I've been working on a Hafler DH-220 as a learning project. I just got it back to operating condition (yay!) and I want to finish the project by cleaning up the wiring, replacing the connection hardware, and replacing or upgrading as many of the caps or other parts that are deemed worth it.
Currently I plan on replacing the power filter caps with higher capacity Nippon capacitors. I plan to replace the electrolytic caps on the driver boards, but I haven't selected a brand yet. I'm considering replacing more of the capacitors, but I haven't identified a clear reason to do so, or a brand to use if I do.
Any suggestions for vectors for improvement, either reliability or sonically?
Currently I plan on replacing the power filter caps with higher capacity Nippon capacitors. I plan to replace the electrolytic caps on the driver boards, but I haven't selected a brand yet. I'm considering replacing more of the capacitors, but I haven't identified a clear reason to do so, or a brand to use if I do.
Any suggestions for vectors for improvement, either reliability or sonically?
Only replace the electrolytics (especially C8), not the film types. Use major quality brands, like Nichicon.
Check especially the resistors R35 and R37, and replace if they are discolored or off value.
A better quality and power rating R34 would also be good.
Clean the dust off the heat sinks ans retighten all the hardware on them, too.
Check especially the resistors R35 and R37, and replace if they are discolored or off value.
A better quality and power rating R34 would also be good.
Clean the dust off the heat sinks ans retighten all the hardware on them, too.
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If your speakers are 8 ohm there's little point increasing the filter cap values, 0.01F is sufficient - add more and you stress the other PSU components, risking premature failure or frequent fuse popping (hence the soft-start suggestion, which is probably a good idea anyway). For 4 ohms yes somewhat larger caps could make sense. If you are not needing the full output power of the amp there's no real point increasing the capacitance.
Note that ripple current rating is important for choosing replacement filter caps.
It might make sense to measure the ESR of the existing caps to see if they're living up to their specs.
The only benefit of increasing the capacitance is perhaps a fraction of a dB extra headroom. Do you need that extra headroom at full power? Then you probably need a more powerful amp to begin with, or more efficient speakers perhaps.
Note that ripple current rating is important for choosing replacement filter caps.
It might make sense to measure the ESR of the existing caps to see if they're living up to their specs.
The only benefit of increasing the capacitance is perhaps a fraction of a dB extra headroom. Do you need that extra headroom at full power? Then you probably need a more powerful amp to begin with, or more efficient speakers perhaps.