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-   -   capacitor in series protect speakers from getting damaged due to signal clipping (http://www.diyaudio.com/forums/solid-state/221305-capacitor-series-protect-speakers-getting-damaged-due-signal-clipping.html)

crunch123 10th October 2012 05:01 PM

capacitor in series protect speakers from getting damaged due to signal clipping
 
Hello guys. I love to drive my amplifier to the max, but also worried of clipping that could eventually damage my speakers. Will connecting a capacitor in series protect my subwoofer's from getting damaged?

kevinkr 10th October 2012 05:03 PM

No, as it won't prevent square waves from getting to the voice coils of your subwoofers. A limiter ahead of the power amplifier driving them will be much more effective.

jan.didden 10th October 2012 05:07 PM

A sub will not get damaged by clipping, it's the tweeter that's in danger.
Clipping generates higher harmonics that can overdrive a tweeter because there is where the xover sends the higher freqs.
So to protect your tweeter from clipping, you need something that blocks the signal more with higher freqs. That's an inductor.

jan

crunch123 10th October 2012 05:07 PM

well why not ? The head of a square wave cannot go pass a capacitor. It will be blocked . wont it ?

jan.didden 10th October 2012 05:16 PM

Quote:

Originally Posted by crunch123 (Post 3196570)
well why not ? The head of a square wave cannot go pass a capacitor. It will be blocked . wont it ?

Not sure this was addressed at me, but here goes:
The 'head' of the square wave is the low frequency signal itself. Woofers are carefully engineered to handle that ;)
The cap in series would only attenuate the signal you want to hear.
Its the spray of higher harmonics that is created by clipping that can damage your tweeter.

jan

crunch123 10th October 2012 05:21 PM

Ok then, will reducing the treble frequencies make tweeter's safe ?

indianajo 10th October 2012 05:38 PM

Yeah. You can reduce treble frequencies by putting an inductor in series with the speaker. These are expensive. You can also put a small capacitor to ground (bypass) ahead of the low power parts of your power amp. This would be the input transistor or the input op amp. These are cheap and can be salvaged from old TV's or some other junk.
Peavey has a dynamic treble cut circuit in the input stages of their amps called the "DDT" , like the old PV-1.3K I'm working on . the schematic is on electronicservice.com. When too much high frequencies are detected, it squeezes the input signal to the supply rail (+16v) with a jfet. This cuts the input to the first op amp. There are a pair of PV-4 's with DDT for sale this week in my area for $150 ea. Probably need heat sink cleaning, input jack cleaning, re-e-capping and maybe a newer fan, but a good project to learn soldering on.
If you read Peavey's "white paper" on their website about speakers, he was paying for a lot of service replacements for speakers because of too much high frequency. So he asked somebody to invent the DDT.

jan.didden 10th October 2012 05:42 PM

Quote:

Originally Posted by indianajo (Post 3196611)
You can also put a small capacitor to ground (bypass) ahead of the low power parts of your power amp.

I think the OP was worried about hf generated by clipping. Attenuating hf before the amp doesn't do anything against that.

jan

crunch123 10th October 2012 05:43 PM

Quote:

Originally Posted by indianajo (Post 3196611)
Yeah. You can reduce treble frequencies by putting an inductor in series with the speaker. These are expensive. You can also put a small capacitor to ground (bypass) ahead of the low power parts of your power amp. This would be the input transistor or the input op amp. These are cheap and can be salvaged from old TV's or some other junk.
Peavey has a dynamic treble cut circuit in the input stages of their amps called the "DDS" , like the old PV-1.3K I'm working on . the schematic is on electronicservice.com. When too much high frequencies are detected, it squeezes the input signal to the supply rail (+16v) with a jfet. This cuts the input to the first op amp.

Oh actually i do not have access to the tweeter's crossover circuitry. In fact its inside the speaker enclosure. However i can lower the treble frequencies through my graphic equalizer. Will this measure protect my tweeters ?

indianajo 10th October 2012 05:51 PM

If the clipping happens before your graphic equalizer (like in a pedal or zener diode clipper or something). then, yes. If the clipping is happening in your power amp, you'll have to buy a "crossover" between the speaker and amp, which is expensive. Or build one out of high current inductors, which is also expensive.
Bottom line, learn to clip with a pedal or a tube preamp or tube head or something.


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