Repair a Mackie SRM 450 Speaker The Speaker is making a crackling sound while playing. The sound keeps cracking up.

The pop itself isn't necessarily a bad thing, but a burn smell and the fact that it's only outputting a crackle likely means that the built-in amplifier circuitry has been overloaded. This can happen a few ways:
1) Faulty power, either a bad cord or a bad outlet
2) Plugging the output of a power amplifier into this speaker - because it has a built in amplifier, this speaker only wants a non-powered line input
3) If the Thru output is (accidentally) plugged into anything that provides phantom power, that could overload the circuitry.
4) A short due to liquid or moisture contact - these cabinets are most certainly not waterproof
In any case, the amplifier part of the circuitry IS replaceable. If you're not comfortable buying one and replacing it yourself (I'd recommend eBay), take it to any shop that sells similar items. If you're extremely lucky, it was just a fuse that needs to be replaced, but chances are you'll need to replace the whole amp.

I believe there is an internal fuse in these which, according to a friend who has these, seems to blow occasionally for no apparent reason. He has also had to send two back for replacement and would not buy again, they seem to be inherently unreliable although they sound great.

Make sure you are driving LINE LEVEL signals to this and not mic level signals.

What\'s the question, are you asking about eyebolts, SRM 450 or McKenzie speakers?



Let\'s assume speakers. These are quite nice vintage speakers and were fitted in a number of units back in the day. Depending on the use they are going to be put to you\'ll need to find the dimensions of similar boxes for the same use and speaker size from (ideally) makers who used these speakers or something similar. It\'s going to be a bit suck it and see and will also depend on if you are looking to use an infinate baffle, sealed or vented enclosure.



Try Speakerplans com

It would be very unusual if the blue LED is burned out. They should last a million years. I suspect the power supply has a problem.

Mackie say this is not a user service part. If the fuse has blown there is probably a fault in the unit being their reasoning. I know for certain they tend to blow for no apparent reason so it is worth giving it a go. They are 5 x 20 Slow or time fuses. 7A for 120V and 4A for 230V

If you've changed the tweeter and the sound is still muffled the fault is with the HF amp, or the cross-over. You will have to send the amp assembly for repair as it is all surface mount components in there -nothing you will be able to fix yourself. Sorry for the bad news!

Crackling is usally one or two things my guess would be bad grounding of the amp or bad connection with the jacks or plug it self try to make it crackle on purpose by jiggling the jacks see if it has any effect on the crackling try to narrow your possibilitys

There is an entire crossover circuit inside that is BEFORE the amp section. There are 2 separate amps: one for HF and one for LF. Can you describe the noise you are hearing in more detail? Is hte sound effected by the gain controls at all? What happens without any input?

Thanks,
Dan

First thing is to verify that a ground loop from your driving equipment is not causing the problem. Easiest way is to drive it with a BATTERY operated little CD player so no ground loop could exist.

Verify that your power cord is in tight and try another cord to verify it is OK.

Beyond this, service is probably required. If unit is out of warranty, you could have a person open it up to see if anything is obvious.

A possible proble is bad connectors or worse, a cracked circuit board.

Analyzing if noise is from both the woofer and high range speaker is a first step.