My first step by step LM3886 illustrated build

[kgb_m3]

Hello everyone, I'm new to the forum and would like to share my first LM3886 amplifier build. It all started from a new sound card purchase (Auzentech X-Fi Forte) and a small issue with my Logitech z-2300 2.1 system. Initially I was planning on upgrading the Logitech sub and satellites, but once I ripped the guts out, it seemed like a waste. I quickly sold the setup and used the money toward the following build.

The build started with lots of research and with the help of this forum and similar others, I was able to put together a parts list. After 2 weeks of waiting and driving around like a maniac trying to piece things together, I was able to gather all required parts minus a 50k ohm dual gain audio pot. This can wait till I'm closer to being finished.

So far I was able to put together the power supply and test the output voltage.

Some amp and power supply components


hand matching resistors


one rail completed




both rails completed




testing output dc positive voltage 37.3


testing output dc negative voltage -37.3


My plans for the weekend are to begin the amp channels build along with customizing my aluminum enclosure for the entire setup.

I would like to hear some ideas on bookshelf speakers and a custom sub/amp. For now I'll be using Polk monitor 30 to run off the lm3886 and a self powered Onkyo sub. I plan on building the crossovers and buying separate components along with the cabinets. So any ideas or suggestions would be highly appreciated.

More pics to come as the build progresses!

[zei]

Nice build thread!

Keep up the good work


/JZ

[kgb_m3]

I got one channel to work today, sounds really good. I threw the right channel together just for testing purposes with the minimum amount of components.

For now I got a few pics of the point to point test build on the right channel.

Small components









Chip amp complete


Powersupply filter caps


Right channel assembled for testing and tuning

[kgb_m3]

New Update...

Haven't had much time to work on the amp lately, but there's a lot of progress since last post. I was able to build and test one channel, play around with some numbers and components to get the best possible sound so here are the pics of how it currently sits...

Aluminum Case purchased for $5, a little scratched but will do. Will polish later.
Power supply attached








Power Supply wires shrink tubed




Fuse and power switch added







Heatsink attached for one channel




Left channel completed, ready to attach to heatsink




Right channel in build progress







I'm waiting on the RCA chassis mount jacks and volume control pots with knobs, once those arrive and the right channel is completed, it should be finally finished.

As far as the sound goes, it's absolutely amazing. Extremely clear and detailed highs along with tight mids and some decent bass. Can't wait to build a better pair of bookshelfs to eventually replace the Polks.

[AndrewT]

I just love the sight of all that insulation.
Your P2P looks very good for a first attempt, much better than mine.

[kgb_m3]

Thanks man!

I'm in the process of designing a PCB board in Eagle for both the PSU, left and right channels. Should look much better and be assembled much faster. For my first build though, I wanted to build the entire thing from scratch, learn some things as I go and try out different configurations to get the best sound out of a specific setup.

[raypalmer]

m3 Excellent thread! Makes me feel like a wimp for using the PCB's!

Very tidy work too, I love the powder blue heatshrink! Gotta get me some of that

[kgb_m3]

Thanks! PCBs look sooo much cleaner though

If you guys have any pics of your setups, feel free to post them. I'm always looking for new ideas.

[kgb_m3]

Another Update:

Amp completed for the most part. Been running for 3 days now and I'm absolutely addicted to the sound.

The station:


Amp:





I'm going to run it for another 2 or 3 days, then pull it out, shrink tube and organize the rest of the wiring, polish the enclosure and install the lid. I'll be also wrapping part of the enclosure in carbon fiber vinyl.

Currently I'm running Polk 30s and Polk self powered 12" sub. I'm looking for ideas for some custom speakers so if you guys have any let me know.

[ianpengelly]

Very tidy indeed mate, as someone else said it does make me feel less of a man for using a PCB. You have done a great job of thinking through where each of the components were going to fit and the need to maintain lead wires for the external connections. I just hope if you do a PCB the sound doesn't deteriorate.

Have you seen much of Peter Daniels work? He does some amazing point to point work and yours is definitely in that ball park for a first build.

Are you driving the amp straight from the soundcard?