I've recently built two 10'' woofers, "broke them in" and then measured their main T/S parameters.
As the intention of the "breaking in" is to loosen the surround and spider, I sought a frequency that got me very large displacement without being too slow, so I chose 28 Hz for both, let each run for 48 hours at a reasonable fraction of full power (none of them overheated, I checked the temperature several times in the first minutes to make sure it wasn't going to overheat).
The first one immediately began popping/clicking. It isn't a very loud sound and the voice coils are almost surely not rubbing against neither the top plate nor pole piece, they were very well centered and the spider on them is quite small and rigid, as well as the cloth surround.
The second one didn't click for the first minutes but then began clicking too, identically to the first one.
Noting they were on free-air, not in a enclosure, and they were sitting over a pile of felt and glass wool to avoid transmitting the vibration to the ground.
This clicking sound seems to be mostly tied to the displacement and has the same loudness from 80 Hz down to 10 Hz, but below it it progressively needs more displacement to happen, until that at 1 Hz it doesn't happen anymore, the lowest frequency it happens is 2 Hz (I mean, at least when respecting its max displacement).
Here (sndup or soundcloud) I've played it at 10 Hz for you to hear. In the beginning I put the microphone right ahead of the dust cap, then after the first snap I moved it to the border of the dust cap, and after the second snap I moved it around the surround.
Note that the sound is very "quick", it sounds like a click that happens once in each cycle.
And it happens only in the "upward" motion in each cycle, never when it's moving towards the bottom, which means there's one click for each cycle, not two.
Plus, I didn't manage to reproduce that by moving the cone with my hand either, being that I can move it at 3-4 Hz without much effort.
What could it be?
It surely isn't my amplifier, as it doesn't happen in other 8 ohm 10'' and 8'' speakers I have in the same signal level.
I checked the tinsel wires, doesn't look like them.
I also thought the borders of the surround could be hitting the border of basket itself somehow, but doesn't seem to be it, and I'm having a hard time pinpointing the sound.
I've also had this exact clicking sound in a 10'' poly cone sub I've bought 15 years ago, but I never got to pinpoint what was it neither, I've rebuilt it about 8 years ago and it never clicked ever since.
As these woofers will be playing chiefly from 100 Hz upwards (my sub will take care of the rest), I don't think it will be a major problem as I've never heard this clicking at those frequencies (and it's covered up by the sound too) but still, I want to understand what kind of mistake could cause that.
Thanks!
As the intention of the "breaking in" is to loosen the surround and spider, I sought a frequency that got me very large displacement without being too slow, so I chose 28 Hz for both, let each run for 48 hours at a reasonable fraction of full power (none of them overheated, I checked the temperature several times in the first minutes to make sure it wasn't going to overheat).
The first one immediately began popping/clicking. It isn't a very loud sound and the voice coils are almost surely not rubbing against neither the top plate nor pole piece, they were very well centered and the spider on them is quite small and rigid, as well as the cloth surround.
The second one didn't click for the first minutes but then began clicking too, identically to the first one.
Noting they were on free-air, not in a enclosure, and they were sitting over a pile of felt and glass wool to avoid transmitting the vibration to the ground.
This clicking sound seems to be mostly tied to the displacement and has the same loudness from 80 Hz down to 10 Hz, but below it it progressively needs more displacement to happen, until that at 1 Hz it doesn't happen anymore, the lowest frequency it happens is 2 Hz (I mean, at least when respecting its max displacement).
Here (sndup or soundcloud) I've played it at 10 Hz for you to hear. In the beginning I put the microphone right ahead of the dust cap, then after the first snap I moved it to the border of the dust cap, and after the second snap I moved it around the surround.
Note that the sound is very "quick", it sounds like a click that happens once in each cycle.
And it happens only in the "upward" motion in each cycle, never when it's moving towards the bottom, which means there's one click for each cycle, not two.
Plus, I didn't manage to reproduce that by moving the cone with my hand either, being that I can move it at 3-4 Hz without much effort.
What could it be?
It surely isn't my amplifier, as it doesn't happen in other 8 ohm 10'' and 8'' speakers I have in the same signal level.
I checked the tinsel wires, doesn't look like them.
I also thought the borders of the surround could be hitting the border of basket itself somehow, but doesn't seem to be it, and I'm having a hard time pinpointing the sound.
I've also had this exact clicking sound in a 10'' poly cone sub I've bought 15 years ago, but I never got to pinpoint what was it neither, I've rebuilt it about 8 years ago and it never clicked ever since.
As these woofers will be playing chiefly from 100 Hz upwards (my sub will take care of the rest), I don't think it will be a major problem as I've never heard this clicking at those frequencies (and it's covered up by the sound too) but still, I want to understand what kind of mistake could cause that.
Thanks!
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I would have originally said the rca's or XLR's (I skimmed your post) but If you've swapped then to test and it still does it then it's not that. Amp would be my next guess as you mentioned at DC the noise stopped. I would isolated it from other equipment and stand them facing up even to see if the issue is still there... The above two though are my best guess unless there's some rad Induced noise in the line from an electrical appliance!
Sometimes an incomplete glue joint can cause noises like that.
So check underneath the cone, where the surround attaches to the cone edge or where the surround attaches to the basket.
So check underneath the cone, where the surround attaches to the cone edge or where the surround attaches to the basket.
What about a metal fragment (like an iron filling) caught in the pole piece gap. It would be right at the entrance, not within. Look with a good torch.
