Any op-amp from BurrBrown like 2134 or 2604 should fit this job perfectly. The op-amp also should be changed (later). Both from Elna Cerafine (non-polar version – special order parts?). Then, I replace the two coupling capacitor and one supply capacitor. I trace the circuit a little bit more by using TDA7265 datasheet. Photo above shows the important circuit of TDA7265. I remove the standard cable to the subwoofer and replace it with this cables. You also can see two wires (orange and white). They are not the high price capacitors since I don’t have any intention to pay this upgrade cost more than the price of the MX5021 itself 🙂 I think I will need to drill it someday 😉 Two first pairs capacitors come from Elna, the last pair comes from Sanyo (Gold version). I have to create a wire extension to fit that. The 10.000 uF is the lug type so can’t fit the small hole on the PCB. Photo above shows the side of the main capacitor. I don’t change the parts on TDA7295 since I believe the subwoofer should be fine with stock parts (to save the cost to). This is quite important since that TDA provide amplification for the satellites (I expect smoother mid-range and treble).

I also change the coupling and supply capacitor for the TDA7265. You can see the value, 4700 uF, 2200 uF, and 1000 uF. Well, they come from “well known brand”, Samxon. Photo above shows the removed main capacitor. One for driving the both satellite (TDA7265, 2×25 Watt), and one for subwoofer (TDA7295, 80 Watt). We have two chip for amplifier here, one is TDA7265 and other is TDA7295. We can see two big rectifier, some big capacitors (removed from the board), and some op-amps (all are ST4558C). I opened the Altec MX5021 subwoofer yesterday. Now, it’s time for the electronic parts 😉 I discussed the mod of MX5021’s satellites. If you haven’t read my previous article, please click here.

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