|   Sub Pops & Hums Only At Power UP: | Doug C
Jul 26, 2002 8:24 AM | | I have an 18" Velodyne that is about 5 years old and have always had this situation at power up. It happens about 50% of the time when turning the sub on. I'll get anywhere from 1 to 20 rapid fire pops followed by a very noticable hum for about two minutes that gradually decreases and then the thing is virtually dead silent.
The pops are loud enough to cause concern but the unit always seems to work just fine after each episode. I usually leave it powered up at all times to avoid this condition. Thunderstorms went through this morning so I turned my system off. Turned it back on later and got the pop and hum again. Everything else in my system was completely powered off when I pluged the sub in.
Anyone else experience similar conditions?
Doug C. |
| re: Sub Pops & Hums Only At Power UP: | raindance
Jul 26, 2002 10:48 AM | | If the sub does this even when the inputs from your system are disconnected, it is probably a fault in the "soft start" circuit of the sub amplifier. This circuit usually disconnects the speaker on initial power-up and reconnects it after a small delay, once the output of the amplifier has stabilized and the DC content has minimized. What you are hearing is probably the result of DC being applied to the speaker, which will cause you to hear mains hum (ripple). If you remove the grill and look at the speaker, you should see it doing quite a large excursion when all this occurs. This will probably damage the speaker eventually.
This same circuit is supposed to disconnect the speaker whenever a DC offset occurs, to protect it from damage.
Hope this is helpful. |
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