Scratchy cone on a 6.5" - Audio & Electronics Forum

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Scratchy cone on a 6.5"
Monday, July 02, 2007 12:18 AM
The other day I noticed that at my blaring volumes (I know I know, don't play it that loud...yada yada yada...) my rear left 6.5 infinity refference speaker started distorting badly. An hour later, I took the rear deck off and pushed on the cone and there I have it, it sounded scratchy and looked like the tinsel leads were all black and stuff. Now I have these comming from a 4 way amp that is 60 watts each channel at 4 ohms (my rears were rated at 4 ohms) and 90 watts at 2 ohms, and doesn't work down to 1 ohm. So I was wondering what causes the scratchy sound from the cone when the speaker blows. My guess is that it's the voice coil, but is it caused from Under or Over powering them. I don't think I clipped them a whole lot, if at all, (their power handling is rated at 60 watts) and my gain was around half way, maybe less for the rears. So I believe I was giving them full power at my maximum volume that I play at (HU goes to 35, but I tuned the system to 20 for safe measures), so my max volume is 20 on the HU. So, I need to know what caused that so I can prevent that with my next speaker pair.

As of now, I thought of a temporary remedy. I'll just cut the tinsel leads going down the cone since the cone's shot anyway, and since they are coaxials, I'll just use the tweater. Now, for my second question, if I cut off the 6.5" cone from recieving power, will the OHM of the speaker that the amp sees change. I don't want to drop the ohms down to below 2 as that will cause headaches with the amp. Would the tweater have the same ohm as the larger cone? or would it be some insane number like .5 ohm since the tweater is smaller and in a coaxial setup, takes less power to operate, thus less load?

Aside from that, I'm open to suggestions about how to keep the speaker from blowing. And NO not playing it at loud volumes is not a suggestion, so please none of that "play it quieter and you won't have that problem..." posts. I have aftermarket speakers and an amp, and I'm gonna damn-well use them! lol.

Re: Scratchy cone on a 6.5"
Monday, July 02, 2007 4:53 AM
I didn't read the entire post. Just the first sentance or 2, and here is my conclusion:

You had speakers that were going to be *this loud* off *this* amount of power. You pushed the amp too hard, trying to make them louder than they were going to get. By doing so, you sent a clipped signal to the speakers, and that speaker didn't like it.
You now have a blown speaker. the voice coil is rubbing. Get new speakers and smarten up with the volume knob


On the other hand....you have other fingers.

KevinP (Stabby McShankyou) wrote:not funny... i just can't find that funny... not with 2 copies of the Candyland board game on your shelf.

Re: Scratchy cone on a 6.5"
Monday, July 02, 2007 9:44 PM
lol, kind of figured, but by turning the volume knob to where I usually have it, I played an assortment of different music and tested what voltage I was getting out of the amp and plugged in all the numbers on a scratch pad to the 'how to find how many watts I'm sending to my speakers' found in another post and I'm about 5 watts short of my amps max RMS (It's kicker so it doesn't even have a 'maximum wattage' rating on it, cause' it doesn't need it. lol) and that is at the loudest point in a rammstein cd I have 'Du Hast' Everything else is around 10 to 20 watts under max avaliable wattage per channel. That's why it's puzzling me. But like I said, I may have clipped it a few times because when I got the amp, I just guessed where the gain knob should be and I ended up turning the gain knob up and just lowering the maximum volume that I'll set my HU to, which made up the difference and appeared to put out to the amps capability.

Not to bag on your or anything since you're a respected member of the forums and I find your posts VERY informative and they've helped me out numerous times, but you only read the first sentence and I explained everything in the sentences after that. I'd appreciate it if you read maybe 2 sentences or 3? Reading the whole post would be nice, but if you don't have to, then why read all those lines? Lol, thanks for the info though, it proved my suspicion of it being the voice coil rubbing.

So, anyone else know whether cutting the midrange out of a coaxial will alter the speakers OHM rating?
Re: Scratchy cone on a 6.5"
Tuesday, July 03, 2007 4:52 AM
hahaha, yeah, I got lazy. It looked like the question could be answered by only reading the first 2 sentances lol.

but honestly, whether I read the whole thing or not. If you push on the cone and it scratches as it goes down or comes up, the VC is rubbing. It simply is what it is, no matter what the effect was that caused the damage, the end result was a rubbing voice coil and a crappy sounding blown speaker.




On the other hand....you have other fingers.

KevinP (Stabby McShankyou) wrote:not funny... i just can't find that funny... not with 2 copies of the Candyland board game on your shelf.

Re: Scratchy cone on a 6.5"
Tuesday, July 03, 2007 10:48 AM
to be honest with you i dont think that was the problem. its possible if you have a lot of crap in your trunk you over heated it or the tinsle leads shorted, or something. who knows, maybe you did push it too hard.

as for clipping the tinsel leads for the mid and only running the tweeter, you should be fine. both the mid and the tweeter should be at 4 ohms



1997 RedR - ZedR
Re: Scratchy cone on a 6.5"
Tuesday, July 03, 2007 3:05 PM
First of all, the only way you are going solve the problem and not continue blowing speakers while playing at your desired level of volume is more power; either bridge the amp to get more power to 2 speakers and get another 2 channel, or get a new 4 channel with more power. Also, do you have a sub? By the sounds of it you were trying to blast Du Hast, which is a fairly bass-heavy song on speakers that never were, and never will be able to safely reproduce those frequencies (unless you have your high-pass filters set somewhere around 80-100 Hz like you should). So basically, get more power or your next set of speakers will be toast just like these ones.
Re: Scratchy cone on a 6.5"
Tuesday, July 03, 2007 4:42 PM
Yea, I forgot to post up what I had the amp crossover at. It's set to hi-pass everything above 200hz. And yes I do have a sub, actually 2, they're very small 8" and they pack quite the punch for their size, but I never over do those. So as far as frequency goes, I could probably do with just setting the equalizer at my HU to cut the bottom and mid a little and raise the top (it gives me 3 options: Low, Med, Hi. I forgot what the Hz points were though.) And I'll just compensate the loss of bass to my sub by upping my amp's bass boost. So theoretically it should protect the mids for the future speakers and for my fronts since those haven't blown...yet (they're sony Xplod 4x6's. Well due for replacing.)

So I'll experiment with cutting the tinsels on the back speakers and see what I get out of it. I just don't see how the tweeter can be 4ohm and the midrange is 4ohm and have it be wired at 4ohm at the amp, it's either gotta be 2 or 8 ohm at the amp if that is true, however if the tweeter is 2 ohm and same with the midrange, then it would make more sense, especially since they would be wired in paralell due to the bass blocker on the tweeter. (can't bass block the tweeter and still have sound on the midrange if it's wired to series...that I know of. ) So I'll probably have to bring the gain all the way down and adjust the volume from there and then run a test to see if the amp goes into safemode shutoff......OH, actually I've got a multimeter that can measure OHM. Ok, problem solved. Thanks guys, I appreciate the help.
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