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Nasty problem - ideas?

On two occasions now, during a movie, I've heard a sharp, unpleasant 'snap' through the right channel (or sub, which is on the right?) during dynamic passages. I haven't heard it on 2 channel only, even at high volume. On the one hand, to narrow down the source requires having it happen repeatedly, but it's an ugly sound, and I'd rather not have it keep happening and potentially damaging something, so I thought I'd post here to see if any of you have experienced something similar.
Nothing in the system changes between 2 channel and HT, although the sub is obviously worked harder during HT, and last night I heard it during Olympus Has Fallen when the C130 was going down (for those of you who've seen the movie). Maybe the volume was a little high, the wife thought we were having an earthquake ;)

Anyway, thanks for any input. It's a sharp 'SNAP' that is either a tweeter, or something electrical in the sub amp at first thought.
english210
10 responses Add your response
jeffb28451
129 posts
 
I had the same issue and after decades in this hobby, it was a bear to find. I replaced tubes, etc., because I didn't want to strip the whole system down(quite complex). I had to do it anyway and finally, some of that old gear I'd stashed away (because nobody wanted it) came in useful. I went back to solid state, 2 channel basic and tracked it down after several hours, to small, hard to see, speaker wire interference/arcing at higher volumes only. I thought I'd blown out PM4 Lowthers before that ($$ouch). Hope you're as lucky as I was.

Not the fault of the gear, but if you have recently added Walker links or other RF "sinks" at either end of speaker cabling, start there and make sure you have not gotten wires too close.

Good luck.
tls49's avatar
tls49
1,351 posts
 
Your description sounds like the bottoming of a woofer, either the sub or main speaker. That means it is being pushed a little too hard. I'm guessing the subwoofer. You'll just need to turn it down, or get a more powerful subwoofer.
english210 OP
175 posts
 
Ok, thanks, I'll retry the same passage with the sub turned down - it was impressive, but didn't seem too loud. Maybe it was too much. Thanks.
philjolet's avatar
philjolet
2,306 posts
 
you could try the switching the cables from left to right and eliminate the source etc... until you find the problem

good luck
swampwalker's avatar
swampwalker
5,138 posts
 
I'm also guessing that the sub bottomed out. it's pretty hard to diagnose at a distance but luckily this issue is pretty easy to test.
pbnaudio's avatar
pbnaudio
1,613 posts
 
Bottoming out a woofer sounds kinda like a rimshot on a drum. Its quite easy to check if the woofers in you sub can do this. Pressing the cone in with your finger tips in a circle around the dust cap, if you can make the back end of the voice coli former touch the back plate on the pole piece its most likely where the noise is coming from. On a properly designed woofer the suspension will - maxout - before the former touches. And don't worry you wont harm the woofer by performing this test, these things are sturdier that one would think.

Best of luck

Peter

Peter
english210 OP
175 posts
 
Ok, thanks all. I checked the volume on the sub, and it was at about '10 o'clock', so I turned it down a little, replayed the passage I remember having the problem on, and it didn't happen. I'll check the woofer travel tonight when I get home, and verify it's possible. It is a sharp, high-pitched 'snap', not unlike your description of a rimshot.
english210 OP
175 posts
 
Pbnaudio - I did that check on the sub, and it did bottom out in travel before it touched anything in the back. I'll do some more checking/investigating....
johnnyb53
3,510 posts
 
IME, some of the AV Pre/Pro programs set the LFE level too high. You might check the channel levels in your pre/pro and dial back the LFE (sub) output by around 4-5 dB. That's about how much too high my auto setup sets it.
english210 OP
175 posts
 
OK, also worth a look. I must admit, I don't trust the YPAO, but don't have another system for EQ'ing the system/room. I have just adjusted everything to 'flat', and input my measurements to each speaker, and it seems ok. I dialed back the sub volume, and haven't had a recurrence yet....
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