Genexxa Pro LX5 Speakers - Tart 'em up or Chuck 'em out!

[The Grand Wazoo]

The Genexxa Pro LX5 speakers were a bit of a bargain in their day - they cost £70 apiece in Tandy and were interesting because they had the unusual tweeter design that had recently appeared on some very much more expensive speakers from a new American company called Linaeum. There was a bit of a buzz about them in hi-fi circles as being rather special, not least due in the UK, to coverage from Ken Kessler in HiFi News.
After a while, the hysteria died down and people realised that they weren't the wonder speaker that they had originally been touted as. Yes, they had some incredible strengths, but there were some major weaknesses.

http://imageshack.us/a/img826/9180/2s4l.jpg

I bought my pair at least 15 years ago for use with a PC and they were fine for that purpose at the time - no fancy DAC's, just an old integrated amp being fed by an internal soundcard. Tried out on the big system for a short while, they sounded pretty good....but the flaws were obvious. Mainly there was not much bass at all - fairly expected, considering their tiny size. What bass there was, however was really not that good at all because it boomed a bit and was rather tuneless.

Since then they've been used in makeshift systems in the garden, on holiday, for spells working away from home.......the list goes on.

Last year, though, the foam woofer surrounds gave up and I've been meaning to get them going but never really got around to it (where have I heard that before?!)
During the interim though, I've been thinking about how some of the other problems could be addressed. I've never messed about with speakers much, except for doing some basic rewiring and a recent driver refoaming, so I was a bit cautious about all this but I finally came up with a plan!

Let's have a look at what we've got then.


Tiny cheap woofer
Cast aluminium cabinet with a very thin wall
Plastic front baffle
Basic crossover built of basic components
Ropey wiring




Woofers
My thoughts were to first, and most obviously, repair the woofer surrounds - not too tricky as I had a go at this a short time ago. As I said, they're tiny - the cones are about three and a half inches in diameter! I considered changing them to different units but I thought I'd try and wring a bit more out of the original units and see where that got me first.

Woofer with new foam surround

http://imageshack.us/a/img9/9313/2u4c.jpg




Cabinet Bracing
The cabinets must have been a source of some of that bass waffle, so I had to try to think of a way of applying some bracing to the side walls - they were vibrating quite a bit when the volume was turned up. I considered drilling holes and putting a threaded bar across from side to side and then tightening nuts on either end. I thought it would look awful and didn't really want to make holes in the cabinets.

My solution was to apply outward pressure to the walls by using a big (16mm!) connecting nut with a bolt at each end and to crank it up tight in extension. There was a short bolt at one end, done up right into the connecting nut and a longer adjustable one at the other end - this was secured with a lock nut. The bolt heads sit in sockets that are drilled into squares of 18mm ply, which are in turn hot glued to the walls. The heads were then glued into the sockets.
The result? The walls are dead as a dodo - excellent! I also whacked a bit of Ded-Sheet on the inside of the top cabinet wall for good measure.

Cabinet bracing (note how thin the aluminium walls are)

http://imageshack.us/a/img191/4529/durt.jpg



Front Baffle
This is a bit flimsy so I thought it could do with a little help.

Baffle as standard - front

http://imageshack.us/a/img15/6441/53fj.jpg

Rear

http://imageshack.us/a/img801/9011/jxyy.jpg

The obvious thing to try was a bit of Ded-Sheet. Nice and cheap at under two quid a sheet from Wilmslow Audio - half a sheet did one baffle. This was a bit tiresome because of the manufacturer's attempt at bracing the baffle with many, many moulded ribs. Each section had to be made to measure and there weren't many that had their dimensions duplicated elsewhere on the baffle. I think it looks pretty tidy once finished. I also wanted to do something with the longer of the two reflex ports that are molded into the panel, so I made a sock for it out of some packing foam.

Finished front baffle

http://imageshack.us/a/img821/2725/08gp.jpg



Crossover

Now then, I went a bit mad on the crossover! I wanted several things from this part of the job:


Put some high quality components in there
Get it out of the cabinet but try to keep the speakers as portable as possible
Reconfigure it so that it can be bi-amped - I've been bi-amping for years and I am totally sold on its benefits


First off - I had a look at the wiring situation. Well, in for a penny, in for a pound - while I'm in there I may as well change that too. I had a problem though - the tweeter wires are fed through a hole in the top of the main cabinet and then do an immediate 90 degree turn to the solder terminals. The geometry and the fact that I didn't want to do any drilling in the aluminium, made it impossible to use my cable of choice, so I had to go with slim. I had some thin solid silver/ptfe stuff in my cables box, so that was used.

I bought some Clarity Caps and good quality air cored inductors and then started thinking about how to house it all.

New Crossover

http://imageshack.us/a/img692/8004/3n0e.jpg

My solution was to put the parts into a cast aluminium box, to which I then applied the trusty old Ded-Sheet.

http://imageshack.us/a/img708/7567/ps7z.jpg

The final part of the puzzle was to maintain the portability - I was able to keep it all reasonably compact by bolting the crossover box to the holes through which the old terminal plate was attached. I actually left the old plate in place with the old crossover components and sockets removed, as it was easier to seal that up than it would have been to get an effective seal between crossover box and cabinet. The old bolts were long enough to reach through to the threaded lugs in the cabinet.
No separate boxes, no extra connections and the speakers look just the same from the front (but a little pregnant from the side!) A lick of paint all round is required at some time......but not today, eh?

Crossover Box Mounted

http://imageshack.us/a/img849/4800/5a0t.jpg


http://imageshack.us/a/img823/3603/0vb3.jpg



The Moment of Truth

After first checking everything with the meter, I made a quick test by connecting them up to an old (and expendable!) receiver - amazing, they work!
They went onto some good quality, heavy stands and were hooked up to the Mark Levinson power amps. They look a bit dwarfed by the normal speakers in this room!

Little and Large

http://imageshack.us/a/img62/4449/lidq.jpg

[synsei]

Aaw Chris don't leave us on tenterhooks dude, how do they sound? Excellent work by the way... :)

[wiicrackpot]

Chris,

Where did you get the foam surrounds?, i have 2 pairs that i need to re-foam for my sister the next time i visit.

[The Grand Wazoo]

I got them from Fred at AudioFriends in Holland - about 18 Euros for the pair.

[wiicrackpot]

Thanks, had a look but don't know which one it is, so fired off a email and included a link of this thread. :)

[The Grand Wazoo]

I've deleted the emails now, but Fred & I discussed it for a bit after I sent him the dimensions I'd found on Simply Speakers (http://www.simplyspeakers.com/optimus-speaker-foam-edge-repair-kit-fsk-5Ji.html) - a US website where they offer a similar service. He sorted me out with something suitable.

This is what I sent him:

5" GRAY, ANGLE CONE EDGE ATTACH FSK-5Ji
Outer diameter:
4-9/16" (116mm)
Roll outer diameter:
4" (102mm)
Cone diameter:
3-3/8" (86mm)
Inner diameter:
3" (76mm)
Foam roll width:
5/16" (8mm)

[walpurgis]

I had a pair of the tweeters, they were unusual. It's not a true ribbon as some implied. If I recall, its a thin figure eight plastic foil driven back and forth from the middle by a flat coil.

What is the purpose of the bubble wrap around the bass port. If it's for damping it may be better to use something else, maybe felt. Bubble wrap has sealed pockets and will rob your small cabinet of vital volume.

[The Grand Wazoo]

It's not bubble wrap, it's stiff-ish expanded foam.

[synsei]

So how have the mods improved the sound of these little beauties Chris?

[The Grand Wazoo]

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!

[synsei]

Wow, sounds like a bit of a result. I like what you have done with the crossovers too, once painted that box won't look too bad at all hanging off the back. It would be interesting to team it up with a decent well matched sub-woofer. Nothing huge mind, maybe a unit with an 8" driver to keep it all nice and compact. Now that would be a helluva speaker system to take on holiday with you or even use at home in a second system :)

[Barry]

What an excellent post Chris!

Congratulations - I'm impressed by both the ingenuity of your solution to brace the cabinets, and by the quality and neatness of the work done to deaden the front panel.

Well done!

[The Grand Wazoo]

They sound very good indeed with the Radford too.
I have them about 8 feet apart and now that I've tightened everything up, the soundstage extends about another three feet either side. It also has really realistic height and the depth is there even when you stand right in front of one speaker.

I only paid about forty pounds for mine, but that was quite a while ago now and they weren't really that well known. A lot of them are/were in the hands of non-hi-fi folks because of their original price and where they were sold. They appear on Ebay regularly for about seventy quid nowadays.

[The Grand Wazoo]

Thanks Barry - it's taken a while to come together but it's been really interesting and rewarding. I may actually have a go at making a completely new baffle at some time - a good solid lump of timber would be good, I think.

[Spectral Morn]

Hi Chris


Very interesting article.


Regards Neil

[walpurgis]

It's not bubble wrap, it's stiff-ish expanded foam.

Ah, that should be fine. Nice little project in any case Chris.

You could possibly extend the bass and reduce boominess more by blanking one of the bass ports or at least introducing some resistance with compressed Declon open cell foam in one or both ports. This may lower the system resonance and clean up the upper bass. I'd imagine the boxes were originally tuned for a prominence around perhaps 70/80Hz, just to give the impression of bass body.

[The Grand Wazoo]

Hi Geoff,
I have been looking at this with some experiments - stuffing the ports with straws is something that others have done. I haven't tried straws but I have used various different types of foam materials, from very open to very tight and dense.
To be honest, the effect so far has only been detrimental - I'm assuming the effectiveness of the bracing method that I have used has done all the work in regard of reducing boom and waffle. I don't think I'm imagining that the velocity and power of the blasts of air that emerge from those tiny ports (they're so small that they will apparently only take about 6 drinking straws!) seems to have increased significantly. This implies to me that the bass driver is starting and stopping very quickly indeed?

[Tarzan]

Excellent work there Chris!

[Rare Bird]

The drinking straw thing does work to a certain extent..

[Stubies]

this is a stunning bit of work and ingenuity! very nice !! :)

[walpurgis]

I don't know what type of foam you may have used in the ports Chris, but I'd only use the open pore/cell type myself. It's the kind used in port bungs and foam grilles. You can sometimes get a sheet cheaply by buying an industrial filter of some sort. The straw idea at least dates back to the seventies Celef speakers and is intend to keep the pulses through the ports linear, although it does add some resistance. Thinking about that, you could use straws longer than than the ports to tune the resonance downwards a bit, just extend them back into the boxes a bit. Bond them together with white wood glue.

[The Grand Wazoo]

Yes, I have known about the straw thing for a long time.
To be honest, from what I've seen from trying all sorts of different materials, I can't see any merit in pursuing the idea of doing anything with the ports. The bass, such as it is, is tight as a nut - I simply can't see it being improved in this instance.

[bobbasrah]

A box of drinking straws and an experimental day wouldn't hurt Chris.
I remember my first DIY speakers by Dave Berriman used the technique, and the difference with and without was quite noticeable...
YMMV

[The Grand Wazoo]

I'm not dismissing it entirely. When I tried putting things in the ports prior to the modifications, it made a difference. However, as I said, since the bracing and other things have been done, stuffing the ports with anything I have tried has always been detrimental, though to different degrees.
Before I do anything else I will let everything settle down - that usually takes a couple of weeks for new driver surrounds and, apparently the capacitors may develop as time goes on. There are also one or two other things I want to do like removing the plastic tray that the tweeters are mounted on, for example.

[6L6]

Fantastic work! Thank you for sharing!

:) :) :)

[istari_knight]

Nice project :) Would definitely play with different cabinet stuffing's as it looks very reflective.

[Gordon Steadman]

I remember the rags raving about these in the dim distant past and I could never believe that something that could be bought from that source had a chance of being any good. Never heard them though so its interesting to see how you have made them acceptable.

Have you tried blocking the port entirely? I have never been a fan of ported speakers. The only ones in our household are my wife's JBLs and, apart from replacing the tweeters with Celestion HF1300s, she won't let me touch them. She reckons that nasty hump in the bass is good for heavy metal!! I guess it might reduce the bass output with such a small unit though. I went through all the stuffing, drinking straws bit over the years and just prefer the natural tightness of sealed speakers.

Great project.

[walpurgis]

You can't beat a bit of "natural tightness"!

[The Grand Wazoo]

I remember the rags raving about these in the dim distant past and I could never believe that something that could be bought from that source had a chance of being any good. Never heard them though so its interesting to see how you have made them acceptable.

Well, actually they were not bad speakers before. Not at all bad - and excellent in some respects. All speakers (and other products, for that matter) will obviously have their own particular set of compromises. If you were the sort of person that is able to accept the compromises of almost any other small monitor, then these would be pretty good, actually. In my mind, as standard, they are far less compromised than an LS3/5a, for example!


Have you tried blocking the port entirely? I have never been a fan of ported speakers.

Yes, that was the first thing I tried when I started messing about with the ports. I tend to think that going from standard to the opposite extreme is the best way to assess the worth of the unmodified version. From that point, I worked back through the various densities of material that I had to hand, referring back to the standard as I went. I'm a big fan of the old Acoustic Research speakers, so a sealed box is something that I know and love! It didn't work for me here though.


Great project.
Thanks, I really enjoyed it!

[MartinT]

Very ingenious solution to the cabinet damping issue, Chris, while keeping the quite nice cast aluminium cabinets. Have you tried filling them with lamb's wool or similar?

I remember the fuss made of the Linaeum tweeter at the time but confess I've never heard one. Excellent project!

[The Grand Wazoo]

Hi Martin,
Yes, it wouldn't have seemed right to damage the cabinets by drilling them or damaging them in some other way - they are quite nicely made.
Lambswool is something I hadn't really considered and may try after a little while. The speakers are certainly improving as time goes on - the soundstage grows wider daily! They just don't sound anything like the little pipsqueaks that they look like - no problem with filling the room and, rather tellingly I think, they sound good at low volumes.

[wiicrackpot]

Spot on as regards to sound levels but don't expect sonic acrobats from it,i drove mine with a Musical Fidelity A100, within it's envelope it was lovely,
it was the hifi mag write up at the time that got me investigating, rest is history, :) very good at what it does but still not as good as my reference tiny speakers,
the tiny RCL 'the small speaker' though, pure LS3/5a killers. :cool:

[aquapiranha]

I have a pair of LX-5's here. I wasn't sure what to do with them, might have a go. I was keeping them in case the tweeter might come in handy.

Sent from my GT-I9300 using Tapatalk 4

[The Grand Wazoo]

I'd recommend having a go at them Steve, it's definitely worthwhile.

Back to the work, I've found a way to use some beefier cable without drilling the cabinets - more photos later.
However, I've realised that one of the tweeters is a bit quieter than the other - I'm not really sure how to deal with this.

[Stubies]

Perhaps a resistor on the louder one?

[The Grand Wazoo]

Yes, I thought of that - I might give it a go, but it feels a bit like treating the symptoms rather than the disease.
I'm on the look out for another speaker or pair, going cheap cheap!

[The Grand Wazoo]

Martin(T) has very kindly sent me some of the lambswool that was left over from his Gale speaker project for me to try here in the little Genexxas. Is there a rule of thumb to go by for the quantity of material to use for a given cabinet size? I know it has to be teased out and fluffed up, but how much should go into these tiny 5 litre cabinets?

[MartinT]

Hard to say for sure, Chris, but the lambswool was fairly squashed in the box I sent it in. I would tease it out to about 150% of its volume and use enough at that density to fill the cabinets.

[The Grand Wazoo]

OK, I'll try it at that Martin. Thanks

[MartinT]

The theory behind lambswool or any other filler is that it slows the air from increasing in temperature upon compression and therefore makes the volume 'appear' to be larger from the driver's point of view. It also helps to dampen cabinet nodes. Anyway, it should certainly help such small cabinets.

[Gordon Steadman]

With all the box speakers that I play with from time to time, I have removed ALL damping materials and just made sure the panels are as stiff and inert as possible. Whilst the filling might smooth out the response a bit, in general, I have found that it also deadens the sound to a degree so prefer the boxes empty and lively. I suppose there may be a limit sizewise but I would rather have a bit of life than a dead smooth response.

As ever, each to their own. Be interesting to see if it improves things to your ears.

[DSJR]

My experience is that acoustic foam around the panels works well, but loose stuffing may be not as predictable. You need to have *something* in the box cavity to break up standing waves though.

[istari_knight]

Exactly my experience too, panels lined with acoustic foam & little bit of lambs wool behind the bass driver seems to work well.

I keep reading the 'teachings' of a chap that makes his own speakers... he says one should remove *all* stuffing & line the cabinet walls with 10mm steel plate just like Joe Akroyd did for the best sound. Now, I've owned many Royd speakers & whilst some did have steel plate on the cabinet walls *every single one* was crammed full of BAF wadding so I think he's a little confused there :lol:

[MartinT]

10mm steel plate

:eek:

[istari_knight]

:eek:

:eyebrows:

It does something to the sound but whether its preferable or not would depend on the listener... I suspect fans of BBC/Spendor/Harbeth would find it detestable !

[The Grand Wazoo]

Well then, back on the job in hand. I devised a way of using some cable that appears to be more up to the job, so the latest work has been devoted to rewiring both speakers - one last week and the other one this week. The reason for using thin cable was because the original speakers have an arrangement where the tweeter cable leaves the crossover (on the back of the terminal tray) and goes up through a small hole in the top of the cabinet. From there, it is attached to the tweeter tags. I didn't want to drill the cabinets to make this hole bigger, so I stuck with weeny wire. My solution is to bring the tweeter feed up from my crossover box (which is externally mounted on the back of the speaker, remember), outside the cabinet & straight to the tweeter. I sealed the original hole with some of that wonderful hot melt glue.

During today's work, I measured both tweeters for resistance and found 0.6R difference between the two.

I also followed Martin's suggestions about the lambswool and it seemed like the right amount to stuff a cabinet with was 19 grammes, so both units were treated to that too. We're also playing about with drinking straws - I found some black ones, although red looked quite natty!

The upshot is that the hi-fi has been given a proper working tonight and these speakers sound fantastic. There's still that slight channel imbalance, though it doesn't seem nearly as prominent as before for some reason. Juiced up with the Radford, they sound great, but they really leap into life when they get the bi-amped Levinson power amps up their jacksies. I have heard plenty of pairs of small monitors over the years but I've never EVER heard any that were so able to fill a room with such a massive sound. And they completely disappear - the music is just there, hanging in the air and the imaging is phenomenal. They're stood next to the massive Mirage M3si's and, you'd be forgiven for not knowing which speakers were playing. It's only the lack of deep bass that makes you realise it's those teeny little pipsqueaks at work.

Amazing.....just amazing.

[MartinT]

What a great outcome, Chris. It's good to know that the basics of the Genexxa (tweeter, cabinet) have what it takes to make something great from what appears to be mundane. Well done!

Oh - and it proves once again that you can never have too much power :)

[Marco]

Just found this thread... Fantastic stuff, Chris, and a great read! It's always nice to see vintage gear, with latent sonic potential, brought to life in this way. No doubt that the little Genexxas sound ace.

The only thing lacking in your latest update was that it would've been nice to have seen some piccies of the improved wiring, so we can compare it with the previous picture you posted, with the weedy stuff in situ... Pretty please? :)

The attenuated tweeter on one channel, however, is something that would really annoy me (I'm a stickler for accurate channel balancing), especially as the effect of the lower level on one side appears to be so audible. Therefore, I'd test all the components in line with the tweeter, and check that they measure to spec, and if all seems well there, buy another pair of speakers, from which to rob one of the tweeters.

In any case, a 'donor' pair would probably be a good idea, should anything in your current ones unexpectedly go pop. Anyway, matey, good work and enjoy!

Marco.

[The Grand Wazoo]

Thanks for the comments Marco.
The tweeter thing is something that I can't live with long term either, so rest assured, there'll be efforts made to sort this out. I actually missed out on a pair of speakers on Ebay yesterday because the owner thought they were too heavy to post (what's wrong with these people?). Some lucky sod got 'em for a mere 30 quid.
As for photographs, yes I know but the light was crap last night and there was a whole load of music to play, so you lot will have to wait!

[Marco]

Lol... No worries - look forward to it. I'm just a stickler for 'completeness', especially with projects in the DIY room :)

Marco.

[The Grand Wazoo]

A cheeky offer was made and lo, the Angel of Parcelforce came upon the House of Wazoo, and the glory of the music shone round them.

And the Angel said unto them:
"Fear not: For behold, I bring you good tidings of great joy, which shall be to all tweakers.
For unto you is delivered this day a Saviour, which is your Genexxa speakers.
And this shall be a sign unto you; Ye shall find them wrapped in bubble,
That pesky driver that you own, will give you no more trouble!"

http://imageshack.us/a/img844/1064/iz53.jpg

It's twins! Here they are newly delivered, in their manger and wrapped in swaddling bubble. Aaah, ain't they cute?

[aquapiranha]

Cool! Interested to see how it goes before I perform major surgery on mine. ...

[The Grand Wazoo]

For the first time, I was able to compare modified with unmodified versions last night and it's safe to say that I will not be reverting my original pair back to how they were. The improvement is in every area. They are just far, far superior to what I had before.
I'll swap the tweeters and take some more photos of the finished item in the next few days.

[The Grand Wazoo]

The latest developments in the project:


New / Old Tweeters
When I found the time to get the donor speakers checked over & I popped the top off the first tweeter, I couldn't believe the quantity of dust that was there. It had formed a thick mat on the top section of the unit. Here it is after spending about 10 minutes cleaning it!

http://imageshack.us/a/img546/8718/jr3z.jpg




Then, after a lot more work.....shiny!

http://imageshack.us/a/img542/660/4ul3.jpg



Wiring Changes
The new wiring arrangement has the connection between the crossover and woofer running through the back of the crossover enclosure, into the back of the cabinet, as before. The difference now is that the tweeter connection comes out of the top of the crossover box and straight up to the tweeter terminals. This is the only way I could do it with the wire I wanted to use without drilling the alloy cabinet.

http://imageshack.us/a/img594/1664/oty3.jpg



Infernal Internal Damping
I'm now playing with various quantities of wool stuffing. This much was way, way too much - the whole bass/mid sound was totally over-damped.

http://imageshack.us/a/img96/8420/sren.jpg

I'm currently running them with almost no wool at all, which is much better. I'll try putting in a bit more at a time until I'm happy with the balance but I can't see them needing much, to be honest. Clusters of drinking straws were tried and rejected because I couldn't stop them from making their own noise. I think this is because the diameter of the ports is so small and the volumes I like to play at mean that the pressure through them is extremely high. They sounded just like something hard touching the bass cone as it plays staccato rhythms. I tried all sorts of methods of using them until I realised that they weren't bringing anything to the party anyway. A shame, as I found some nice black straws that you couldn't see!




So the current state of play is that, the tweeter swap has been made and the balance is restored nicely as far as is possible to tell with the ears available to me!
With the preamp set to mono and the speakers sat right beside each other, swinging the balance from left to right demonstrates no perceptible differences, so all appears to be good.



A final picture of the new external wiring arrangement and how I trimmed the grilles so it all fits neatly together. The grilles come off for serious listening.

http://imageshack.us/a/img33/3828/k5e3.JPG




The original model name of these speakers was Genexxa Pro LX5, but due to the modifications and especially, the new crossover enclosure it was obvious that a new designation was required so they've been renamed the Wazoo Pro(lapse) LX5!

[synsei]

Very nice Chris. All that remains is to pick up a nice wee sub to reinforce the bottom end and you may well have a giant killing speaker system there ;)

[Reffc]

Hi Chris

Nice to see so much care being taken with trying to improve something like this. Have you accounted for the change in inductance value that placing the inductor in a metal box will make? This could shift crossover slopes quite a bit but I guess if they sound good, trial and error may win out. For info, if that's a die-cast Aluminium box, placing an air-core face down will usually reduce actual inductance value by 15% or more (more considering the lid on the box...you may find that inductance value is 20 to 25% down compared with the inductor in free space, so it could be worth trying an inductor 25% higher in value). This needs to be considered by anyone considering using metal as a crossover enclosure.

[Beobloke]

Chris,

Only just seen this thread and that's some nice work you've done there. I had a pair of the LX5s years ago and, like you, I felt sure there was more performance to be released from them - I'm glad you've done it!

Two small observations, if I may, though. Firstly, I completely concur with Paul's comments above - the crossover would be far better off in a plastic box for best results. The metal ones look nicer but they affect the inductors.

Secondly, assuming the inductor is in series with the bass driver and if you fancy experimenting further, try replacing it with a bigger iron-cored item. When voicing loudspeakers I have always found that air-cores work best on the treble but the bass end really benefits from an iron-cored item - generally the bigger the core and thicker the wiring, the better.

[Reffc]

Chris,

Only just seen this thread and that's some nice work you've done there. I had a pair of the LX5s years ago and, like you, I felt sure there was more performance to be released from them - I'm glad you've done it!

Two small observations, if I may, though. Firstly, I completely concur with Paul's comments above - the crossover would be far better off in a plastic box for best results. The metal ones look nicer but they affect the inductors.

Secondly, assuming the inductor is in series with the bass driver and if you fancy experimenting further, try replacing it with a bigger iron-cored item. When voicing loudspeakers I have always found that air-cores work best on the treble but the bass end really benefits from an iron-cored item - generally the bigger the core and thicker the wiring, the better.

+1


My advice is for frequencies below 1KHz, Ferrite or P Core high power handling (to avoid core saturation which otherwise increases distortion) inductors are the way to go; aim for DCR of 0.2Ohms or lower in this position. These are sometimes sold as "super High Power" or some similar description. If no description is given, take the power handling of the speaker drive unit and multiply by 1.5 to 2 as a rule of thumb and rate the inductors for this power as a minimum.

For frequencies over 1KHz, air core are usually better sounding, but keep DCR to around 0.25Ohms and no more if possible. This usually requires wire diameters of between 1 and 1.5mm, or the use of low resistance copper foils.

[The Black Adder]

I've found that air-core on the bass seem to be better (from a listening point of view rather than measurements). I guess that is something to mess and have fun with.. :)

Remember you must match resistance with a resistor in series if required.

+1 for casing, acrylic or wood is best. Use nothing metal.

[MartinT]

Great work, Chris. They must give you a lot of satisfaction.

On the subject of bass inductors, I replaced my Gale GS-401C inductors with air-cored ones and they sound fast and potent. Mind you, the originals were air cored too, so I'm not sure that ferrite inductors for bass is a universal rule.

[Welder]

Air core here, hand wound on Tufnel bobbins (well, on a lathe to be correct).

Wooden boxes outside the enclosure for the crossovers.

Anyway, a little common sense would be appropriate. As far as I can see, this is Chris having a bit of fun and learning something about speaker building in the process. I very much doubt he’ll be wanting to throw diamonds and pearls at this one.

[Reffc]

Great work, Chris. They must give you a lot of satisfaction.

On the subject of bass inductors, I replaced my Gale GS-401C inductors with air-cored ones and they sound fast and potent. Mind you, the originals were air cored too, so I'm not sure that ferrite inductors for bass is a universal rule.

I'd agree with that Joe. It's not universal but it is a useful guide. Like all these things, listening will determine the voicing you prefer. For Tannoys, I happen to prefer air cores for the bass, but they're so far the only exception I've found. Most speakers that either I build or repair seem to sound better using ferrites for applications under 1 KHz.

On the topic of common sense John, we were only trying to warn Chris of the pitfalls of placing inductors in metal enclosures. We're not trying to spoil any fun, quite the contrary, I'm sure that everyone contributing wants Chris to enjoy this project. The advice was to help avoid some pitfalls that could mess up the crossover response when it's pretty easy to avoid doing that. I'd say that was just common sense ;)

[MartinT]

Thanks, Peter ;)

[The Grand Wazoo]

Have you accounted for the change in inductance value that placing the inductor in a metal box will make? This could shift crossover slopes quite a bit but I guess if they sound good, trial and error may win out. For info, if that's a die-cast Aluminium box, placing an air-core face down will usually reduce actual inductance value by 15% or more......

That's interesting, thanks. I had no idea!
However, the speaker cabinet, from which the crossover was removed is made of, guess what.....cast aluminium! I don't suppose the two boxes would have the same effect would they? Probably not!

Seriously, thanks to everyone for your interest in what I'm doing and, yes, it is for fun. And yes, I am learning. And yes, all comments are appreciated!