Focal Tweeter Repair

[laverda]

Originally Posted by sreten

Hi,

This is getting very sad. You made a mistake, admit it.

rgds, sreten.

replace 'is getting' with 'has got'......

[Kindhornman]

Okay guys,
Was looking at this thread and thought that I could answer this question with no prejudice. I took an old Focal T120 Ti driver apart. Not an easy thing to do, they went and used an adhesive to mount the front plate. If you can believe it there are no alignment pins. Terrible design if you ask me. Looks nice but how would you ever align a replacement diaphragm, only the screw holes make the alignment!!!! The surround is indeed a foam suspension, there is no mylar or Kapton under the foam. The foam is the only thing there, I am looking at the back of the diaphragm here. On the plus side, these are some of the worst sounding and measuring domes I have every heard. Most of the high frequency is nothing but titanium noise, very hashy in the upper frequencies. And those domes in the Wilson products are Focal drivers, I have not love of that brand, purely a market driven company and the higher the cost the more people will say they are fantastic. They always used common European drivers, nothing you couldn't buy for 1/10 to 1/100 the cost of the Wilson designs. Pay enough for advertising and you too could sell $100,000 dollar speakers..........

[JMFahey]

Interesting.
You say the dome "floats", its edge is not glued to the front plate (or a rigid ring attached to it) but is held in its position only by a foam ring and nothing else?
I'd love to see that.
Since you pulled the dome , would you please be so kind as to post a couple of pictures, both from the front and from the back?
Thanks.

[sreten]

Hi,

You can see it is the images already posted, a foam edge suspension.
They all have similar, as a standard design feature, and a design quirk.

rgds, sreten.

[bear]

The original T120 has a fiberglass dome, or maybe kevlar dome. Think it was fiberglass. It did use a flat foam surround. I have some. The smaller T90 was the same.

Later they went to titanium domes and rubber (santoprene, likely) surrounds...

_-_-bear

[sreten]

Originally Posted by bear

Later they went to titanium domes and rubber (santoprene, likely) surrounds...

_-_-bear

Hi,

I can't recall any Focal inverted domes with rubber surrounds.

rgds, sreten.

[bear]

Department of free and unsolicited advice:

To make these tweeters sound MUCH better:

- run with a small series inductor, set so that the inflection point is just above ~10kHz. This flattens the slightly rising response of the tweeter and makes it sound *much* nicer

- add ferrofluid to the gap. You need the *right* ferrofluid, the stuff for woofers is NG. This does not drop the high end! In fact it extends the high end, and lowers the IMD and THD by an audible amount.

Now that these tweeters are somewhat passe I don't mind spilling the beans. Please credit me if this gets used and dredged up at some future time - please don't claim it. Not that it's that important.

(Dave Wilson - don't you dare claim this.)

_-_-bear

[bear]

Originally Posted by sreten

Hi,

I can't recall any Focal inverted domes with rubber surrounds.

rgds, sreten.

I am not near them, but I can post a picture, if you wish.
Trust me, they made them.

[Kindhornman]

I'll have to get out the camera for this but the titanium version is using a rubber and not foam surround. I do have one of the Kevlar ones somewhere in the collection of test devices, They may have had the foam surround, I don't recall. I would take bear up on his suggestion as stock these are some pretty horrible sounding dome tweeters. I wouldn't be surprised if Wilson didn't do something to them if they don't sound awful. The upper frequencies will soon make you want to turn off whatever they are in, very ear fatiguing to say the least. As I said the titanium ones had no means to center the voice coil except the screws holding the face on that is the complete moving assembly. There is no sub-assembly, no replaceable face plate, it is all in one. They used a small amount of adhesive to hold the assembly in place and I had to literally break the assembly when I tried to take it apart. The voice-coil detached from the dome when I go it to let go! I would be very careful if the newer Beryllium dome is assembled the same way, you will not be happy if you break one of those!

[bear]

Yeah, I used a mic sitting above the dome and a sine sig on the dome to align it while looking at a scope. I figured that their mfg method just did not result in the dome being perfectly centered on the faceplate, and the gap being small, it was enough to make it impossible to put alignment pins in and make it fit every time...

They sound very nice with those two mods... Wilson, afaik did not do the two mods, but he (at some point in time) claimed ferrofluid. But honestly I have not seen any speaker with ferrofluid in the gap when I got to take it apart, but I haven't taken enough apart I guess...

_-_-