Hi, i am making lm1875 bi-amp. One for tweeter and one for mid-range. Does anyone knows the best circuit scheme for this?
And also do you know some scheme for active crossover around 3kHz?
And also do you know some scheme for active crossover around 3kHz?
The LM1875 is an OpAmp, given your project, it is an perfect opportunity to build the XO around the amp for much less stuff in the way.
dave
dave
Maybe its silly question but what does it mean? i am new in this and i am still learning. Sorry 😀
Instead of building an amp with a separate OpAmp XO you can eliminate the need for that by wrapping the XO around the LM1875.
I can read and recognize an active XO but designing one would be a task for me (doable but…), there are many examples and many here with very solid skills at this.
My active XOs tend toward simple PLLXOs, in my ACA a simple change to a smaller input cap makes it into a midTweeter amplifier.
But if you need something faster (what are the speakers you wish to use?) something like a 2nd order or even a 3rd order SallenKey can be wrapped around the LM1875.
If you take this approach, the amplifiers do become dedicated.
dave
I can read and recognize an active XO but designing one would be a task for me (doable but…), there are many examples and many here with very solid skills at this.
My active XOs tend toward simple PLLXOs, in my ACA a simple change to a smaller input cap makes it into a midTweeter amplifier.
But if you need something faster (what are the speakers you wish to use?) something like a 2nd order or even a 3rd order SallenKey can be wrapped around the LM1875.
If you take this approach, the amplifiers do become dedicated.
dave
I would like to build something like studio monitors and when i saw the schematics of some monitors that are selling, they are using another opamp to divide the frequencies to each amp. But you say that i can play full range signal to both and than use passive ox?
The LM1875 is a POWER opamp. And not that nimble. OLG may be 'only' 50dB at 20KHz.
IAC, if/when the power amp clips, the filtering goes haywire.
It is usually worth the extra 19 cents to have an opamp just for filtering.
matej123, the internet is FULL of crossover plans. I'm not sure what you are asking?
I'd avoid posting harsh personal comments and judgements like those above, about any member, new or experienced here.
LM1875 though, is still great bangs-per-buck. I was given a very well planned and pre-assembled Chinese board for testing some weeks ago and it sounded every bit as good as typical LM3886 type builds.
LM1875 though, is still great bangs-per-buck. I was given a very well planned and pre-assembled Chinese board for testing some weeks ago and it sounded every bit as good as typical LM3886 type builds.
Apologies
I still think he should have got his basics right, that was a basic question.
2.1 populated board kits with 3 x 2030A are very cheap here..
Easy to make the amp, add power transformer, and signal in
Rectifier and smoothing caps are included.
Childishly simple, hence my comment..
4.1, 2.0 and 5.1 kits are also common.
I still think he should have got his basics right, that was a basic question.
2.1 populated board kits with 3 x 2030A are very cheap here..
Easy to make the amp, add power transformer, and signal in
Rectifier and smoothing caps are included.
Childishly simple, hence my comment..
4.1, 2.0 and 5.1 kits are also common.
Hi, I'm sorry if I wrote something wrong, I'm from the Czech Republic so I don't know much English so it's possible that I wrote something stupid. However, yes, I have recently sign up Because I've been trying to solve it myself all along, but since the chip is old, there is lots of different things about this chip, so I don't know what's best.
Decide output need.
That will tell how many chips needed, 1875 is good to 32W, more than enough for most homes.
Single chip is enough then, 2 chips not needed.
Read the app notes and so on.
Then go ahead.
That will tell how many chips needed, 1875 is good to 32W, more than enough for most homes.
Single chip is enough then, 2 chips not needed.
Read the app notes and so on.
Then go ahead.
Yes, but i already have 18-0-18V trafo so that means 25-0-25V after rectification and according to datasheet i can get around 20w from one chip. I have 25w woofer and 25w tweeter so its fine to use one chip per speaker right?
I will suggest you to use a bridged amplifier for bass/woofer and a single ended for treble. Of course if the speakers are 8Ω minimum.
You need a larger voltage excursion for bass. There are several examples for schematics like thin on the forum.
You need a larger voltage excursion for bass. There are several examples for schematics like thin on the forum.
Great suggestion, it always needs more power in woofer section.
My suggestion would be to go slow and modular. Rather then build all on one board, make active crossover first. Line in, two lines out. Check its performance with well working other amplifiers. Then build those amplifiers based on LM1875. Test independently. Then use.
Long time ago I used something like this, its 2.1 amp, for sub and two bookshelf. It was easy to use, made just few small mods to suit my application.
https://www.parts-express.com/Yuan-Jing-LM1875-2.1-Audio-Amp-Board-2-x-25W-50W-Y24-320-6510
My suggestion would be to go slow and modular. Rather then build all on one board, make active crossover first. Line in, two lines out. Check its performance with well working other amplifiers. Then build those amplifiers based on LM1875. Test independently. Then use.
Long time ago I used something like this, its 2.1 amp, for sub and two bookshelf. It was easy to use, made just few small mods to suit my application.
https://www.parts-express.com/Yuan-Jing-LM1875-2.1-Audio-Amp-Board-2-x-25W-50W-Y24-320-6510
Before you start working at the crossover I suggest to do first measurements with the final speakers in final box. You need to know exactly the type of crossover (not only the crossover point) and to implement, if is necessary, some adițional filtering like a notch filter.
Thank you all for your advice. Now I'm working on active xo and if everything will be fine I will somehow deal with the amplifier. 😉