Fi Audio 18BL warranty issue - failed after an hour of use

[keep_hope_alive]

maybe you just heated that coil up and it unwound

that would be my normal assumption as well.

but that's assuming it sustained 2kW for any appreciable amount of time, which it didn't. even the 2-3 minute demos on music weren't anything near full amp capability. i've seen these same subs do more than that for hours daily.

that gets to my original question, how many have seen a coil unwind and what were the circumstances? how many have had a brand new sub fail within hours and why was it (besides pure SPL destruction purposes)?

obviously, to get the coils to unwind they need to be hot enough for the glue to let loose. the amps never went into protect and the coils aren't shorted. they weren't ran long enough to overheat from extended use (only pushed a few minutes at a time). if they coils were mis-matched, one coil would heat up more than the other. that is the only concrete evidence we have right now, mismatched coil DCR.

[DDtC]

that would be my normal assumption as well.

but that's assuming it sustained 2kW for any appreciable amount of time, which it didn't. even the 2-3 minute demos on music weren't anything near full amp capability. i've seen these same subs do more than that for hours daily.

that gets to my original question, how many have seen a coil unwind and what were the circumstances? how many have had a brand new sub fail within hours and why was it (besides pure SPL destruction purposes)?

obviously, to get the coils to unwind they need to be hot enough for the glue to let loose. the amps never went into protect and the coils aren't shorted. they weren't ran long enough to overheat from extended use (only pushed a few minutes at a time). if they coils were mis-matched, one coil would heat up more than the other. that is the only concrete evidence we have right now, mismatched coil DCR.

Whatever it is its bad QC. I guess they needed something else since the spiders stopped catching on fire

[garychoffmann]

I've had 2 coils unwind, one was on a concept 12 & the other on a t3 12. Both replaced the subs pronto as defective coil. I had a 4 inch coil I bought for a recone once. You could slightly see that it was pullong a little bit. I sent it back in and they said "moisture damage" and asked if I had cleaned it with water or amonia..... I didn't so they sent me a new one. Only 3 i've ever seen personally in my 22 years of car audio

[T.I.K.]

Whatever it is its bad QC. I guess they needed something else since the spiders stopped catching on fire

Wait what?

[DDtC]

Wait what?

Tensile leads use to catch the spiders on fire. User error as in way overpowering for most but come on.

[T.I.K.]

Tensile leads use to catch the spiders on fire. User error as in way overpowering for most but come on.

Lol, yeah over-powering or not, I feel like those shouldn't catch fire.

[DDtC]

Lol, yeah over-powering or not, I feel like those shouldn't catch fire.

You think.

[mlstrass]

I've reconed several subs with unwound coils for diff people. 8 out of 10 times it's clipping and the coil, or what's left is black. Other few times it's been thermal/over powering and glue heats up. These subs were seeing 2-3x RMS and playing music for extended periods.

My one question: wast most of the music/burps around 50Hz or so? If so did you notice very little excursion out of the sub as that will create a lot more heat with little to no movement to cool the sub.

Could just be a case of too much power/too little excursion and the sub overheated and let go. BL's aren't exactly killer strong subs...

[-BenBen-]

When My sp4 spiders caught on fire in my trunk, and it was a defective sub..i lost all hope in fi

[T.I.K.]

When My sp4 spiders caught on fire in my trunk, and it was a defective sub..i lost all hope in fi

In fairness, lead wires catching on fire seems like a supplier issue. As somebody who has worked in a quality engineering position before, let me tell you that lots of problems like these are completely out of manufacturer control. Yet, nobody understands the concept of process flow and how many different companies are involved in a finished product. So many people over-simplify the process to rationalize pinning the tail on manufacturer.

While it could be Fi's mistake that tinsels were catching on fire, the build house could have compromised the leads, or the raw materials supplier might have made defective wire/sheathing. I'm sure that it was thoroughly investigated, especially considering the safety issues involved with the malfunction.

[keep_hope_alive]

I've reconed several subs with unwound coils for diff people. 8 out of 10 times it's clipping and the coil, or what's left is black. Other few times it's been thermal/over powering and glue heats up. These subs were seeing 2-3x RMS and playing music for extended periods.

My one question: wast most of the music/burps around 50Hz or so? If so did you notice very little excursion out of the sub as that will create a lot more heat with little to no movement to cool the sub.

Could just be a case of too much power/too little excursion and the sub overheated and let go. BL's aren't exactly killer strong subs...

good questions. music covered a wide range and the tones weren't that long in duration. clipping didn't happen, i'm sure of that. scopes don't lie. and nothing was black, coil looks new just unwound.

there was plenty of cone excursion with initial testing around 50Hz, and i agree that the coil would heat up if the cone wasn't moving to create airflow to cool the coil.

maybe i need to take a closer look at cone behavior in the box and if the cone seems to "stall" around certain frequencies. even still, i would expect it would take longer, since the music was constantly changing and the tones were higher.

the intent is a daily system, not an SPL monster. Box is tuned around 28Hz. The sub in there now does just fine.

[mlstrass]

But the sub in there isn't getting 2x RMS I'm guessing. That makes a big diff on how the sub reacts in the enclosure vs normal power...

[SPLaudio]

post pixs of sub plz.

the coil cost more than $10 and not 3-$4 eather for a 3" coil,lol. i know what coils cost even in big quanity.

[sundownz]

trust me, it costs fi more than $10 in parts for a recone. just the coil is about $10

If they are using 8-layer flat wind coils from Precision in Florida... the coil itself is 2.5-3x that much. A 4-layer round is still 1.5x that much if it's fairly long.

Either way -- they do use Precision coils at Fi; I am just not sure what type in that model driver -- Precision makes some of the best coils available and a coil that is simply defective is almost unheard of as far as a coil just sliding off of a former.

So that would leave us to figure out how the coil got so hot so quickly.

When you used the scope did you test it on the music signal as well in case the level was different ? The amps made in the style of the Massive Nano (similar design to Audiopipe) make a VERY weird and jagged wave with spikes when clipped on the ones I've tested. We did some testing here a few weeks and when we pushed amps of that design into clipping the coil smelled rapidly; same clamped power on a Korean Class-D (which clips very smooth and flattens out up top) no such smell.

Either way; good luck resolving your issues

[dbeez]

Well heres what fi told me years ago no matter what happens to a sub or how it fails its always customers fault they can never have a bad part. I had a coil unwind as well 5 burps.