Optimus / Genexxa LX5 crossover

liffy99

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I've a pair of these and about to refoam the woofer surrounds and damp the cabinet. I've heard that simply replacing the stock crossover components can be beneficial too - but I know nothing about electronics (a friend can solder !).

What I've been told to look for is;

1) An air cored 1mh inductor and

2) A 6.2 microfarad capacitor

But I've little idea of what types / brands of these to look for (e. electolytic / film etc - it's all Greek to me).

Does anyone know what I should be trying to order or has done this mod (was it worthwhile) ?

Cheers

 

hearingisbelieving

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Just did a quick google on these speakers and apparently they were quite cheap back in the day and their crossovers use fairly basic spec components. That is good news as it wont cost you much to improve.

I wouldnt worry too much about the inductor - the cap will yield the best bang for buck improvement.

Depending on your budget, I would go for these:

Ansar Supersound Polyprops (£15):

http://www.cricklewoodelectronics.com/Cricklewood/home.php?cat=155

They dont have the exact value you need so buy one 4.0uF and one 2.2uF cap per speaker and wire them in parallel(your friend should know what this means but a quick google will reveal all) to acheive your required 6.2uF.

These caps offer fantastic value for money

If your budget wont stretch that far then for £4 you can get some very basic Mundorfs:

http://www.hificollective.co.uk/components/mcap_bipolar.html

Again they dont do a 6.2uF cap so get a 4.7uF and a 1.5uF

Could be well worth it as someone who did a similar mod(but also increased the stiffness of the cabinet) reported:

"Well, it's early days yet Dave but it's safe to say that they've been utterly transformed.

All of the bass problems (apart from the depth, of course) have been addressed as I had hoped. The boom has gone. The definition is improved immeasurably. It's now possible to imagine that the bass player has an instrument with more than one string. There is a far more realistic 'snap' to everything.

The thing I didn't expect was the effect that the cabinet bracing has had on the tweeter. Before I did anything to the crossover or wiring, I played with the concept of the extending bolt and tried exerting a variety of pressures on the walls in order to prove my theory and it became obvious to me that by stopping the cabinet pumping and wobbling, the tweeter is now able to perform far far more convincingly. The difference that this has made is quite amazing - the image and soundstage are properly holographic and if you shut your eyes, the speakers themselves simply cease to exist. This aspect of reproduction is important to me and has informed the way my system has evolved over the years.

To say that I'm chuffed with the result is a massive understatement.

And best of all, I fully expect them to improve!"

 

rdale

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I've had a pair of LX5 for about 28 or 29 years, and I've probably listened to it for more years since then than other much more expensive speakers I've owned. I first modified them about 12 years ago and changed the stock components for a better polypropylene cap and an air cored inductor instead of the cheapo ferrite core inductor and  I used Chord Carnival wire. I also added some foam to the interior as the stock cabinet only has a single small piece of damping material in it. The inductor is 1.0 mH, and the cap is 6.2 mF.

Then more recently the foam surround disintegrated and I refoamed them.

This weekend I modified my original modifications. I used Duelund cables for interconnects and speaker cables, and so I thought I'd use Duelund DCA20GA. That is quite thin but the LX5s are tiny, and I'm using a Miniwatt 3.5 watt per channel single ended EL84 amp and so I thought high definition was more important than current carrying. I upgraded the SCR cap I used to a ClarityCap SA which is quite a bit bigger. I kept the air cored inductor. Then the other change I made was to roll up some bubble wrap and put it in the top half of the speaker - that is suppose to inciease the effective volume of the enclose. I kept the drinking straws in the ports.

I've been listening today and I really think the sound has taken a jump forward. Bass is tighter, and there is more detail. I expect both the Duelund cable in the ClarityCap to need about 50 hours to burn in, and so I'm hoping the sound will improve still further in the next week or two.

I was hoping to add some pictures to this post but there doesn't seem to be any option to select local pictures anymore.

 
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rdale

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I've had a pair of LX5 for about 28 or 29 years, and I've probably listened to it for more years since then than other much more expensive speakers I've owned. I first modified them about 12 years ago and changed the stock components for a better polypropylene cap and an air cored inductor instead of the cheapo ferrite core inductor and  I used Chord Carnival wire. I also added some foam to the interior as the stock cabinet only has a single small piece of damping material in it. The inductor is 1.0 mH, and the cap is 6.2 mF.

Then more recently the foam surround disintegrated and I refoamed them.

This weekend I modified my original modifications. I used Duelund cables for interconnects and speaker cables, and so I thought I'd use Duelund DCA20GA. That is quite thin but the LX5s are tiny, and I'm using a Miniwatt 3.5 watt per channel single ended EL84 amp and so I thought high definition was more important than current carrying. I upgraded the SCR cap I used to a ClarityCap SA which is quite a bit bigger. I kept the air cored inductor. Then the other change I made was to roll up some bubble wrap and put it in the top half of the speaker - that is suppose to inciease the effective volume of the enclose. I kept the drinking straws in the ports.

I've been listening today and I really think the sound has taken a jump forward. Bass is tighter, and there is more detail. I expect both the Duelund cable in the ClarityCap to need about 50 hours to burn in, and so I'm hoping the sound will improve still further in the next week or two.

I was hoping to add some pictures to this post but there doesn't seem to be any option to select local pictures anymore.
I added 0.1 mF Audyn True Copper caps as bypass caps to the 6.2 mF ClarityCap SAs. Here is the crossover showing the two caps, the air cored inductor at the bottom and the Duelund cabling:

Lx5_crossover.jpg

When I first added the Audyns, the sound changed to a more mellow rich tone. If the caps were valves, I would describe the ClarityCaps alone as as 'Sovtek EL84', whereas with the Audyns they went in a richer 'Psvane EL84' direction. The Audyns have now had about 100 hours, and the ClarityCaps maybe 200 hours. For a desktop system it is sounding great, the detail is allow there throughout the range, and even the bass is better than it used to be problem because of the cabling and bubblewrap I added. But in this system, the quality of the sound of the Linaeum tweeter seems mostly limited by what caps are in the crossover.

Here is a picture of my desktop system in the back room of my flat:

headphone_system.jpg

I run it in the day playing jazz, and I can go in the back room and listen when I need a break from work. The MiniWatt N3 is the valve amp on the left in the picture, I use an original Hugo as a DAC which is pretty detailed and I can hear all of it with the modified Genexxas.

 
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greybeard

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Then the other change I made was to roll up some bubble wrap and put it in the top half of the speaker - that is suppose to inciease the effective volume of the enclose
I am intrigued at the use of bubblewrap. I know adding acoustic stuffing allows the driver to see a bigger enclosure, what are the benefits of bubblewrap?

 

rdale

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dave

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Interesting read. I guess if it's fairly tightly constrained and in a fabric bag it can't really vibrate, all I could imagine was crinkly noises... some one was thinking outside the box so to speak.

I love my LX5s, mine sounded best up close to the wall, counterintuitively, with a sub.

 

rdale

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Interesting read. I guess if it's fairly tightly constrained and in a fabric bag it can't really vibrate, all I could imagine was crinkly noises... some one was thinking outside the box so to speak.

I love my LX5s, mine sounded best up close to the wall, counterintuitively, with a sub.
I like my LX5s on IsoAcoustics stands at the front of my desk - the bass is very clean after the latest mods with bubble wrap. When I sit between them they are like a large pair of headphones as the treble is omnidirectional.

 

dave

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When I sit between them they are like a large pair of headphones
Hmm, interesting, I haven't tried that arrangement. I would probably knock them off the bench with my elbows. I will try it one day though.

 

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I got it from this discussion where someone mentioned that Sonus Faber used bubble wrap in their speakers:

http://techtalk.parts-express.com/forum/tech-talk-forum/48847-why-bubble-wrap-instead-of-poly-fil

And so I thought if it's good enough for Sonus Faber, it's good enough for my Tandys.
The thread seemed to not reach a conclusion in 2012.  

Ive a large roll of 'small bubble' bubble wrap in the garage and given I've got no appreciable work until July I think some testing with the effects on my 18" Volt driver bass units might take place.

 
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rdale

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The thread seemed to not reach a conclusion in 2012.  

Ive a large roll of 'small bubble' bubble wrap in the garage and given I've got no appreciable work until July I think some testing with the effects on my 18" Volt driver bass units might take place.
That sounds a really interesting experiment. My LX5s are too small to be worth using as a test bed for the effect of bubble wrap - they are certainly sounding really good compared with before, but I would be surprised if it was a measurable difference. The bass might be affected by the other changes I've made with the Duelund cable and higher quality capacitors.

 

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Hi Richard

i did some testing of bubble wrap inside my bass cabinets today .....I think it's quite positive - have a look at my other thread 

 
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rdale

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Hi Richard

i did some testing of bubble wrap inside my bass cabinets today .....I think it's quite positive - have a look at my other thread 
Yes, that was an interesting read - it looks like it did make a subjective as well as a measurable difference. 

 

rdale

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I heard about replacement LX5 drivers on another thread and ordered some:

LX5_Drive_Units.jpg

I can't find the thread that mentioned the drivers. They were about $35-49 dollars or so I think, plus a lot of shipping to the Canary Islands. The new driver is a lot heavier than the old one 648g vs 1125g and it is also deeper. The depth was a bit of a problem as the large ClarityCap at the back of the cabinet needed a bit of squashing to get the two halves of the cabinet back together. But overall the driver is great and not much more than the refoaming kit I'd used on the previous driver. After a bit of break-in the LX5s sound better than ever.

 

rdale

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I just upgraded the binding posts to KLE Classic Harmony. The original binding posts have a square hole and I needed to drill that out. It was a bit fiddly to solder as the cross over components are attached directly to the binding posts and one side had three wires. The speakers are sounding great but the KLEs need quite a lot of breakin 50 hours I think.

IMG_20220213_154901.jpg
 

rdale

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I heard about replacement LX5 drivers on another thread and ordered some:

LX5_Drive_Units.jpg

I can't find the thread that mentioned the drivers. They were about $35-49 dollars or so I think, plus a lot of shipping to the Canary Islands. The new driver is a lot heavier than the old one 648g vs 1125g and it is also deeper. The depth was a bit of a problem as the large ClarityCap at the back of the cabinet needed a bit of squashing to get the two halves of the cabinet back together. But overall the driver is great and not much more than the refoaming kit I'd used on the previous driver. After a bit of break-in the LX5s sound better than ever.
The LX5s were sounding really great with a pair of REL Tzero subwoofers, but recently I've been hearing a distorted rattling sound from the right hand speaker. I took a close look today and saw that the foam surround was beginning to break up. It has started to break up on the left speaker too. In less than a year - what crap!
IMG_20220616_191335.jpg
So I've ordered a refoaming kit from Simply Speakers which is the same one I used to repair the original drivers. It cost $58 including shipping, and involves quite a bit of fiddly work from what I can remember.
 

Lawrence001

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Rather annoying they don't look like foam, and I can't see any damage in the photo.
 

rdale

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Rather annoying they don't look like foam, and I can't see any damage in the photo.
You can see cracks in the bottom left of the surround if you look carefully at the photo. I had thought that this sort of problem had been solved in modern speakers. The original foam surrounds on the original drive units lasted 20 years, but I don’t think I’ve abused the new ones as my Miniwatt N3 is only 3.5 watts per channel.
 

Lawrence001

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Too low a power can be more likely to cause damage than too high due to clipping, but this affects the voice coils rather than the surround. I wonder if they were in storage for years before you bought them. Maybe they were cheap as they were old and sold on to a reseller, it happens a lot.

Looking at them, much of the reason for the weight would seem to be a second magnet to shield them from a TV nearby, that's usually what's in those large circular cases at the back.
 

rdale

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Too low a power can be more likely to cause damage than too high due to clipping, but this affects the voice coils rather than the surround. I wonder if they were in storage for years before you bought them. Maybe they were cheap as they were old and sold on to a reseller, it happens a lot.

Looking at them, much of the reason for the weight would seem to be a second magnet to shield them from a TV nearby, that's usually what's in those large circular cases at the back.
Yes I think the most likely explanation is that they were NOS. I did run some measurements with REW to measure the new subs and I wonder if that produces more cone excursion and did the damage if they were already in a fragile condition.
 

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