Have I blown my sub?

sparx

sparx

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Basically I have just fitted my sub which I used to have in another car (it was in there for about 2 years with no problems).

I had been listening to it for about an hour or so and the cd changer changed cds and put an incredibly bassy track on which I immediately thought was a lot louder than the previous tracks I had been listening to.

It played the track for about 10 seconds and then the bass completely went, all I could hear was a kind of scratchy sound where the bass should have been. I have since fiddled with the gain control on the sub and I can just about get a very low volume bass sound if the gain is almost at minimum, if I turn it up I get nothing.

Sub volume on the HU (which I had also used with this sub for 2 years in the same set-up) was set at about +3 volume (it goes up to +8). Gain on the sub was also set quite low, bass boost was set to zero.

Sub is an Infinity Basslink 10" sub, head unit a JVC KD-AVX1.

It's weird that it would suddenly blow after having no problems with it in another car with the same HU.

Any thoughts?

Many thanks in advance,

Jamie
 
push the cone in on the sub - if you feel scrapping its dead im afraid
 
I can't do that very easily as it's an enclosed sub, I'd have to start taking it apart to get to the cone.

Any other thoughts or is that the only way to be sure?
 
Hmmmmmm its either mechanical or electrical - as its an active box I think either way its probably dead.

first impressions, Im guessing that either the bass on the track that you said was louder was causing the internal amp to clip and that has fried the coil (electrical problem) or it over excurted and the voice coil former has knackered - scratching from a loud speaker is a symptom of that.

did it make a nasty clang before it went silent (vc former hitting the back plate of the magnet)
 
If you have a multimeter, set it to ohms and check the impedance across the speaker terminals (if you can get to them). If it's open circuit then it's fried.
 
Thanks for the responses, very useful:

thejoose

did it make a nasty clang before it went silent (vc former hitting the back plate of the magnet)
Click to expand...

Didn't hear anything like that, just the bass which suddenly stopped and all I could hear was a rattling / scratching sound where the bass should have been, now I don't even get that.

AndyMac

If you have a multimeter, set it to ohms and check the impedance across the speaker terminals (if you can get to them). If it's open circuit then it's fried.
Click to expand...

Are you talking about back of the sub as it doesn't have speaker terminals, just the twin RCA input on the back which goes to the sub out on my HU, the only other connections are remote on, live and ground.

I do have a multimeter, so can I still check it somehow? What reading would I get if its fried - I'm presuming zero?
 
No you'd need to get to the speaker terminals to check the impedance. Zero would mean it's a short circuit which would have fried the amp, open circuit is no reading at all which means the voice coil is fried. 4 ohms or similar means the VC is intact and it must be the amp. But the symptoms sound awfully like you've blown the voice coil.
 
Hi Andy,

Bear with me as I am not really that au fait with car audio (more of a home cinema expert).

OK, so the speaker terminals where - on the HU or the sub? Why would that tell me if the sub is fried if I don't use the speaker terminals to feed the sub?

Basically, in fcukwit's terms how do I check if it's the amp or if it's the sub.

Thanks!
 
The speaker terminals on the sub.
If these are inaccessible then it's irrelevant, but I can't believe it can be that difficult to get to the speaker wires on the amp that feed the sub.
 
OK, this is where the confusion lies. I am not using the speaker terminals on the sub, I am using the twin RCA / phono inputs. If I put a multimeter accross here would that work?

Thanks.
 
No. The only way to tell if it's the amp or the sub is to separate the two. I know the amp on the side of the Basslink is integral to the sub enclosure, but inside it will be connected to the sub speaker. You will have to either remove the amp or the speaker to get to the terminals in order to test it, but TBH it has to be one of the two so even when you find out which one what are your options?
They're only £149 so I doubt replacing the faulty component is likely to save you much money as buying spares for high volume low cost ICE is usually as expensive as just replacing it.
 
the basslink is a powered box
imho i dont think it will be the sub i would hazard a guess it is the amplifier which has gone not the sub
 
AndyMac - OK, I finally get it now (duh). I think you're right, if it is fcuked then it won't be worth repairing. I have actually purchased a replacement already - a Vibe 12" Pulse 3 powered sub. If the BassLink does still work (which is unlikely) I can always sell it on.

Just a final question, what would cause the amp in the sub to burn out (I don't want the next one to go this way)? It wasn't set at high levels and I had it in my previous car without any problems. Would it make any difference if it wasn't properly grounded? Are these things built to last or is 3-4 years about their lifespan?

Thanks again.
 
Well they're built to a price, so wouldn't have the normal protection circuitry of a more expensive amp & sub combo such as soft clipping. The sub is likely to be over rated in terms of power so when they say 250wrms that's exactly what you get (if you're lucky), whereas better quality products will be under rated and can actually handle 30-40% more than that without failing. Likewise with the amp. You pays your money etc etc.
 
OK, thanks for that. Well the one I bought in replacement retails at £250 which I suppose is mid-range for a sub. It's a Vibe 12" Pulse 3 powered sub, from what I have read it is a fairly decent sub for the price.

I hope that the extra money spent will mean that it lasts longer than 3 years!
 
OK just installed the new sub and it sounds a hell of a lot better than the Basslink - so maybe it blowing was a blessing in disguise?

I have been reading up a bit on sub wiring and discovered an interesting idea regarding the remote on wire:

Instead of wiring the remote on wire to the blue/white striped remote wire, wire it to the yellow power wire which is fused (the blue/white one is not). It then states that your sub will be protected more as the fuse will blow in the yellow wire before frying the amp in your sub.

Does this make sense and would it offer more protection for the amp in my sub?

Just need to know before I put all the HU back in and tidy it all up.

Thanks.
 
The remote should be controlled by the HU

when the HU is on power to the sub on

wiring it to the yello wire - which i assume will be the switched ignition wire will turn the amp on whenever the ignition is on.

if you are paranoid about blowing your amp with the HU remote out just add a fuse inline with the remote - I have never heard of a remote line blowing an amp.

use it as intended and you will be fine

and if you liked the upgrade from the basslink to the vibe - hurry up and low the vibe so you can buy a real sub and amp combo that will really sound good! (for alot less than the vibe cost you as well)
 
Excellent, thanks for that info. Guess I am paranoid now that my other sub blew. I'll leave it on the blue remote wire and maybe add a fuse as soon as I have time.

Cheers,

Jamie
 
audi upgrades
and if you liked the upgrade from the basslink to the vibe - hurry up and blow the vibe so you can buy a real sub and amp combo that will really sound good! (for alot less than the vibe cost you as well)
Click to expand...

LOL - Yeah, maybe if the Vibe goes bang I will consider that. I'm just a bit lazy and don't want to have to add loads of wires and find places to hide extra amps.
 
I thought I had finally put this one to bed now that I have a new sub BUT...

I took the car out for a drive to enjoy some music, towards the end of the journey I noticed that the bass wasn't quite right, it seemed to be intermittent.

Having a closer look it now seems that the bass isn't appearing where it should, the sub definitely kicks out bass but not consistently. It seems to miss certain beats, instead of being in rhythm with the music it's appears to be almost out of time with it, occasionally booming and then giving up again.

I am literally at the end of my fcuking tether with this. Can someone please save my sanity before I rip all this stuff out and put the Audi **** back in!
 
Just to add a bit more info on this - Tried wiring the sub to the rear left and right pre outs on the HU to see if it was the sub output that is the problem, no - exactly the same.

Secondly I can get the sub to work as it should at very low volumes (bass is in time with the music and constant) as soon as I turn the levels up on either the HU or the sub's amp I get the intermittent bass problem again.

It's almost gone the same as the Basslink, but I can still get some sound out of it whereas the Basslink I couldn't get anything at all.

What the hell is going on? I've never had this trouble before, but with this new car I've had two subs go wrong!
 
I'd check the power connections. Where have you run the power from and where is the amp earthed. If the problem is volume related it could be the earth is poor or the amp is struggling to pull enough power thus producing a severe voltage drop when you whack the volume up and the amp is cutting out. You could also stick a multimeter on th power connections and see if it's 12-14v regardless of volume. If it suddenly dips to below 12v then it's not getting a good enough power feed. The remote on issue is irrelevant as all remote on feeds only provide a tiny amount current, just enough to trigger the relay in the amp. If in any doubt just connect the remote on temporarily to the perm live on the amp. Don't leave it wired this way as it'll drain the battery pretty quickly.
 
another vote for bad earth hear - where are you running the power for these units from
 
Thanks guys, I will check the earth connection. The wire connecting the earth to the chassis of the car is definitely not as thick as the wire connected to live - I'm sure this is the wiring which came with the Basslink which is pretty poor if this is the problem.

The live is connected straight to the battery with an in-line fuse at the battery end. Not sure what gauge the wire is, I'm guessing the standard is 8 gauge?

I have the earth wired to a bolt which I presume is connected to the chassis of the car, I will check this as well. What happens if it's not? Surely I would get nothing?

So I guess the next question is, if the ground wire is not thick enough and not connected to the car's chassis will this have fcuked the amp in the new sub or can I just replace the wire and away we go?
 
Just replaced the earth wire with a more sturdy one and relocated it to one of the seatbelt bolts - not sure the original position I had it was in direct contact with the chassis of the car.

I don't want to be premature, but I think that has fixed the problem. It's now more bassy than before and all the bass beats are as they should be.

I've had to turn the HU down to +1 for the sub (which is as low as it will go), the sub's volume is about 1/4 turn; before the HU was set to +3 and the amp on the sub was about 1/3 turn.

A thousand thanks to AndyMac and thejoose for your help!

Will the fact that it wasn't properly grounded do any permanent damage?
 
You'd know if you'd damaged it. The only damage would be clipping (square wave) going to the sub which would fry the voice coil, but if it's working now then you will be OK.
Glad you got it sorted.
 
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