Speakers crackle during certain dialogue

[littleruss21]

ok i have a marantz sr5400 reciever with
2 DM602.5 Front Floorstanders
2 DM601 Rear Bookshelf
1 LCR600 Center Channel
1 ASW650 Subwoofer
All are Bowers & Wilkins, i have ammassed this system over a number of years so you imagine its importance to me.
The problem is during certain parts in movies mainly during dialogue with no soundtrack(Mothman Prophecies when they are in the bathroom with will patton pointing the shotgun at richard gere...also on the movie 21 grams when the preacher is yelling at the congregation and benicio del toro is apart of it) ok well during these parts there is some crackling at the end of thier speech on the last syllable...it only seems to be at certain pitchs because in other parts of the movie there will be dialogue with no music , and the volume will be loud, and there is no crackle...i have tried to tweek my amp but i am afraid i don't know what a lot of the stuff means...i am almost sure it isn't a blown speaker because it handles music cds and even music in movies just fine at very hi volumes now the center channel is on the lower shelf of my tv stand but i mean it has rubber grommets between it and the glass...so i guess i need to know what to try and remedy this...if you need more info just ask i really just appreciate the help


thank,
andrew

[einsteinjb]

Nobody replied yet? And your very first post no less? How rude. :)

OK well I'll try to help you a bit. I'm familiar with the B&W DM600 series though you didn't say which Series you have, the original, S2 or S3. Doesn't matter for the purposes of troubleshooting, just wondering. I'm also not familiar with your Marantz receiver.

Now when you're watching these movies and this happens, exactly how loud is it? Hard to qualify I'm sure but are you watching LOUD? You may have something loose in your center tweeter. I would suggest first seeing if it happens at lower volumes. If not then it's not just a glitch in the soundtracks.

Then you might try swapping the center for another speaker and listening closely to see if it does it on that speaker as well. Have you determined it's definitely coming from your center? If not you'll need to go put your ear close to the center to make sure it's coming from that speaker and that one only.

Here's a remedial question: you don't happen to have the center channel volume cranked up in the receiver's setup menus do you? If you do you might be overdriving that channel.

You really just need to use basic troubleshooting methods like this to track down exactly when and where it's happening, under what circumstances. listen closely to each speaker til you know where it's coming from, or disconnect speakers til you locate it, etc. If you try all this and you become certain it's the center channel's tweeter physically doing something, you should probably take it to your B&W dealer to have it looked at. I don't think getting a 600 series center tweeter repaired would cost a fortune. It's always possible you have a very slight tear or something like that in the tweeter that's not preventing it from working most of the time or at lower volumes but that does cause it to spit at you in especially challenging moments.

Hope this helps.

[hifiman]

I've had this problem since the days of those new-fangled HI-FI VHS VCRs. Often times the recording level on movies is too high and I would get a crackling sound from one speaker or another. Since making the switch to DVD it happens infrequently, but I do get a crackling from time-to-time. I too have never had the crackling from other sources.

[tbewick]

I've heard some fuzziness in the speech with Dolby Digital soundtracks at high volumes. It's possible that you are hearing the effect of AC-3 compression. I've found applying a treble roll-off/cinema eq helps to reduce the audibility of this fuzziness. In this post I've included the eq curves of the THX re-equaliser (on the left) and the Denon cinema equaliser (on the right) [Source: Home Cinema Choice]. The quality of Dolby Digital playback will vary with the quality of the Dolby Digital decoder. Maybe on more expensive receivers, such compression artifacts will not be audible. DTS tracks I've heard don't have this problem.

It is also possible that you are playing the receiver at too high a volume and that it is clipping. B&W speakers are known for their clarity, but they can be quite difficult for the receiver to drive at high volumes. In fact, B&W have been criticised for not testing their cheaper speakers on less powerful amps (they do their tests on 1 kW Krell monoblocks). Most people buying their cheaper speakers won't be using such a capable amplifier. B&W also use their own standard when deciding what impedance their speaker is. Their newer speakers rated at 8 ohms can dip all the way down to almost 3 ohms, making them more demanding on the amplifier.

It could also be that you are hearing faults on the original soundtrack.

[MACCA350]

tbewick wrote:
It could also be that you are hearing faults on the original soundtrack.
Unless littleruss21 is pushing his equipment to clipping levels, then this is the most likely answer. Check this by playing the same scene at low volumes, if its still there then it is most likely in the recording.

I have heard this crackling in a some movie tracks played at any volume and, from memory, its almost always in the dialog, and mostly when someone is yelling/shouting. I believe this artifact is made in the recording studio when they do the voice recording. When the recording is taken, you can imagine the person is yelling or screaming into the Mic at only a couple inches away, this then will be mixed into the track at any volume level, so you could have a loud recorded voice playing at a softer level to match onscrene action in the final mix.

How loud can their Mic's record before adding distortion products? I don't know, but a person can yell over 130db at a couple of inches. I don't know how much above 130db cause thats the limit of my SPL meter and my Miss's topped that without even blinking:eek:

So if you hear this at low volume, and unless you've blown your tweeters, there is not much you can do about it. As tbewick said, Cinema EQ may help

cheers:)

[einsteinjb]

tbewick wrote:

Unless littleruss21 is pushing his equipment to clipping levels, then this is the most likely answer. Check this by playing the same scene at low volumes, if its still there then it is most likely in the recording.

I have heard this crackling in a some movie tracks played at any volume and, from memory, its almost always in the dialog, and mostly when someone is yelling/shouting. I believe this artifact is made in the recording studio when they do the voice recording. When the recording is taken, you can imagine the person is yelling or screaming into the Mic at only a couple inches away, this then will be mixed into the track at any volume level, so you could have a loud recorded voice playing at a softer level to match onscrene action in the final mix.

How loud can their Mic's record before adding distortion products? I don't know, but a person can yell over 130db at a couple of inches. I don't know how much above 130db cause thats the limit of my SPL meter and my Miss's topped that without even blinking:eek:

So if you hear this at low volume, and unless you've blown your tweeters, there is not much you can do about it. As tbewick said, Cinema EQ may help

cheers:)
I would hope that any legitimate movie studio producing big budget movies would be using sound engineers good enough to know how to set their input gains and other settings for whatever mic they're using in a given recording situation... I would HOPE. Such of course is not always the case in the real world. And even good engineers make mistakes, like not realizing how loud a particular actor or actress might get while doing a particularly energetic scene and not being prepared for it. It's always possible that there was clipping in the signal path somewhere, and maybe the engineer pointed it out or maybe not, but maybe the director said I don't care, that was the take I wanted, we're not doing it again (Can't you fix it in the mix? :rolleyes: )

Point is things happen and it's definitely possible that the noise you're hearing is in fact on the source. Try the suggestions we've made like listening at a lower level or switching speakers or even checking it out on someone else's system and it should be fairly easy to track down where the problem is occurring.

[Lee Batchelor]

Hey Andrew!

I have a rather large home theatre, in fact, it isn't really a home theatre, it is a real theatre system suited for about 200 people. I do get center channel distortion on occassion and I would say it is over-modulation on the part of the mixdown engineer. I say this because I can put another source in and play it through the same sound field on the amp and there is no distortion. If the engineers messed up the final mix-down, you're stuck with it. If all your programs sound this way, then there is a problem elsewhere.

Hope this helps..........Lee

[kellyk75]

Andrew,

Did you ever find the solution to your problem? I am experiencing something similar but on not as nice a system.