AVS Forum banner
Status
Not open for further replies.
1 - 13 of 13 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
Greetings, thanks for looking.


I have a Paradigm reference v2 system consisting of 100 v2 front, CC v2, and 20s rear. Powered by B&K Reference 4430 (200w x 3) across the front and Parasound (85 w) rear, Sony Ta-e9000es pre/pro set to 80 Hz crossover.


I occasionally hear distortion from the center channel during peak output type movie scenes, typically when someone in the scene yells. I recently watched Identity and heard distortion repeatedly. The next night my wife made me watch Chicago and I did not note any distortion at all. Similar volume. I do note distortion from the center channel at some point in most films.


My question. Is the Paradigm Ref CC prone to distortion and others on the board have experienced similar nastyness, is it the amp or pre, or are some films recorded poorly and distortion is evident regardless of equipment?
 

·
Premium Member
Joined
·
5,900 Posts
Simply put, you are out of headroom. Either the center speaker or the amp is distorting, and it is unlikely anything is wrong with them. I would suspect the speaker is being overdriven by that big amp. Either you are listen too loud, you're sitting too far away, or your room acoustics are not helping. Try setting your center channel highpass to 100 Hz, or even 120 Hz and see if the problem goes away. Make sure the center is not calibrated too hot.


You have very good equipment, and I don't think that's the problem.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #3 ·
Thanks for the reply Paul.


I will try and adjust the crossover to a higher frequency. However, the distortion seems to be associated with higher frequencies such as a scene where a woman screams. Maybe eliminating 80-100Hz will allow the amp speaker combo to run more efficiently. Worth a try.


I sit about 15 feet from the center speaker, and the wife never lets me turn it up to volume levels I like. So, even at what I consider moderate volumes I will notice distortion.


Room acoustics are a definate possibility. This is the third room this setup has been placed. All environments have a had similar results. So possible, but seems unlikely.


I had a Paradigm Ref LCR 450, had similar problems and sold it. I had hoped the new CC V2 would fix the problem and it has not.


I may not understand the concept of headroom. I thought headroom was dependent on amplifier power and speaker efficiency. If I have a powerful amplifier and an efficient speaker, isn't it less likely to run out of headroom?
 

·
Registered
Joined
·
1,106 Posts
I see six possible causes for the distortion (there could be more), you should consider designing experiments to eliminate each, one at a time, though read all the way through before doing anything:


1. Speaker busted. A small problem with the speaker cone may only show itself under high-stress loads. Try swapping the center and one of the LR to see if the problem follows the speaker. This is also a test for #3.


2. Speaker distorting because of too much power. This is a tough one to test. See #4.


3. Amp busted. One channel could be flaky. Try swapping around speaker wires and/or input signals (also see #1).


4. Amp distorted. You're pushing it too hard. If you are right that the power is big and the speakers are efficient, this must be deafening volumes to do this.


5. Source. If it only happens under high volume, then this probably isn't it, though your DVD player *could* be putting out too much juice for the input stage of your preamp - try another DVD player.


6. A tiny near-short in the speaker wires causing arcing at high volumes. A visual test at the back of the amp and the back of the center should suffice, though using a completely separate set of speaker wires for the center would be wise. Of course, the near-short could be inside the speaker, that would be a PITA to find (if possible at all).


The new data points of your old center doing the same thing and your listening volume being non-life-threatening seems to eliminate #1, #2, #4, and #6. The fact that you said it only happens in high volume situation points to #5 not being it either (though it isn't completely eliminated).


Based on what you have given us, I think you have a fault with your amp.



Bill
 

·
Registered
Joined
·
576 Posts
"I recently watched Identity and heard distortion repeatedly. The next night my wife made me watch Chicago and I did not note any distortion at all."


Just my amateurish 2 cents: I noticed distortion on that DVD as well and none on previous DVD's. I then watched "Head of State" and noticed distortion. All of this was during dialog - particularly loud passages. I hadn't noticed on other DVD's and tried several.


After further investigation, I concluded that:


A) The copies of these DVD's had a poor dialog track.

B) I needed to adjust my delay settings on the center channel.


Not saying this will solve things for you, but it seemed to for me.
 

·
Registered
Joined
·
383 Posts
Quote:
Originally posted by drbrousters
"I recently watched Identity and heard distortion repeatedly. The next night my wife made me watch Chicago and I did not note any distortion at all."


Just my amateurish 2 cents: I noticed distortion on that DVD as well and none on previous DVD's. I then watched "Head of State" and noticed distortion. All of this was during dialog - particularly loud passages. I hadn't noticed on other DVD's and tried several.


After further investigation, I concluded that:


A) The copies of these DVD's had a poor dialog track.

B) I needed to adjust my delay settings on the center channel.


Not saying this will solve things for you, but it seemed to for me.
I think you're on the right path. A simple experiment to confirm this would be to compare the DVD in question with one where no distortion was noted previously. And then use a SPL meter to make note of the prevailing db levels. If huge differences exist, then it could be the levels used on the distorting DVD soundtrack. Apparently, a few DVDs do set the levels set too high, which results in distortion during loud passages.


I've detected distortion with two of my DVDs. One of them was the theatrical version DVD of LOTR:FOTR; it was apparently mastered with no dialog normalization present, and the levels were well above industry norms. On my system I detected audible distortion in a few scenes. The subsequent extended version DVD had the levels set noticeably lower, and I did not notice distortion with that disc. The LOTR:TTT theatrical version DVD also didn't have the high level distortion with the FOTR disc.


The Paradigm Studio CC does not distort easily. I own one, and aside from the two DVDs I heard with very elevated levels, I've not heard anything distorted coming out of that speaker, even at very high db levels. I know that the Studio v.1 series had some issues with the tweeter material occasionally separating from the mounting. But, Paradigm redesigned the tweeter, and with the v.2 series, that was not an issue.
 

·
Registered
Joined
·
27,368 Posts
How big are the drivers in the center channel and where is it in relation to yuor TV projector?


Like Paul says....are you room's acoustics poor and / or highly reflective?
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #8 ·
Thanks for the input guys. This is such a fantastic forum. I knew I could find the help I need. I have switched amp channels for the center. Unfortunately Identity has been returned to Blockbuster, so a controlled experiment will be difficult. I also noticed distortion during LOTR (free copy I got for test driving a car). It may just be software based.


Sadly I do not have a dedicated HT room, so my acoustics are run of the mill family room. 21 ft by 13 ft, 10 ft ceiling with an 8ft open entrance way rear right. TV/Wall unit on short wall, CC centered above PioElite 630 HD. Puffy couch, leather recliner (throne), wall to wall carpet, another chair, glass/wood coffe table in center, two windows (large) with drapes closed during movie viewing. Not highly reflective, possibly too damped???


It is nice to hear this is probably not inherent to the Reference CC and a common problem. I will try adjusting the delay, and take measurements with the Rat Shack sound meter. Thanks for your help.
 

·
Registered
Joined
·
27,368 Posts
Does your center sit right on top of your TV? There might be some tweeter diffraction from the tweeter reflecting off the front edge of your televion set. Particulalry if your center sits on the front edge of your TV. The TV acting as an extension of the baffle.


I placed acoustical material as my center sits on top of my very large subs and the tweeters of my center diffracted off the subs. I placed acoustical absorptive material on the edge of the subs to help ameliorate this. SEE my link below as I have a picture of this.


Not the most esthetic solution. You may want to try something if your center is having tweeter diffraction off the TV to decrease this. This can increase center channel sibilance..


Certainly something to try.
 

·
Premium Member
Joined
·
5,900 Posts
I still think you're pushing the speaker too hard with too low a highpass frequency. Did you move the center up to 100 Hz or 120 Hz? If there were distortion on the DVD, it would sound just as distorted at 80 dB as at 105 dB.


Your room acoustics sound pretty good, actually, with wall-to-wall carpet, furniture and drapes. Have you yet mentioned what your electronics are, or am I not paying enough attention?? :confused: :)
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #11 ·
Paul, I have adjusted the crossover to 120 Hz, and will listen for improvement. I think your comment that encoded distortion will be evident at 80 dB and 100 dB is a valid one. I need that DVD back to test that theory. A previous poster stated perhaps the peak levels are set too high. Is this analagous to a careless home recording where the peak levels are not adjusted properly (too high) and the resultant tape sounds like crap. How can they release a DVD on the market with an obvious bonehead mistake like that? If this is the case and the distortion is not encoded but rather due to very high peak levels, how do you compensate? Reduce center level? Reduce dialogue trim? Have another beer and quit being so anal?


I had listed some electronics in the initial post. The only one I have left out is a the source which is a Sony 5 disc DVD carousel (850 is the model number I believe)


Jeff, looked at all of your pics. Sweet HT, family, and home. Excuse the listed order:D . Congrats. I doubt the wife will go for any type of foreign matter between the speaker and the TV in the family room of the Spencer household. The speaker sits on a supplied wood shelf (part of the wall unit) approx 2 inches above the TV.
 

·
Registered
Joined
·
663 Posts
i've got the same center and i push it plenty hard with an average yamaha receiver that runs the center down to around 80hz. that B&K should do a much better job than what i'm running, and i've never heard distortion at reasonable levels. as a matter of fact i have a run of the mill family room and watched Identity and 2 Towers in the last week, and had no problem.


defanitly try Billped's #1. that would eliminate alot of variables.


are you running the same cables to your LR and your center? i wasn't happy with my center's performance until i upgraded the cabling. still never had a distortion problem though.


two other things to try


1. maybe it's not really your center distorting? could be something rattling? who knows? try disconnecting all your other speakers, and just running the center. do you still hear it?


2. do you have kids? is there anything inside that speaker? our 1 year old thought the port on our center would be a good place to store some of his toys...
 

·
Registered
Joined
·
27,368 Posts
Thanks for the nice words!


Just for fun, pull out your center and have it 1 or 2 inches forward of the front of the shelf that it sits on and give her a try. This will decrease tweeter diffraction. Use the center delay on your receiver if needed (particularly if your center is parallel to your mains or, worse, forward of your mains. Pauls thoughts on overdriving seem valid, too, considering your speaker's problem. Do play with the crossover.


I had a similar problem with my old Mirage MC-Si center and it was when I moved it that I got some relief from the sibilance. It sat on top of a television shelf, too.



Let us know how you do!
 
1 - 13 of 13 Posts
Status
Not open for further replies.
Top