Anyone tried any mod’s on the Vifa XT Tweeter?

[kingdaddy]

I read somewhere a few years back that opening up the back and changing the stuffing would be a good experiment on the Vifa XT25 but I never heard any feedback. I got board waiting for the MNF game yesterday and popped my XT out of their dedicated enclosures and just removed the back plastic cup (sealed chamber) and the stuffing altogether and re-mounted them back in the enclosure with the back completely open.

Now I don’t have any measurements to prove it but it sounds a lot more open (forgive the pun) and airy, seems to go a bit lower now as well. I was listening to it isolated when I popped the back cover off and cold immediately hear the tzz sound open up to a fully audible sound of the upper harmonics of a female singer, before it was tinny and buzzy sounding. Now that their back together it is a real joy to hear with the full range going, I cant say what it did to the crossover point but subjectively it sounds much, much better to me.

[kingdaddy]

After mod, BTW, its totally reversable and causes no damage that I can tell or hear.

[dlr]

There's a reason why chambers are used and stuffed. The vent is an excellent open pipe by itself. It's a very strong resonator.

Here's the SPL of a Vifa D27TG-45 with original chamber, no chamber stuffing and one I tried to improve upon.



The one without chamber stuffing will be very much like no chamber at all. The XT25 will be very much like the D27. The motor is much the same except for the copper in the gap. Whatever you're hearing as an improvement is without doubt some severe coloration.

In addition, you'd have to isolate the tweeter as well. A woofer would blow the diaphragm out almost immediately.

Dave

[tinitus]

You really need to round the inner edge of faceplate, but carefully, not too much or you will go through the plastic...I used a Stanley blade
If you dont like that, you could try a smooth it with wax/clay

Also very important is to fill all mounting screw holes with wax/clay(?)

Caution, after reassembling faceplate unit I had a minor failure
One driver voicecoil was touching poleplate, and wasnt playing much...but it was easily corrected by dismantling and new carefull reassembling

Another tricky mod is to remove some excessive glue from inner edge of "surround", but I havent done that one as it means complete dismantling of unit

I have also done very light coating

Important, I really believe it needs an RC in xo, but it could be xo design related, not really sure

[kingdaddy]

The open back is vented into a larger sealed enclosure. I should let the listening tests settle a few weeks before I decide if it’s unnatural or not, for now it sounds much better, but things often change after extended listening.

Thanks for your comments.

[kingdaddy]

Originally posted by tinitus
You really need to round the inner edge of faceplate, but carefully, not too much or you will go through the plastic...I used a Stanley blade

Also very important is to fill all mounting screw holes with wax/clay(?)

Caution, after reassembling faceplate unit I had a minor failure
One driver voicecoil was touching poleplate, and wasnt playing much...but it was easily corrected by dismantling and new carefull reassembling

Another tricky mod is to remove some excessive glue from inner edge of "surround", but I havent done that one as it means complete dismantling of unit

I have also done very light coating

Important, I really believe it needs an RC in xo

I make my own faceplates that have a smooth rounded edge instead of the factory chamfer. Dont know if it does any good, hard to tell.

[Undefinition]

In addition, you'd have to isolate the tweeter as well. A woofer would blow the diaphragm out almost immediately.

I'd like to see that! The tweeter is missile-shaped as it is. You could try and see which bass frequencies pop the diaphragm with the most velocity.

[Ric Schultz]

I removed the back of a Vifa tweeter over 10 years ago and the results were amazing. Before the mod the tweeter sounded way worse than a Dynaudio Esotar I a/bed with. After cutting off the back, I could hear no difference between them (crossed over around 6K with just a cap). You need to cut just the very back off the tweeter and leave the felt wad in there. Otherwise you do get the weird coloration and peak around 2K from the sound going through the vented pole piece hole. The felt wad is enough to kill that resonance. A modded Vifa is a killer tweeter. Naturally, I use the tweeter on top of the box in free air.....and have also tried it in a modified 12 inch waveguide crossed over at 1K using a Behringer digital xover at 48db per octave. Superb sound.....the tweet I used was the cheap older $27 jobbie.

[inertial]

Hi,

Kingdaddy,would be fun try a exp tube ala Nautilus, no?

Cheers,

Paolo

[bambadoo]

I have modified a couple of xt25 drivers according to Steen Duelunds suggestions.
I big difference in sound. Incredible transparent.

1. Remove excessive glue under the silk diagram.
2. Close the "gap" in the voicecoil with some hard glue. That is more or less a design "flaw".
3. Make the "waveguid" bigger.

I took a couple of pictures.
4. My own tweak. Changed the cotton in the backchamber with nature wool.