Found a couple of "LM1875T"

Hey people,

I found these "LM1875T" ( I assume the common, not so bad sounding, fakes as everywhere). I just forgot I have them, as I changed to LM3886 just because of the higher output power. I remember them as really good sounding chips, and it would be a pity to not put them to use.
I thought, maybe I could try two of them for my tweeters, which are powered by LM3886's atm. It's all fully active, so the different output power can be aligned easily.

best regards
If you have an already built and working active system using those LM3886,leave as is.
Not sure what advantage are you expecting from building a new lower powered amp from scratch for your tweeters.

Chipamp used is just one leg of that table, power supply has a strong voice on that matter.
A "lower power amp" based on lM1875 will also require a lower voltage power supply which will also require a new lower voltage power transformer.
I do not see the point.
They both run on +/-27,5V. Power is irrelevant as both, LM1875 & LM3886, are overpowered for a 1", 8Ohm Soft Dome tweeter.
It is said, that the LM1875T is the best sounding ChipAmp, so I thought I'll give it a try.
And no, I won't leave these Speakers as they are. I could, because they sound great, but that doesn't mean, they couldn't sound greater.
It's just the urge to try something different in the search for the best sound I can get.

edit: I'd just change a pcb.
(hmm, it says uploaded 100%, but the pics just won't show up)
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Try to post some pics.I don’t know why you are assuming they are fakes .
these chips are available from
They sound really good, could be the original chip. They take +/- 28.5V, this is ok, too. Sadly all internal protection circuits, like AC & DC short circuit to ground prot. are missing. You have to be very careful with these Chips. If you make "Boohh!" the chip makes "bang!".
I made many audio amplifiers using fake audio ICs like Lm1875, tda2030/50 etc. They all sounds very good; of course at a certain level. You can't expect 30 watts of power from a fake lm1875. That is the difference. A fake chip can't compete the reliability of a genuine product.

Edit- Since two yrs one of my friend is using fake tda2050 stereo with +/-25vDC power supply & 4ohm load. 2×18v 180VA transformer! o_O
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Next try with some pics.


  • LM1875 1200w.jpg
    LM1875 1200w.jpg
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To assure linearity with the 5-pin chips, just use lower voltage. Try regulators.

The point: You want to run your small signal areas (tweeter amp too!) at Less voltage than whatever shoves the woofer. The top portion of voltage varies when moving the woofer and this unfortunately modulates (sounds like clipping) the treble. So, we should operate the small signal and tweeter amplifiers at voltage Less than the high current fluctuation.

Means include:
Separate tweeter amp run on regulators is like stabilized small signal
Stabilized front end on discrete amp = stabilized small signal
Simple divider for front end on discrete amp (see Honey Badger)
Composite chip amplifier = stabilized small signal (See Neurochrome)
And, this simple way to run the 440u amp board caps at 0.7v Less than 10,000u power supply

Alternatively, you can view it as removing crosstalk distortion from your stereo set: When the power fluctuation from shoving the right channel woofer doesn't affect the left channel tweeter, nor vice-versa, then the job is done.
And, there seems to be many different ways to achieve it.

P.S. Instead of guesswork with LM1875 Clones, why not use a real TDA2030 and the datasheet for it?: It is really interesting with d1, d2, bi-amp information, etc...
Tda2030A is a nice sounding amplifier. Good for Clean 10-15watts into 4 or 8 ohm load. Actually right now i'm listening to one (mono), with a FM module. I've both ST & Chinese version(D2030A) & sonic signature is identical. If power requirement is low (efficient spkrs) then i strongly recommend it. The price of Lm1875 is more than double!
ST itself is a licensed version of the original Philips chip, I think...stopped production in 1998 or so.
UTC Taiwan is said to be successor of ST.

In India, the Chinese shipments are of the order 100,000 units per parcel.
Price wise, 20 cents retail for Chinese here, UTC is about 1 Euro from German sellers.
2030/ 2050 / 1875 prices are equal from Chinese sources, 10 cents wholesale, 20 in retail.

The sales volumes speak for themselves as to quality of sound and manufacture.