# JL Audio Fathom F112 subwoofer review by Tom Nousaine



## Ilkka (Jun 8, 2006)

http://www.soundandvisionmag.com/speakers/1853/test-bench-jl-audio-fathom-f112-subwoofer.html

There's a new review on Sound and Vision Magazine by Tom Nousaine. It isn't very long but contains some measurements. One sentence caught my eye...

_Although the F112 has relatively high low-frequency output (104 dB or greater at every frequency from 32 Hz up to the top of its range), *it was not able to reproduce 25 Hz with less than 10% distortion.* It can make plenty of sound at this frequency (104 dB), but with 40% distortion where the upper harmonics are approaching the amplitude of the fundamental._

Notice that the measurements were done in 1/8 space @ 2 m (corner of a room). Though when comparing TN's and Yates' data on Genelec HTS6, they seem pretty close, meaning TN's numbers are pretty close to what one gets in 1/2 space (GP) @ 2 m. Also notice that TN uses 6.5 cycle long "bursts", not longer sine waves or sweeps.

Here's another "In The Lab" .pdf, so you can compare the data to other subs TN has measured.

edit: The test unit was most probably defective. Read more from below.


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## Ilkka (Jun 8, 2006)

A few more thoughts about the test.

It seems that TN's lower limit for SPL is 60 dB. So when he said that the F112 was not able to reproduce 25 Hz with less than 10% distortion, it means that the 10% limit at 25 Hz is less than 60 dB. That is very weak performance for a sealed 12" sub. Just look at the DIY Infinity Kappa Perfect 12" subwoofer I tested; it was able to pull out ~89 dB @ 25 Hz @ 10% THD. Our test results aren't 100% comparable (mine are done outdoors and with more taxing signal), but in any case, JL Audio should be ashamed... :rolleyesno:


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## Ilkka (Jun 8, 2006)

From AVS:



> Suffice it to say that we are quite puzzled by the test results Mr. Nousaine reported. In no way do these results agree with our own measurements and what we know to be the performance capabilities of the f112.
> 
> Having not been present during the testing, we do not know if there was some issue with the product or with the measurement setup that could possibly explain these results. I'll leave it at that until we get more information.
> 
> ...


So let's wait and see if the unit was defective etc. before lighting the torches... :devil:


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## Sonnie (Apr 11, 2006)

That does sound pretty weak coming from JL Audio... I'd certainly expect better.

It must be defective, if not, I agree... shame, shame!


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## SteveCallas (Apr 29, 2006)

I've heard about "defective" sample units so many times it's getting ridiculous  I'll give them the benefit of the doubt for now, but the chances of these results being accurate seem pretty good.


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## Bent (May 24, 2006)

Is "defective" a veiled way of saying that quality control is lax?
It does seem that this is becoming common with manufacturers... would it have performed better if they had product reps present to comfort and console their flagship subwoofer and egg it on for round 2? I think not.


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## Sonnie (Apr 11, 2006)

JL Audio is big into car subs... very popular albeit mostly the teenage and college crowd that could probably care less about 20% distortion at 25-30hz... as long as it's loud and registers 150db on the meter. Of course JL isn't generally building the boxes for those either. Anyway... it may be that they are trying to get into a market they just don't know enough about... pure speculation. The home enthusiast is definitely a different breed from the car enthusiast (in most cases).


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## Guest (Oct 25, 2006)

I can assure you gentlemen that we know plenty about achieving high-output, low-distortion bass. :boxer: 

Nousaine's numbers are simply out-of-whack... either the product has a problem or the test setup/equipment is a problem. The f112 he tested was shipped by UPS from Florida (JL) to Maryland (Dan Kumin for review) to New York (photography) and then to Michigan (for Mr. Nousaine to test). It's quite possible it was dropped or mishandled and damaged. 

We are working with S&V to retest the same unit and a replacement if necessary. I will post on AVS when I have further information.

Best regards,

Manville Smith
JL Audio, Inc.


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## Bent (May 24, 2006)

Well the fact that you joined and posted helps to alleviate my concerns. in fact I'll "almost" retract my complete post...

I truly was thinking that since a number of manufacturers have indicated lately that "it couldn't possibly be a represenatative sample" (or something like that), that it was the pattern answer from which everyone could obtain their scape goat. My appologies.

I look forward to your new informaton - even if it is on AVS :clap:


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## Sonnie (Apr 11, 2006)

Well being that I don't frequent AVS, maybe it will drift back around here for those who might be interested.

I do find it hard to believe that Nousaine's numbers are simply out-of-whack though.... not that's he's perfect.


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## Guest (Oct 25, 2006)

Sonnie said:


> Well being that I don't frequent AVS, maybe it will drift back around here for those who might be interested.
> 
> I do find it hard to believe that Nousaine's numbers are simply out-of-whack though.... not that's he's perfect.


I will be happy to post our test results here as well.

I am quite confident that his numbers are wrong or based on a measurement of a damaged f112... S&V has temporarily pulled the test report pending a re-test.

Cheers,

Manville Smith
JL Audio, Inc.


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## Guest (Oct 25, 2006)

As promised, here are our results using TN's methodology (as close as we could, anyway). See notes for explanations.

Cheers,

Manville Smith
JL Audio, Inc.


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## bobgpsr (Apr 20, 2006)

Very different results! For a 3200 ft^3 room and a 12" dia sealed subwoofer, getting 100 dB SPL @ 25 Hz with 10% THD limit seems reasonable. What are the 2 pi groundplane measurements? Is TN's test sample broken?

Bob


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## Guest (Oct 25, 2006)

bobgpsr said:


> Very different results! For a 3200 ft^3 room and a 12" dia sealed subwoofer, getting 100 dB SPL @ 25 Hz with 10% HD limit seems reasonable. What are the 2 pi groundplane measurements? Is TN's test sample broken?
> 
> Bob


It could be, Bob... as I stated earlier, TN's test unit was shipped to three different places via UPS before he tested it. It may well be broken... or then again, there could have been a malfunction in his test equipment or a setup error.

He has promised to retest the same unit and a different unit if the one he has measures the same as the first test.


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## Ilkka (Jun 8, 2006)

Now those are the performance figures I was expecting to see!

A few notes about your test vs. TN's test.

I don't think the room size makes a large difference when measuring at 2 m. Although wall material can make a large difference. Soft walls vs. concrete walls could mean many dB difference. 

TN's 6.5 cycle bursts should give one ~same SPL, but with lower THD since the VC doesn't heat up as with normal sine waves.

Your data puts the f112 in the 3rd place on the all time list of subs TN has measured: http://members.cox.net/fabulousfrankie/Nousaine.htm That is some serious performance out of a single sealed 12"! The f113 and the g213 should be real monsters. :raped: 

I'm really pleased how you handled the whole situation. I wish there were more manufacturers like you. :T


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## Guest (Oct 29, 2006)

Just a quick update...

After re-testing the same unit he originally tested, TN has determined that there is something wrong with it (likely shipping damage related). We're sending a second unit for him to test.

Manville Smith
JL Audio, Inc.


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## F1 fan (Jul 6, 2006)

Hi Manville,the F112 and 113 are impressive looking products with the promise of great bass in a small package, not easy to do.I was wondering about the design of the amp.
It is stated on your site that it is a classD switching type design but the picture shows a large toroidal transformer mounted on the back panel indicating the use of a linear type of power supply.
Did your engineers feel that the a linear power supply when mated to the switching output stage had advantages in this hi power application compared to a switching supply?The switching supply would have been much lighter and cheaper to implement.I also see that an AC line filter was even included ,nice touch.


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## Guest (Oct 29, 2006)

F1 fan said:


> Hi Manville,the F112 and 113 are impressive looking products with the promise of great bass in a small package, not easy to do.I was wondering about the design of the amp.
> It is stated on your site that it is a classD switching type design but the picture shows a large toroidal transformer mounted on the back panel indicating the use of a linear type of power supply.
> Did your engineers feel that the a linear power supply when mated to the switching output stage had advantages in this hi power application compared to a switching supply?The switching supply would have been much lighter and cheaper to implement.I also see that an AC line filter was even included ,nice touch.


My expertise in amplifier engineering is limited, so I don't think I can answer your question authoritatively. I'll see if I can find out... I do recall that there was quite a bit of healthy discussion in the beginning regarding PS designs, but they did settle on the toroidal transformer pretty early on. I know that switching PS designs can often create EMI issues but I'm not sure if this is why they went linear or not.

As for the AC line filter, thanks for the comment... we really spared no expense to minimize noise... the subs feature ground reference switching for the unbalanced input, optical isolation of the unbalanced inputs and a lot of little engineering touches to keep the possibility of noise as remote as possible.

Best regards,

Manville Smith
JL Audio, Inc.


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## Bent (May 24, 2006)

My ADA 1200 plate amp is a digital amp, with a linear supply (a huge toroid - I think it's 1.5 kVA).


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## F1 fan (Jul 6, 2006)

Bent said:


> My ADA 1200 plate amp is a digital amp, with a linear supply (a huge toroid - I think it's 1.5 kVA).


WOW 1.5kva ,that is a big tranny for a plate amp.


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## Ilkka (Jun 8, 2006)

F1 fan said:


> Hi Manville,the F112 and 113 are impressive looking products with the promise of great bass in a small package, not easy to do.I was wondering about the design of the amp.
> It is stated on your site that it is a classD switching type design but the picture shows a large toroidal transformer mounted on the back panel indicating the use of a linear type of power supply.
> Did your engineers feel that the a linear power supply when mated to the switching output stage had advantages in this hi power application compared to a switching supply?The switching supply would have been much lighter and cheaper to implement.I also see that an AC line filter was even included ,nice touch.


I noticed this too while watching their video clips. I too would be interested to know the reason for using that huge toroidal transformer. What are the advantages? It seems to be working really well though...everyone are giving them huge praise, especially when it comes to transient behaviour/peak output.


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## F1 fan (Jul 6, 2006)

I suspect they did not use a switching supply because of the hi voltage and hi currents required for the massive 2500watt output?Therefore a large transformer and lots of filter capacitance would be required.


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