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FS: UK (cheap) 4 channel diy DSP amp


Paid Member
2007-06-10 12:41 pm
Hi All,

This is a DIY project that I used to use to run my speakers and subs its basically a 4*50W DSP amplifier in a small case. consisting of the following:

  • Mini DSP (original 2x4) with digital expansion board and sub advance plugin (can do stereo 2 way or 2.1 configuration - will supply on CD)
  • 300W high efficiancy auidio SMPS from connexeltronic (SMPS300RE | Connex Electronic) 230V input the output voltage I think will be +/-36V
  • 4 * ebay LM3886 amplifier modules, speaker outputs are on flying 2 pole speakons
  • heatsink case with 10k volume pot wired to mini DSP
  • USB 1 hub

I haven't used it for a year but from memory there are a number of issues:
1. Mini DSP USB flaky have to run it through a USB 1 hub or specific computer, however if a particular system works it continues to work reliably.
2. Pretty turn off thump from mini DSP if power cut which would damage a tweeter
3. Some mains hum noticeable on one of the amp channels
4. Case is a bit small so bits of the LM3886 PCBs are cut off
5. Shutter a bit damaged on one of the TOSLINK inputs, it still works
6. LM3886 amps seem to have too much gain
It was still usable but as I'm not so space constrained I now run 19" rack mount equipment.

Considering these issues I will sell it for £20 (inc P&P for UK) as it would make a decent project but I'm not sure how much is acceptably usable, even the power supply (which works fine) is worth more than that.


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