Amplifier Saga Continues

As most of you know, shortly after buying our house, my 600W Class D amp blew in my car. Well, the timing was horrible. After buying the house, this had very little priority to get corrected. Well, after getting the component speakers installed in my car, I figured it was about damn time to take action to get my amp fixed. Thankfully, it was still under warranty and it would only cost me shipping to get it fixed. Shipping only is much better than having to pay retail for another new amp.

Well, if that was the end of the story, there wouldn't be much of a story, would there. Well, there is more. After they only had the amp for 2 days, they had repaired and shipped my amp back to me. Within the shipping, there was not a single piece of paper outlining what they had fixed. They told me that documentation would accompany the return. I'm worried, but optimistic.

Obviously, since not having it hooked up for the past 9 or so months, I'm excited to have it up and running. Once I got off of work, I didn't waste any time jumping into the job.

I did the general continuity testing. Turned down the gain on the amp, turned the volume down on my head unit and felt the speakers for vibration. The first time there wasn't any. I turned up the gain on the amp and still nothing. Well, this wasn't any response for good reason, while I was waiting for the amp to return, I installed the remote gain switch and it was turned all the way down. So I disconnect the switch and presto, speaker vibration. I took this as a good omen and reassembled my trunk.

Before I departed, I did the same test again. Speakers are still vibrating. So, I jump into the car with the volume low (residential area and late at night). When I get to 78, I turn it up. Immediately I can notice the difference.. I have a full bass channel again. Unfortunately, this was short lived.

Once I got home, I left the radio on and popped the trunk. Speaker vibration was gone and a faint waft of smoke coming from the area of my amp. I'm in a panic now. I quickly grab the drill with the Phillips head bit attachment in place and start removing my speakers to I can get my trunk floor out of the way. The first thought that ran through my mind was "My car is about to catch on fire in my garage, ahh!!!" Well, thankfully, once I got into my trunk far enough, I was able to find that nothing was on fire.

The smoke was coming from the electronics on my amp. Damn it!! Anyway, I am pissed now. The power light is flickering and the fault light is on solid. WTF? I thought this thing was fixed. Am I being screwed here? What am I going to do now. Well, knowing that my car was safe, I call it a night. As I am lying in bed, the thought occurs to me, what if there is something in my system causing the problem.

Well, I know that the power is clean. I reran all of the wires personally and know that all of the connections are good and all of the wires are in good condition. What else could blow my amp? Well, my speakers could. I'm running 2 speakers with 4 voice coils (VC) (each at 4 Ohms) to present a 1 Ohm load to the amp. If any of the voice coils are damaged and are not at their correct resistance of 4 Ohms, then that could damage the amp.

I pull out my (not so) trusty multimeter and try to get a reading on my speakers. Well, my meter just told me that there was continuity but not at what resistance. The next day I bought a new meter and it told me a very bad story. One speaker was well and good. 3.9 Ohms on each coil. The other speaker was not so fortunate. VC1 was 1.5 Ohms and the other VC was only presenting a 0.8 Ohm load. I did the math, with these 4 readings, the amp was seeing a .416 Ohm load. Much less than the 1 Ohm load that it was rated to handle. So, now that I know what the culprit is, when I get my amp back this time, I won't make the same mistake.

Unfortunately, with only one speaker and a shared box environment, I don't have a clue what this will do to my fidelity. I do know that I will have to leave the broken speaker in place to fill the hole so that the ported box will stay in tune, but I'm not sure how a passive driver will effect the sound. I do know that running my amp at a 2 Ohm load will drastically damper its capability. My 600W amp will now run at 300W (at 12 volts) I imagine that it will run about 440W at 14.4 volts. I guess that is plenty when I'm trying to enter a Sound Quality (SQ) competition. I don't need all of the extra power and "boomy" base for SQ.

As for my broken speaker, I have contacted the manufacturer (it is out of warranty) to see if they can repair the VCs at a reasonable cost. These speakers each cost between $125 and $150 brand new. Also, the manufacture has stopped making this line of speaker. I am not certain that they will be willing to fix it for that reason. If they won't play nice with me, then I guess I'll run crippled for a while until I can justify spending the money to get it replaced.

More to come in this saga once I get my amp back yet again.