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What is the cause of my sibilance problem?

I have been fighting a sibilance problem for about a year. I thought I had it beat but it is back. I've tried cleaning and treating all connections, acoustic foam treatment at first reflection points on side and front walls and ceiling, different interconnects, speaker position, and even a different digital front-end. The problem manifests itself as extremely harsh 's' sounds in both male and female voice. I am beginning to wonder if I need to have my hearing checked - I tried headphones and hear the same problem. Well, here is my system:

Aiwa XC-37M CD-changer
MSB Link DAC III with 24/96 upsampling board
B&K Ref. 10 preamp
B&K AV6000 poweramp
Paradigm Reference Studio 60 Loudspeakers
Hsu Research VTF-2 powered subwoofer
Signet center channel
Atlantic Technology surrounds
Sennheiser HD580 Headphones
Home Grown Audio Super Silver interconnects
Monster Cable subwoofer cable
Ted's Excellent Cable speaker wire (mains)
Kimber 4TC speaker wire (surrounds)
Mapleshade Brass cones, weights, and cork/rubber feet
Michael Green 5-shelf Audio Rack.

A Television, the subwoofer, and the Audio Rack sit between the louspeakers; which are approximately 7' apart and 7' from the listening position. My room is highly irregular and ASC claims that $1200 in acoustic treatment is the answer to my problem. I'm not saying they are wrong. But, having experienced the same problem with headphones (and acoustic foam not alleviating the problem one iota) I am beginning to wonder...
gallaine
gallaine OP
114 posts
 
Sorry about the silence. I haven't had much opportunity of late to try some of the suggestions posted. My deadline at work is the end of week - hopefully I can take off this weekend.

One thing I did try was to change the "mode" from direct stereo to several others. Interestingly, the problem was significantly less in surround. I am beginning to wonder if the problem is my loudpseakers. When voice is routed to the center channel the sibilance goes away - or seems to.
gallaine OP
114 posts
 
Update:

I disconnected the Aiwa from the MSB Link III and connected my Sony DVD player to it. After trying both coax and optical connections the problem wasn't solved. I am, however, better able to characterize it. The sibilance is most noticeable in words that begin or end with "s" as opposed to having an "s" in the middle.

I also opened up the MSB Link III to ensure that the upsampling board hadn't been knocked loose. It wasn't. But I did discover something that was a little disappointing. The upsampling board plugs into two rows of pins in the middle of the "main" board. There is a tall capacitor under one corner of the board that prevents the sockets from sitting flush i.e. it isn't completely seated.
sol322
426 posts
 
Gallaine:
Have you tried different IC´s?
Might not be the case but worth trying... I recall a friend of mine who had this situaton with silver IC´s I´m not familiar with your brand though.....
After you solve this or if you want to take a break I can give you some interesting tweaks for your amp. Just for kicks why not you change or swap power cords with your amp to see if this lessens the problem, it might provide you a pointer....
Don´t give up!!
gallaine OP
114 posts
 
Sol322 thanks for the encouragement. I have indeed tried different interconnects and powercords. I spoke with Steven at The Cable Company and I have one or two more things to try before going back to interconnects. Steve was, in fact, the person who recommended reseating the upsampling board and changing transports from the Aiwa to the Sony DVD Player.
bob_bundus
1,834 posts
 
I once had sibilance issues that turned out to be AC power related. The PSAudio should have helped, but maybe you need to try something else? The right combination of AC cords should also help, & a dedicated AC line if possible.
Room treatments normally are worthwhile too, but considering that you even have sibilance in headphones, this points toward the front end, those interconnects, or the preamp itself. Brass cones could also be complicating things; they can add brightness & may not be best for your rig. Try removing them altogether, or repositioning them closer together 1" at a time to add some warmth. Black Diamond cones may be better for you than brass, they are for me. Try the #3's first before the #4's, considering the sibilance. Try to borrow another preamp & be sure it's warmed up?
That brings up another issue, are you leaving at least your front end components on all the time for best sound? Cold transistors sound can be pretty harsh.
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