M&K 12" woofers, Who's got em'? MX-100 repaired but still not working!!

[Seth=L]

I Googled for a bit and found nothing helpful. I was wondering if anyone knows where to find new or used M&K drivers for sale. If anyone here is willing to part with their extra M&K woofers,...John, I wouldn't mind negotiating a price.

I took my M&K in for repairs and I brought it home and tested it. When it was running at lower levels it was fine, I pushed it hard (not to the point of distortion) and after only a few moments if failed. The fuses blew again, I replaced them and the sub exhibited a humming noise and the amplifier 1 fuse lit up and blew.

One last detail. The repair shop put 3 amp fuses into the amp, there are two fuses in the amp and one AC-line fuse rated for 4 amps. I am not certain what rating the internal fuses were supposed to be, but the service tech told me it did not matter what size it was so long as it covered the amperage to run the amp. They told me it would be OK to put 8 amp fuses in the amp, and that it would not harm the amplifier. I just wanted to verify this with you guys.

 

[j_garcia]

WTF? Sounds like it is time for a new sub...

There is an MX-150 on A'gon. Or check eBay for another 100 for parts?

 

[Seth=L]

I do not wish to part with the M&K.

 

[mtrycrafts]

I took my M&K in for repairs and I brought it home and tested it. When it was running at lower levels it was fine, I pushed it hard (not to the point of distortion) and after only a few moments if failed. The fuses blew again, I replaced them and the sub exhibited a humming noise and the amplifier 1 fuse lit up and blew.

One last detail. The repair shop put 3 amp fuses into the amp, there are two fuses in the amp and one AC-line fuse rated for 4 amps. I am not certain what rating the internal fuses were supposed to be, but the service tech told me it did not matter what size it was so long as it covered the amperage to run the amp. They told me it would be OK to put 8 amp fuses in the amp, and that it would not harm the amplifier. I just wanted to verify this with you guys.

Did you by chance measure the spl level where the sub was about to go belly up? Maybe you have reached its limits?

I would not mess with that fuse IF the original was 4A from the factory.

 

[Jack Hammer]

drivers pop up regularly on eBay. But as mentioned, you can pick up a nice used mx150 on audiogon for a good price. I've seen them go for as low as $500.

Did the repair shop see why the fuses keep blowing? Or did they just replace the fuses and 'send you on your way'? If it's that easy to blow them, they should have no problem replicating it. Maybe you should take it back to the shop.

Jack

 

[j_garcia]

To me, it sounds like you need a replacement amp, which is why I would either look for another working 100 on eBay and such that either works and keep yours for parts or buy another one for parts for yours.

 

[Seth=L]

If the drivers are bad, damaged former more than likely, it would be cheaper to get the drivers replaced than purchasing another whole subwoofer. The Selection of M&K subs on Audiogon is sparce and the cheapest one they have looks like it may have more issues than mine. The seller posted "as-is" and seller also states "does not know how to test it". This kind of jargon means dead sub to me, and is not worth the risk.

Mtrycrafts, you may be very well correct. I believe it is slightly more complicated though. If the former is deformed, it is deformed at the base. When the sub blew the first time the coil slammed against the magnet structure untill the capacitors emptied, it made an awful noise that I have no desire to ever hear again.

I will just keep an eye out for the 12" woofers and in the meantime watch how loud I use the sub.

 

[SoundSitter]

M&K woofers available

Howdy, I stumbled on this thread while doing some research on google. If any body still want to buy M&K sound sub woofers they are available from
mavin.com I have bought some parts from them and they are real nice people to do business with.

 

[TLS Guy]

I Googled for a bit and found nothing helpful. I was wondering if anyone knows where to find new or used M&K drivers for sale. If anyone here is willing to part with their extra M&K woofers,...John, I wouldn't mind negotiating a price.

I took my M&K in for repairs and I brought it home and tested it. When it was running at lower levels it was fine, I pushed it hard (not to the point of distortion) and after only a few moments if failed. The fuses blew again, I replaced them and the sub exhibited a humming noise and the amplifier 1 fuse lit up and blew.

One last detail. The repair shop put 3 amp fuses into the amp, there are two fuses in the amp and one AC-line fuse rated for 4 amps. I am not certain what rating the internal fuses were supposed to be, but the service tech told me it did not matter what size it was so long as it covered the amperage to run the amp. They told me it would be OK to put 8 amp fuses in the amp, and that it would not harm the amplifier. I just wanted to verify this with you guys.

Run fast from that tech! He will burn your house down! The idiot has not serviced the wrong part. The problem is not the driver, it is the amp.

I notice a disproportionate number of posts about serious problems with M & K subs. Obviously they are problem units.

 

[Seth=L]

Way to revive an old thread. I am much better educated when it comes to this sort of thing now. Obviously overrated fuses can only end with one result, damaged amplifier. That tech was an idiot.

The subwoofer worked great when I bought, for many months. When it blew the first time it happened under an extreme situation. Since then it blew I think 3 times under situations that shouldn't have caused it, which means when they "repaired" the amplifier the first time they made it worse by using the incorrect fuse rating. Then they where stupid again by just replacing the same part that went the first time (output IC device) and not bothering to test the rest of the amplifier's circuits for damage that was caused by the overage in current it had received due to an incorrect fuse value.

Needless to say I am very displeased with the business that "repaired" the subwoofer. The subwoofer is still broken.

 

[highfigh]

I Googled for a bit and found nothing helpful. I was wondering if anyone knows where to find new or used M&K drivers for sale. If anyone here is willing to part with their extra M&K woofers,...John, I wouldn't mind negotiating a price.

I took my M&K in for repairs and I brought it home and tested it. When it was running at lower levels it was fine, I pushed it hard (not to the point of distortion) and after only a few moments if failed. The fuses blew again, I replaced them and the sub exhibited a humming noise and the amplifier 1 fuse lit up and blew.

One last detail. The repair shop put 3 amp fuses into the amp, there are two fuses in the amp and one AC-line fuse rated for 4 amps. I am not certain what rating the internal fuses were supposed to be, but the service tech told me it did not matter what size it was so long as it covered the amperage to run the amp. They told me it would be OK to put 8 amp fuses in the amp, and that it would not harm the amplifier. I just wanted to verify this with you guys.

That guy needs to stop "repairing" equipment. Putting a fuse in with an excessively high current rating is a good way to burn components that wouldn't burn if the correct size was installed. Circuit traces will burn open before the fuse blows, in many cases. What he told you is BS. This qualifies as a "rework" because, if it was actually repaired correctly, it wouldn't have failed when you turned it on. Ask if they have a service warranty and if they don't, get a refund. If he's the owner, go to the BBB.

Sorry, I have no tolerance for people who don't do their job, especially when they charge for it. I have worked for 4 different electronics dealers and two A/V contractors- this doesn't fly. Putting an 8A fuse in amounts to wrapping it with tin foil and you see the same result- damage to the circuit it's supposed to protect.

 

[highfigh]

If the drivers are bad, damaged former more than likely, it would be cheaper to get the drivers replaced than purchasing another whole subwoofer. The Selection of M&K subs on Audiogon is sparce and the cheapest one they have looks like it may have more issues than mine. The seller posted "as-is" and seller also states "does not know how to test it". This kind of jargon means dead sub to me, and is not worth the risk.

Mtrycrafts, you may be very well correct. I believe it is slightly more complicated though. If the former is deformed, it is deformed at the base. When the sub blew the first time the coil slammed against the magnet structure untill the capacitors emptied, it made an awful noise that I have no desire to ever hear again.

I will just keep an eye out for the 12" woofers and in the meantime watch how loud I use the sub.

Why not have it reconed, if it's actually the driver?

If the cone clammed back and stayed there, the amp passed DC and that's not an indication that it was repaired properly. That shop owes you a speaker AND the proper repair of the amp. If they hadn't given it back to you this way, your speaker would be fine.

 

[TLS Guy]

If the drivers are bad, damaged former more than likely, it would be cheaper to get the drivers replaced than purchasing another whole subwoofer. The Selection of M&K subs on Audiogon is sparce and the cheapest one they have looks like it may have more issues than mine. The seller posted "as-is" and seller also states "does not know how to test it". This kind of jargon means dead sub to me, and is not worth the risk.

Mtrycrafts, you may be very well correct. I believe it is slightly more complicated though. If the former is deformed, it is deformed at the base. When the sub blew the first time the coil slammed against the magnet structure untill the capacitors emptied, it made an awful noise that I have no desire to ever hear again.

I will just keep an eye out for the 12" woofers and in the meantime watch how loud I use the sub.

From what you say in this post Seth, it is possible you need a speaker and amp.

What you describe about the coil slamming against the magnet and making an awful noise, means that there was a massive DC offset caused by the amp failure. This should never happen on a properly designed amp. There should always be a circuit to prevent DC offset getting to a speaker. An amp that does not have DC offset protection, is frankly dangerous and unacceptable. Most cases of failure of solid state power amps involve DC offset, so protection is crucial.

Now you can tell if you woofer has been damaged by this, and it probably has. If the former is damaged you should be able to feel gap rub. You will fell grating as you gently press the cone in and out.

The other thing that can happen to a driver after a DC offset episode, is shorting of coil turns, due to burning of the insulation on the voice coil wire. To check for this measure the DC resistance of the driver. It should not be less than 3.2 Ohms. If it is it needs re coning, or will keep frying the amp.

Now you may love that sub, but you have given enough information, to squarely place the amps in those subs, in the junk never to be used category.

If you insist on salvaging that sub, you need to have the driver re coned or replaced, if you can show that the voice coil is damaged.

Amp repair, or a replacement amp is not a sensible option. If you want to salvage it, then modifying the sub to take a different amp is mandatory.

Whenever I come across an amp with no DC protection, it gets modified so that it has, or goes to the recycling center, just on grounds of safety alone.

Powerful amps with no DC offset protection are dangerous period.

 

[Jack Hammer]

FTR I really I'm really not in a position to speak from any sort of authoritative or otherwise expert position, either professional or otherwise. That said, I really like M&K's products, I own several of their speakers and subs and have nothing but the highest regard for them. I really hope you are able at some point to be able to fix your sub at a reasonable cost. However, If the cost to benefit ratio doesn't look good, perhaps you should consider moving on and looking at something else. Only you can really decide what is best.

Jack

 

[mike_wassell]

Contact Ken Kreisel at kkmksound@aol.com. He is the K in M&K. I have 4 M&K subs and have contacted him a couple of times. He has always been very helpful and replied quickly.

Mike

 

[TLS Guy]

FTR I really I'm really not in a position to speak from any sort of authoritative or otherwise expert position, either professional or otherwise. That said, I really like M&K's products, I own several of their speakers and subs and have nothing but the highest regard for them. I really hope you are able at some point to be able to fix your sub at a reasonable cost. However, If the cost to benefit ratio doesn't look good, perhaps you should consider moving on and looking at something else. Only you can really decide what is best.

Jack

I have done some digging as to why M & K failed, and filed chapter 7 in Feb 2007.

Of all things it was because of counterfeit goods from China. Apparently there was a flood of product that looked identical to M & K but was junk. It was turning up for service and they never made it!

There was a huge amount sold on the Internet, and it was junk. So that may explain why there as been a lot of postings about failed M & K subs.

Any M & K product bought on the net prior to closure, has a good chance of not being M & K product apparently.

 

[Jack Hammer]

I hadn't heard how to tell if the subs were legit or not. The phony speakers looked identical on the outside, but if you took off the back and looked at the crossover it was readily apparent. The fake crossover was really cheap looking and poorly made.

Jack

 

[Seth=L]

Thanks, that's something I plan on doing.

TLS guy, the woofers aren't rubbing when the cones are pushed. I will have to test the resistance of each driver when I get the chance. They are DVCs, is their a specific way to do this test?

 

[mike_wassell]

Contact Ken Kreisel at kkmksound@aol.com. He is the K in M&K. I have 4 M&K subs and have contacted him a couple of times. He has always been very helpful and replied quickly.

Mike

I should have mentioned that this email address is current. I communicated with Ken about 2 weeks concerning a defective volume control on my M&K MX-350.

Mike

 

[TLS Guy]

Thanks, that's something I plan on doing.

TLS guy, the woofers aren't rubbing when the cones are pushed. I will have to test the resistance of each driver when I get the chance. They are DVCs, is their a specific way to do this test?

You will have to tell me how the VC's are connected, series or parallel.

However this may make things easier, as if there is a significant difference in the impedances of the coils you have your answer. Check resistances as connected and each coil separately, and I will try and make sense of it.

If you can find out from Ken what the DC resistance of the coils is supposed to be, then you can decide the issue with certainty. However, if all the coils have different values they are shot anyway.

Can you be certain you don't have a counterfeit amp?