2. tech-talk
  3. 1069370656

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
rsuminsby
152 posts
 
What you describe sounds like a mechanical noise made by the woofer cone exceeding it's excursion limits (although I'm just guessing.)

"Clipping" in the normal sense of the word is the flattening of the sine wave in a signal when an amplifier "runs out of steam", ie, it can't produce the required voltage. The power of the amp, the efficiency of the speaker, room size and placement, and of course listening level are all factors.

Hard to say what the exact cause is in your case. A bigger amp might help, but before you invest, I'd begin by 1) making sure your listening position isn't in an acoustic null (this would require you to really crank up the level in an effort to overcome room acoustics....a losing battle), then 2) moving the sub closer to a corner to try and take advantage of room loading to increase the acoustic output.

If you haven't done some research here on the 'gon or elsewhere on the net for some information on room acoustics and subwoofer placement, it's a good place to start. Proper positioning of the sub and the listening chair can make a huge difference in getting fast, tight. tuneful bass.
robotman OP
35 posts
 
Thanks for the info.

Hmmm... if you're correct (which I assume you are), then my amp is actually overloading the speakers themselves. I usually only have the amp at half power or so and can have this problem. Interesting.

Does "clipping" ever have a load crackling, popping noise associated with it? The sound it is making just doesn't sound good for the speakers! ... so it would make sense they are being overpowered and pushed beyond their excursion ranges.

Is there a quick way to test if it is the speakers or the amp that is the problem?
.
slappy
903 posts
 
You might have blown the drivers.
150W to a subwoofer should not overload it. Maybe your sub drivers are actually 2-4 ohm loads, and it is affecting the amp.

Do the amplifiers get real hot?

If it doesent seem loud, and the amplifier is not cooking, and you still get that cracking my bet is the drivers are toast.
theo's avatar
theo
2,331 posts
 
I concur with Robotman it doen's sound like clipping. Most powered subs will have a matched amp to the requirements of the driver. I would try an ac outlet direct. The HK may be limiting it some. It really does sound as if the voice coil is reaching it's excursion limits, whish is most likely a result of overdriving it. Try reducing the crossover setting.
More to discover