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
It could be excessive low frequency from the cartridge. Do you use a rumble filter?
No filter - just strait from the TT > Phono stage > Preamp. I have heard this suggestion before. I am reluctant to add a filter. I have never needed one before but this system combo is new. 
Wait, did you remove the woofer, or swap speakers?

It could be a crossover component that has gone bad.
I swapped the L and R speaker wires to confirm the problem exists within the speaker. 
Here is a pic of the crossover, if you can get to it and have a meter I would ohm out those resistors.

forgot link
https://www.buchardtaudio.com/shop/s400-black
Fortunately, resistors in a crossover that go bad tend to turn black, along with nearby parts suffering from too much heat, so a visual inspection is often helpful.

But swap the woofers, that will tell you if it truly is the woofer or a crossover issue.

I have blown up woofers before due to pumping when using a turntable.  This can happen at lower volumes than when using other sources. 

If you (gently) push against the woofer and feel resistance / scraping it's probably the woofer.

Once you get the speaker fixed, see if you can fix the rumble problem with a filter, better isolation (my first choice), etc. or you're likely to do it again.
I suspect woofer pumping is the culprit here, but I am seeking advice. Right now the components are stacked on the floor while I wait for my new media console. 

I didn't see any burn marks on the woofer or the stuffing around the crossover. I have a new woofer unit on the way. 

I am thinking about a maple shelf with sorbothane feet on which to place the TT along with a KAB RF-1 filter. Hoping that will eliminate the potential for rumble/pumping in the future. I already have sorbothane pucks between the speakers and the stands. 
Fortunately, resistors in a crossover that go bad tend to turn black, along with nearby parts suffering from too much heat, so a visual inspection is often helpful.
These are large ceramic power resistors. I don't think that they usually turn black, at least I know that I have seen them when they didn't.

Doesn't look like these speakers have any fuses, so hopefully they designed them with at least one of these fuses as the weak link.
Well you "blew up" one and not both so that points to defective woofer or crossover in the one that blew. Talk to the manufacturer and see if they can replace. Or you can take the problematic woofer out of the enclosure and use a 9 volt battery briefly touched to the terminals to see if the cone will move. That will tell you if the coil is burned or if it's a crossover problem.
You could also measure the woofer with an ohm meter. Should be around 8 ohms (typical). I've found the best solution for TT isolation is a wall shelf. Rega sells one for not huge money and you can buy or build a simple plywood shelf to sit on this if your TT is not a Rega.
Good Luck.
This happened to one of my big Tannoys a year ago. Turns out a lead wire to the woofer became disconnected. Most likely the lead came from the factory with a marginal physical connection, and the large amounts of energy thrown around the cabinet during loud listening  (96 dB/ Watt efficient and 15" woofer) eventually shook it loose. Simple to resolve; my tech fixed it easily, and it's worked perfectly since then. No permanent damage to the woofer.

As noted by others, you'll want to make sure you don't have a rumble issue (my current system has absolutely no rumble or woofer flapping). That's extra energy that can only have deleterious effect. 
Post removed 
I used to have rumble problems with all 3 of my VPI tables and nothing worked to get rid of it except a KAB rumble filter for $179.00. My new Technics DD turntable has alleviated the problem so I no longer use the filter.
Did the Technics TT,  stock , out of the box alleviate the problem? Are you still happy with your Oracle mat and HRS record weight ?
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.
Use your nose, no smell means not blown. Probably a loose wire, you may not need the replacement woofer.
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. 
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.
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. 
PS - Another quick test is to use a 1.5 or 9 V battery on the woofer.

It either moves, or it doesn't.

Perfectly safe for all drivers.


I highly recommend the KAB RF-1. It is unique and does more than your average rumble filter. Check it out on his website. I have had one in my analog chain since about 2011.  Can't live without it since I have two subs which I run with my vinyl. It rocks! Dana
no  ,   your amp did  dirty
in dirty out  
This post is the equivalent of..... "My woofer stopped working, what's wrong?".   No other words are needed.  It doesn't matter what you were playing.  Put a meter on the woofer and see if it has resistance.  Put a battery on it and see if it moves.  Either the woofer died, or it became disconnected.  It's very unlikely to be anything in the crossover.

Best of luck!
Post removed