Subwoofer pulsing with no sound
This is the second time I have noticed this happen:
KENWOOD H/U - ZAPCO DIGITAL SERIES AMPS - FOCAL FRONTS - JL SUBS
After installing a new amplifier for my subwoofer and having it work fine for the first few minutes, I turned the ignition or deck power off and then on again, then the subwoofer made some distorted sounds (even at low volume) and then started heaving (for lack of a better word) in and out at a rate of about 1 second per heave. It looked like the sub was going in a n out to max excursion but very slowly. What is going on with the sub or amp?????
The first time this happened was with an Xtant x1001. After switching the amp from non-balanced-input to balanced-input setting it worked fine (I don't have a balanced signal by the way).
Today, after installing a Diamond Audio D7152 to run the same subwoofer (Diamond TDX 12 inch) I had no problems for the first 10 minutes of tuning and playing around with the set up etc., and then after a the vehicle was off for a few minutes, I happened to turn it on again and, at a low volume, the subwoofer was making some small static/burping sounds and I looked at the cone and it was heaving in and out again! I turned the deck on and off about 4-5 times with the same result each time until it finally began working in a normal way.
My concern is that I am damaging the subwoofer or the amp (or both) somehow. The vehicle is my wife's truck so she won't be listenging for strange noises and I am worried she might drive for a long period of time with this going on.
Anybody have any idea what could be causing this?? I do have a line driver running to the amp, but I had a different unit running to the last one so I don't think that is where the problem is.
Any input will be helpfull thanks.
PS - this Diamond amp/sub combo it THE BEST I have ever heard.