Have a problem! Please help..

[Grey Ghost]

Guys,
I have a problem with my speakers. I have the Von Schweikert VR4jr's for my fronts, the VR-1's as my rears and my Center channel is the LCR-15 by Von Schweikert also. I have had all speakers for about 3 months now. Every bass driver in all of my speakers have a "Rattle" in them starting at 1/8" excurrsion. Kevin at Von Schweikert has stated that I am the first to have this problem. What is weird is that the speakers are not blown. They only make this noise at louder volumes. Kevin stated that maybe the speaker had been dropped during shipping which made the magnets decouple from the basket so Kevin sent me 1 brand new woofer to swap out to see if it fixed the problem. The brand new woofer sent immediatly started to rattle. I am sending back all bass units to Von Schweikert for analazis because this has never happen to them. I am powering all speakers with two seperate B&K ref series amps with 220 watts per channel. I have both amps on line conditioners but do not have them hooked into voltage regulators that help maintain 120 volts. Could my home voltage be dipping way down causing a clipping signal to be sent during high volumes? Kevin also stated that they had 500 watts going to each VR4jr at one of the shows. For fun they tried to blow the speakers but failed to do so. I am stumped! Please help with ideas or recomendations. If you feel I need a voltage regulator which brand do you propose I get at or under $1,000 dollars.......

Thanks,
Grey Ghost

 

[JoeE SP9]

Usually woofer rattling or bottoming out is an indication of too much power. Clipping usually results in blown tweeters or tweeter fuses. Did you always have this problem or is it a recent occurance? What kind of pre/proc are you using? Are you using any eq or bass compensation? Have you tried another power amp? What are you using to drive the center speaker? You have only mentioned 4 channels of amplification. What kind of sub if any do you have and how is it powered?

 

[Grey Ghost]

Joe,
Thanks for the reply. The speakers are rated at 350 watts and I am only feeding them 220. The speakers even when they are rattling they do not distort at all. The bass is very clean but they have a rattle. My pre-pro is the B&K Ref 50. There is a built in EQ in my Ref50 which has a loudness setting which I do not use. I set it to variable. I have used all factory pre-sets for crossover slope etc. I have a Velodyne Spl-1200 series 2 sub with its own amplifier built in. What is weird is that the Center channel has a tweater and two exact drivers for which the crossover deplicts what signals the speakers recieve. The speaker recieving the bass information rattles, the driver recieving some bass information and vocal information does not rattle BUT it has the same excurssion as the bass driver when turned up loud enough to move the speaker. I was told that at the CES show after hours that they hooked the same speakers up that I have to seperate 500 watt monblock amps and tried to blow them and could not. I feel I am in the twilight zone. What do you think now Joe.......anybody else have any information or ideas?

Thanks,
Craig

 

[Az B]

I've run into this before with DIY speakers. It would rattle like the woofer was blown with very low frequencies... rarely with music but several movies could get it to rattling even with low SPLs. We swapped drivers, reconed drivers, bolstered the cabinet, sealed the cabinet again, and it was finally solved by plugging one of the ports. It was very odd since both cabinets were indentical, but only one did it.

At any rate, try plugging the port and see what happens. Even if this is not a solution, it's a step towards finding out what's causing it.

 

[Rob Babcock]

Are you dead certain it's the drivers and not something being excited within the listening room? You'll often find certain freqs where your room will really rattle.

 

[JoeE SP9]

Maybe I'm missing something here, but I still would like to know what you are using to drive your center channel speaker. Have you tried to run a phantom center?

 

[Grey Ghost]

Joe,
My center channel power supply is a B&K ref3220 amp with 220 watts per channel. My center channel is rated at 200 watts RMS. All speakers are hooked up to two different amps my 3220 & my 2220 all speakers woofers have the rattle. Do you guys think it might be my Pre-amp that is sending a bad lower frequency to my woofers? Thanks for your inputs guys...

Grey Ghost

 

[toquemon]

I have no idea of what is happening, but, in a logical basis, i would start by eliminating possibilities: try the speakers with other amps, thy the amps with other speakers, thy the preamp with other amps....until you find what is going on. Every time i do this tipe of analysis, generally i solve the problem.

Cheers!

 

[mtrycrafts]

Usually woofer rattling or bottoming out is an indication of too much power. Clipping usually results in blown tweeters or tweeter fuses. Did you always have this problem or is it a recent occurance? What kind of pre/proc are you using? Are you using any eq or bass compensation? Have you tried another power amp? What are you using to drive the center speaker? You have only mentioned 4 channels of amplification. What kind of sub if any do you have and how is it powered?

If I remember correctly reading somewhere else, clipping doesn't blow tweeters, but over powering it certainly will. Try it sometime. Send a high frequency sine wave to the tweeter until you cannot hear it anymore, then from that volume setting increase the volume. You will be surprized how quickly it blows about 20watts. Certainly will not take the max power of the speakers ratings.

 

[mtrycrafts]

I have had all speakers for about 3 months now. Every bass driver in all of my speakers have a "Rattle" in them starting at 1/8" excurrsion. Kevin at Von Schweikert has stated that I am the first to have this problem.

Isn't it amazing how many companies respond like this? I am alwasy the first one to bring broblems to their attention. Amazing. No one else compalins I guess, even after many years on the market.


They only make this noise at louder volumes.

How loud is loud? What spl levels?

Kevin stated that maybe the speaker had been dropped during shipping which made the magnets decouple from the basket

All five was dropped? Curious.

so Kevin sent me 1 brand new woofer to swap out to see if it fixed the problem. The brand new woofer sent immediatly started to rattle.

Either they have a production problem, unlikely, or you are driving them too hard?


I am sending back all bass units to Von Schweikert for analazis because this has never happen to them.

If you have an spl meter, you should let them know at what level this happens.

I have both amps on line conditioners but do not have them hooked into voltage regulators that help maintain 120 volts. Could my home voltage be dipping way down causing a clipping signal to be sent during high volumes?

Unlikely but if you have a volt meter, check it.



Kevin also stated that they had 500 watts going to each VR4jr at one of the shows. For fun they tried to blow the speakers but failed to do so. I am stumped! Please help with ideas or recomendations.

Need more investigation, a visual inspection of the drivers?

If you feel I need a voltage regulator which brand do you propose I get at or under $1,000 dollars.......

Most likely not your problem.

 

[JoeE SP9]

If I remember correctly reading somewhere else, clipping doesn't blow tweeters, but over powering it certainly will. Try it sometime. Send a high frequency sine wave to the tweeter until you cannot hear it anymore, then from that volume setting increase the volume. You will be surprized how quickly it blows about 20watts. Certainly will not take the max power of the speakers ratings.

In most cases when tweeters are blown on a speaker system it is because of insufficient power in the amplifier which causes it to clip thus sending an ultrasonic pulse down the speaker wire causing the tweeters to blow. An access of power in a speaker sytem usually manifests itself as woofer rattling and bottoming out. The resulting very audible noise and distortion causes one to lower the volume.

 

[Grey Ghost]

Thanks for all of your inputs. All woofers in my speakers rattle starting at 1/8" excurrsion. At -15 on my volume control the rattle is apparent. At volume 0 the rattle is still present but not much worse. The woofers do not distort nor can I make them. I have never had my volume control past +5 and usually play normally at -15.

I will be running a test when my woofers return next week. I will be running my analog cable from my DVD player directly to the back of my 3220 amp. I have a gain control on my amp and will adjust it to see if I can here the rattle then. If the rattle is not present then it is my Ref 50 sending a distorted signal somewhere in the lower frequencies. I feel this is the problem and not the speakers. What brings me to this conclusion is that my center channel has a midrange tweater and a woofer the woofer and the midrange are the exact same speaker BUT they recieve different information from the cross over. Even though they recieve a different frequency to reproduce their excurrsion is identical at higher volumes. The mid range does not rattle but the woofer does......I will post the solution when it has been pin pointed. Just a very irratating process....

Thanks for all of your inputs,
Craig Elder
Grey Ghost

 

[mtrycrafts]

In most cases when tweeters are blown on a speaker system it is because of insufficient power in the amplifier which causes it to clip thus sending an ultrasonic pulse down the speaker wire causing the tweeters to blow. An access of power in a speaker sytem usually manifests itself as woofer rattling and bottoming out. The resulting very audible noise and distortion causes one to lower the volume.

Ah, but if the power is in the high frequency band, your woofer will not show any anomaly and your tweeter is up in smoke.
I need to check and save the page on clipping and tweeters.

http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/clipping/page1.html

http://www.rane.com/note128.html

http://sound.westhost.com/tweeters.htm

It appears that tweeters are over powered first, well before clipping happens. Tweeters are low power units.

 

[dreadstar]

To much power?

It is possible you have the bass settings on your DSP set to high thus sending a high level of bass to the drivers on your mains. try different settings.

Your amps are more than strong enough to cause severe excursions on your woofers if the frequency going to them is at the resonance of the cabinet they are enclosed in.

Are your speakers ported or sealed and if ported what type of encloser? And how are they damped?

Having more power than required has always been my choice. To little can cause alot more problems