I want to build some Composite LM3886

[Clueless but avid]

Hey people,



I've built some tiny 2.5-way active floorstanding Speakers (2x 5" Mid/ Bass + 1" Softdome driven by three LM1875) which sound in my ears better than I ever expected.

I've built quite a few LM1875 Amps in different Variations, but it seems I'm not able to get original Chips in Germany. Most Resellers do not offer this Chip anymore, and Mouser, the only Shop where I found it seems to want 20€ tax, which is a whole lot of money.
The idea is to build some composite LM3886, because this Chip is available everywhere. While I used Breadboard Boards for the LM1875 Amps, I want to make some PCB's for the LM3886es. Problem: many Threads, countless postings about this Stuff.

So my first Question: which PCB should I choose (the my_ref, or the audiophile approach or whatever), and where do I find a downloadable File with the best LM3886 PCB ever?


Best regards & many thx

J.

 

[chermann]

Hi

yes you are right....its not easy to get a "original" LM1875 . for your speakers you need 6 pcs of LM1875 ...so 10 pcs is not bad -->
At the Texas instrument Shop (you have to register) you will get 10 pcs of LM1875 for 3,1 each - deliver+tax to my country is 6,99 Euro
sum= 38,09 euro


chris

 

[tomchr]

I'll throw my Modulus-86 into the mix.

If you'd rather build from scratch, Kitchin (et al.) "Composite Audio Power Amplifiers", Electronics Now Nov. 1992 is a good place to start. It'll take a bit of simulation work to adapt the circuit for the LM3886 and its quirks, but it's possible to do.

If you're interested in the quirks of the LM3886, I cover quite a few of them in my Taming the LM3886 article series: Taming the LM3886 Chip Amplifier

Tom

 

[chermann]

Good point by Tom!
if you want to start seriously with LM3886 then:
about 63 euro for a bare pcb Modulus 86 or about 36 euro for a bare pcb LM3886 done right

chris

 

[Clueless but avid]

Hey Guys, I'm registered here for about 2 years. In this time I've read each Word on Neurochrome for at least a minimum of 5 times. Why? Because the Modulus- Series are excellent engineered Amplifiers and I always try to adapt the good things when I have to study autodidactic. The Problem is, my Profession is that of an industrial Mechanic. Industrial Mechanics are used to work with only two tools: A Hammer and a big Hammer. I'm pretty good at soldering, but as an old man of 50 years it's not always easy to learn audio electronics from the start in a foreign language. I guess most Users on this board are decades of experience ahead of me.

I'm a pretty different DIY Guy, too. A lot of things I cannot afford, I build myself. As a mechanic I'm good at Metalwork and as a 69er I still practice those ancient Knowledge-Rites like reading everything I find to a theme that interests me.
If I was the average DIYer I'd buy a couple of Modulus- Amps & everything is fine. For a fully activated 2.5-way Stereo/ Subwoofer System this would be 7 Amps. I cannot afford even one of them. But hey, so I have to dive deeper in and make those missing things by my own.

For I havn't managed to read those hundreds of sites with postings about the "my_ref", the "Modulus" and all the other LM3886 Composite approaches I just ask for your Recommendation with which PCB I'll have the least Problems & the best Sound.
Btw. at the moment I'm listening to Music with my Speakers driven by Fake LM1875, and those aren't sooo bad. I really like what I hear, but in my Imagination there are so many Speakers & Amps that need to be built, I have to go further than fake LM1875es.
(missing shrinking Tube on the Pic depends on missing shrinking Tube, but the wires cannot touch each other)



Best Regards
J.