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Right Subwoofer being "sucked in" when Amp is turned on.
Right Subwoofer being "sucked in" when Amp is turned on.
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Old 27th July 2009, 03:03 AM   #1
eddiemoffett is offline eddiemoffett  United States
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Default Right Subwoofer being "sucked in" when Amp is turned on.

I'd appreciate it if anyone can help. I just bought a used Alesis RA-100, and whenever I turn it on, my right subwoofer gets sucked in all the way. It seems like it's getting too much power or something. Any ideas?

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Old 27th July 2009, 03:22 AM   #2
Samuel Jayaraj is offline Samuel Jayaraj  India
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It is more likely that the DC offset voltage is relatively high in that channel.
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Old 27th July 2009, 03:36 AM   #3
Jan Dupont is offline Jan Dupont  Denmark
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It can only be DC-offset causing this type of action.
Free Schematic and Service Manual downloads www.audio-circuit.dk, Spare time company (just for fun): www.dupont-audio.com
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Old 27th July 2009, 05:14 AM   #4
SQLGuy is offline SQLGuy  United States
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Hi Eddie,

Just to be clear, in case you're new to this, this is a pretty bad sign. It means the amp is in need of repair and could easily damage speakers it is connected to. Do not use it until it's been repaired. The problem with the amp itself could be as simple as one or two small transistors that are bad, or as complex as the whole output section blown.

Sorry for the bad news.

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Old 27th July 2009, 05:37 AM   #5
DCPreamp is offline DCPreamp  United States
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Is the woofer getting pulled in and it stays in, or does it just pull in and then relaxes back to normal?

If it pulls in and stays, then you have a serious problem.

If it pulls in, then returns to normal, then you may have a minor problem or it may be a fluke with Alesis amps (like a weird bridging turn-on spike only affecting one channel).

Either way, address it and correct it or you could lose your speakers.
"Believers cling to the myth despite the evidence, reinterpret the myth to suit the evidence, or lie about the evidence to support the myth." "To err is human; to blame errors on external factors is even more so."
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Old 20th November 2009, 01:35 PM   #6
Mcurmi is offline Mcurmi
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I have the same problem and i have had a channel blown on the amp and i was not turning on since i was staying in the protect mode. Now i changed 4 transistors and 2 rectifiers and the amp is turning on but the sub woofer is being pulled in and stays in. What else should i check apart from transistors??

By the way my amps's channel was damaged because it was turned on without any heat sink (therefore over heating)
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Old 20th November 2009, 03:56 PM   #7
Spiny is offline Spiny  United Kingdom
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Please disconnect the speakers! Use a meter to measure the offset, there is no need to attach speakers.
Once the source of the problem (driver transistors, Outputs, power supply etc ) has been found then test using a dummy load (8 / 16 ohm heavy duty resistor ) and make sure it is well before attaching your speakers.
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