Computer 4.1 speaker system


2020-01-02 11:35 pm
Hello everyone,

I have an old Klipsch ProMedia 4.1 computer speaker sound system. The specs are 4x60 watts and 1x160 watts for the sub-woofer.

It's starting to head south. When I initially turn it on, I hear a LOT of crackling from the speakers until the system warms up. One day, it’s going to go out on me completely.

I've done some research and learned that the problem with this system is; that over time some of the solder joints begin to fail. Finding the offending bad solder joint is like finding a "needle in a haystack." I’m guessing that it’s a result of the expansion/contraction they experience when the system is turned on/off.

So, because I absolutely LOVE the sound of these efficient little speakers/sub-woofer, I'd like to be able to continue to make use of them and Klipsch doesn’t make them anymore.

Could I get a couple of inexpensive digital 2.1 channel amplifier boards (one for the front speakers and sub-woofer and a second for the rear speakers)?

There are two outputs from the computer, one for the front speakers and a second for the rear speakers and I use the computer to control the system so I don’t need the control knobs that are part of the current system. I’ll just power it on when I turn on the computer. I never use the computer without having the speakers on.

My questions are (if this is possible):
1. What digital 2.1 channel amplifier boards should I use?
2. What power supply would be best?
3. Do I need a speaker delay protection board(s)? I want to protect the speakers.
4. What other considerations am I missing?

Thank you,
You don't have to find the bad joint/s. Fire up the soldering iron and go through them consecutively, doing all of them. It won't take that long. If it fixes the problem, then an hour or so has been productively spent and you will continue to enjoy them. It will take less time than the outlined alternative.
A good inspection of the board can't hurt either way. Use a good loupe; if you don't have any, maybe you've got an old wideangle SLR lens floating around instead (a 28mm f/2.8 with some decentering issues is my weapon of choice here).

I'd start with anything that could be affected by thermal stress, like the power amp ICs or 3-terminal voltage regulators.
I'm with the others on this one ... before giving up on your current electronics, go over the circuit board(s) and redo all the solder work.

Use a medium heat iron and heat up each joint (don't be surprised if some of them boil) and add just a tiny bit of fresh solder as you go.

Also check for bulging or soft electrolytic capacitors and replace them, especially in the power supplies.

I've "rescued" many a dying board this way and some of them are still in use years later.

There are also a number of options for replacements boards with TPA3116 or TPA3255 chips are good choices. But be careful, don't buy the cheapest because you risk getting counterfeit or recycled parts and don't buy the most expensive because they are likely to be overpriced, rather than better.

Something like THIS, might serve... but as always, when refitting an existing product nothing ever fits exactly so be ready to fabricate knob plates and brackets as you go.