sibilence....any cures out there?

I have recently accuired a pair of Nola Viper 1A speakers, while their performence is outstanding generally, the only problem is highlighted sibilence on vocals which is very annoying!!! Is this down to the speakers? Would a change of interconnects help? Any ideas from you guys would be appreciated greatly...
Sibilance is usually evident in an ultra detailed tweeter. Cause is a usually a bright source. Many recordings (vinyl or CD) are not the best, which can excite the tweeter. Cables can tone things down a bit, but if it's really a problem you might look at your amp and or source. A chain of ultra revealing components can get harsh on all but the best of recordings. One or the other, or both, may be the issue. Or maybe the tweeter in the Nola is just not to your liking.

Did you have this issue with your previous speakers?
Swampdog, Try some absorbtion at the first reflection points along the side wall and ceiling, if possable try some on the back wall also. Sibilence can also be caused from the high frequencies bouncing around the room.
do u have a bright sounding room with slap echo problems?
You could try a product like Jim Goulding's Diffraction Be Gone:

You could even DIY your own to see if it gets rid of the problem. All you need is some self-adhesive felt from your local hardware store and a pair of scissors :)
Replace the capacitor to the tweeter with some vintage paper
In oil ones.
Agree with the treat the room posts, especially first reflection and bass traps.
Treating the room will not fix the direct sound. The issue is an elevated mid treble, not an "ultra detailed" tweeter. (Does the Viper use ribbons?) Only real solution is to flatten out the treble with equalization. You'll need a calibrated SPL meter and test tones.
Best and cheapest way is to toe your speakers in til they converge just in front of your listening position. This usually helps in imaging too. It's easy to try anyway.
As with all audio performance, assuming nothing is broken, 95% of the sound you hear is your speakers and your room.

Sibilance is in the 5-8000hz range which means it's in the tweeter.

Start by playing around with speaker placement, and also try changing where you are sitting. Moving a couple of inches can change things by 5-10db.

Next is to figure out what is going on with your room. Have you taken a thorough analysis of your room's acoustics? If not, time to look into room acoustics.

Alternatively, change your speakers back.

No cable change will fix your problem, (unless you have a broken cable)
Being a previous owner of the Nola Viper 1A, (which have been upgraded to the Viper 1X's), the brightness/sibilance you are hearing is most likely RF infiltration into your system somewhere upstream and the speaker is only revealing that problem.

The Vipers use high quality M-caps in the mid/high frequency x-overs so these are not the issue as I experienced very little brightness/sibilance in my setup with the 1A version. The Reference lll AlNiCo tweeter upgrades completely eliminate any brightness and are a huge step forward in transparancy/musical detail and reveal that the stock 25mm magnesium dipole domes can sound forward but this indicates a problem elsewhere as mentioned before.

RF infiltration comes from several places but mainly from poor power isolation especially from digital components and from appliances used in the home/community. If you can, try isolating your digital component(s) with an isolation transformer or a PS Audio UO. In addition, poor/budget quality IC's/Speaker cables will be a factor here as well as the Viper is a very detailed speaker and as such will reveal any shortcomings in the cable chain.

In short, the cleaner your AC mains and the level of isolation with regards to RF will pay large dividends here
and should be given due consideration.

Before you get too carried away, do the positioning thing. Then try different speaker wires. I was surprised with relatively inexpensive speaker cables from Ultimate that took over from the very cheap temporary ones when I had moved and required extra length. Solved a sibilance issue that I was convinced was the room.
Do you use a tube preamp/amp? If so, the brand of tube can have an affect. In my system Sylvania is too sibilant. I sold the Sylvanias to a guy in town - his system is darker sounding than mine - and the Sylvanias were a great match. He said he was hearing details he had not heard before and loved it.

Also, in a friend's system good, high quality copper speaker cables sound great, but when we put silver cables in the system it was extremely sibilant. But like mine, his system is very transparent.
From my experience, Nmmusicman's advice applys to all speakers and all systems. I would add noise caps and RF blockers. I would specify at least two power conditioners on different circuits. I would and do place big bricks on my power conditioners since vibration is also a factor. Low humidity is another factor which is diminished by Spring (static electricity). Get rid of RF and AC noise, vibration, and static electricity and what do you have left? Music if you are lucky.
Its time to upgrade.
Don't believe it. Tweeking is fun and worthwhile.
I ended up curing my system's with less toe-in and also interconnects. For me, interconnects were very frustrating and costly to evaluate and I feel extremely lucky I ended up with ones which mate perfectly with my system. Now I can listen to Diana Krall and Eva Cassidy "Live at Blues Alley" without being bothered by sibilance. YMMV.
Yep. Toe in is cheap and easy and doesn't involve any sort of Voodoo.
Diana Krall has naturally sibilant singing style. If you don't hear Diana's sibilance the system may not be resolving enough.
swampdog, Jylee is on to something. What kind of music do you listen to? Some sibilance is natural. On rock and pop recordings I hear a lot of processing of female vocals. See Adele for recent example. WTF they do that for?
All Copper Cables !! A very simple but effective way to address this issue. Mostly sibilance is not a function of equipments unless they are horribly mismatched. It is more of a creation of associated accessories like Cables, bad power, isolation techniques etc. If you could start simple copper cables from Mogami it will tell you if it is a step in the right direction. Mogami makes very balanced sounding cables at sold at throw away prices so it will not cost you much. I had faced a similar issue long time back and it was my speaker cable at fault.
Jylee - It is not that I hear no sibilance. It is that it is no longer to the degree which bothers me. My system is resolving, just not hyper so. I miss no details of the music. I also agree with Pani - I prefer well designed copper cables which is what I ended up with - wonderful for the music and helped cure overly sibilant sound. Resolution vs. hyper critical sound is surely a battle (at least with gear which costs less than five figures, or perhaps all gear?), but one which can be won.
Hi Swampdog... Brother, if you follow all the advice above, you just might find the problem after spending a couple grand... Alot of good advice but varies widely.
I would take it a step at a time, looking at cause and effect. Start with positioning, does it fix it I would change positioning even in ways you wouldn't normally listen just to get the effect your room has on your speakers. How does it change it if any? Next I would listen to a couple of sources, does this only occur listening to a single source? Next I would get my cables out, if you don't have a stash, I would borrow a few, Problem not solved. I would ask a few people to take a listen to their amp or preamp, do either one of yours have a hot spot? I haven't listened to your speakers, but they review well. If you can, get someone close to give you brief loans of an item at a time, If none of this fixes it, Its the Room or fold and acknowledge a speaker problem. you'll figure this out. Good Luck, Tim
Many thanks to all you guys who gave your time to help with my problem..and guess what...some of you were right...I re-positioned the Nola`s and changed the interconnects to pure copper ones and "hey presto" it damn well worked! Well done and "many thanks"to you all.....cheers