A You've already done a bit of troubleshooting that has revealed a couple of points. First, by connecting both speakers to one channel of the amplifier, you have proven that both subs are still functioning. However, I wouldn't be ready to jump to the conclusion that your amplifier has a defective channel at this stage. Until we confirm the input signal, the amp may not be the problem. Since you connected both speakers to the left channel, swap the RCA input plugs-if the sound disappears, connect your speakers to the right channel of the amplifier. At this point, if the sound returns, the problem is upstream of your amplifier. If the sound doesn't return, then it really is a problem within the amplifier. It will need to be sent to the repair technician.
About the safety question-you can run as many speakers as you want off of the left channel, but there will be some restrictions. First, your total speaker load must match the amplifier's capability or you'll cook the remaining channel. Second, don't expect it to sound as good as a whole amplifier. You'll be running on half of the amplifier's power, which will result in a small loss of output.
Q Can I put two 10-inch woofers in the same un-vented box? It seems that when one cone is moving in and the other is moving out, there could be sound distortion, attenuation, and just general crappy sound. My sub box fills the back seat of my Mustang and takes two 10-inch subs, each in the same volume. Will it work or should I put a baffle between them? There's about a cubic foot of space for each sub.Bob Found, Calgary
A Yes, you can put a pair of woofers in the same cabinet, and yes, you will get crappy sound if you get any sound at all. The reason for this is from your description-the cones must never be moving in opposite directions, but instead must be moving together in an acoustically coupled environment. If the cones are moving in opposite directions, then they are wired incorrectly. Just reverse the connections on one of the woofers and you're back in business.
You can use identical woofers sharing the same cabinet, provided the cabinet is the correct size. For example, if one woofer requires a cabinet volume of 1.2 cubic feet, then two would require 2.4 cubic feet. Whether there is a dividing wall, or "septum," is up to you. However, there are a couple benefits gained from adding a septum. First, the septum will strengthen the cabinet, allowing for the production of tighter bass. Secondly, if one woofer fails, the other one won't behave any differently, and will also be protected from possible damage. If you have two woofers in your cabinet and they are moving in opposite directions and you still have bass, I suspect that one woofer is disconnected or blown, and the other one is just shoving it around.
Q I have a Clarion head unit and am using the DSP7500 with the CDC-1255z CD changer. I noticed that the changer and DSP have a fiber optic output and input. If I used the connections would there be a big difference in sound? And can I use any fiber optic cable?Anonymous
A More products are now being equipped with fiber optic or coax digital connections. Understanding the signal path will give you the best chance of determining which connection method is preferred. Most products have both analog (RCA) and digital connections. As I mentioned earlier, converting to and from digital can be more of a problem than just staying in the analog domain.
If you took the analog output of a CD player into a preamp input of a digital processor, then you'd be converting from digital to analog in the CD player, and then back to digital as the signal enters the DSP, and then back to analog as it exits the processor. In other words, all those conversions can't help but degrade the sound quality slightly, and the degradation gets larger (compounds) as more circuitry is used.