JL Audio f112 blown speaker?

What I don't understand is the fact that all the reviews basically rave about this sub and yet they have this so called disortion in the way. I have tried everything in my power now to drive this F113 to the point where I should be getting distortion or cabinet resonation. I have a dedicated line and a Lessloss power cord on it right now so maybe that has something to do with the sub not distorting. I feel this sub is great for movies and outstanding for music. It controls the higher frequencies with precise accuracy ("very real musical bass")and zero localization.

Do we even know what excursions were taking place when this distortion was taking place?

The HT Shack Subwoofer test graphs are colored with a variety of measurements at various SPL outputs, all at less than insane levels. Many of the curves show what could hardly be called insignificant amounts of distortion.

If you look at an equal loudness contor plot of our hearing sensitivity then you will observe that the sound of 10% distortion will be much louder to our ears than an orignal 20Hz tone => because of our lack of hearing sensitivity at 20 Hz you hear the distortion louder than you hear the music.

Refer to the bottom of the page (last two plots) to see what Seigfried Linkwitz has to say about distortion at low frequencies.

Linkwitz suggests that 1% THD is the kind of distortion you ideally need in a sub - if you want to hear what is on the recording.

One would have to drive this F113 to insane levels before hearing any distortion. As an owner I can promise you this.
The testing that is being done on these subwoofers are not real world. They do show what happens on a graph which does not mean too much to me. I would much rather listen to the sub in my own listening room and try to calibrate and integrate with the mains and room. The JL Audio has great features for doing this. Do we even know what excursions were taking place when this distortion was taking place?

JPL,

4" is peak to peak - so 2 inch in and 2 inch out. This is the absolute maximum - it would probably sound even more distorted than 10% THD at those type of excursions.

I turned up the F113 to levels I would never play normally and watched this excursion. Maybe 1" of excursion outward was noticed. To push this any further is not normal. At least for music. Movies may be a different story and I have had it loud enough to make it feel like my couch was being lifted. With one of these in a room 18' wide 40' deep and 10' high I have been extremely impressed. Two of these in this room will just work that much easier and give more depth and extension. It's going to be fun.

I am also glad I don't hear this compression.

JL use a 3.5" voice coil it should not normally compress too much at high
levels.
However, it appears to be a long coil short gap design which explains the high
harmonic distortion (around 10% and sometimes above). The long coil short gap
would be typical of PA and rock concert woofer designs - some manufacturers
make similar drivers in two versions (one short coil with less SPL output but
better accuracy and one long coil for more SPL) perhaps JL113 may lose power
due to very high excursions (4" peak is an unbelievable excursion- WOW!)
as the coil moves well outside the linear magnetic range, which woudl explain
the compression and THD. There is no doubt it is an excellent sub - one of the
best out there.

Yes, thank you for everyones comments and advice. I was seriously concerned that it was something else in my system.

Like Jp1208 I am extremely satisfied with my JL Audio sub. It sounds terrific with movies and music, both, and have no intention of going any where else.

Rshad000, Hope all is well now. I just love the musicality of the F113's. Really changed my thinking on subwoofers so I will be getting another soon. Nice to know that JL Audio stands behind there product and takes care of people in a timely manner. Things like this do happen in audio and I have heard of some horror stories besides mine. I am also glad I don't hear this compression. This would make for an unpleasant experience and a return to vendor journey. HT Shack highly recommends the JL Audio subs. The JL is one of the best they have ever heard from what I read. I highly encourage people to read what the tester wrote on at least the F113. Can't say I really looked into the F112.

After sending in my subwoofer to JL Audio they tracked down the problem to a preamplifier component in the sub. I beat the odds and got two of them with the same exact issue in a row.

Sounds like they changed supplier or got a bad batch. These things do happen even with great products. Funnily enough though - the HT Shack Subwoofer tests reported another problem with the JL sub they received for testing - so this incident may not be as isolated as it seems - check the HT shack subwoofer test forums for details. I don't remember what it was - I seem to remember they observed significant audio compression below 40 Hz at high SPLs..

After sending in my subwoofer to JL Audio they tracked down the problem to a preamplifier component in the sub. I beat the odds and got two of them with the same exact issue in a row.

JL Audio's service can not be beat and they have taken care of me again.

a) have you contacted your dealer?
b) since the JL factory has helped you already, are they helping you now?
c) if you have NOT done (a) or (b) why would you be asking on here?
d) The above poster Shadorne has a very good point. I suggest you carefully check your interconnects and also, if possible, examine or have someone examine the signal at the sub end of the cable with a scope to determine what is really going on. There have been instances where preamps do such things as oscillate outside the audio passband and put out lots of voltage while doing so.

If you need any additional assistance with this then please contact me.
Barry

Put your sub on an seperate circuit if you can.Try using a heavy duty extension cord and run the sub to a different outlet away from the rest.The JL's have a limiter of sorts built into it. I found it running test tones thru it, didn't damage it at all and I found the absolute max I can drive the Fathom to. Did you calibrate the sub using test tones to the recommeneded 75 db setting?

Also...I have the sub, speakers, amps, processor and TV all on one circuit. I know, not ideal at all, but my room layout doesn't permit much else.

Thanks guys. This is all good advice and I will give it a try.

To answer your questions...

I have the cross over on my center and surrounds set at 80hertz and my L/R set at 60hertz; plus the LFE going to the sub.

I only have the volume set to a little under halfway.

My guess is the games are just driving it really hard and compounding whatever problem I have.

Make sure the connectors of your cables aren't touching adjoining cables on the back of your processor. Make sure your connectors aren't loose on your cables.

This is an amplifier problem or power supply problem in your sub. This is not good - especially if two units have done this. Perhaps JL have developed a QC problem with some parts they are using. Alternatively, if your Classe has a fault perhaps a high level DC or transients are reaching the XLR input on your sub and damaging the input buffers by over driving them. If your XLR cables are wired correctly none of the three wires should be connected to the connector or shield and all three lines should be isolated from eachother.

sounds like a burnt voice coil, are you rolling off all your bass off your main speakers and your LFE to the single sub? This can sometime overwhelm a sub depending on the crossover level, plus gaming runs the sub continuously versus a movie.
Do you have your sub located in the correct place? are you pushing it hard but sitting in a null? Put the sub in your listening position and walk around the room where you might put the sub and place it in the loudest location. Then use the EQ to cut, because if you are sitting in a null you will keep cranking the sub and overdrive it.

The only other thing I can think of is that your power voltage is damaging the digital amp in the JL audio. What else is on that circuit? unplug everything on that circuit. tighten up the connections on all plugs and light switches on that circuit since they are wired serially typically. I had a an electrical that didn't tighten down the wires on the back and the + jumped off and was shorting on the back of the outlet. Be careful of live outlets!

I abused my F113 pretty hard with U571 before I sold it and it didn't even blink.