom is willing to spend some of his limited free time testing building and testing this accurately should be welcomed.
Thank you.

Quote:
Originally Posted by billshurv View Post
Looking at the plots you could easily say that (stability aside) the XY still has low enough THD to be below known audibility thresholds and so into a benign speaker should be audibly transparent.
Maybe... I have yet to hook up the XY board to the stereo. It would not surprise me at all if that rather extreme jump in THD+N above 2 W is quite audible.

Quote:
Originally Posted by billshurv View Post
Would love to know the history behind the printed chips tho.
Me too. I'll post to this thread if/when I have sharable results from TI's analysis.

Tom
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Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 10th July 2016, 07:29 AM   #12
olaru is offline olaru
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Okay , looks like I have to clear the waters.
First thing, it's bad to compare 11$ Kit with 35$ pcb, like you compare Kia with Ferrari ....that's why I got started, it's not fair , and even the chip was fake
And why did you spend 11$ for that kit? I thought it's a stereo one,not mono!
Tom, you got ripped off, these eBay sellers made you pay more than you sHould.
I did not mean that you need to lower the prices for me. No , thank you! For you , for your business ! But dont worry about me or the other customers!
I did not mean to upset anybody

Last edited by olaru; 10th July 2016 at 07:40 AM.
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Old 10th July 2016, 07:32 AM   #13
bommetje is offline bommetje  Netherlands
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Default white labeled lm3886T and 0,5ohm output resistor

In Jeff Rowland lm amp... not a 11 dollar amp
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Old 10th July 2016, 09:16 AM   #14
Mario Pankov is offline Mario Pankov  Europe
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XY LM3886 Kit Review &amp; Measurements
The LM3886 chips are fakes, Chinese sellers offer them for 1 a piece. They do fail - I know it because I bought some from a local diy-er some time ago and have used them. They are very different from the TI branded ones I also buy from Mouser.
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Old 10th July 2016, 09:46 AM   #15
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by bommetje View Post
In Jeff Rowland lm amp... not a 11 dollar amp
Jeff probably buys his LM3886es from a TI distributor. He uses a 0.5 Ω ballast resistor as he's running multiple LM3886es in parallel. He probably also paid attention to the component selection on that 0.5 Ω resistor and chose one with a low temperature coefficient.

Tom
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Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 10th July 2016, 09:58 AM   #16
korpberget is offline korpberget  Norway
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Okay here comes the stupid question: So is the XY kit any good for anything?
There is a whole thread addressing mods of that kit. Anyone tried it?
Just curious as I have the XY pcb's laying here. LM's bought from a serious place - no fakes.
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Old 10th July 2016, 10:29 AM   #17
bommetje is offline bommetje  Netherlands
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I just bought those xy-boards to put together as my first diy amp. And then I read that it could be fake lm's... Mmm. Might as well use them now, but in the future I will purchase with a little more wisdom.
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Old 10th July 2016, 11:19 AM   #18
Naaling is online now Naaling  Portugal
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This comparison is not unfair because of the price difference.
Its invalid because one board uses known genuine components and the other known fake components.
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Old 10th July 2016, 12:46 PM   #19
thejohn is offline thejohn  South Africa
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Tom, I have a few unused Chipamp.com boards lying around if you'd like me send you one. It would be interesting to see how it compares... I could send it populated with all the R's & C's from their kit too if you like...
John
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Old 10th July 2016, 01:54 PM   #20
sangram is offline sangram  India
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Tom,

Can you help with THD vs frequency - comparison - at 1W? It's probably, given what I remember you posting at some point, more representative power level for normal listening.

No question yours has the edge at high power outputs, but it's not like we listen at those power levels anyway. I know for a fact that the XY board is quite poorly designed, specially around the feedback ground, but some P2P techniques help with that gremlin.

Not trying to diss your product, just curious as the 1W performance seems quite comparable for both products so am keen to see how it was distributed over frequency. Some FFTs would also be nice, if possible.
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