I have chance to mod the Altec MX5021. I think so far MX5021 is one of good candidate to be modded (though I prefer Altec CS21 or 621/641 series, but they have been discontinued).

The target of this mod should fulfill 3 main criterias:
1. Affordable
2. The components should be easy to find
3. Significant result
It’s quite challenging for me, since you know that I don’t (never) expect much from a multimedia based computer (some of them are good, but not good enough for my taste). Anyway, since this is just for fun, so let’s do it.

Here’s the Altec MX5021 system:

This system has a little bit bright sound, metallic, a little bit harsh, not too detail for music, and average mid. I think the subwoofer is for movie (THX Certified) than music. Need to be improved a little bit in the low bass region. I think it’s good enough for most people, but not for me πŸ™‚

The internal crossover uses “bad” non-polar eletrolytic. Also you can find small inductor with ferrite. This is bad. Very bad. They use 1st order for high pass section, F3 at around 8 kHz I think (if I calculate them correctly). The two mid woofer is not working on same region. I think they build a bandpass filter and both woofer works in different region. Need to fire up my simulator to check the actual graphs, but since I think this is just for fun, I don’t sweat a lot πŸ˜‰

The components are: 4.7 uF, 6.8 uF, 47 uF, 0.8 mH, and 0.25 mH.

Below is just another view of the stock crossover.

I removed all the “tiny-little-cute” capacitor from the board. Made by Samxon. A well known brand for Capacitor in China, I guess. I’ve seen a lot of electronic consumer product use this brand.

All of the capacitor were upgraded. I used better capacitor for the high pass filter (the black tube). And for the mid-woofer application, I chose the lower grade (yellow tube) than the one used for the high pass filter. Because this is non-elco based capacitor, so you can see the giant size of the new capacitor. Well, I don’t have enough space there. Sorry for bad layout πŸ˜‰

I’ll do more mods within next few days. I’ve order a special inductor and hope they can make it in small size so I can fit them inside. The cable also will be upgraded to a better one. Especialy the signal cable inside the crossover.

The result so far:
The high extension is absolutely better. I can hear more detail, even from music like Siti Nurhaliza (Cinta Tak Berganti), to Kari Bremens (A Lover in Berlin) and Rim Banna (The Mirror of My Soul). Even my friend (not an audiophile) can hear the different! The mid woofer have not reached my satisfactory level. Cable and capacitor size should be checked again. Will do soon. It’s clear enough that I need a new inductor to fix the mid-woofer. Just hope the ordered inductor can be fitted inside (though it’s crowded enough) or otherwise I need to find a better placement.

The subwoofer also need a little fix. But it should be on my last priority.

Read more:
http://jimmyauw.com/?p=120