SL3 makeover

I have been meaning to post this project for some time just had to make the time ...
in case anyone else was attempting to update a classic ML product
it all started when I purchased a pr that were a bit damaged , the top support bars had come apart , I rebuilt these with epoxy and brads then did the body work w/ a type of bondo .

Then I opened up the backs and had a peek inside ...the stock XO's were a shock to say the least and time had taken its toll on a few of the caps
I wondered how I could ever expect these spkrs to sound good with this type of stuff inside ?
I know some of you guys use an outboard unit like a Beringer ...but I don't have one and have even less experience
I decided to renew this crossover using the same values but with a higher quality of parts
proceeding I designed the layout on a piece of pine that fit the board after I moved the spkr terminals to the middle from the lower R side .
Using Obligato caps for the panels and Black Gate for the bass I rewired all the signal cable w/ DH lab silver sonic .

Buttoned it up and listened for awhile ...better...
the point where the panels cross to the woofer is now more difficult to detect , everything sounds smoother , more dynamic .

con't

the next phase a few months later was to put the spkrs back on the bench and remove everything , the back cover all attached wiring , the stators , the woofers , the accoustifil stuffing .....

the oak strips were a bit dated with a yellowing stain so I stripped them and refinished 'naturally' giving each a few coats of Varathane

I cleaned up the inside of the woofer cabinets then I covered every square inch of it with an accoustic sound deadener ...it is about 1/16" of a butyl rubber mastic type of compound that has peel & stick on the back and an aluminum skin on the top ..its goes on quite well ...and sticks !

the stock LED was not to my liking so I removed it and fabbed something new , a rectangular clear 'lens' with a new orange LED inset at the rear at this time .

After examining the woofers I was satisfied that even at its age they were still intact , no damage so I decided to keep em ...but the mounting system had to change !
the 8 steel screws that held it into the 1/2" thick MDF was not going to fly .
I got some steel T nuts and cut off one corner enough to clear the spkr hole then using heavy parrallel pliers I pressed them flush into the MDF
I put some glazing tape around the inside of the woofer flange ...using brass 10/24 machine screws tightened in a pattern as attaching a wheel to a car I fastened the woofer in a way that makes it pretty integral with the cabinet ...solid !

Connecting all the wiring again ( woofer , LEDS etc )
liberal silicone sealant applied to all holes in cabinet
I packed the insides of the cabinets with the same fill as I removed previously
and carefully attached the backs again .

Installing the new replacement stat panels was next ..they fit fine and look good w/ the new clear spars
the woofer grills were a mess from previous damage so I reversed them ..fine !
then attached the wood retaining strips , and bolted on the spikes ..Voila !

more of the final results ....

Would be most interesting if you also had a stock pair of SL3s against which you could compare your mods....I have SL3s too.

Bernard hello
well that would be fun but I can tell you that the update is better...the panels need some more time to open up but already it is more enjoyable , the bass is now amazing and the crossover is mostly seamless
..it really has breathed new life into them
cheers

One thing you may also want to do is bypass the electrolytics with very high quality (e.g. polypropylene) small value (0.1uF) caps. It is supposed to improve the high frequencies.

did you try the bypass route Bernard ?
I wondered about that but somebody told me a passive XO is not the place to use a BP ?
but if it does not work ..out it comes, right

I have used bypass caps when upgrading caps, but have not used them separately, so cannot really tell if they do make a difference.

Bernard, great job!

Thanks for sharing the details and the pics.

Nice job with the mass damping of the box as well. They can really use it.

Are you sure those woofers are up to snuf? Generally just based on age they’d be due for replacement, but given how that pair seems to have been treated (or environment it was in), I’d be suspect.

Replacement woofers are not that expensive, and given the effort you’ve put, in so far, seems like a good next step

Great job!
This thread is giving me inspiration to get my Sequels re-done. Are those Alpha-Core inductors you've used? If so, I've had good results with them on other projects.

wow, really nice job with the SL3's! They really look awesome! I stil have the original panels and woofers on them and they sound incredible... I guess I will eventually have to replace the panels... Is there a big difference in the sound and look of the new panels?
Looks like someone must have dragged them on a rough surface for them to get all scratched up like that!


My "bass" driver is still flawless as well, and I am using 2 JL Fathoms for the sub bass anyway (well 80hz and down) so that probably helps not push them too hard. I also have mine bi-amped with my Sunfire amp.

Enjoy!
gordon

Holy-! All of that work from someone who had a concern that you're LESS talented than others on the board? I doubt it-but if so,I don't think anyone could do "more with less",as they say..congratualations! Incidentally,your clear labor of love inspired me to suggest another thread on this amazing speaker-so,thanks and continued great listening. :music:

Well done, Bernard! Kind of sad someone let them deteriorate that way. Good idea turning the woofer grills inside out.

What make and model woofers are those?
Did you measure the inductors' values and replace with like values (and what brand?) or redesign the crossover?
Any more details about the stands?

John the woofers seem to be in good shape ...however down the road they may be removal candidates . I did think of replacing / upgrading them but I could find no aftermarket driver w/ the same specs /Q etc , new stock ones from ML are available though ...so far so good for now

Tube60 said:

Great job!
This thread is giving me inspiration to get my Sequels re-done. Are those Alpha-Core inductors you've used? If so, I've had good results with them on other projects.

Click to expand...

yes Alpha core inductors , good experience also
thanks for the comments !

gordonmenninger said:

wow, really nice job with the SL3's! They really look awesome! I stil have the original panels and woofers on them and they sound incredible... I guess I will eventually have to replace the panels... Is there a big difference in the sound and look of the new panels?
Looks like someone must have dragged them on a rough surface for them to get all scratched up like that!


My "bass" driver is still flawless as well, and I am using 2 JL Fathoms for the sub bass anyway (well 80hz and down) so that probably helps not push them too hard. I also have mine bi-amped with my Sunfire amp.

Enjoy!
gordon

Click to expand...

thanks for your comments
Gordon the new panels are different to my ears and so far have not broken in fully after 200 + hours but they continue to improve ..I am exercising patience
the spkrs were damaged during shipping
..in regards to your bass , do you have an outboard sub w/ JL drivers ..or ?

miles ahead said:

Holy-! All of that work from someone who had a concern that you're LESS talented than others on the board? I doubt it-but if so,I don't think anyone could do "more with less",as they say..congratualations! Incidentally,your clear labor of love inspired me to suggest another thread on this amazing speaker-so,thanks and continued great listening. :music:

Click to expand...

Miles thanks for your positive comments !
I am just a DIY guy who loves music ..like most of us here in this area
I have gleaned inspiration from the forum so if I can give some back that would be rewarding
cheers

Tosh said:

Well done, Bernard! Kind of sad someone let them deteriorate that way. Good idea turning the woofer grills inside out.

What make and model woofers are those?
Did you measure the inductors' values and replace with like values (and what brand?) or redesign the crossover?
Any more details about the stands?

Click to expand...

hey Tosh , the spkrs were damaged during shipping to me unfortunately ,so there was a choice before I started work
I don't know about the woofers there are no real markings on them , as I said in another post I had wanted to upgrade them but could find nothing that would match the few specs that were available , but after cabinet treatments the bass has come into its 'own' in a not insignificant way .
the XO was populated with like value components ..ALPHA INDUCTORS amongst them .
say how are the front trim railings coming ?

bernard991 said:

thanks for your comments
Gordon the new panels are different to my ears and so far have not broken in fully after 200 + hours but they continue to improve ..I am exercising patience
the spkrs were damaged during shipping
..in regards to your bass , do you have an outboard sub w/ JL drivers ..or ?

Click to expand...

yes, i meant to say that I have the stock ML bass drivers and 2 JL audio Fathom subs sitting to the side of each speaker.