A Real SL 2000 Hack. Replace stock (burnt voice coils) with "silk diaphragm dome ".

Gardenstater

Right and it is absorbing 99% of sound above 620 Hz (they claim). That's pretty low for a tweeter and I don't know what their crossover is in that driver. But it would be interesting to bore out the polepiece of a dome tweeter and mount something like this assembly on the back of the tweeter. Your 3D printer would be ideal for making the labyrinths as would Rob's CNC milling machine.

xschop

I like Yamaha's version of their rear chamber tubes. They have them on tweets and mids separately.

https://hifi.be/gfx/20180425114051_Yamaha_NS-5000_rs_chamber_GT.jpg

Gardenstater

Cool. Maybe that's from their experience with motorcycle exhausts lol. Looks like some sort of destructive interference addition manifold.

txcoastal1

Gardenstater wrote: »

Cool. Maybe that's from their experience with motorcycle exhausts lol. Looks like some sort of destructive interference addition manifold.

Hmmm you got me thinking...could this technology work on a toilet bowl to drown out the infamous brown note

VSAT88

I call bull$hit. lol

VSAT88

xschop wrote: »

I like Yamaha's version of their rear chamber tubes. They have them on tweets and mids separately.

https://hifi.be/gfx/20180425114051_Yamaha_NS-5000_rs_chamber_GT.jpg

Looks like an aliens flashlight

VSAT88

Gardenstater wrote: »

Cool. Maybe that's from their experience with motorcycle exhausts lol. Looks like some sort of destructive interference addition manifold.

Like an old RD 250. An expansion chamber.

Gardenstater

https://www.youtube.com/watch?v=HLA4TbVkRkQ

VSAT88

.

plastic_avatar

Ferrofluid = I'm curious about that, before I button these tweeters up...

Continued testing in Monitor 12 boxes = They sound very smooth compared to the old clear domes. I expect even better things with the right crossovers

Wish I had an extra 2000 coil assembly... I'd make one and send it to one of you guys to test against the other versions... Oh! I do have an extra!

So if anyone has the setup to test the Wuhans against other tweeters, I can send one... or does that data already exist?

VSAT88

plastic_avatar wrote: »

Ferrofluid = I'm curious about that, before I button these tweeters up...

Continued testing in Monitor 12 boxes = They sound very smooth compared to the old clear domes. I expect even better things with the right crossovers

Wish I had an extra 2000 coil assembly... I'd make one and send it to one of you guys to test against the other versions... Oh! I do have an extra!

So if anyone has the setup to test the Wuhans against other tweeters, I can send one... or does that data already exist?

Far as I know everyone is testing all these with their ears. I don't think anyone has done anything otherwise. I would like to know if anyone has though.

VSAT88

I have only put the fluid in some tweets that came with fluid from the factory. They are the ones in my Snell speakers. I think it could be used with the Wuhans but no way to know for sure till someone tries it. I don't have any fluid left over and no real time to try measurements so I shall not be the guinea pig in this project. Wish you would try it though

VSAT88

TEST

VSAT88

This d@mn vanilla SUX

xschop

You should try the Vitamin A oil drop and spread to a sheen, with no excess.

plastic_avatar

On coated domes... is it only the outside that is doped, or the inside, too?

How about the surround bulge?

Figured I'd ask before I hit the last steps and assemble for good.

xschop

Only the mfr. can answer that question. As for the wuhans, none of them look coated at all, compared to an RD-0194/8.

The very light coat of oil takes the edge off them, smoothing them down comparable to the 194's, IMO.

Drill and taper the pole-pieces, stuff with lamb's wool and then compare to a set of factory 194's.

plastic_avatar

I can't drill my own pole pieces right now. That's a whole lotta hours I need to attempt that. I just don't have your skill.

I'll dope and finish assembling the Wuhans as is, and expect to drill pole pieces somehow in the future (after I replace the coils in the crossovers and do a Dread).

Testing clearance on my tweeter insert with the original dome. It fits as snug as I can manage without touching. Same height as the original felt.

And I'll have a spare if anyone wants to test.

xschop

Conjunctivitis

plastic_avatar

xschop wrote: »

Conjunctivitis

Ha!

Pink-Eyed Wuhan

VSAT88

Lordy,

plastic_avatar

Only 2 of my tweeters had the thin paper-like pad between the tweeter/plate and the pole/magnet.

What do you lot use as a replacement?

I'm trying to print a replacement, and wondering if a light adhesive applied to both sides of the pad, to create a bona fide air seal in the tweeter's rear, would be beneficial?

plastic_avatar

You guys and your hard work modding. I really appreciate all your work.

To any lurkers who wonder:

- Is it worth it to mod rather than buy the 194?

If you want to save some bucks, it's totally worth it. Sooooo much better than the SL2000 to my ear. I'm still dialing in my mods, but even running on 40 yr-old crossovers before I rebuild my 1C... they really please (I've still got great hearing, and haven't lost all my highs to age yet).

- I've never done this, it looks too hard.

It's not! It's actually hard to mess it up, imo. These guys did all the experimenting. Guys like us can just read, ask questions, then mod from a much easier place than they did!

I'm really happy with the results, I learned a lot, and got to put money towards other things. I'll likely move on to another model before I would replace the Wuhans with the 194. Though, I might try a completely different dome next, if I can match specs...

Got yucky SL2000's in your Polks? Move on up to Wuhans! Kick that unpleasant hump in the highs to the curb!

plastic_avatar

I removed the backers/gaskets I made.
If anyone wants them for other projects, I'll put the file up on Shapeways or something.
Why did I remove it?
The coil is shallower than the coil on the original 2000 dome. It sounded like the Wuhan with the gasket was a little muted. It seems to be a little more... vocal... with the thin gasket removed. I guess every little bit helps.
I think an experiment worth trying might be to use a thinner top plate, to allow more of the coil down into that magnetic field.

Also, is there a technical reason why the top plate is metal? Does it actually matter? The part we're really concerned with is the gap between the rod (pole piece) and the magnet, yes? How might the Wuhan perform if the top plate were removed, and a much thinner (gasket thin) plate were created? Since the voice coil on the Wuhan is shallower, would dipping it down into that field a bit more affect its sound?

xschop

I believe at rest, the coil centerline should be in the same plane as top plate centerline, no?

plastic_avatar

xschop wrote: »

...the coil centerline should be in the same plane as top plate centerline, no?

[thinks]

I think without puts the lower than centerline.

But it's all my ear without proper, electronic measurement.

Side note: Going back through the thread from the start... you guys are awesome.

@VSAT88 @Tony M @xschop

You guys are the Holy Trinity of this. I'm thankful I get to go to church here.

Gardenstater

https://www.youtube.com/watch?v=HLA4TbVkRkQ

plastic_avatar wrote: »

I removed the backers/gaskets I made.
If anyone wants them for other projects, I'll put the file up on Shapeways or something.
Why did I remove it?
The coil is shallower than the coil on the original 2000 dome. It sounded like the Wuhan with the gasket was a little muted. It seems to be a little more... vocal... with the thin gasket removed. I guess every little bit helps.
I think an experiment worth trying might be to use a thinner top plate, to allow more of the coil down into that magnetic field.

Also, is there a technical reason why the top plate is metal? Does it actually matter? The part we're really concerned with is the gap between the rod (pole piece) and the magnet, yes? How might the Wuhan perform if the top plate were removed, and a much thinner (gasket thin) plate were created? Since the voice coil on the Wuhan is shallower, would dipping it down into that field a bit more affect its sound?

It is one of the poles in the magnet motor. Changing it in thickness would effect the height of the gap and would change the magnetic flux density also.



PS: I have no idea how the KEF Metamaterial video got in here because all I did is quote your post and add my screenshot of the magnet motor lol!

plastic_avatar

Ahhhhhh.

I wondered if it had to be steel, or would copper matter, or did it even matter to have it on top of the magnet at all. Or, if a wound copper wire would do the same thing...

Trying to find real, digestible info online is difficult for the why and because.

Gardenstater

plastic_avatar wrote: »

Ahhhhhh.

I wondered if it had to be steel, or would copper matter, or did it even matter to have it on top of the magnet at all. Or, if a wound copper wire would do the same thing...

Trying to find real, digestible info online is difficult for the why and because.

I'll see if I bookmarked anything that explains loudspeaker magnet motors. The ferrite donut magnet is axially magnetized after assembly. One side will become a N pole and the other side is S pole. The backplate pole piece is assembled to the N pole of the magnet and the frontplate pole piece to the S pole. So they become the N and S poles of the magnet motor. It absolutely has to be a material that has high magnetic permeability. Copper is completely out. I think what is usually used in common loudspeakers is C1008 or C1010 low carbon steels. Pure iron, like 0.999 Fe is super expensive but would have a great deal more permeability, as would other materials that are super expensive also.

plastic_avatar

The basic list of documented mods, parts/labor to upgrade an SL2000 into a Wuhan:

- The Wuhan textile dome (2 styles... snug plate and full plate around the tweeter).
- Mod the Polk faceplate to accommodate the Wuhan dome (level of difficulty depends on the faceplate style and/or version of tweeter purchased).
- Use a custom faceplate like @xschop's milled end-game beauties, or make your own like my 3D-printed ones.
- Replace the felt pad behind the dome (some come dome-shaped and some are cylindrical, but there's no definitive version/ material/ dimensions, and someone might experiment with crazy hybrid diffusers like I did).
- Determine whether to use tweeter backing gasket/pad. This might depend on whether the Wuhan domes remain consistent. Has anyone checked the voice coil height between the snug and plate versions?
- Make sure the screws you use to put it all back together aren't too long, so you don't pop the metal top plate off the magnet.
- Coat the domes with a doping material to smooth out the sound- just like on other tweeters.
- Add material to the back of the faceplate. Armacell? Dynamat?
- Make new gasket for mounting tweeter to cabinet.
- Glue plates to magnet if fine, disassemble and fix if off kilter.

Super-duper mod for the brave:

- Drill out and vent the pole piece. Difficulty level expert.

Did I miss anything?

Thought: So how does venting the pole piece affect the magnetic field?

Less material, and would the void change the