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Did Fleetwood Mac's "The Chain" blow up my woofer?

System: Ortofon 2M Red > Musical Surrounding Phonomena II > PS Audio Stellar preamp > M700 monoblocks > Buchardt S400 

Phonomena is set to 46db of gain, 200pF capacitive, 50k Ohms resistive

The other day I was playing "The Chain" off of Rumors, and one of the woofers stopped entirely during the bass guitar interlude. It just went completely silent, no pops, crackles or distortion. The tweeter is fine, and I reversed the L and R channels to confirm this problem is in the right woofer. The volume level was a "strong" listening level (30 out of 100 on the Stellar), but not loud. We were still able to converse just fine without raising our voices much at all. I have certainly listened to these speakers much louder with other sources.

I understand the power amps are overkill, but I figured my ears would bleed far before I was in danger of blowing anything up. Was this distortion? Subsonics? Woofer pumping due to poor TT isolation? Or a simple defect in the driver?


jayy42
stereo5's avatar
stereo5
6,385 posts
 
Yes, right out of the box and stock, the Technics took care of the rumble problem and no more woofer pumping at all!  I LOVE both the Oracle mat and the HRS weight.  I owe those 2 tweaks to you and I am very grateful.
gregdude
222 posts
 
Use your nose, no smell means not blown. Probably a loose wire, you may not need the replacement woofer.
jayy42 OP
4 posts
 
No smell that I could detect and no loose leads on the woofer.

Interesting that the DD turntable stopped the woofer pumping issue. Do you think it was truly the DD motor that made the difference, or just a different tonearm/cartridge pairing? 

How do I tell if I have woofer pumping without risking blowing up the driver? I think I will have to go the KAB rumble filter route for now and I will continue to work on TT isolation. 
audiorusty
270 posts
 
Hey Jayy42

I spent many years in live audio and have blown up more woofers than I care to remember. When ever we thought we had possibly blown a speaker our first test was always to push back and forth on the paper cone with our finger tips. If there was no movement or we felt resistance and heard a scrapping noise while pushing, the speaker was toast. If it moves freely your issue is elsewhere.

I also have a DD turntable and tonearm that are about 40 years old and have very poor damping properties and I have serious issues with rumble and speaker pumping. The first thing I did was make sure the the turntable was level. This alone improved the issue. I then purchased some isolation pads from amazon for about $8.00 for four. The ones I purchased were 4" square and are comprised of a piece of cork sandwiched between two layers of black rubber and are about 1" thick. Placing these pads under my turntable if they did not eliminate the rumble issue they greatly reduced the problem to the point that I no longer notice the issue.
mulveling's avatar
mulveling
1,895 posts
 
If you have woofer pumping it should be visible, because the woofers will be moving a great distance at sub-sonic frequencies. Sometimes lighting can highlight the issue. When I upgraded my rack & turntable to the current ones, absolutely all traces of woofer pumping completely vanished - not that it was too bad before. It can be either your turntable, or lack of isolation, setup, or any combination. If everything is right, a rumble filter will not be necessary.

And my tech also checks the woofer's freedom of motion - if that's all good your woofer's mechanics are usually OK. 
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