Need help fixing broken sub

[mstailey]

I've a broken M&K MX-150 THX sub that parts can't be found for at this time. However both drivers are in fine shape and I was wondering if I could just change the sub to use an external spare amp that I have rather than the plate amp that powers the sub. My pre/pro has bass management so a cross-over would not be needed at the sub.

After reading my understanding this sub is a push/pull design. Would my idea work? If yes how would you wire the drivers? My first thoughts that I'd have to add some sort of speaker wire binding posts but am drawing a blank from there.

[Geoff St. Germain]

Yeah, you could switch it to use an external amp. The drivers are wired out of phase so that the cones both move toward/away from the inside of the enclosure at the same time. I'm not sure what the impedance of the drivers themselves are, so it's hard to say if you should wire them in series or in parallel. If you have a multimeter you can get a good idea of the impedance if you can't find the specs for the drivers.

[mstailey]

Hi Geoff,
Thanks for the quick reply.

The drivers are 4 ohm. Marked on the speaker and tested with a multi meter. Driver 1 = 3.9, Driver 2 = 3.8

So, if memory serves wiring in series the amp will see 8 ohms?

The amp drives 8 ohm loads @ 400 watts. So before the sub went down the plate amp (M&K specs) stated 150 watts. By wiring in series am I in effect doubling the power handling capabilities - say 300 watts if wired in series?

Also how will the power be distributed to each speaker in the cabinet? In otherwords how much power will each speaker see?

[mayhem13]

There is a surplus company that has replacement amps for your sub. they're $99 a piece and would be the best solution to your problem as they were designed specifically for your driver and cabinet. Apexjr.com

[mstailey]

Thanks mayhem13,

The amps listed on the site are not anything what I have. But thanks for the point.

The problem is not the amp, it's a combination of the cross-over and line transformer, or so I've been told by a good outfit. They stated the parts are M&K IP and not to be had.

I really hate to just get rid of this sub

[trich2]

Did you ever find or fix your amp? My amp got struck by lightning last month and keeps blowing an internal fuse. I hate to lose this sub! But would like to repair it or find a replacement amp. Let me know!!

[Mike P.]

Hi Thomas, what sub do you have?

[trich2]

I have a M&K MX-150THX. I have had the sub for about 9 years. I hate to lose this sub just because the amp is bad. I am trying to find a replacement amp or maybe try to fix it myself. Any advise?

[Mike P.]

Your options are to get an estimate on repairing your present amp, or replacing it with another one. As Anthony pointed out, ApexJr.com has a couple of surplus M+K plate amps.

http://apexjr.com/amps.html

[mstailey]

Hi trich2,
No I did not find any plate amp (ApexJr or otherwise) for the MX-150 THX so sub is still down. I did contact the new M&K (mksoundsystem.com) and they stated replacement parts should start being available in the next month or so. We'll see...

Mike.