Blown my 3rd Morel MDM-55, suggestions?

[longblock454]

My current set of DIY loudspeakers consists of the following:

Morel MDM-55 Mid (200 watts RMS/285 watts max)
Morel MDT-30S 1-1/8" Soft Dome Tweeter (200 watts RMS/280 watts max)
Dayton ST255-8 10" Series II Woofer (250 watts RMS/350 watts max)

And a:

Dayton XO3W-625/5K 3-Way Crossover 625/5,000

All powered by a Europower EP1500.

The failure is caused by over powering, I know this, just can't help it! What I can do (besides turning the volume down) to help prevent this? Perhaps a higher wattage mid or some sort of protection?

To my untrained ear this is a good sounding setup. Morel doesn't sell a higher wattage model, and from my searching no one else does either!

Any opinions or suggestions?

Thanks
Andy

 

[mashaffer]

Try crossing the midrange up higher so that it doesn't have to absorb all of that low frequency power.

mike

 

[5th element]

Well there are two way the drivers could have failed, mechanical or electrical failure.

The first is when the tinsel leads delivering the signal to the voice coil break due to over excursion.

The second is when the voice coil overheats and breaks.

Both problems can be solved by setting a higher Xover point, or steeper slope.

 

[longblock454]

Thanks for the suggestions. The only other pre-built (building my own is not a problem though) is the:

Dayton XO3W-700/5.6K 3-Way Crossover 700/5,600 Hz

Could that 75Hz make the difference?

All of my failures have been heat related.

 

[69stingray]

625-Hz is only 1.5 octaves above the 380-Hz Fs of the midrange. If you can assemble your own crossover, then assemble a 4-order X-Over at 750-Hz or a 2nd at 1,500-Hz (just a suggest on starting points for Fc).

 

[Moondog55]

You could always rebuild using dual mids for greater power handling, or go active and use steeper slopes?? or both?? Behringer crossovers are cheap, those drivers aren't, save big dollars in the long term

 

[sreten]

..... And a:

Dayton XO3W-625/5K 3-Way Crossover 625/5,000

.....To my untrained ear this is a good sounding setup.

Thanks
Andy

Hmmm .......... I doubt it ......

http://www.partsexpress.com/pdf/295-110.pdf
Not the ideal choice to cross to a 2" dome midrange.
The Dayton c/o is completely useless and wrong.

Your probem is likely mid over excursion that might be fixed by using
a larger cone midrange but the set will likely still sound poor, off the
shelf crossovers do not work well at all.

I'd suggest a Seas midrange driver and a properly designed c/o.
3-ways are never easy, lots of information below.

🙂/sreten.


http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spkrbldg/

http://www.zaphaudio.com/
http://www.rjbaudio.com/projects.html
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.humblehomemadehifi.com/
http://htguide.com/forum/forumdisplay.php4?f=39

 

[longblock454]

All, thanks for the information. I had no idea my crossover choice was so poor! I'll read through the provided links searching for direction.

This time i'll post my direction before buying/building!

Andy

 

[Caferacer]

If you can't redesign the crossover, put a 3db l-pad in between the crossover and the mid. 2ohm resistor in series and a 20ohm resistor in parallell. That will pad the mid down just a bit and protect it. In addition, the generic crossover will "see" a flatter impedance and work better.

 

[psemeraro]

Polyswitch with a 10 ohm resistor in parallel.
EV has used this method for 20 years to prevent their tweeters from blowing up.

The polyswitch is the same as a strait wire so no audio passes thru the resistor. Once the polyswitch trips, then the signal passes thru the resistor which reduces the level about 6dB.
Only cost a few $$$ for the parts and goes together easily.

http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=41&ObjectGroup_ID=237

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=017-10

 

[longblock454]

All,

I am thinking of buying this:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=248-668

A Behringer 3-way active crossover. I have enough amps and the above unit is about the same price as building two custom crossovers.

Any reason not to go this method?

 

[Moondog55]

no problems with my set-up using these units, but wait until they go on sale