Bi Amp using LM3886

jamal

Member
2010-09-20 1:53 pm
I mean ,I intend to build 3 amplifier using Lm3886 for each channel that is left and right. each amp is suppose to amplifier a specific range of frequency.then I need a active cross over network to seperate the various freq. that is high mid and low freq. this I will feed to the invidual amp and feed to the woofer ,mid range and tweeter seperately.
 
I understand all of that, but my point is still valid, and you didn't answer my question, so it is impossible to give you meaningful help. The LM3886 has a high-ish impedance input, so driving it is trivial (0.1%). That means that the other 99.9% of the crossover design is about what it does. Do your speakers need steep or shallow crossovers? Do you know the crossover frequencies?

2-Way Electronic Crossover

Linkwitz-Riley Electronic Crossover

Linkwitz-Riley Electronic Crossover - A reader's experience

3-Way Electronic Crossover Network

12dB / Octave Linkwitz Riley Crossover

Project 123
 
I understand all of that, but my point is still valid, and you didn't answer my question, so it is impossible to give you meaningful help. The LM3886 has a high-ish impedance input, so driving it is trivial (0.1%). That means that the other 99.9% of the crossover design is about what it does. Do your speakers need steep or shallow crossovers? Do you know the crossover frequencies?

2-Way Electronic Crossover

Linkwitz-Riley Electronic Crossover

Linkwitz-Riley Electronic Crossover - A reader's experience


3-Way Electronic Crossover Network

12dB / Octave Linkwitz Riley Crossover

Project 123

Hello
That is a bunch of Op-Amps, capacitors and power supplies. I know because I built all the LR4 crossovers and chip amps for a 3-way active system with Rod Elliots PCB’s. When all was finished I used it to power the system in my basement shop. Rod’s PCB’s are the least quality that I have built. With no solder mask you need to be very careful not to bridge any traces. The system using active crossovers is near magic as Rod says.
DT
All Just for fun!
 
Hi jamal it might be better if you tried to find out more about active crossovers from the Net and then come back to the diyaudio forum with any issues you have after reading up on crossovers.

I think what you are trying to do is really good. Some one mentioned Rod Elliot's site. That is a good place to start. I think it is "Elliot sound products". Put that in google and you will find a good article there.

Good luck.
 

jamal

Member
2010-09-20 1:53 pm
thanks everybody ,btw I am still new to cross over network and bi amp. I just completed my chipamp using LM1875 it sound so good but never come closer to my Cyrus 1 Amp. I install LM1875 board inside a KEC amplifier and throw away the old power Amp that was using UPC 1188. it sound terible ! full of distortion.
now I am building the LM3886 stereo amp. if the sound quality justify, I build the tri-amp. gee it sound off topic...........sorry guys and thanks for the help
 

jamal

Member
2010-09-20 1:53 pm
Leadbelly,you mean I going to have impedance matching problem between the filter and LM3886 input? any help that. and thanks for the links.
DualTriode, are you impress by the tri amp. near magic. really? this make me more enthusiastic
Jonathan Bright I need a proven working circuit to wire up the cross over.
 
Hi Jamal
As Leadbelly suggested its the speakers that will define the crossover characteristics, However if you don't know the exact frequencies then I would suggest that you rent an electronic crossover (2 or 3 way) from a pro music supplier, and after carefully reading the instruction manual, you can experiment with different values. But beware if you make an error with the selections or connections you can easily destroy your midrange and or tweeters. Once you have your preferred setting you can than proceed with the design and build of your own custom crossover.

Cheers
Philip
 
Hi Jamal,

if you don't have any information of your speakers, you can follow the impedance measurement shown in this link Passive Crossover Network Design to estimate crossover set points. you don't need any special tools to do the measurement. PC sound card can be the sine generator.

BTW, I am using dbx 234XL electronic crossover and LM3886 in my active speaker project.
 
hi everybody, Harolda. I was looking at the B! on the net. B! come with a single power supply and the LM3886 is dual rail supply. does it matters......thanks

I use a B1 buffer with symmetrical a power supply. You can info on that in this forum. There is also a thread on the cross over i use, something like two B1's and a crossover. I use battery power supply for my cross over at the moment, with +/-9.6V racing battery packs of 2300maH. By using to batteries you can connect them such that you get a symmetric power supply.

Like this:

battery 1 +
battery 1 - connected to battery 2 + - this is GND.
battery 2 -

Battery 1 supplies the + voltage
Battery 2 supplies the - voltage

I use a switch to disconnect the batteries and switch them into parallel for recharching.