B&W LCR600 tweeter distortion

[kevsam]

Hi, I just upgrade my centre speaker from Mission 75c to the B&W LCR600 S3, and I'm having some problems with it, there is some distortion on certain dialogue that on my old Mission does not exists. I've changed to another LCR600 from the seller but the problem was still there. We tested the 2 LCR 600 at the shop with another amp (AVR7300) and it done it again.
Then we checked with a JBL centre thet he had at the shop and it worked fine. The salesman told me that maybe the B&W are too sensitive, but I rather have less sensitive speakers than the tweeter distortion.
I've even called the B&W technical support but he said that he has to be on site for problems like these, well that's impossible because I'm from Malta.

A film that does the distortion is The Pacifier at the middle of chapter 8 when Vin Diesel goes up the stairs and he begins to talk with the girl.
Anyone had this problem? Can somebody please suggest a solution please?

Thank you

[Sim reality]

Just out of curiousity... Does your 604s exibit the same distortion or just the LCR600?

[kevsam]

Hi Sim, I just connected the 604 on the center channel and yes it makes the same distortion but at a little bit higher volume ( I think because of the sensitivity difference). It is like the tweeter material is the problem then. Can it be that B&W it's not compatable with Harman/Kardon?

Thank you

[Sim reality]

I think it's more listening preference then...

I am willing to bet that the mission center you were using had a silk dome tweeter which has better damping charateristics at the +20KHz frequencies so the aluminum is sounding very "bright" in comparison...

In theory you shouldn't hear the "break up" frequency of the B&W tweeters as I think they only start somewhere around 25-27KHz but you might have better hearing that the "average human".

What you should do will depend on what you plan to do with your system... If you are planning to upgrade the reciever in the near future you could look for "warmer" electronics (denon, rotel, etc...) or if you are planning to keep the Harman/Kardon maybe trade the LCR600 for something with a silk dome tweeter.

I think I encountered the same sensation (a slight "ring" to the higher frequencies) when I moved to equipment with metal tweeters... But your brain "breaks in" after a while and then you wonder how people listen to silk dome tweeters because it lacks the "sparkle".

I guess the standard answer applies: I would play around with different setups if you can borrow different equipment and see if you can make a combination you like.

[Phil Rose]

I'm willing to bet that you're overdriving your receiver. 75 Watts (under the best of conditions) isn't very much power for the center channel. The center channel is the most important channel in your HT setup. Many people recommend double the power to the center. Also, the AVR7300 at 110 Watts isn't much of an increase over the 75 that you have now.

First off, make sure that your crossovers for all speakers are set to 80 Hz and use that big Velodyne to do the bass. That's what it's for. This may unload your receiver enough to allow you to play your system louder. Next would be to get a much bigger receiver or a separate outboard amp for the center channel as a minimum.

If you're planning on keeping your B&W mains you want to at least have a matching B&W center so that when sounds pan across the front they don't change tone from different voiced speakers. The rears are also important in voicing but no where near as important as the front 3.

If you don't really care about keeping your B&Ws then go look for some very efficient speakers. The B&Ws are about 90db give or take. If you can find a different brand that is 93db then that's the same as doubling your amplifier power and you should be in good shape.

Bottom line - I don't think there's anything wrong with your speakers. It's the matching of the speakers to the amp. Something has to change or just listen at a lower volume.

[Sim reality]

I agree with Phil with the crossover setup and if that doesn't work change speakers/electronics but I think 75 watts is enough for a Home Theatre (you will need more headroom for Music) application (provided you are not using this in a large room).

The 600 series are not really that hungry a of speaker and frequencies under 80Hz is fed through the subwoofer, the channels should have enough headroom unless you are listening to it rather loud.

The missions you had in the centre were not particularly sensitive (87dB) so if you where going to have clipping it would have be worst on the mission centre and not better.

IMHO what you are hearing is the tonal shift in the response of the speaker where the aluminum drivers do not "roll off" above 20KHz. Harmon/Kardon electronics also tend to be on the bright side which is accentuating the difference.

[PewterTA]

I just listened to that same point with my Rotel 1095/1098 combo on my LCR600 S3/DM604 S3s set at a decently high level of 75 (reference is 80 or 82 for mine I believe) and I did not notice any of this distortion you are talking about.

I agree it could be H/K being on the bright side, combined with B&W speakers being bright... it's like a double knock out punch maybe? Did you happen to try the LCR600 with any difference receiver when at the A/V store?? That would've been a test of mine I would've done.

[kevsam]

Thanks for your reply everyone. The 75 watts of the H/K are enough and it goes louder without distortion (with mission center ) than my older Denon AVC-A1D 140 watts THX amplifier, that when I listened to HT as loud as with the H/K it always gone to protection mode. I wish I had the Denon here to try with but it's still being repaired from last January :M . I can hear the distortion with only -30db volume setting so I don't think I'm overdriving the amp. All speakers are set to small and crossover for fronts is set to 40hz and 80 for the rest. I think the problem is for the brightness combination as sim and PewterTA said.

Thanks everyone I really appreciate your help.

[PewterTA]

Have you tried turning down the HF/Treble and see if it still does it. You could then tell if you are overdriving the high frequencies, but not necessarily the entire speaker?!

[kevsam]

Hi, PewterTA I've tried decreasing the Treble as you said and there is no distortion but the sound is dull. With eq off and treble set to -2 no distortion, with eq on and treble set to -8 no distortion both sounds dead.
I had a look at your great DVD collection and saw that you have Lord of The Rings The Fellowship of the Ring extended version. I have Lord of The Rings
The Fellowship of the Ring extended version too but it is Region 2 not 1. What I'm having is the same distortion with the dialogue on DTS that there is on chapter 11. It always makes it even if I turn the treble to -10 and set the volume low. I am sure that's a software problem. It only does it on DTS on Dolby Digital it's ok.
Can you please check it to see what distortion I'm talking about?

Thank you

[PewterTA]

Yeah I'll watch that as soon as I get home and let you know if I hear anything. LOTR: FOTR: EE Chapter 11, DTS, gotcha!

I'm going to guess though that I doubt I hear any distortion of any type on there as that IS my favorite set of movies, watched them all sooo many times. The sound on those movies rivals anything else I've heard...

I'll check though, maybe I'm in la-la land when I watch them and don't notice it....

Though I thank you, I just realized I don't have LOTR:ROTK: EE listed in the there, I'll have to make sure that's added, I never realized it wasn't a part of the list! Doh!

[PewterTA]

Just checked it out... Everything sounds pretty fine to me in that part...

That's where the Hobbits are in the woods and watch the Elves leaving right before chapter 12 where it switches to Gandalf riding to Minis Tirith right?

Ahhh almost had me watching the whole series again!!!! lol. That might be a weekend adventure or something....

The only thing I did know is there was a little bit of a lisp when they said their 's's on some of the words when I had it cranked up, but nothing that I would otherwise notice if I wasn't doing some critical listening....

Course I'm a somewhat brighter type of person, I'm one of the rare few that has the Rotel 1098 and has the HF at +2 because at 0 it sounds too dull to me.

[kevsam]

Thanks PowerTA, then this is a problem with my system. I have found a thread on a different forum with similar problem to mine but they have different components so I cannot compare. http://www.hometheaterhifi.com/forum...8980#post18980

I think I will link this thread in the H/K club to see if someone else have H/K and B&W setups.

Thank you for your help everyone.

P.S. Do you think a power amp will solve the problem? It will not solve the LOTR problem because it will even do it on the headphones.

[Stoney]

Just a thought, do you think you could be overdriving the input of the HK? If you are using the coax input, try the optical and see if that makes a difference.

[kevsam]

Thanks for your reply Stoney, I've try them both with no luck but I remember
when I had my old Pro Logic amp and stereo VCR that some time there was like a clicking sound that when I reduce the input db it was gone. I don't think you can make input adjustments on coax and optical inputs.

Thanks

[PewterTA]

It's a digital signal, so there is no "volume control." The Loudness is designated by a string of bits 01010111 01010100. Which sent digitally, is not like an analog signal that can be over-driven.

[Stoney]

Just another speculation here. Would it be possible that the DAC's can't keep up at the higher frequencies and therefore create a distorted sine wave output? You could check that by letting the DVD player process the signal and run it to the amp analog. (that is assuming your source has a decoder built in and the amp has analog inputs)

[kevsam]

Thanks fo your suggestion Stainley, I've tried but it did it too. Yesterday I picked my Denon, only the left and right channels are working and I connected the center output from the the dvd to external in righ front of the Denon and connected the LCR600 to right front amp connection, It does the same but a little bit less. So this has to be a problem with the LCR600, I think the "roll off" that sim said. can it be because of the frequency, the mission goes up to 20kHz and the B&W goes upto 22kHz. I've checked the JBL frequency on there site and is 20kHz too and the tweeter is Titanium-laminate dome. So maybe the difference in the crossover is making it. Can it be the distortion (zzz) that I'm listening is in that 2kHz?

Thank you.

[Sim reality]

Given that your 604s exibit the same problems it's probably not the LCR600 but somewhere else in the system... But I have really no idea where (could be as simple as something near the speaker resonating at high frequencies or as complex as there is some sort of interferece and some 2nd or 3rd order harmonic)

I don't suppose the B&W dealer (or his installers) has any ideas either? (At least they can hear the problem... We are kind of doing this blind.)

My question would be is the sound you are hearing a "change in the sound" or "something that bugs you"? If it's something that bugs you... As much as I love B&W... I would suggest looking for another centre speaker. You could end up looking for the problem for months and just get frustrated and wish you could return the speaker, which ruins the whole home theatre experience.

[kevsam]

Thank you sim. I will take your advice and tell my dealer so they try to fix this. I hope they will call B&W and solve the problem.

Thank you all.