JL 12w0 vs Kicker F8a WTF?!

[phunky.buddha 10+ year member]

Yes, it's a weird matchup: old school Kicker Freeair F8a vs old school JL 12w0

Kicker F8a spec sheet

Here's the situation- I have both of these drivers hanging out in my garage. I'm planning to build a box into the unused space under the floor of my wife's Mazda 5. Based on some rough measurements, I think I have about 1 cuft to work with. The goal is to build a subwoofer into her car while buying as little as possible.

I modeled a few enclosures in WinISD, and was wondering if I could get opinions/feedback on the graphs. The SPL lines are based on 220w input (JL e2150 bridged mono).

Cyan = Kicker F8a recommended large box, .78 cuft, 36 Hz

Yellow = Kicker F8a 1 cuft, 42 Hz (seemed to be the best curve)

Red = JL 12w0 1 cuft sealed

Green = JL 12w0 1 cuft, 35 Hz

Orange = JL 12w0 recommended ported box, 2.5 cuft, 28.5 Hz

Phase plot Delay plot

1. Can that F8a really get as loud as the 12w0? It only looks to be a dB and a half away at max. I realize that the F8a won't go anywhere near as low, but it seems to ride right on top of the 12w0 sealed box curve's low end dropoff.

2. Is 220w in a ported box too much for the 12w0? It's only rated for 125, and my amp probably puts out more than its 220 rating.

3. Are these "boxes" too small for the 12w0, considering that JL seems to recommend smaller than ideal enclosures, and their recommendations are all larger than the space I have available?

4. Anyone had experience with this super old Kicker Freeair? I know mine powers up and moves smoothly, but I haven't heard it in a box.

Thanks for any input!

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[THATpurpleKUSH 5,000+ posts]

winisd is not accurate and cabin gain will change everything around on you. I would bet the JL will get louder due to more cone area and probably more motor force

 

[phunky.buddha 10+ year member]

Hmm. You're absolutely right on the cabin gain- but again, is 220w too much for the 12w0 in a ported box? Is 1 cuft too small for a ported box on the JL?

 

[btdickey99 5,000+ posts]

Hmm. You're absolutely right on the cabin gain- but again, is 220w too much for the 12w0 in a ported box? Is 1 cuft too small for a ported box on the JL?

It isnt too much power... Years ago I ran 4 W0 12s ported on 1000w rms with no problem

 

[btdickey99 5,000+ posts]

Hmm. You're absolutely right on the cabin gain- but again, is 220w too much for the 12w0 in a ported box? Is 1 cuft too small for a ported box on the JL?

It isnt too much power... Years ago I ran 4 W0 12s ported on 1000w rms with no problem

 

[wickedwitt 10+ year member]

Hmm. You're absolutely right on the cabin gain- but again, is 220w too much for the 12w0 in a ported box? Is 1 cuft too small for a ported box on the JL?

The 1 cu ported box looks very peaky, and peaks late (ignoring cabin gain), the orange curve (jl recommended) by far looks the best as far as frequency range. I'd do it, especially if you have the room.

 

[phunky.buddha 10+ year member]

It isnt too much power... Years ago I ran 4 W0 12s ported on 1000w rms with no problem

Wow, what were the box specs? If you were anything near the recommended size/port, I should be even safer in a smaller ported box right?

The 1 cu ported box looks very peaky, and peaks late (ignoring cabin gain), the orange curve (jl recommended) by far looks the best as far as frequency range. I'd do it, especially if you have the room.

So the cabin gain would exaggerate the peak too on the 1 cuft box, right? Looking at my delay graphs, would that make the sound really messy? A 26ms delay makes it seem like I would lose half a note at 20Hz- or is that something that you normally wouldn't be able to hear at all?

 

[wickedwitt 10+ year member]

So the cabin gain would exaggerate the peak too on the 1 cuft box, right? Looking at my delay graphs, would that make the sound really messy? A 26ms delay makes it seem like I would lose half a note at 20Hz- or is that something that you normally wouldn't be able to hear at all?

Being as that ~200hz is mono and not really stageable (except newly thought of as 50hz+ to be stageable by a few big SQ people), you really aren't going to hear the delay unless it gets so far behind the time correct mid stage that you are actually processing the mids before the sub wave gets to you. I'm running 40' of speaker wire to my subs after they see a 25' RCA run to the amp. My subs are still not noticeably behind my mids.

As for the box, the cabin gain wouldn't accentuate the peak, as it would more than likely move it to a higher hz. This could cause even more music to sound terrible as you would have low output on most musical bass, and nearly force your sub into a one note wonder type of setup. Subs are not supposed to be midbass drivers, that's what decent mids are for:naughty:. Anyways, I digress, but if you are wanting a good solid sound across the entire musical spectrum; build a larger box so the output curve is more flat. Go large on the port area so as not to have any port noise, and tune somewhat low so you have control over the lower end of the music spectrum.

GL

 

[phunky.buddha 10+ year member]

Being as that ~200hz is mono and not really stageable (except newly thought of as 50hz+ to be stageable by a few big SQ people), you really aren't going to hear the delay unless it gets so far behind the time correct mid stage that you are actually processing the mids before the sub wave gets to you. I'm running 40' of speaker wire to my subs after they see a 25' RCA run to the amp. My subs are still not noticeably behind my mids.

Ooooooh ok. I'm glad you actually posted the frequency thresholds- I guess since I cross my subs at 100Hz or under most of the time to keep my mids happy I'll probably be ok. I know that I can definitely hear the sweet spot moving around my car when I've played with timing increments as low as 3-5ms on my CDA-7998, but that was with my bright mains and in a car where I could actually hear the rear speakers. If a 25ms delay isn't noticeable on subwoofer frequencies, then I'm guessing I should just port everything in every car to extend my response huh? Would I be able to tell at 25ms on a sub if I noticed 5ms on the highs? I guess it doesn't matter since it's only one driver and the delay above 20Hz never goes longer than 11ms. I need to remember to read the graph in the right spot and ignore the extreme ends of the line.

I guess I should just extend the box in my truck to run the full width of the cab under the seats and port it for the single driver that's already in there (10w1v2) instead of running two sealed in the same volume too- the model seems to show similar SPL but much lower extension with one ported vs two sealed. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

As for the box, the cabin gain wouldn't accentuate the peak, as it would more than likely move it to a higher hz. This could cause even more music to sound terrible as you would have low output on most musical bass, and nearly force your sub into a one note wonder type of setup. Subs are not supposed to be midbass drivers, that's what decent mids are for:naughty:. Anyways, I digress, but if you are wanting a good solid sound across the entire musical spectrum; build a larger box so the output curve is more flat. Go large on the port area so as not to have any port noise, and tune somewhat low so you have control over the lower end of the music spectrum.

Ok, I understand- so the higher peak would move the sub response past the crossover cutoff or put it in a range just under that would make the sound muddier/boomier? I run JL Evo VRs in the S2k and PG RSDs in the truck, so I can usually keep the crossovers low enough while keeping the drivers happy at high volume- so the sub(s) should never see midbass. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif If I was upgrading, I'd get mains of similar caliber. I don't want to spend money in the Mazda 5 though since it's normally hauling kids (can't turn it up much), so I don't know how low the current Kenwood 3-ways that are in it will extend before I have to pass off to the sub. I'd love to build a larger box, but I can't intrude into the passenger compartment any- going larger than the cavity under the floor would mean permanently removing the third row of seats since the mount over the space I want to build into. In that case, I guess I should just run a sealed box since the range is similar without the large peak? 1.2 cuft is probably as large as I can go, and that's if I take up every last bit of volume except the spare tire itself.

 

[wickedwitt 10+ year member]

Your ears are much more attuned to hearing misses in the highs. A 5ms delay can make highs sound muddy, but thanks to loading and the behaviour of lows, you won't lose sound accuracy in a 25ms delay from the subs. Yes, always always run ported if you have the opportunity. Not only does it sound cleaner if built properly, but it does give you extra output in the event you ever need it. Doesn't sound so constrained on the lower end of the music spectrum either.

Higher peak is going to make it boomier, and lower your output (not to mention sub cone control and thermal handling) on anything >10hz below tuning. The higher tuning itself doesn't cause the two things in parenthesis, as they are universal traits, but it will increase the frequencies in which you will have to overcome those obstacles. In all honesty, if it were me I would set your low pass at 80 on a low tiered slope (12db) if possible so it slowly blends into your midbass. Won't make as sharp of an output drop off on stuff right at that 100hz mark. Just me though, may sound completely different to your ears.

 

[phunky.buddha 10+ year member]

You're a big help, thanks for posting so much so quick!

So don't worry, just port it and be happy. Got it.

Then if the tuning frequency is something like say.... 29Hz or less, I don't need to worry about a high pass filter on the sub amp to keep it from unloading under the port frequency? Is there a port frequency limit I should always try to stay under to prevent sub driver damage without having to filter at the amp?

I always run my sub crossovers at a 12dB slope. I like lower crossover frequencies (63Hz on my 7998 sounds pretty good), but my mains always seem to have trouble when crossed at 80. 100 seems to keep the distortion at bay- this is on both the PG RSD 6.5 and the JL Evo VR 6.0 speakers. Maybe others have taken them lower without breaking up the cone?