The output opamp of the miniDSP4x10HD is an JRC2068 with a DMP8 outline. As i have the idea to replace this opamp i just compared the outlines and footprints of DMP8 and SO8 packages. It seems that the footprints differ not too much - so a SO8 opamp should fit into the footprint of the DMP8 package. Has anybody done this change yet?
Is the C in series to each output really needed? The opamps have dual supply rails and the signal coming from the DACs output is symmetrical, so i assume there is no DC offset at the output (not verified yet). If i am right i think it could be replaced by a simple piece of wire... any opinions anyone?
Is the C in series to each output really needed? The opamps have dual supply rails and the signal coming from the DACs output is symmetrical, so i assume there is no DC offset at the output (not verified yet). If i am right i think it could be replaced by a simple piece of wire... any opinions anyone?
If you own an AVO, I would put that in DC V mode and hook it up the outputs one by one. Before the caps 😉
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footprint is different enough for it to be hugely risky to change the opamps. They work well and the measurements are superb https://neurochrome.com/pages/minidsp-4x10hd so why risk bricking it? If you want to upgrade you'd be better using a different DAC, which can be done as the I2S signals are available on headers.
changeing the opamps is no big thing for me as desoldering and soldering SMD semiconductors is part of my daily business - so i see no huge risk for me in doing so. The question is if it is worth the effort. Will there be an audible improvement when changeing the parts to some others with a well known lower THD plot, like the LM4562 for example? On the site you have linked Tom writes miniDSP could have done better when choosing the NJM2068. He too thinks it is not the optimal choice...
yes, i read that too. But his reason for not changeing them is the DMP8 outline to that he assumes the SO8 outline will not fit. As the pin to pin spacing is the same (1,27mm) and the row to row spacing is only slightly different i assume a change is possible...
In which case fill your boots, but you'll be probably the only one who has tried this. Also note putting a superfast opamp that likes to pick up RF in a place where a slow one was can require a little bit of work. Blaze a trail and report back!
Are there small value capacitors around the op amp? Part of a low pass filter perhaps.
If so, they could be replaced with film/foil parts, ie Wima fkp1, or emz polystyrene, etc.
The 2068 isn’t bad at all really, I bought a bunch for testing, but maybe some sockets there so you can plug in whatever?
If so, they could be replaced with film/foil parts, ie Wima fkp1, or emz polystyrene, etc.
The 2068 isn’t bad at all really, I bought a bunch for testing, but maybe some sockets there so you can plug in whatever?