Clipping indicator in a class D amp? - Page 2 - diyAudio
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Old 18th July 2012, 08:58 AM   #11
AP2 is offline AP2  Italy
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Quote:
Originally Posted by ssanmor View Post
Thanks!, yes, perhaps "mean" can mean tough or other things in a different context: with "mean" I "mean" "average"
hi,
of course, know well in mathematics "mean".
the correct way, regardless of that the result is a LED, or a cell in order to vary the gain "ALC" or other circuit. in principle is correct, the wiring diagram of the link. not be surprised that some companies have developed ALC, with the detect only on one side of the signal. as some stupid current protection in same way. one said...
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Old 27th July 2012, 01:03 AM   #12
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if I were to set the gains using an oscilloscope with no load on the amp, will it still clip at the same volume, even though with the load the voltage rails will sag?
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Old 27th July 2012, 07:23 PM   #13
dangus is offline dangus  Canada
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I don't know if that circuit will work with a Class D amplifier, but it wouldn't cost much to find out. Or contact Rod Elliott and ask him.

A better approach is to use an amp chip that already has built-in overload detection. The TA2024 does; you just have to add something to buffer the output and stretch the pulse so an LED stays on long enough to be visible. Arjen Helder's TA2020 and TA2024 MkIII amps have overload outputs, but I can't tell if it includes a pulse stretcher. Still, it'll be much easier to work with than having to solder directly to a pin on the chip. http://helderhifi.webnode.com/products/product-2/ http://helderhifi.webnode.com/products/product-1/

The Yamaha YDA148 chip takes it one step further with selectable options that prevent clipping: you can set it so the amp turns itself down, or compresses the signal to prevent clipping.

Last edited by dangus; 27th July 2012 at 07:42 PM.
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Old 27th July 2012, 07:29 PM   #14
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I'm not entirely sure how a class D amplifier IC would help me?
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Old 27th July 2012, 07:37 PM   #15
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just found this very simple circuit:

http://www.siliconchip.com.au/cms/ga...=0&a=30810&i=5

I don't need it to be entirely accurate, just need a reasonable guide as to when the amplifier is being pushed into clipping, both on music, and with just tones
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Old 27th July 2012, 07:52 PM   #16
dangus is offline dangus  Canada
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The subject is "clipping indicator in a class D amp", so aren't you using a class D amp? And that's why I'm concerned that a circuit designed for conventional linear power amps may not work properly with a Class D amp with a bridged output.

Otherwise, sure, the voltage rails will sag. Whether that is a significant problem, I don't know. Small amounts of clipping should be inaudible, unless clipping causes the amp to misbehave in other ways.
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Old 27th July 2012, 07:57 PM   #17
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I think you might be missing the point.
I have a 1500watt, class D, car audio, monoblock amplifier.

I need an indication of when/how much its clipping.

Another amp I have has a clipping circuit built in, has an LED that just starts to illuminate just as clipping on an oscilloscope occurs, by the time its badly clipping, the LED is fully on.

Not really the point though.

Amplifier doesn't run a bridged output stage.
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Old 27th July 2012, 09:28 PM   #18
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If I understand correctly, you want a circuit that maintains just before squaring the signal? i mean, you can adjust what should be the max?
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Old 27th July 2012, 09:37 PM   #19
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I want a clipping indicator that starts to illuminate as the amp just starts to clip.
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Old 27th July 2012, 10:08 PM   #20
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I'm going to build the negative rail variant, (I have loads of BD139s), of the SC circuit, I'll let you know how it works out. Maybe next weekend before I get around to it though...
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