Altec Lansing MX 5021 Modding

Don't worry about it. All are fine speakers, check what you like the best and be happy. Because it requires tampering with hardware, it's not safe for everybody to do anyway!

Enjoy your new speakers.

How about replacing the stock resistors with MFR's. And also replacing those generic green colored 0.1uf caps with better ones.

Well, they're already MFRs (though 5% and not 1%), so IDK how much improvement you'd get by just changing them out. I think the cutoff for price of mods/quality is somewhere near the best with the mods I did. Of course there is room to do more, but the main power opamp has average specifications, at best. More mods might be meaningless from a quality perspective, plus the board is not meant for resolders/repairs, and the tracks come off real easily (just pushing a component from the top side will push the track out - I had a nightmare troubleshooting a broken trace).

Also there are no 0.1 uF in the signal path at all - but some of those generic green caps are used in the feedback path for the bass amp (which was not a a target for many mods, since I didn't have any plans for improving that section). Opamps already have bypassing as far as I remember, those were ceramic SMD caps. Changing them out may be of no use.

Sangram where can I find Hi quality capacitors in bangalore.
I have some 4.7uf metallised polypropylene(yellow tube) capacitor bought from SP road. Is it any good for the satelite?

Yup, those are not too bad, they're what I used in the motherboard (the Thermax caps). I use a pair of 4.7uF as input caps in one of my chipamps, and it's fairly transparent, with only the slightest touch of hash at HF. Very usable, and better than FCs.

I seem to remember that Railton on SP Road was a good source of industrial parts (which is = significantly more expensive and marginally better products). That said it's been ten years since I left Bangalore so I'm not really sure. I'm not sure you can get good electrolytics though. I've never found any in any market in the country, so I prefer to import mine.

As an update for anyone who's watching this thread, I changed out 4 or 5 opamps to NE5532 sourced locally. Made a pretty significant difference to the midrange, cleared out the last vestiges of grain. Those 4558 opamps are quite horrible, but in the bass section they'll be just fine. All the opamps relating to the satellite section were changed out, the opamps cost me 12 bucks each (INR).

I also added a pair of RCA jacks to the back instead of the wimpy little 3.5 mm jack, so finally one can use real interconnects. Alas, I find that the sound quality from the rear input is not up to scratch compared to the dock input. Earlier they sounded exactly the same (thus validating that the mods really did make a difference).

I have a modded SB Live hooked up from my download rig to the rear input (using the wimpy little jack) and the modded Delta 66 to the dock input (using a specially made interconnect). There is a significant difference in the midrange quality between the two inputs. The rear input passes through one extra opamp, so maybe some investigation is warranted, but I have no patience to do it.

Just so you all know, the main audio controller is a custom made ST chip, very difficult to find for sale. Be careful with the MXs, if you blow or otherwise damage the chip there's no way it can be replaced.

I also added small 10uF bypass caps on the satellite amp. I have no idea if it made any difference.

No more mods are planned for the MXs, and I plan to retire them from active duty in a few months' time when the Dynes are properly set up (thanks, Zhops!).

For the below mentioned caps,
C50, 52: 2.2uF
C41, 46: 1uF
Since I don't have the FC's can I replace them with white box type film caps(Don knw the technical term) or should I with thermax type.

There are two problems with the box type caps.

1. They can be either Metallised Polyester(MKS) or Metallised Polypropylene (MKP). the former is horrible for audio. If they are PP, then they are usually outstanding caps (my .47 Vishays are MKP types). Trouble is you have to be able to identify them when buying, or you'll waste your money.

2. They are usually very, very large, and their lead length is fixed, so soldering them in place of the electrolytics will be quite an ask. The Yellow caps can be soldered in, standing up vertically.

That said the good box types (MK series) usually provide far superior sound to the yellow tubes you find in India (exotics are made in the rolled up version, but those are not available here).

I would put the box types if I could figure out they were MKP for sure, and I found a way to fit them on the board. If I was unsure of any one of these two things, I'd use the yellow caps.

Any similar tips for a Creative Megaworks 5.1 550 ??

Sure, why not? Just send me your set for experimentation. If it works out, I'll make a new thread for it!

If it doesn't, well, those are the breaks!!

Oh man !! When I start working and can afford to, I'll definitely do it

Bring ti to my place. We can dissassemble, take pics and send to him. Much cheaper

@IAUDJ : If you're picking up a set of caps, please get one set for me too

@sangram : no luck with the OPA2134 will try again in 2 days

Don't worry about the OPAs. I would suggest swapping in NE5532, which are easily available and deliver adequate performance for the speakers. After that it's diminishing returns. The amp is anyway not the best of performers, so exotic opamps may not help very much.

About the Megawoorks, trace the circuit for me too, as without that it's useless.

@SunnyBoi
Free?
For a premium?

@Sangram
The box type caps(bought locally) I have is not as large as you say. I think I have the wrong ones, because size wise I don see much prob in replacing the elect. caps with these.

A 2.2uF poly cap, even polyester, will be much larger and have a wider pitch than those small electros. Pretty sure you have the wrong cap, either the value or the type of cap does not sit with what I know. A 2.2uF/63V MKP has a 30mm lead pitch, whereas MKS would be 10mm minimum. Electros were 3-5mm, IIRC.

Sunny: YGPM.

Bumping this thread as many seek it.

Can this be added to the guides section??