Using neurochrome website: For ambient temperature 40°C and heatsink temperature 60°C, Junction temperature 125°C, for supplied voltage of ±25V and pairing with 8 ohm speakers,
2°C/W→Heatsink requirement for stereo 1°C/W approx.
3°C/W→Heatsink requirement for stereo 0.5°C/W approx.
These calculation has been done without taking into account crest factor or any other averages.
2°C/W→Heatsink requirement for stereo 1°C/W approx.
3°C/W→Heatsink requirement for stereo 0.5°C/W approx.
These calculation has been done without taking into account crest factor or any other averages.
An IC you buy very (suspiciously) cheap may be defect but you can often see traces from desoldering.
Else, the normal trick is to rename an IC with a similar functionality and an identical pin layout to a more expensive type of IC. For the LM1875 it may theoretically be a TDA2030 but then you can often see that the top surface has been grinded before the new type was printed.
Else, the normal trick is to rename an IC with a similar functionality and an identical pin layout to a more expensive type of IC. For the LM1875 it may theoretically be a TDA2030 but then you can often see that the top surface has been grinded before the new type was printed.
Anyway to find out?
Recently I bought a LM1876TF, it does sounds quite good but the marking text is a little bit blur.
Recently I bought a LM1876TF, it does sounds quite good but the marking text is a little bit blur.
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My 1st try in diy-audio was the LM1875 China kit with the blue PCB (wich may also be seen on yt @ johnaudiotech). It has become really cheap (1,70€ I think at the moment, it was about 6,00€ when I ordered it), but both circuits worked at first try and I am really impressed. I've built two little 2-way speakers, 8 liters closed, 1x Gradient W130 AL 8 & a Monacor DTM104/8 1" tweeter with just a capacitor as highpass in front of the tweeter.
Sure this isn't a setup for these deep, growling, wall shaking frequencies all people seem to like most
. I am on a very very small budget, but hey, if there is a God, he loves low cost Subwoofers. The 8" Mivoc AW 2000 costs just 35€ and fits the two 5" Gradient speakers pretty good. The subwoofer has a 11liter closed enclosure and is driven by another China chipamp-kit wich has two TDA7293 in parallel mode.
It's all still under construction but I'm totally blewn away how good this combination sounds as it is. As a music player I'm using my Soundcard, an Asus Xonar D2X, wich works as a subwoofer crossover, too. I set the cutting frequency at 74Hz and that sounds pretty ok for me.
My room has about 40m² and I can say, it sounds great and if I wanted to, i could wake up the complete neighbourhood. So max. volume isn't a problem either.
Some people may be a bit sceptical about the LM1875 with just about 20 - 25W, and sure, it's not made for driving 15" woofers or 4-way passive monsters, but with a potent psu with some electrolytic capacitors its a fine chipamp. I'm planning to go from 2-way to 2.5-way by adding another 5" Gradient just to put 1 or 2 dB in the "woofer- gap" and as I have some more LM1875 chips, each chassis will get it's own chipamp. I'm an absolute beginner in diy- audio, but I read much and at the moment I'm trying to get into the Equalizer APO and I'm building a PC for audio measurements. It's all new for me, and it wil take a while, but I'm totally motivated because the music sounds soo good now.
And, I'm going to buy another AW 2000 + chipamp and I'm curious how they sound in BR enclosures (each it's own).
What I wanted to say, I'm totally into the LM1875!
Some pics (as I wrote, "under construction" the chipamps will be mounted in the speakers, somewhen ...)
Greetings J.
Sure this isn't a setup for these deep, growling, wall shaking frequencies all people seem to like most
. I am on a very very small budget, but hey, if there is a God, he loves low cost Subwoofers. The 8" Mivoc AW 2000 costs just 35€ and fits the two 5" Gradient speakers pretty good. The subwoofer has a 11liter closed enclosure and is driven by another China chipamp-kit wich has two TDA7293 in parallel mode.It's all still under construction but I'm totally blewn away how good this combination sounds as it is. As a music player I'm using my Soundcard, an Asus Xonar D2X, wich works as a subwoofer crossover, too. I set the cutting frequency at 74Hz and that sounds pretty ok for me.
My room has about 40m² and I can say, it sounds great and if I wanted to, i could wake up the complete neighbourhood. So max. volume isn't a problem either.
Some people may be a bit sceptical about the LM1875 with just about 20 - 25W, and sure, it's not made for driving 15" woofers or 4-way passive monsters, but with a potent psu with some electrolytic capacitors its a fine chipamp. I'm planning to go from 2-way to 2.5-way by adding another 5" Gradient just to put 1 or 2 dB in the "woofer- gap" and as I have some more LM1875 chips, each chassis will get it's own chipamp. I'm an absolute beginner in diy- audio, but I read much and at the moment I'm trying to get into the Equalizer APO and I'm building a PC for audio measurements. It's all new for me, and it wil take a while, but I'm totally motivated because the music sounds soo good now
.And, I'm going to buy another AW 2000 + chipamp and I'm curious how they sound in BR enclosures (each it's own).
What I wanted to say, I'm totally into the LM1875!
Some pics (as I wrote, "under construction" the chipamps will be mounted in the speakers, somewhen ...)
Greetings J.
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Wow! Very very nice project. Very good dedication from you also.
Initially I was thinking to buy this board. But as the price was only 2 USD per board I was very skeptical about the authenticity of the IC. May be these ics are salvaged from the old amplifier. I don't know.
What I am looking from the lm1875 isn't the power, but quality clean sound. Your project is very inspiring. Thanks for sharing.
Initially I was thinking to buy this board. But as the price was only 2 USD per board I was very skeptical about the authenticity of the IC. May be these ics are salvaged from the old amplifier. I don't know.
What I am looking from the lm1875 isn't the power, but quality clean sound. Your project is very inspiring. Thanks for sharing.
Ok.. i was worrying it's fake item but somehow it sounds good.
I'm using 15v@50va ct transformer and the sounds is not bad at all even undersize. I also tried with 12v@200va ct transformer too.
I'm using +/- 23VDC w/ 7x 2200µF/35V @ each side of rail for the LM1875's & +/- 32VDC, no it's a lie, it's 31,5V w/ 3 * 10000µF/50V @ each side of rail for the TDA's.
Thats what I could get for the few bucks I had at that time. I'm going to order 2 toroids w/ 2 *18VAC (25VDC)/ 80VA for the satellites & a bigger one w/ 2 * 24VAC (35VDC)/ 300VA for the sub.
edit: I forgot my question: the subwoofer- amp is as I got it out of the bag. The big red capacitor has 3,3µF and i think, I've read somewhere, for better bass- amplification this value can be lower, maximum down to 0,68µF. Should I change it for lets say a 1µF cap?
Thats what I could get for the few bucks I had at that time. I'm going to order 2 toroids w/ 2 *18VAC (25VDC)/ 80VA for the satellites & a bigger one w/ 2 * 24VAC (35VDC)/ 300VA for the sub.
edit: I forgot my question: the subwoofer- amp is as I got it out of the bag. The big red capacitor has 3,3µF and i think, I've read somewhere, for better bass- amplification this value can be lower, maximum down to 0,68µF. Should I change it for lets say a 1µF cap?
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You're thinking backwards. 3.3 uF is bigger than 1 uF, NOT smaller. Making it smaller will block more bass.
Leave the cap alone.
Thanks for the answer. I remembered this in the exact opposite direction. From now on, I won't forget that. Again something learned .
Pity your answer couldn't safe this poor chipamp. Must have been something like what happened '86 in Tschernobyl. My luck I had the camera at hand ....
.Pity your answer couldn't safe this poor chipamp. Must have been something like what happened '86 in Tschernobyl. My luck I had the camera at hand ...
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Correct me if I'm wrong, but I think the LM1876 is just two LM1875's + mute and standby options in one chip.
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