Modding Altec Lansing MX5021 speakers

[RejZoR]

Ok, I've decided to buy Sound BlasterX AE-5 when it comes out next month and for the sake of upgrading the whole experience, I'm planning to mod my Altec Lansing MX5021 speakers. They served me well for years and since they are one of rare few with wall mount option, I'm gonna buff them instead.

Specifically these key areas:
- capacitors in both satelites
- capacitors on the main amplifier
- OP-AMP in the amplifier
- replacement of power converter to more quality toroid transformer (allegedly, this should fix annoying hissing)

I'm planning to replace ALL key capacitors with Nichicon Muse Gold capacitors. For OP-AMP, I was looking at BurrBrown OPA2134PA. It's considered high end and I could get one for price of peanuts. So, I'm even willing to go with something even more high end, I'm just not sure which one is appropriate since I don't know the parameters important for OP-AMPs. For capacitors, voltage and capacitance, no problem. But for OP-AMS, no clue. I also haven't opened up the AMP unit yet, unsure about the complexity of the PCB underneath. Looks fairly simple from above, but I don't know how's it below. I don't have professional solder iron, just very basic clumsy one...

EDIT:
I'm also wondering how to tell orientation of OP-AMPs? I'm assuming it's important how you place them in.

I've also seen some ridiculous Orange OP-AMPs that have tiny PCB sticking out of the plug pins/base. Is that compatible with MX5021 or not? Might be willing to go crazy with OP-AMPs even up to 30€ (the BurrBrown is like 5€ with shipping). Just need to know what to pay attention to when picking them up.

 

[R00kie]

I'm also wondering how to tell orientation of OP-AMPs? I'm assuming it's important how you place them in.

The OP-AMP's have a little notch or a small indentation on the surface that you have to align with the one on the socket:

Same will go for the cylindrical ones, they will have the same markings on the PCB.

Also, when choosing one, make sure to get the ones you need, be it a mono one or a stereo, otherwise, if you pick a mono one for a stereo use, it will either be too quiet or you'll get a difference in volume between the channels.

 

[RejZoR]

Anything else worth paying attention when picking up OP-AMP ? Do they separate in terms of bit depth and frequency range they can work with (or work at)? I'd like to expand the frequency response, although speaker drivers are probably the most limiting factor anyway.

 

[R00kie]

most OP-Amp's operate at very similar frequencies, all they do is just boost the output signal, and colour the sound depending on their characteristics.

The one's that I've used previously were LM4562, and LME49720, the latter being a bit more powerful and neutral, and the former a bit warmer.
And yes, if your speakers aren't good enough, you probably won't notice the difference.

 

[RejZoR]

I'm actually more looking for more detailed sound rather than warmer. But still not too detailed because that often ends up being harsh on the ears.

Any idea on the transformer? I've read somewhere that better toroid transformer supposedly fixed the hissing with MX5021. Just yesterday, I've noticed I can actually tone down hissing noise if I lower treble/bass parameters to zero. Volume knob doesn't seem to affect it, but treble does. Doesn't eliminate it entirely, but lowers it significantly. Some say it's transformer issue, others pre-AMP overdrive. What's your opinion?

Been using it with zero treble and bass amplification, only colorizing audio using Creative Crystalizer and EQ and the sound is... interesting. First few seconds felt like something was missing, but now it kinda sounds really detailed. Probably because treble and bass frequencies don't drive over all other frequencies. I'm assuming.

 

[R00kie]

The hissing you describe is the noise floor of the speaker system you have. I have a similar issue with my amplifier when there's literally no sound coming from the speaker but there's that annoying background hiss. I've been reading about it and people seem to recommending changing the default caps in the amp. But it can also come from the power outlet itself or the cheap cabling on the satellites.

 

[RejZoR]

I've replaced thin satelitte cables with proper high end thick copper wires specifically for speakers. Good thing MX5021 have same cable ports as HiFi systems so it was a snappy replacement. MX5021 is not grounded system afaik. Never had this issue with Creative speakers in the past, essentially used on same wall socket. I do use power surge in front of everything. That should actually help afaik.

 

[RejZoR]

Damn, was checking eBay for cheap OP-AMP sockets and they cost more than OP-AMP itself. Usually in 10 pcs quantity only. A bit annoying.

 

[5DVX0130]

Damn, was checking eBay for cheap OP-AMP sockets and they cost more than OP-AMP itself. Usually in 10 pcs quantity only. A bit annoying.

Search DIP8 socket...
Pages, upon pages, and for less than $1.

 

[RejZoR]

What the frigging hell!? Tried to open one satellite and at first the screw was really hard to move and then its head literally snapped off. I literally can't open it. It's like some idiot glued it together and rammed screws through the glue. Tried two screws and both snapped off. Insane. Why even bother using screws!? Got 3 others out and the last one just got the cross obliterated. Awesome...

 

[RejZoR]

Ok, just ordered all the goodies.

1x BurrBrown OPA2134PA + socket
8x Nichicon Gold capacitors for pretty much everything
2x 4700uF Nichicon Standard Audio (because I couldn't find any 4700uF 50V Gold's that aren't from China. I'm really not in the mood of waiting 1 month for the components. besides, the ones from Europe were actually cheaper in general.

I think it'll be a good upgrade even if it's not the best "Gold" one. Was thinking of replacing some more stuff, but after checking the other side of PCB, I don't think my tools or soldering skills are good enough to replace others, so I'm keeping those stock. I'll already be sweating with the OP-AMP socket with those 8 pins. Pretty crowded with zero margin for error. Transformer is a big ass unit and the number of wires is a bit confusing, so I'm leaving that one out for now. If I could live this long with a bit of hissing, I can do now. Hoping to boost the quality as whole though.

Total cost, roughly 50€ with shipping costs. Seems reasonable considering speakers were around 150€ back in the day iirc.

It's possible it'll make literally no difference or that I'll even ruin them. But hey, it'll be a great learning experience

 

[RejZoR]

Also noticed transformer was totally loosened up and rubber feet on subwoofer moved all the way to the edges of the sub frame XD Nothing double sided TESA tape can't fix

 

[RejZoR]

So, the OP-AMP was first to arrive Just need socket for it and then I might already start working as components are arriving from different sellers.

 

[RejZoR]

The Nichicon's golden goodness has arrived. Now I just have to receive the OP-AMP socket and we're starting the project (might actually change caps ahead of OP-AMP and replace that one in the end. The guys were so cool they chucked in 2 extra ELNA Audio capacitors for free as well. Much appreciated

 

[R00kie]

Those are some nice caps there, let us know how it goes.

 

[RejZoR]

Ok, so I've made a first cockup that I just realized as I was about to replace capacitors in the satellites. The capacitors used are non-polar. Genius me bought polar ones. Yay. So, today we're only replacing caps in the amplifier unit...

 

[RejZoR]

Oh wow. Just fired the speakers with just primary capacitors replaced on the amplifier and in all honesty, I was a bit skeptic about the perceivable differences in sound as people describe them after replacing caps. Deep down inside I was expecting no real difference. But this stuff actually does make a difference. I'm still a bit shocked actually. Best way to describe it is "more colorful" sound. Before I had to use special EQ and sometimes even Creative's Crystalizer to really bring sound to life. Now it sounds almost like that without any EQ or Crystalizer. If I turn these two on, the sound almost feels too harsh now. I've also noticed switching Crystalizer or EQ ON/OFF in Sound Blaster Z panel (software setting!) now emits a clicking sound from speakers which wasn't there before. Not sure if that's a good thing or not, but capacitors alone changed that, which is interesting.

Now I actually can't wait to change the OP-AMP and order some bipolar Nichicon Muse capacitors for the satellite speakers. Dis gonna be gud

A quick photo session of capacitor replacement...

ORIGINAL CAPACITORS:

NICHICON GOLD CAPACITORS:

 

[Nuckles56]

What were the old caps used in it?

 

[RejZoR]

Samxon. A Chinese capacitor maker. Supposedly they are alright, but not for audio applications where Nichicon, ELNA and the likes still dominate the market and are highly praised by audio enthusiasts. As a sheep, I'll just follow the audiophiles flock hehe And based on my current experience, it's not just a herd effect, capacitors alone do in fact affect the audio reproduction. And I've used identical capacitance, supposedly, if you use higher, they "smooth" out the sound. But I like my audio detailed and it was right choice to go with same capacitance as originals. Voltages are higher, but that doesn't matter much for as long as it's the same or higher.

Old Samxson capacitors are still in good condition (no leaking or swelling) so I'll save them if I'll ever have to fix anything else. They'll be just fine for that.

Lol, just received OP-AMP socket. Plural. 15 pieces. Didn't check order correctly and I've ordered 15 pieces lol. It was just 1 GBP so it's not end of the world. Lots of spares XD Not enough time to replace it now, but I think I'll do it in the evening after work. So excited

EDIT:
I wonder what are other 4 OP-AMPs for. There is one closest to heatsink which is supposedly the important one which is scheduled for replacement, but what is the other cluster of 3 OP-AMPs for down there next to largest caps (and the one closest to them), they are all of the same make. I'm assuming they are there for subwoofer and satelittes, but I have no clue which is which exactly.

Ok, one of the small "tri" cluster capacitors had a loose solder somehow which wasn't apparent from other side of the circuitry. Resoldered that better and cleaned the contacts around OP-AMP socket, some solder remains could potentially be bridging the gaps between contacts, causing crackling on left channel. Seems to work fine now. Have still replaced that one capacitor back to stock one anyway.

Interestingly enough, either something went bad during whole process, but bass is now a lot weaker with new OP-AMP. New capacitors enhanced it all, but this OP-AMP toned it down. It seems to still work if I crank it up on the speakers bass controls or if I adjust EQ, but without it, not as deep sound. Though, Max Payne piano theme music seems to have just enough bass, so it seems to really depend on music...

I have to admit my heart dropped down in my pants when left channel started crackling, thought I ruined the circuitry. To my luck, I managed to fix it. Wheeeew

Now, off to (re)ordering caps for the satellites...

After destroying old OP-AMP and installing the socket with new high end OP-AMP I've decided to replace the capacitor as seen on image above. Turns out that was a mistake. I was blissed by absolutely jaw dropping sound for few seconds and then left channel started crackling horribly. Solution? Unplugging the subwoofer speaker from the circuit board. Then both front speakers work fine, I just have no bass. So, next thing tomorrow morning, I'm re-soldering the old capacitor back. I thought I've made an unwanted connection when soldering the OP-AMP socket, but that seems to work just fine as I'm listening to music without sub now for 5 minutes with no crackling.

Not sure what's going on here. Both are polar type, same voltage, except Nichicon has 4.7uF instead of original 1uF. In general that shouldn't be an issue, but in this case, it is somehow. I'm not electrical engineer enough to figure it out. So, returning that part of circuitry back to original state is my best bet here.

EDIT:
God damn, just after posting this, I got harsh interference. Unplugging just to be sure, I'll be fixing this tomorrow. It would suck if I killed the speakers XD

 

[RejZoR]

I think I've kinda inadvertently turned my multimedia speakers into monitor speakers. Before, everything kinda had a lot of treble and bass. Now, high quality music sounds really good, rich and detailed highs, good bass reproduction. Where lower quality or lower production quality music kinda lacks any kind of bass and often sounds either dull or very harsh.

 

[R00kie]

What about the noise floor? Have you managed to lower it?

 

[Frick]

I think I've kinda inadvertently turned my multimedia speakers into monitor speakers. Before, everything kinda had a lot of treble and bass. Now, high quality music sounds really good, rich and detailed highs, good bass reproduction. Where lower quality or lower production quality music kinda lacks any kind of bass and often sounds either dull or very harsh.

You are on the path to enligthenment, grasshopper.

 

[biffzinker]

EDIT:
I wonder what are other 4 OP-AMPs for. There is one closest to heatsink which is supposedly the important one which is scheduled for replacement, but what is the other cluster of 3 OP-AMPs for down there next to largest caps (and the one closest to them), they are all of the same make. I'm assuming they are there for subwoofer and satelittes, but I have no clue which is which exactly.

This might prove helpful since someone else has already did the same modifications.
http://vc-junk.blogspot.com/2010/08/altec-lansing-mx5021-modification.html

 

[RejZoR]

What about the noise floor? Have you managed to lower it?

Yes and no. I've turned both, treble and bass settings on speakers (both) to zero. Didn't eliminate the background hiss, but has significantly reduced it. To fully eliminate it, I'd have to use a better quality toroid transformer. Only problem is, there are like 8 wires from transformer unit tot he amplifier PCB. If there were just 2 for + and - since I'm assuming it's using DC for circuitry anyway, that would be perfectly doable. But it has like 8 or even 10 contacts and that's just too much for my skill and lack of any kind of serious tools like voltmeter.

You are on the path to enligthenment, grasshopper.

I have these speakers for so long they already paid themselves back with usage alone. Current investment of about 60€ and getting this out of them is incredibly impressive. I've also ordered 2 pairs of Nichicon Muse Bipolar capacitors for the satellites and then my project will be completed. I'm not going hardcore modifying it totally because I don't have the right equipment (replacing that one OP AMP was a nightmare and I had to destroy the original OP AMP in the process). I want to keep them functional as I've already almost ruined them in the process, but managed to save the day. Not gonna risk it twice.

It does sound nice, although my ears need to readjust a bit to less artificially rich audio. Next step is Sound BlasterX AE-5 when it comes out. It's the reason why I've decided buffing my existing speakers

This might prove helpful since someone else has already did the same modifications.
http://vc-junk.blogspot.com/2010/08/altec-lansing-mx5021-modification.html

I've also used these resources:
http://jimmyauw.com/2007/03/15/inside-altec-mx5021/
http://jimmyauw.com/2006/12/15/altec-mx5021-speaker-mod/
https://forum.lowyat.net/topic/1616553/all

Again, I'm going with a middle of the road path, replacing critical components, but not going all out crazy with it. A lot of guys killed their MX5021 in the process and I was also quite close to that. Got a pair of two more capacitors to replace in both satellite speakers and that will conclude my modification. I love these speakers too much to ruin them. Especially because no one makes wall mountable ones anymore so this makes it even more important for me.

 

[Ferrum Master]

TDA7265... I played with them when I was 13 years old and had no money.

HIGH OUTPUT POWER
25 + 25W @ THD =10%, RL = 8Ω, VS = +20V

@ THD =10% ???????? Don't push it more than 15W. It's bonkers... even TDA2030A or more comparable TDA2052... found in ancient TV sets... they were a bit better, build some heavy modded TDA7294, still I disposed how the they worked. You can't turn a integrated turd sounding into something decent, well i was underaged and a bit more stupid and that was it... no more of them... thank you.

Doing all this is... well. Replace the faulty elements, okay that's fine. Don't increase the main filter cap capacity, you will cause high inrush current and the bridge will pop some day. But I wouldn't touch the sound stage.

Sounding brighter? It is a usual sign of RF oscillation... a fake feeling, it went cuckoo after few mins, so you are lucky it didn't explode, those end gainclones like to do that. Also... I really do not recommend changing BJT's OPamps to FET inputs on the blind... why? You saw it there... FETs are faster and more capricious to the surrounding PCB quality.

Only thing that you could do is actually bypassing the existing coupling caps with some 0.1-0.01uF polymer cap underneath and it would bring you the same results for sure.

Instead of all this money waste... you could omit all that board and replace with something more... mhm... expensive... not 2$ unified end devices driving your precious cones. The result is a different different kind of harmonic distortion peak spectrum, thus the likeness changes... having so much distortion it really changes, without measuring it's quite hard, don't trust your feelings, especially with women and electronics.