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Old 24th November 2005, 12:40 PM   #1
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Default soft start for amp/crossover

I've read about the delayed relay that shorts the output to ground until the crossover has had time to warm up.

What other methods are available?

One idea is that I might power the crossover directly from its own unswitched supply, so it stays on all the time that the amp is plugged in. Of course, plugging in while switched on or power outages might cause pops.

Is the start up noise just a nuisance or potentially driver damaging? My current set-up has 4" full ranger without a tweeter if that makes a difference.
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Old 24th November 2005, 01:00 PM   #2
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The best thing to do is add DC protection and delay muting to your power amps outputs. If you are using a decent bought amp this feature will be already present. Then just switch your stuff on/off in the right order.
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Old 24th November 2005, 02:25 PM   #3
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If you don't have any problems with power up you don't need to do anything about it. Minor startup transisents won't hurt the speaker. If you buiuld a gianlcine and do it right you'll get a totally silent turn on and turn off.
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Old 24th November 2005, 04:56 PM   #4
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OK then, I'll try without anything (on test speakers) and come back if I do have noises.
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Old 24th November 2005, 05:14 PM   #5
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If you are using any of the LM chips that have built in mutes, you can just add a slow start with an extra cap and resistor. See the LM4780 datatsheet for details.
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Old 24th November 2005, 06:46 PM   #6
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hmmm, a good reason to buy another lm3886 kit. At the moment I've got 1x3875 and 1x3886.
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Old 24th November 2005, 07:18 PM   #7
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Quote:
Originally posted by jimbo1968
OK then, I'll try without anything (on test speakers) and come back if I do have noises.
How much thumps/noise/other irritating phenomina is dependent of the whole chain. My two Gainclone designs are dead silent but it's possible that you still may get some startup noise in some combination.
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