Sub almost airborne

[walter duque]

Yesterday afternoon I went home on a break from work and noticed that my dowwfiring sub was cracking so hard that I thought the enclose was going to blow apart, it almost lifted the sub off the floor (it's around 100#) Sub is about 15 years old and I did replace the driver a few months ago with exact same driver. Now last night when I went home I checked it again and it was fine. What could have been the problem? I did drive this sub very hard for many years.

 

[Patrukas777]

Yesterday afternoon I went home on a break from work and noticed that my dowwfiring sub was cracking so hard that I thought the enclose was going to blow apart, it almost lifted the sub off the floor (it's around 100#) Sub is about 15 years old and I did replace the driver a few months ago with exact same driver. Now last night when I went home I checked it again and it was fine. What could have been the problem? I did drive this sub very hard for many years.

Well, since you live on the moon, the gravity is .1655 of the earth's. Maybe that has something to do with you sub flying??

 

[j_garcia]

It was while you were playing something or it was doing it on its own? If it did it on its own then something in the amp is dying.

 

[walter duque]

Well, since you live on the moon, the gravity is .1655 of the earth's. Maybe that has something to do with you sub flying??

You might be on to something.

 

[walter duque]

It was while you were playing something or it was doing it on its own? If it did it on its own then something in the amp is dying.

I was playing something when I realized what was happening.I shut everything off except the sub. It sounded like someone is pounding from the inside with a hammer full force. It was so powerfull that it almost lifted that thing up and now it's OK. Could it be the amp is on its way out?

 

[skers_54]

I was playing something when I realized what was happening.I shut everything off except the sub. It sounded like someone is pounding from the inside with a hammer full force. It was so powerfull that it almost lifted that thing up and now it's OK. Could it be the amp is on its way out?

It sounds like the amp may be giving out and dumping current into the driver. That would explain the tremendous output and force. Did you get a look at the driver while it was doing this?

Since you recently replaced the driver, do you know what was wrong with the old one? Sometimes failing amps will cause drivers to fail too. Could be that the amp was dumping current and caused some of the loops of the voice coil to fuse, dropping the impedence and causing it to pull more current.

Do you have a multimeter handy? If you do, you should measure the DC resistance of the driver and see if it has deviated significantly from its spec.

 

[walter duque]

It sounds like the amp may be giving out and dumping current into the driver. That would explain the tremendous output and force. Did you get a look at the driver while it was doing this?

Since you recently replaced the driver, do you know what was wrong with the old one? Sometimes failing amps will cause drivers to fail too. Could be that the amp was dumping current and caused some of the loops of the voice coil to fuse, dropping the impedence and causing it to pull more current.

Do you have a multimeter handy? If you do, you should measure the DC resistance of the driver and see if it has deviated significantly from its spec.

Now what would be the problem, the amp or the driver? I don't know much about the technical stuff. There was so much force going into that driver that no amp can produce. This was brute force pounding that thing. Now could this damage my pre-pro?

 

[MidnightSensi]

This sounds like an amp failure to me also. I know what you mean about the violence of it, it's insane. When they go bad sometimes they send out a clipped signal, which looks like a square wave to the subwoofer. Makes them go absolutely crazy and, generally, blows them. Depending on the box and driver, the suspension might blow, or the voice coil might get so hot it expands to the point of locking up. When you press on the driver, you'll feel scraping.

This sounds like an amp failure to me also. Something could be grounding itself on the amp, so when you play music and it heats up it'll ground/short something or maybe the vibration. Hard to tell. Does the amp smell at all?

 

[skers_54]

Now what would be the problem, the amp or the driver? I don't know much about the technical stuff. There was so much force going into that driver that no amp can produce. This was brute force pounding that thing. Now could this damage my pre-pro?

Well, in the situation I described (which is just a guess and may not be right) it would be the amp causing the drivers to fail. If the driver was failing, you'd get flapping or buzzing. Since the output was rediculously loud and not so much "farting", it points towards the amp.

As amps fail, their output may become unregulated. This would dump a lot of current (aka power) into the driver causing it to produce extremely loud sounds. This also produces a lot of heat which can fuse the voice coil windings. This causes more current to be drawn from the amp because the impedance of the driver is now lower. So it's kind of a vicous feedback loop.

One of the things that people here talk about when drivers fail frequently is an amp problem. Since you just replaced a driver and are having issues again, I'd look at the amp. In your first post you mentioned a cracking and hammering. That could be the driver bottoming out and slamming into its support structures. Bottoming out usually occurs because of too much power being applied by the amp. And in this case, it's not the amp producing power like it normally would; it's basically the amp is dumping whatever power it gets from the mains directly into the driver, kinda like a short circuit or a really bad turn-on thump.

So, it's a case where the amp is damaging the driver, but the damage to the driver is compounding the problem with the amp.

I don't think it would damage your pre-pro unless the thing just absolutely exploded (but then you'd have bigger issues to worry about, also not saying that that's likely to happen). Even then, it's unlikely because the power from the amp output stage would have to climb backwards through all the internal circuitry and up the cable back to your pre-pro.

 

[walter duque]

[

QUOTE=MidnightSensi;715789]This sounds like an amp failure to me also. I know what you mean about the violence of it, it's insane. When they go bad sometimes they send out a clipped signal, which looks like a square wave to the subwoofer. Makes them go absolutely crazy and, generally, blows them. Depending on the box and driver, the suspension might blow, or the voice coil might get so hot it expands to the point of locking up. When you press on the driver, you'll feel scraping.

This sounds like an amp failure to me also. Something could be grounding itself on the amp, so when you play music and it heats up it'll ground/short something or maybe the vibration. Hard to tell. Does the amp smell at all?

[/QUOTE]
I think you and skers 54 are right on with that. No smell from amp and no scatching sound from driver. Tonight I am gona take a look inside and check it out. Last night when I turned it on again it was fine, so it's got to be the amp. Thanks for all your help. It was like a piece of firewood smacking around in there at full force, kind of a scary moment, I thought the box is going to blow apart. Could that amp be fixed since replacement cost is $545.00

 

[MidnightSensi]

[

I think you and skers 54 are right on with that. No smell from amp and no scatching sound from driver. Tonight I am gona take a look inside and check it out. Last night when I turned it on again it was fine, so it's got to be the amp. Thanks for all your help. It was like a piece of firewood smacking around in there at full force, kind of a scary moment, I thought the box is going to blow apart. Could that amp be fixed since replacement cost is $545.00[/QUOTE]

You could pull the amp off and see if it is something obvious, but it probably will need to be replaced.

I had a Velodyne HGS-18 that did that. It was really obvious though because the amp smelled. Then I replaced it, and maybe six months later it did it again. Finally gave up on it figuring their amp just sucks. Had so little in it I didn't want to put more money into it.

If you don't want to spend 545, you could try another (cheaper) plate amp. Although if it doesn't fit it will become a project.

 

[skers_54]

I think you and skers 54 are right on with that. No smell from amp and no scatching sound from driver. Tonight I am gona take a look inside and check it out. Last night when I turned it on again it was fine, so it's got to be the amp. Thanks for all your help. It was like a piece of firewood smacking around in there at full force, kind of a scary moment, I thought the box is going to blow apart. Could that amp be fixed since replacement cost is $545.00

You could pull the amp off and see if it is something obvious, but it probably will need to be replaced.

I had a Velodyne HGS-18 that did that. It was really obvious though because the amp smelled. Then I replaced it, and maybe six months later it did it again. Finally gave up on it figuring their amp just sucks. Had so little in it I didn't want to put more money into it.

If you don't want to spend 545, you could try another (cheaper) plate amp. Although if it doesn't fit it will become a project.[/QUOTE]

I agree. You'd need some pretty sophisticated test equipment and knowledge to repair the amp yourself. You could ask around locally about repairing it, but I don't know how much that'll save you. It would at least tell you if the amp really is bad.

Before spending the $550 on a new amp, you'll want to check your driver to make sure it didn't get damaged. Even if it's not scraping, the voice coil could be damaged, the surround could have torn, etc. Definitely give it a thorough look.

What type of sub do you have? Some subs (especially sealed) have EQ built into the factory amps. I don't know how to check that besides calling the company. I think that's something to find out before buying a cheaper plate amp. You can get around that with an external EQ, but that would be a project in itself.

 

[walter duque]

You could pull the amp off and see if it is something obvious, but it probably will need to be replaced.

I had a Velodyne HGS-18 that did that. It was really obvious though because the amp smelled. Then I replaced it, and maybe six months later it did it again. Finally gave up on it figuring their amp just sucks. Had so little in it I didn't want to put more money into it.

If you don't want to spend 545, you could try another (cheaper) plate amp. Although if it doesn't fit it will become a project.

I agree. You'd need some pretty sophisticated test equipment and knowledge to repair the amp yourself. You could ask around locally about repairing it, but I don't know how much that'll save you. It would at least tell you if the amp really is bad.

Before spending the $550 on a new amp, you'll want to check your driver to make sure it didn't get damaged. Even if it's not scraping, the voice coil could be damaged, the surround could have torn, etc. Definitely give it a thorough look.

What type of sub do you have? Some subs (especially sealed) have EQ built into the factory amps. I don't know how to check that besides calling the company. I think that's something to find out before buying a cheaper plate amp. You can get around that with an external EQ, but that would be a project in itself.

[/QUOTE]
I do have an extra channel on my power amp (350 into 8 ohms-500 into 4 ohms). It is a designated channel for a sub. Could I use that amp to drive the sub and what would it take to do so.
It's almost like this http://www.sourcespeaker.com/SW12ULT-DFSub.html one. Don't forget mine is old.

 

[MidnightSensi]

I do have an extra channel on my power amp (350 into 8 ohms-500 into 4 ohms). It is a designated channel for a sub. Could I use that amp to drive the sub and what would it take to do so.[/QUOTE]

Sure. How many watts was the plate amp? If it was around the same output as your amplifier outputs, it would be a good fit.

All it would take is a speaker cable from your amplifier to the subwoofer drivers positive and negative terminals. You could remove the plate amplifier and put speaker terminals there instead.

 

[markw]

Two step solution.

Since the crossocer is external to the sub/amp box, you might want to first remove the sub's built-in amp.

Send out to someone who can check it out, provide an estimate of it's repair.

and, for temporary use, implement that spare monster amp you've got lying around.

If the sub amp can be fixed economically, go for it and re-install it.

 

[walter duque]

Since the crossocer is external to the sub/amp box, you might want to first remove the sub's built-in amp.

Send out to someone who can check it out, provide an estimate of it's repair.

and, for temporary use, implement that spare monster amp you've got lying around.

If the sub amp can be fixed economically, go for it and re-install it.

Is there any kind of crossover required or is the crossover from the pre amp going to work. I can't just go from the power amp to the sub driver or can I?

 

[walter duque]

Checked driver, it's OK. All the screws where loose. That could'nt have anything to do with it, could it? For now it sounds fine, but I am sure the amp is going to act up when it gets hot.
Thanks for all your help.

 

[MidnightSensi]

Checked driver, it's OK. All the screws where loose. That could'nt have anything to do with it, could it? For now it sounds fine, but I am sure the amp is going to act up when it gets hot.
Thanks for all your help.

Likely not. You said the subwoofer has some years under its belt, probably some fatigue in the wood along with the vibration caused the screws to loosen a bit.

 

[walter duque]

Just got E-mail from Source Technologies, it's the amp. New amp will arrrive on tuesday. Now that's what I call customer service. Replacing amp after 15 years I think that's nice. I really do appreciate all the input. Thanks to everyone again.

 

[skers_54]

Just got E-mail from Source Technologies, it's the amp. New amp will arrrive on tuesday. Now that's what I call customer service. Replacing amp after 15 years I think that's nice. I really do appreciate all the input. Thanks to everyone again.

Glad I could help. Great news, and sounds like a great company...