LM1875 distortion... any alternatives?

[Havoc]

I was looking at the LM1875 to make an amp with about 5W max output and minimal component count. It looked fine until I saw the distortion graph.

The quoted distortion looks great with "0.015% at 1kHz and 20W". Problem is that in a living room and normal speakers, you very rarely use 20W. So if you look at the graph, then distortion is more 0.07% around 1W. Which is about 10 times more then the LM3886. And that hump is really strange compared to almost any other amp, chip or discrete.

Any better solutions? I'm looking at a minimal components amp that can do around 5W bearing in mind that in the end I might need 24 or more of them.

 

[steveu]

https://www.digikey.com/en/products/filter/linear/amplifiers/audio-amplifiers/742?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALGGABxwDsIAuoQA4AuUIAyuwE4BLAHYBzEAF9CtAMyIQKSBhwFiZENOkAGegFYATMzadIPfsLGTKNRtHloseQiUjk99KtJ0hCeinBju3iC+-vSMPn4BNEEhMDSaMdJgOhRePtK+FAnpSXDZVhrS0TlgcBA+ATAUFDGVqbX0VTANVeHBNGDSZUEUNBoUBj4dXYPtnXCyPvSaHaNuM50x0x01UwtpwctgzT5wOtL0o1o6MJrl6ponmpMF0hQ37vTJQY96568b8dJVQV8wn9cYDsQI1Wr96HA9PlrJDzjDfODIZ89Ho8r8ynAEIQGL0NjiaMD8W0wICAkESd84uTAU9yWA9DANHT-odyfdIVjwOytGyuhleRMbmBuRthf9PGy4BR-pLpcDhVKqYQ-FkGLLpuSdKVnlIdPsDpr9llDXdzskOatwDoOaLraj5Xa1bqOcUrRzOds7UL-pDLZ6keSAjo+oHdDQ-UGaKLw3FRrRpVHyTGCUmE8Tk674-B8rQaNYc3nrHGpdZRSWwuTy5nyx6S-FK3mZjFNJo9EkYskipa3vs8x3e5ye118kPuj5OxN+11u56aHNaDM2m9IQyYlCrmu2ylN55gSit21eoUNiiYFC925tuc242l0UOiPUsk5hQwpcYjo34PP08Rz-hR+YQ6lYZ6NLUtDWuBBIjjAtCwbUSTbLUKR+LUZ56ksviMoYIAcFwvCCKIEiEAAtAYtgKPwACuKjOOQXhMOITFAA

I expect other vendors also have selector guides.

But this is one of the trade-off using chip-amps. Personally, I think they are good enough, but if you want < 0.1% THD at low levels then you want a discrete amp where you can tweak the idle bias.

 

[b_force]

A composite amplifier with a LM1875 is a nice alternative

 

[Bare]

The 'distortions' in the 1875 are innocuous. Fixate on something else !!
The Distortions inherent with My Firstwatt amp are far larger (on paper)
Yet it's the Best sounding /performing amp I've ever had And I've had most amps.... starting from 1967

 

[adason]

I was looking at the LM1875 to make an amp with about 5W max output and minimal component count. It looked fine until I saw the distortion graph.

The quoted distortion looks great with "0.015% at 1kHz and 20W". Problem is that in a living room and normal speakers, you very rarely use 20W. So if you look at the graph, then distortion is more 0.07% around 1W. Which is about 10 times more then the LM3886. And that hump is really strange compared to almost any other amp, chip or discrete.

Any better solutions? I'm looking at a minimal components amp that can do around 5W bearing in mind that in the end I might need 24 or more of them.

If you do not like lm1875, than build lm3886. Its does not matter what wattage you use it for.

 

[NareshBrd]

At low levels, you must have sensitive speakers.
And for that level, you must have trained musicians' ears to make out the distortion.
In real life, does not matter.

Or look at Class D modules, quick and easy alternate, may have lower distortion than 1875.

 

[abraxalito]

Why not use LM1876, its distortion is considerably lower than LM1875 at 1W (almost 20dB lower) and it reduces the component count of a stereo amp by one.

 

[availlyrics]

Problem is that in a living room and normal speakers, you very rarely use 20W. So if you look at the graph, then distortion is more 0.07% around 1W. Which is about 10 times more then the LM3886. And that hump is really strange compared to almost any other amp, chip or discrete.

Speakers have more distortion like in single digit percentage, so even a modest 1% will still be magnitudes larger than any chipamp's distortions. If you can get hold of genuine ICs , good PCB layout and +12/-12V PSU, you will get clean power upto 6W

 

[availlyrics]

you must have sensitive speakers.

You are right, I had used it on 92dB sensitivity speakers , room shaker!

 

[Havoc]

Yes, speakers distort more. But I don't like the shape of that curve. And I don't play music at very high levels.

That lm1876 looks good. And less components is also nice. Think I'll go that way. Time to start a pcb...

 

[tomchr]

+1 for LM3886 or a composite amp (with either LM1875 or LM3886). You can reuse the LM1875 power supply with the LM3886 as long as it provides at least ±10 V. You'll get about the same output power as you would with the LM1875 and lower distortion.

Tom