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Old 3rd February 2005, 09:55 PM   #1
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Default Concerned, Please Help

Once I get my Brahma 12" , I will need a way to power it. I have a memphis SHP 10" right now being powered off a weak reciever. I have my main reciever for my Home Theater, and then a seperate reciever powering this subwoofer. It seems to work well. But recently I've been asking questions about if underpowering a sub can hurt it.

If someone could, please tell me if running a high power sub... like a brahma or memphis SHP, will get hurt buy powering it with a 100 watt reciever.

If so, how and why.... and..... What else can I do?

Thanks
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Old 3rd February 2005, 10:14 PM   #2
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Default not a problem...

Hi,

A brahma has a huge motor assembly and voicecoil, assuming your receiver doesn't dump DC current you can play it as loud as you want. The brahma is not going to give a hint of strain at 100w, so theres a good chance you'll end up clipping the receiver, which will sound bad, but shouldn't be damaging. You may even find the reciever will shut off, which is even less fun...

Stuart
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Old 3rd February 2005, 11:49 PM   #3
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Thank you very much for your reply. Is there any way to see if my reciever is dumping DC current into it? My dad has a bunch of testing equipment, so if there is a way to tell, i can probably find the right tools to do it.
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Old 4th February 2005, 12:01 AM   #4
simon5 is offline simon5  Canada
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You will ear it, it will sound bad.

If your dad got a multimeter, check DC voltage between speaker terminals when the speaker is playing.

Put the meter in DC and not AC.
In DC, the multimeter should read near 0 volts.
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Old 4th February 2005, 12:34 AM   #5
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Default DC offset

Hi,

Just as Simon says, the DC at the output of the amp should be less than a 0.1v (100mv), it will probably be less than half this. You need to measure it with no speaker connected and the volume at minimum. If you have been using it driving another speaker with no issues, I'm pretty sure it won't be a problem.

Eventually, if you really can't get enough power out of one channel of your receiver you could try bridging the left and right channels. This gives a big increase in theoretical power, but in practise many lightweight receivers simply shut down or die.

Stuart
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Old 4th February 2005, 03:14 AM   #6
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Ok, Thanks. I just checked the DC Current level and it seems like that isn't an issue. So that's good new. Thanks a bunch.

- Jeremy
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Old 4th February 2005, 04:00 AM   #7
simon5 is offline simon5  Canada
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Default Re: DC offset

Quote:
Originally posted by Stuart Easson
[B]Just as Simon says, the DC at the output of the amp should be less than a 0.1v (100mv), it will probably be less than half this. You need to measure it with no speaker connected and the volume at minimum.
Yeah, but if he want to see if the receiver is clipping when driving the subwoofer hard, he need to have the speaker attached with the volume quite loud, with the multimeter in DC voltage setting, between the speakers terminals, so in parallel with the speaker.

The multimeter in DC voltage mode won't break something, the impedance is like 10 megaohms, so it's invisible to the receiver.

If in very loud passages the DC voltage climbs, then the amplifier is clipping a bit.

Don't put in in DC current mode in parallel with the speaker, because the receiver will fry hehe! If you want to check for DC current, it needs to be in series with the speaker.
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Old 4th February 2005, 05:36 AM   #8
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Default Hopefully no big deal

I think the audibility of the distortion from any sort of gross clipping will be pretty obvious before output asymetry causes serious DC offset. The japanese receivers I've owned shutdown after a little while of serious clipping.

Stuart
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Old 4th February 2005, 05:51 AM   #9
simon5 is offline simon5  Canada
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True, you're right on that.
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