Jump to content
The Klipsch Audio Community
Sign in to follow this  
Jeff Matthews

Cornwall woofer flutters at specific frequency

Recommended Posts

Do I have a bad speaker or what? The left woofer on my Cornwalls will flutter when a specific bass frequency is hit. I know it's the same frequency because the stanzas in a tune repeat for the bass guitar, and it will flutter on particular songs at the same note in repeating stanzas. It sounds a little bit like bending one of those spring door stops and letting it go. Doy-y-y-y-y-y-ing. The flutter lasts as long as the note... or less, so it's not like the system sounds bad all the time. Actually, it plays great on most everything.... Just that certain frequency.

Share this post


Link to post
Share on other sites

He's joking! He's joking!

Have you absolutely ruled out objects near your speaker that could be vibrating at that frequency? When I play certain movies with big low freq effects, various things in my room will buzz at certain freqs and volume levels. Is any part of the grille loose? Woofer mounting screws are tight? Back cover is tight? Sorry I don't have anything else to offer.

Share this post


Link to post
Share on other sites

more system info ...

preamp..?? microphonic tube ...??

scraping V.C. ....???

are you perhaps bottoming the Woofer ..???

crossover parts hangin loose..?? gotta open that cab

Share this post


Link to post
Share on other sites

"Crossover parts hanging loose...??" That's the best bet...

Based on your description of the sound I will guess that speaker wires inside the box going to the woofer are touching something - maybe the back of the cone itself. It may be just a few millimeters from touching and only buzzes with an excursion that comes back to meet it. You might try (very carefully) to press the woofer back a bit and see if it feels or sounds like its touching anything? If you try this, you want to press the cone part of the woofer with the sides of both hands to spread the pressure - make sure your hands are clean. The safer approach would be to take a direct look at the wires behind the woofer...

Paul

Share this post


Link to post
Share on other sites

Thanks for your suggestions. I'll take a look inside the cabinet. It is definitely not some other object. It is the speaker or something inside. Grills are actually linen material stapled to box and trimmed. All is tight outside. I'll check inside.

Somebody wanted to know other components. Crown Microtech 1200 amp. Yamaha pre-amp (I'd have to look at model, but it's good (and just a pre-amp anyway). Ands a decent Harmon Kardon CD-Player (single disc).

I'll post again after I look inside.

Share this post


Link to post
Share on other sites

I had a simular experiance with one of my Khorns about 15 years

ago. One particular frequency made the speaker sound like it was

self destructing. Not a super low frequency either, I would

say it was probably 80 -100hz or so.

I took in my bass bin to the local dealer, and they could not reproduce

the symptoms untill they played the woofer in the open air. I

ended up just replacing the driver.

JM

Share this post


Link to post
Share on other sites

I suspect your music is hitting the resonance of the system, which will

vary somehat between drivers. The CW is tuned to about 38 Hz .

This stanza could be exciting the system resonance in a big way. If you

are really freaked out, get both woofers replaced with a matched pair.

It is possible that your "flapping woofer" is developing a problem with

the surround or spider, but, short of abuse, that is a rare thing for a

K33.

Share this post


Link to post
Share on other sites

I had a Klipsch Chorus that sounded similar to what you described and it was one wire turn of the voice coil toward the back of the voice coil that had come loose. I replaced the woofer at that time.

Definitely search for anything loose in the speaker and if nothing else try swapping the woofers of the left and right speakers and see if the problem swaps.

mike[:)]

Share this post


Link to post
Share on other sites

Just a thought , could this have anything to do with the standing wave problems that I have read about here on the forum ? Ie. the reason they changed the woofer position in the new Cornwall .

Share this post


Link to post
Share on other sites

An old soundman's trick-- Try rotating the bass driver by 90 degrees or 180 degrees. If you are having a problem with the voice coil, spider or suspension, that might change the stress patterns on the woofer enough to cause the problem to disappear or get worse. If so, replacement is indicated. The woofers have a lot of moving mass suspended compared to smaller drivers and over time, the effects of gravity and use can take a toll.

Share this post


Link to post
Share on other sites

When I got my used Cornwalls, I noticed one would make a flatulating sound (not to be funny) when I turned it up. Come to find out, when I ran my hand along the back of the cabinet, there was air coming out with the hard hittin bass. Just tighten them up. I put window sealer on mine.

jc

Share this post


Link to post
Share on other sites

Have you tried that CD on another system? On several occasions I have got all worked up over a "problem" only to discover that the flaw was actually something that had been recorded. Once, I had a K-horn in all its pieces for the second time in as many days when I decided to go listen to the disk on my wife's car system. Oops! There it was.

This is the reason I get annoyed at some of our brothers who are always tweaking with their Klipsch gear. They hear something that sounds "suspicious". It must be time to recap the crossovers! The truth is that most CDs are grossly over-mixed which bleeds much of the life from the sound. Others are just sloppy. In your case, maybe it was the musician's woofer and not yours!

I hope I'm right. It'll save you a lot of time and money.

DRBILL

Share this post


Link to post
Share on other sites

When I worked for a Klipsch dealer as a tech, I saw the problem you describe twice... the first time was a customers unit, a CW I, and I found leaks along the baffle board. I was able to seal it by tightening the screws on the supports and applying wood glue. The second one was my beautiful 'busy grain Oak ' CW II's (1985)... which were purchased with the employee discount. After about a year, I got a terrible fluttering sound at certain bass frequencies. I discovered that the cabinet had warped and split in the seams. Jim Hunter later informed me that they had purchased some wood that was incorrectly stored and it later developed warps. They replaced the speakers with a new pair, also 'busy grain Oak', and included 'matched' drivers with B&K spectrum analyzer response curves.

Anyway, if you have access to an oscillator, try to find the offending frequency and play detective.

Dave

Share this post


Link to post
Share on other sites

Seriously have you traded the speaker wires speaker to speaker to see if it follows a channel in your system to confirm this is something that the woofer is doing or the system is doing it to the woofer?

Craig

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...