Audio Altec Lansing MX 5021 Modding

Re: MX5021 modding

AFAIK you have to import the opamps.

As I've mentioned earlier, the NE5532 is what I used for the MX. It is a drop-in replacement for the 4558s it uses, and is of sufficient quality for the final power stage and speaker setup of MX. Any more expensive opamps may be pointless, as the limiting factors of the output quality lie elsewhere.

Basics of audio circuitry - a good place to start is Rod Elliot's pages. sound.westhost.com I also haunt diyaudio.com, which is a friendly DIY community like this, with a specific focus on audio.
 
Re: MX5021 modding

In the DIY audio forum they have mentioned a site

Digi-Key Corporation - USA Home Page (US site)

But they also have in other countries very close to us is Singapore, HK. Price is cheap. If we can find some quality components at reasonable price with shipping we can think about it.

What is MSOP and SOIP ? They have mentioned in that site

Note: If the pre-amp in creative x-fi are crappy ones then whats the need of changing the op-amp in the speaker? will two pre-amp increase the noise and reduce the sound quality?

My Observation: The purpose of crappy pre-amp in the analog out makes to think users to switch to costly digital-out channels in which there will be no pre-amp from the card end. So there will be increase in clarity few cents:bleh:
 
Re: MX5021 modding

1. D-K is what I always use. The prices there are the lowest of all country sites, IIRC, the shipping is quick and the product is always highest quality.

2. SOIC and MSOP are package types for the chips. For the MX, you need DIP and for soundcards and other SMD boards, SOIC is what is mostly used.

3. The entire chain needs to be of good quality. The X-fi isn't a particularly well-built card in stock form. It IS advisable to mod the entire chain. If you like SMD soldering, the Alien DAC is a great entry-level card that whips the X-fi silly. Or else, modding the X-fi should give reasonable results.

4. As for the length of the chain, it is possible to remove a few stages, but unless you have good test equipment, it is difficult to estimate results. The driver and receiver need to be configured to cancel noise of the transmission line (the cable). In short runs it may be possible forfeit one or both of the same. In a noisy environment and the absence of appropriate driver/receiver, the line may pick up noise and interference. So unless you have equipment that measures down to those levels, it is advisable to not omit any stages.

5. The MX doesn't have a digital input, so this is not feasible. As an aside, the supposed superiority of digital inputs on speakers is not universally true. It depends on the quality of the DACs on the digital speaker (unless of course it uses digital amps as well, in which case you're at the mercy of the system as a whole). A tricked-out Auzen Prelude, for example, may have much superior analog performance than a Z5500's digital to analog circuitry, and it may be advisable to hook up such a combination through analog rather than digital.
 
Re: MX5021 modding

sangram said:
1. D-K is what I always use. The prices there are the lowest of all country sites, IIRC, the shipping is quick and the product is always highest quality.
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Whoa!! nice detailed writeup..How much is the shipping charges for these opamps and capacitors. Rough estimate. Any tax will be added in India?

sangram said:
2. SOIC and MSOP are package types for the chips. For the MX, you need DIP and for soundcards and other SMD boards, SOIC is what is mostly used.
Click to expand...
Will there be any difference in size between these? what is browndog adaptors? couldnt get much info:S
 
Re: MX5021 modding

Shipping is usually 20-25 dollars for a full shipment, IME.

The SOIC is much smaller, and are pad based (DIP uses holes). Browndog adapters transfer between sizes. You get adapters that plug into DIP sockets and have pads for SOIC, and pad-based adapters that fit a DIP chip.
 
Re: MX5021 modding

Interesting post i have found over the Net:

Don't underestimate the NE5532. We have just completed a very comprehensive set of tests on the NE5532 and on various substitutes. We have not found anything that will equal the tranparency provided by the NE5532.

Some have suggested susbstituting OPA2134 op amps in place of the 5532s. This is a bad idea! Our tests show an increase in both 2nd and 3rd harmonic distortion, and the addition of higher order (4th, 5th, 6th, and 7th) harmonics that are virtually absent from a stock DAC1. In addition, IMD will increase, and SNR will degrade.

The NE5532 is power hungry, it has high input bias currents, and high offset voltage, but it can drive high-level low impedance circuits with ease. The 5532 should not be used with low signal levels, and it should only be used in low gain circuits. Also, the offset voltage must be managed with appropriate design techniques. I believe the NE5532 has aquired a bad reputation because it has often been missapplied. The DAC1 is carefully designed specifically for the NE5532 op amp. It may surprise you that the NE5532 was selected for transparency and not on the basis of cost.

If very low noise is of prime importance, it is recommended that the 5532A version be used because it has guaranteed noise voltage specifications.

I have dropped my idea of importing opamp's. Now 5532A is available here?
 
Re: MX5021 modding

SunnyBoi said:
5532s are freely available ehre, 10rs each.
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Hi,
Have you come across any other opamps mentioned in diyaudio forum, available in Bangalore?. what about capacitors of audio quality and what do you recommend?
I am planning to get MX coming month i am not gonna wait for the warranty to expire:p
 
Re: MX5021 modding

Get them in front of the console to avoid reflections from the sidewalls, which is probably messing up the imaging.

Also the rear of the speakers is firing into a secondary enclosure formed by the walls of that cabinet. Will cause a big shift in the speakers' tone. I'm not sure what it sounds like now, but I'm pretty sure it can't be very good.

The sub is placed fine, if you sit right there. As you move further back from the table, the bass will boom as there is a resonant cavity that the port will be firing into.

Short answer, if you sit right in front of the PC, you're probably OK as long as the sats have some space to their left and right.
 
Re: MX5021 modding

My rig died, so i thought why not start work on speakers. SO opened it up today. SOme pics.













Sub looks liek it has a missing opamp. Has got me confused a bit, what I have is nothign like the pics I've seen on the net. Need guidance here.

Will try to swap all opamps by tomorrow morning.
 
Re: MX5021 modding

Good good;

Where did u source the NE5532s??? For hw much?? :)

Available @ B'lore, Chennai?? :huh:

What're the other choices than a NE5532?? :p
 
Re: MX5021 modding

All opamps out.

Sangram, I have a doubt. Had bought about 10 of the NE5532s. Packet got mysteriously opened, 2 lost. Out of the 8, 4 of them are "NE5532P" and the other 4 oare "KA5532"

Which ones to use and which ones to avoid? Cant believe I didnt see that before buying :ashamed:

Gannu, NE5532s are 10rs each. You'll need 5-6 opamps for the sub.
 
Re: MX5021 modding

STUPID PCB. traces coming off. :( already damaged 1 hole, partially damaged another. damn have to use wires :(
 
Re: MX5021 modding

SunnyBoi said:
STUPID PCB. traces coming off. :( already damaged 1 hole, partially damaged another. damn have to use wires :(
Click to expand...

Yeah, seems like the PCB is very bad; Keep a superglue handy Sunny. :)

Sangram's posted here:
Jimmy’s Junkyard Blog Archive Inside Altec Lansing MX5021: Amplifier Mod

The board is pretty bad, all the traces come off easily, so watch it when replacing caps or opamps. smallest amount of heat is enough to break the trace. Keep superglue handy for fixing.
Click to expand...
 
Re: MX5021 modding

Sorry for being AWOL for a while, and I had switched off notifications and subscriptions.

You need to stop desoldering.

Use a hobby knife or snippers to cut the pins off the opamps, then use a soldering iron and a small pin to clean up the holes.

The traces are really bad, maybe they've gotten worse with the newer sets.

Use a desolder braid to clean up the solder, then pry the opamps out of the socket. Never push towards the board, only upwards (away from the board, toward the component side). A downward push will damage the trace. The braid worked for the opamps. I had big issues with the cap desoldering, as th moment I pushed the caps down or wiggled them slightly, the trace would lift off the board.

I have no idea what those KA5532 are. Probably a knock-off. The 5532P is the one to use. You'll probably need one more trip to pick up more of them.

The fact is that the board you have looks almost the same as mine, with the exception of the missing opamp. Mine is here, though a low res shot. Getting closer on Flickr - Photo Sharing!

IIRC I changed U9, U7, U12, that missing opamp, and U5 OR U6, only one of them is used in the satellite signal path, the other in the subwoofer signal path (there's a quad opamp soldered on the back of the board near where those electrolytic caps are, I didn't touch that either). It's been a while since I did the mods, and I documented the cap changes but not the opamp changes. You might as well change all of the 4558s just to be sure.

Last thing - you have a cap there called Samcon. It's a con. The correct brand is Samxon. Far as I can see, there is a mix of these two types of cap throughout the board (the black ones are the dubious ones, the blue ones are the original spec).

Another thing that points towards the reduction in quality is the crossover. The original Altecs had a dual-coil crossover, and we can see the location for that coil marked very clearly. It's as if someone pulled it off the board, though there is no silkscreen and no holes for the leads - this is probably a new version of the crossover with the same dimensions (to avoid retooling everything). This will substantially affect the performance of the satellites, as the second coil basically was a low-pass for the lower woofer. We can expect the farfield performance of this crossover to be substantially worse than earlier version, but the nearfield should not suffer much.

The big gray Vishay caps are to be soldered parallel to the big yellow Samxon cap. That cap actually looks quite decent compared to the one mine had (the earlier crossover had two tiny green caps). You may not notice much difference with this cap.

I hope you haven't got gypped on the set. I have a bad feeling about this.
 
Re: MX5021 modding

@Sangram:

Uh, li'l confused from ur first post as to what to buy... :huh: I mean the type of caps; Got an idea of the op-amps frm the ^^^post..

Can u provide a list of components??? And where to buy these??

PS: Cant PM u either... :(

Wont changing those op-amps alone provide a change in the depth and clarity of the sound?? I mean should the caps be changed as well??

And btw should all these be attempted after the burn-in period?? Or can we do it straight out of the box???
 
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