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What causes clipping?

I am trying to understand why my Kinergetics SW-200 subs are clipping so easily. I had a thread in "speakers", but realized this "tech talk" forum might be a more appropriate forum to help me understand what actually causes clipping.

I am mostly using my system for home theatre with a HK AVR300 receiver and pairing the subs with Spica TC-50's. The Kinergetics seem to be easily overwhelmed when "bassy" scenes come up in movies. But, other than when aliens are landing, they don't seem very loud.

The Kinergetics have their own 150W x 2 amp which is fed from the pre-amp out on my HK receiver. The receiver only has a mono pre-amp out, so I am splitting that to the L/R Kinergetic amp inputs.

What I am calling "clipping" is when the subs make a fast, loud, popping noise. A fuse in the Kinergetics sub may also burn out if this goes on for a long time.

1. What causes the clipping? Is it the sub amp being overloaded or is the speaker itself in the sub being overloaded?

2. Would a bigger sub amp solve the problem? If so, any recommendations?

3. Can clipping be caused when the amp can't get enough current to power the speakers? For example, I have the Kinergetics amp plugged into the switched AC outlet on my HK receiver. Can the amp be overloaded as it tries to suck the power it needs through the AC cable maybe causing a dip / spike pulse to the speakers?

4. Does room size or speaker placement have any affect on clipping?

Thanks for the help.
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robotman
eldulcesol
197 posts
 
Robotman, for me I had to use a 5.1 out on the dvd player to the 6 ch. in on the receiver. What I did was set everything to large, sub yes,set the distances, effects and volume controls almost to the max. This is on the dvd player menu. Check also to see if your dvd menu has a sub freq. on it.

After that, then try to tweak the volumes with the HK. I believe the SW200 xover is 80hz. If you can, adjust the sub out freq on the HK to that. If you are finding out that the tweak volumes on the HK are at two extremes, fronts -10 center +10, go back to the dvd menu and make some changes. All this is possible if your dvd menu has the capability to do this.I know all of this is a pain, especially if you have to go through 4, 5 steps just to get to the audio menu on the dvd player as I had to do.

Try the other suggestions from above about placement and not plugging the amp to the HK. Also, if your are not sure about the condition of the amp and subs, try it out with a different receiver or system to be sure.
eldartford
4,262 posts
 
If these SW are acoustic suspension (sealed box..no vent) your box might have a leak. Tighten all the mounting screws on the drivers. Check for any other source of leakage.

Test the polarity of the drivers by touching the speaker wires to a battery. Make sure that the cones move in the same direction.
robotman OP
35 posts
 
It is a sealed box. I don't see what I could tighten on the box. What are the drivers? An air leak would make some sense, although everything seems really tight on the speaker box.

What type of battery would you use to check polarity? I assume you mean compare the the left pair of speakers and right pair of speakers move the same direction? Or do you mean the two speakers in one box? I can also just try reversing the red/black wires on the right side and see if that makes any difference.

I don't have an expensive DVD. I'm just using a PS2 or TiVo as the source through an optical cable for movies. I also read in the HK manual that if you set your speakers to "Large", there will be NO signal set to the subs. I didn't confirm this, but I will.

I did try plugging into the wall and didn't notice any change in the problem volume point.

Thanks for all your ideas!
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eldartford
4,262 posts
 
Robotman...The "drivers" are the things with cones that move in and out. Since your SW has a built-in amp I guess that you can't get at the amp output wires that go to the drivers. If you could get at those wires, a 9 volt battery momentarily connected to the amp output terminals (and therefore to the drivers) would verify that the two drivers in one box are not hooked up with opposite polarity. That would be a long shot but worth checking if it was easy.

Your sealed box could leak around the drivers. or around the amplifier if it is in the box as I suspect. Tighten the screws everywhere, and use silicone rubber sealant if the gasket is faulty.
robotman OP
35 posts
 
The subs have an external amp. I highly doubt that the two speakers / drivers would be crosswired inside the sealed speaker box. I also can visually see that both speakers in the box are moving in and out in unison.

Would reversing the black / red speaker wire have any effect? I didn't think it really mattered which way you hooked up the speakers. I'm pretty sure everything is matched up, but just one more thing for me to try.

I'll also make sure everything is sealed well, although it all seems pretty rock sold.

Is there anything inside the speaker box that could be failing? I wasn't sure if there are any electronics inside the box itself.

Thanks again for your ideas.
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