I bought a pair of these off Ebay to play with,
Audiophile HiFi Stereo 2.0 Channel Power Amplifier DIY Kit & Assembled Board | eBay
Powering them from a standard 42-0-42 unregulated supply, toroidal/bridge/15,000uF caps, with 0.1u accross both main caps.
With one amp only powered, everything is fine, but when both amps have been running for a few seconds there is oscillation in the region of 7MHz from both. This is with nothing connected to the output terminals.
Have added 0.1 caps across the 100uF supply smoothers on the board, no difference.
Boards don't look 100% like the schematic on ebay, but I've added extra caps across what looks like the compensation cap, if anything, that made things worse.
Have run them from a bench twin 30V supply, everything worked OK, but I take it that it has a really low output impedance, so snubs out the oscillation.
Anybody have similar issues with the MX50SE?
Thanks for any suggestions
Huw
Audiophile HiFi Stereo 2.0 Channel Power Amplifier DIY Kit & Assembled Board | eBay
Powering them from a standard 42-0-42 unregulated supply, toroidal/bridge/15,000uF caps, with 0.1u accross both main caps.
With one amp only powered, everything is fine, but when both amps have been running for a few seconds there is oscillation in the region of 7MHz from both. This is with nothing connected to the output terminals.
Have added 0.1 caps across the 100uF supply smoothers on the board, no difference.
Boards don't look 100% like the schematic on ebay, but I've added extra caps across what looks like the compensation cap, if anything, that made things worse.
Have run them from a bench twin 30V supply, everything worked OK, but I take it that it has a really low output impedance, so snubs out the oscillation.
Anybody have similar issues with the MX50SE?
Thanks for any suggestions
Huw
I experienced the same with a different kit.
A proper Zobel and output inductor eliminated the problem.
A proper Zobel and output inductor eliminated the problem.