Replace Dyneaudio Tweeters or Sell As Is? Newbie Seeks Advice?

DO NOT buy one of the replacements mentioned. All 3 have radically different impedance curves.  They would not act anything like each other with your dyn crossovers.  One of them had a 1mm xmax. No suitable.   Next the ferro fluid issue.  
I have purposely removed ferro fluid from MANY tweeters.  In every case, it lowered fs and sensitivity increased slightly, but other than that, the other tweeter specs remained fairly consistent.  The warning about drying out fluid or worrying that needs to be replaced is valid.  If it really worries you,  thoroughly clean out the gap and either replace the fluid or leave it out completely.  A different fluid should be fine if it is good quality and the original is completely removed.  Or, you can run them without fluid.  Some worry that without fluid that they can damage easier,  yes fluid is for heat dissipation,  but when you remove it,  fs will lower a bit.  If the crossover point is high enough, I would remove it,  if not, I would make sure that you have fluid. 
As far as replacement.  If you can send me a good tweeter, I will spec it for you at no charge and truly help you find a proper replacement and be aware, that may not be easy. I hope this helps,  Tim

Thank you all for such helpful insights! 

Mids and Woofers, definitely stick with OEM or repair OEM,

Tweeters: I meant to get specific recommendation from Madisound, they know equivalent specs/performance.

The crossover has already done it’s job, the same impedance and efficency/sound level is more important, if needed, go a speck higher, not lower.

General joke is that by the time you can afford good stuff, your hearing of highs is likely already reduced.

And, you are selling them don’t forget, just don’t hide the truth from buyer.

Hi OP!

The diaphragm replacement is your best bet.  You'll sell them for a lot more if they are fully working than for "guess what's wrong" price.

Replacement of tweeters is otherwise a difficult ask, as the crossover is designed for a specific electro-acoustic device.  You can't just go willy-nilly looking at the physical size and get it right. Sometimes you get very lucky though.

I'd suggest that if the diaphragm replacement is not an option you then sell as-is.

my dynaudio tweeters kept burning out on my JSE Infinite Slope Model II’s. I asked Madisound for advice, I substituted Focal Tweeters, they sounded terrific, and never burnt out.

I would get a written price quote for the OEM tweeters, and a written quote from Madisound for a replacement recommendation

perhaps give both options to a buyer, help with the 'as-is' sale

or, put something in there, give the burnt ones to the buyer, the buyer can always 'upgrade' back to original later.

You could ask around for substitute suggestions. Aside from getting similar performance, you have two issues: size of hole, and size of Dynaudio’s faceplate, because the wood may be a different color behind the faceplate if you put a smaller faceplate on. You can enlarge the hole if needed if handy. A new sub-plate can solve a new smaller diameter faceplate.

https://www.madisoundspeakerstore.com/speaker-drivers-page-17/?p=catalog&mode=catalog&parent...

a price example, this Morel is only $85. fit/specs may be way off, just to give you an idea, you can get high quality tweeters in there for far less $.

https://www.madisoundspeakerstore.com/morel-soft-dome-tweeters/morel-mdt32s-1-textile-dome-tweeter-a...

another morel $56.

https://www.madisoundspeakerstore.com/morel-soft-dome-tweeters/morel-mdt29-1-textile-dome-tweeter-al...

double magnet, clearance $24.

https://www.madisoundspeakerstore.com/soft-dome-tweeters-vifa/peerless-dx25bg60-04-1-textile-dome-tw...

there are other sources, but I like Madisound.

when pulling the domes out, move slowly. the ferro-fluid is viscous.

If one pulls the dome out slowly, most of the ferro-fluid will slide off the old dome and remain in the gap.

as the new dome will be without the correct level of ferro-fluid in the gap. It will arrive completely dry.

the way to lessen the severity of this slight problem.. as much as possible, is the mentioned slow removal of the old dome, so most of the ferro-fluid slides off and remains in the tweeter motor’s magnetic gap.

the next question regards availability of ferro-fluid and obtaining some for correct performance of tweeters. The deal is that there are many types and viscocities of ferro-fluids and getting the right ferro-fluid is always a problem.

Not just any ferro-fluid will do. The driver response parameters will change and there can even be 'spray' out of the gap when the tweeter is moving at maximum excursions.  This problem occurs if the viscosity is too low (too fluid).

To add, we can't even get any shipped across the us-can border, into Canada. as it is somehow illegal to ship? Permits required? safety packaging? It's a weird one....

Here you.  Ask for a pair of replacement diaphrams. Fairly simple replacement will save you a ton.

Submit a request – Dynaudio (zendesk.com)