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.
.
robotman
While I certainly don't want to contradict Eldulcesol's first hand experience. I think it prudent to warn you that the Spicas are not full range or "large" and are not know for durability, original replacement parts may be hard to come by and matching other drivers around their unusual cross-overs might be tricky. You might want to excerise some caution in shifting some of the burden of the Kinergetics to the Spicas. THX usually rolls off a bit of the top end something the Spicas tend to do on their own. As such I suspect there is some very good suggestions here, keep the volume down and proceed with caution.
I did some experimenting over the weekend.

The Spica's are not full range speakers and if I don't call them "small" speakers on the HK receiver, NO signal will be sent to the subwoofer. Granted that they are physically large speakers, but their range is considered "small".

The SW-200 are "stereo" L and R subwoofers which have two 10" speakers in each box. The HK sends out a pre-amp mono subwoofer signal cutoff at 100Hz, so I split this and then go in the L/R pre-amps on the Kinergetics amp.

I found an old Enya CD which had some good simple monotone bass notes which helped me diagnose a bit more.

I tried switching the L/R speaker cables from the amp to the speakers. The problem stayed on the right speakers after the switch. This tells me that the amp is not the problem, but the right speakers themselves are having a problem.

But here are some notes / questions:

1. The problem is that both 10" speakers inside the right speaker sub box are vibrating to their extremes causing a jackhammer sound. This originally sounded like out-of-control, distorted, popping in the bass movie scenes, but with the clean Enya monotone, it was a steady pounding noise and I could visibly see what was happening.

2. Although the right speaker set has this problem, it sounds perfectly fine until it gets turned up to a loud volume.

3. I can turn the left speaker sub up quite a bit more and get it to do the same thing.

So... does this sound like a problem with the right speaker set or possibly a small room problem? I was wondering if there is some effect I don't quite understand where the speakers aren't able to create the bass they are trying to generate which causes this over excursion problem and speaker jackhammer effect. If it is actually a problem with the speaker, what could it be since they sound fine up to a point?

Any ideas welcome. Thanks for all your help!

John
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.
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.
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!
.