M&K MX5000 MK II: Popping sound is blown driver(s)?

A truly "blown" driver won't make any noise...just like a "blown" light bulb doesn't produce light.

Popping makes me think amp clipping. I know you turned down the signal in your Denon, but did you check the gain controls on the amp itself? Maybe the girls wanted a little more bass and the volume knob is the answer. Either way, you might want to walk through your channel calibrations just to eliminate that variable.

To check for a deformed voice coil, you can gently apply even pressure to the cone. Feel for any uneven resistance and listen for scratchy sounds. Alternately, remove the drivers and connect to a battery to excercise them a bit...again observing for unusual noise/motion.

With internal cabinet volume, we might could identify a driver that would work satisfactorily. However, any custom EQ M&K built into the amp is an unknown quantity that may or may not work well with a DIY replacement.

There's a member around here who was an M&K technician or engineer...maybe he'll chime in.

-Brent

Try switching the phase control switches on the back. I have messed with the phase switch while playing some material and has caused a loud "thump" before, so I'm wondering if the amp is the culprit. There was a thread at some point in here on how to clean the switches on the back as they have had some problems over time.

For now, I would remember where you have the switches and flip them up and down a couple of times. Then, play some of the material that is causing the popping sounds and hang out by the sub. Slowly "press" the dip-switches "in" not up or down, and see if you hear the pop come or go. I know it sounds crazy, but I remember people having the same problem.

There are a number of somewhat esoteric things that can overall contribute to that popping sound.

Yes, the amp clipping is certainly one of them, but most of the time NOT the culprit.

You are probably hearing one of the drivers bottoming BECAUSE it does not have enough air pressure to work AGAINST.

The DUAL driver M&K's have the bottom driver MECHANICALLY inverted and electrically inverted as well. The NET result of this, (and EVERYBODY has trouble with this concept,) is that both drivere are IN PHASE ACOUSTICALLY, that is, the cabinet is "acting" as if it were a point source. Both CONES are moving away from the cabinet at the same instant. The cabinet is not ported, but rather the drivers are coupled to the same "space inside", and of course this means the drivers are airtight the way they are coupled to the box. (and everything mounted to the box must be airtight, as well)

Therefore if one driver (for example the bottom facing one) gets a rip in it, or the edge might tear, etc then the other driver now will not have any back air pressure to work against, and therefore IT will bottom. Therefore the driver that is popping is probably the GOOD ONE!
IF one of the cones bottoms for a long time at high volume, then WHILE it is bottomed it is drawing more current which means it is getting hotter. Eventually this will lead to the coil being harmed in some way, up to and including smoldering... Hey, if you haven't been to a rock concert where the sub cabinets have caught on fire you haven't lived !

The drivers used in the 5000 were rather amazing custom drivers made by Sanyo, with a rather unusual (especially for 15+ years ago...) magnet and shorting ring design. Do not be misled by what "looks" like a rather small gold-iridite colored back can over the back of the magnet assembly.

I suggest laying the unit on its side, take off the front grille, and feed it a nice 15 Hz signal from a test CD. Feed the CD player (or an MP3 player with the mp3 file burned onto an SD card, whatever) right into the sub directly and of course slowly advance the volume control on the sub with the filters off. Watch BOTH drivers at the same time. You should immediately be able to discern if one of the drivers is bad, or ripped, or whatever.

if you need test signals burn your own from here:
http://www.realmofexcursion.com/downloads.htm
or here:
http://www.realtraps.com/test-cd.htm

Of course it's possible it's something else or additionally wrong, but from my experience the failures of that sub were very few indeed, and I know studios who beat the daylights out of those subs for years doing rap mixes with no problems .

Now here's the sad news... that driver is not available, and I'm sorry but I don't know what part number (of anybody's driver) to suggest.
Chris Hagen might know, but I haven't seen him on here in quite sometime.

IF, while doing this, there might be a problem with the volume control or one of the other pots on the backplate, the instructions to clean that up are here:
http://www.soundoctor.com/service/

Good luck,
Barry

Hi Wayne,

I came upon your thread by accident. But my MKII problem sounds very similar to mine. I own a pair of MK IIs and both are plagued by dust buildup on the volume controls. I have to unbolt the back panel so that I can access the volume panpot and give it a good clean. ( I use some sort of a lubricant I can get you the name if you like) I then give the volume several good twists and attempt to wipe up any residue. After that the sub is good to go.

Hopefully this helps you out.

Regards,

Mike

Sorry to be a bearer of bad news but the popping sound from your sub means that your sub cannot handle really low frequency base (LFE). Your sub is "bottoming out".
Good news is that your sub's drivers are not damaged yet, the bad news is that you would need a bigger badder sub. Take a look at the HSU, SVS, EPIK, or AV123 subs.

The only temporary fix for this is to lower your AVR's gain significantly.

I had the same issue with my old sub until someone on this forum explained my problem to me, and I endede up upgrading to a HSU VTF-3 MK3 sub, and no more bottoming out for me.

I have never had any problems with my MX5000 MK II subs bottoming out. The MX5000 MK II can take a pretty decent beating. With that being said an upgrade to badder subs would be an option but Wayne probably paid a pretty penny for it. Hopefully Wayne does not have any serious problems with his sub.

What brought me to this older thread was an internet search.

I have a pair M&K's 350 powered subs that I have had in service for 4 years. I purchased one of them from a local M&K authorized dealer and the second one from an internet M&K distributor. They seem to have two different drivers based on the silk screen labeling on the cones and the cabinets are slightly different.

Today, right in the middle of watching the Eagle's "When Hell Freezes Over" DVD the sub behind the couch started popping in sinc with the bass drum. That happens to be the unit I bought from the authorized M&K dealer. Like the original poster of this thread, to stop the noise I have to turn the sub down so low it's pointless to have it on at all. The other sub works fine, and I've tried the switches on the back for phasing, etc., and it doesn't help.

One responder to this thread suggested a better sub, but in my mind I haven't come across any that I would call better than the 350 or 5000 M&K's. These speakers have been flawless even at the highest volume levels with a variety of action movies and musicals. At times I though the drywall was literally coming down. Maybe I wore it out?

I'm going to see what the experts recommend as hope to find and fix the problem. Thanks for your time.

Hi Wayne,

Don't fret my friend, I'll lay money on the fact that one of your drivers has a rip in the surround ...... just as soundoctor predicted. I say this with confidence as my THX 5000 have just encountered the exact same symptoms and they are now back safely in my HT room after being repaired by my friend who just happens to re roll speakers for a living.

He warned me several months ago that he had re rolled about 5 THX 5000's in the past year that were all about the same age as mine (10 years) and he thought mine would "go" any time soon. One night while listening to a DVD at a very moderate level I heard the exact same "popping" noise you spoke of....more of a "crack" really. I immediately stopped the disc, grabbed a torch and very carefully examined the surrounds. At first I couldn't see any damaged but when I very gently ran my finger around the surround my finger went straight through a small tear at the very top of the forward facing driver.

I removed the drivers the next day and took them to my friend who had them re rolled, with a double excersion surround, within 48 hours. I re installed them that night and very nerviously played a test disc at a low level gradually increasing the volume as my confidence grew.

To my amazement they sounded tighter and deeper than ever before, they truely are an amazing sub and I'm yet to hear anything that comes close.... at any price point!

So take it from me, run your fingers around the surrounds (the bottom speaker will need to be removed to do this properly) and when you confirm they are torn (at least one will be) take them to a trusted speaker repairer and spend the lousy $200 it'll cost to get them repaired and you'll be enjoying the best bass in the business for at least another 10 years.

My very long winded 10 cents worth.

Peter

Can you recommend a speaker repair service in the Northest, preferrably the upstate NY area ? I m in Warwick, NY 10990.

Thanks,

Joe

FYI I have the MX-150THX and starting having the same popping sound the above owner describes. I found that the bottom magnet on both of my woofers had separated from the woofer. I just used a glue gun and problem solved.