Some while ago I bought a pair of bare boards from KMTech - 3-way analogue crossovers with on-board LM3886 "gainclone" chip amps - intending to populate them at some point. Some projects need to "mature" for a few years before they are ready for prime time, so they gather the right thickness of dust. I came across the boards shortly after the last show and decided that they were ripe for development - having played with miniDSP tech in my recent builds I was interested to see how an analogue setup would fare driving my 3-way Tannoy-based speaks that I took to stoke. So I decided to start accumulating and salvaging the necessary bits. The biggest issue was sourcing the LM3886 chips - these have become a particularly rare form of unobtanium in recent years, and as a result, genuine chips (there are lots of nasty clones around) are at a premium, so being a cheapskate, it took a while to accumulate the 8 chips required (the bass channel uses 2 in parallel) at prices that didn't cause too much grief.
I've been slowly building these up, plus the necessary power supplies - the boards have their own rectification/smoothing, and need separate twin rail AC supplies for the power amps and the crossover sections, so the PSUs are just a couple of metal boxes with BFO torroids in each.
Finally finished building up both boards and PSU boxes yesterday, so I've been testing the first board one a channel at a time with a nasty 2" driver to make sure there are no surprises when I connect up the real deal. So far, all has gone smoothly. It will now take a few more hours to arrange proper connection to the speakers and to start adjusting the levels on the 3 channels, but so far, so good.
The component side of the board:
The LM3886 chips are mounted on the back of the board:
One of the PSU boxes:
I've been slowly building these up, plus the necessary power supplies - the boards have their own rectification/smoothing, and need separate twin rail AC supplies for the power amps and the crossover sections, so the PSUs are just a couple of metal boxes with BFO torroids in each.
Finally finished building up both boards and PSU boxes yesterday, so I've been testing the first board one a channel at a time with a nasty 2" driver to make sure there are no surprises when I connect up the real deal. So far, all has gone smoothly. It will now take a few more hours to arrange proper connection to the speakers and to start adjusting the levels on the 3 channels, but so far, so good.
The component side of the board:
The LM3886 chips are mounted on the back of the board:
One of the PSU boxes: