Signs of a blown sub

[Sizzlechest]

My sub recently started only producing bass when my HU volume is around half or higher. I get absolutely no bass at low volume.

The sub is a sundown audio sa12 d2 wired to 1-ohm powered by a soundstream rub1.1000d @ 1000 x 1. Lowpass filter is at about 75 hz.

My first thought is the head unit itself. Its an android double din unit from China that has weak pre-outs. When I mentioned concern with the hu, someone on android hu forum said the sub may have a short which may be why it is only working when the amp is outputting higher voltage/watts to it. Does this sound possible to anyone (no pun intended). It still hits hard when the volume is high, just nothing at low volume. Its almost as if a certain volume level is an on/off switch for the bass... really weird

I was going to pull the sub tonight and check the resistance on the voice coils to see if that checks out. My next test is going to be trying a different output source to rule out a HU issue.

Click to read more...

 

[groundcrusher]

It could very well b the head unit hard to tell until you pull the sub and check the leads make sure they haven't vibrated loose but it would seem like it would cut in and out when the bass hit if that was the case

 

[groundcrusher]

Try setting to 80 or little higher to see if makes a difference

 

[groundcrusher]

Check your volts to your may have a voltage drop real bad or a very weak power supply (bat or alt)

 

[ace_800 5,000+ posts]

Our test it using an MP3 player/Ipod

 

[Sizzlechest]

@groundcrusher why would voltage issue come into play at low volume, wouldn't it be the other way around when demand is high?
@ace_800 yes that is my plan

 

[Bass Addict 10+ year member]

im bettin its the hu

 

[groundcrusher]

My bad yall I didn't mean to put that on here was for another post I was doing I didn't even realize I put it here till now

 

[Boominburban]

These are deffinate sings of a blown sub ......

 

[Sizzlechest]

I tested the resistance on Monday night with a DMM and it was 0/not registering and I assumed this is because I was testing it on the enclosure +/- leads, not directly on the sub itself.

Today, I rigged up a headphone plug to RCA plug and played some music through my phone connected directly to the amp and it was doing the same as my HU -- no bass until high volume. At this point I'm saying FML and figured I'm buying either a new amp or new sub.

I pull the sub out of the box and immediately see something bad (see below). After seeing that I thought it was a huge possibility of being the cause of my issue. I decide to check the resistance of each VC anyway, and both came in at 2.5 so that was a relief.

View attachment 26552182

The negative terminal was black! I fortunately had some good 12 gauge OFC speaker wire left over from my recent install. I sanded all of the crap off of the terminal on the jack and soldered fresh OFC 12 gauge speaker wire directly to the terminal to ensure a good connection and got everything reconnected in my car. Fired it up and it played perfectly!

After:

View attachment 26552183

In the picture above you can see the base of the wire is black. On the terminal itself it had this black stuff caked onto it which was hard to get off even with 2000 grit sandpaper (its all I had).

I don't know what I was thinking when I wired the sub into the enclosure. I used the crappiest connection you can think of. It was old beat up crimp terminals that did not hold onto the jack snug at all.

Thank you everyone for your feedback!

 

[skylineTT 10+ year member]

Well, there ya go.

 

[Boomin_tahoe 5,000+ posts]

Never seen a burnt speaker wire before....

But glad the problem was easily solved....and cost free

Troubleshooting can be a ***** sometimes.

Oh yes...for those that may not know, easiest way to test/check to see if a sub/speaker is blown is with a battery. Like the one in your flashlight. Doesn't have to be big or small. Take that battery and either 1 or 2 pieces of speaker wire and take one end of the wire and put it in one of the pos or neg terminals. Do the same with the other speaker wire. Now take the battery and the little "bump" on one end of the battery will be + (positive). Take the pos end of the spkr wire and put it on the battery. Same with the neg side, You won't get hurt if you do this. This should move the sub upwards just a little. If it moves downward, revers the wires and try again. For DVC subs, 1 of the coils must have a speaker wire hooked up (+ and -) and do the same with the other coil. Same results.

Another thing you can do is press firmly on the cone with your hand gently, downward. At times you can hear a "scratching sound" if the speaker/sub was blown.

 

[Sizzlechest]

I'm not sure if that burnt part is from this sub or not. That wire was a hand-me-down from a bandpass I used to have which blew an Earthquake sub years ago. But the terminal being all charred up makes me curious. Could this be caused by a weak/insecure terminal connection?

 

[Boomin_tahoe 5,000+ posts]

I'm not sure if that burnt part is from this sub or not. That wire was a hand-me-down from a bandpass I used to have which blew an Earthquake sub years ago. But the terminal being all charred up makes me curious. Could this be caused by a weak/insecure terminal connection?

I would stick to fresh new wire to save yourself any trouble later on down the road.

Or....if your so broke, strip off that charred end and crimp on another female connecter on there.

 

[Sizzlechest]

Of course, as I said, I sanded the jack and soldered fresh OFC 12 awg to it.