Too much power for subwoofer install?
 

I used to have two 12" subs installed in my RAV4. I built a custom box myself, 4 cubic feet and ported with tuning frequency at 33hz. I was running the subs at about 1200w RMS combined. I wanted to install some subs in my FR-S and I was going to transfer the amplifier in my RAV4 to my FRS. It does 600w @ 4 ohms, 1200w @ 2 ohms, and 1600w @ 1 ohm.

Before I get into choosing a sub and designing a box for it, I'd like to know if anything above 600w RMS is too much for a car this small? I was looking at a 10" Alpine type R, handles 1000w RMS @ 2 ohms so I'd have no problems providing power to it but I don't know if it would be overkill. would a single 10" around 600w RMS be a better choice? What do you guys think?

OEM audio is 100 RMS @ 2ohm for reference and is pretty clean

Nothing says you have to run it flat out, and you'll have plenty of headroom.

I had a 10" Type R in my Yaris sedan. It was a 1042d, so much lower RMS. Powered with an Alpine M450, iirc. The sub box was a sealed box, and this configuration was plenty for the Yaris.

I say go for the Type R, you can always keep the amp gain down, and use a sealed box for a more crisp bass response. And just turn up the gain when your is a bass heavy mood.

First, off, there is no real thing as too much power if you already own the amp.

The other thing is, no matter the size of the car, the more cone area/linear excursion a subwoofer has, the lower distortion it will be.

Technically, yes, I can "limit" the power from the amplifier by using a higher impedance subwoofer. My amp can deliver 1200w @ 2 ohm, but only 600w @ 4 ohms. That's why I asked the question; I don't know if I should use all the power my amp has to offer. Most subwoofers I'm looking at can be wired for 4 ohms or 2 ohms.

So I take it I should get a subwoofer that has a relatively high xmax? Regarding cone area, I'm probably going to stick with 10", maybe a 12" if I can design a ported box with the right volume that will fit in the trunk of the FRS.

Less power at more distortion... That's a little wierd

If you don't have enough power to get as loud as you want, then you'll end up clipping the amplifier, which increases distortion exponentially. So, if he already has the amplifier, it does no harm to use it, as it can be gained down as he noted, and this will prevent any possibility of clipping.


To the op, as far as xmax goes, that's a tricky thing. The only car audio manufacturers I trust xmax specs from are jbl, jl audio, and alpine. They generally post linear xmax, which is the maximum cone excursion before a certain distortion threshold is reached (20% for subwoofers, 10% for all other sizes). Just about all other manufacturers list xmax as some variation of the measurements of the voicecoil, which doesn't guarantee that it will have that much excursion while keeping distortion down. That said, the type r you are looking at is a very good subwoofer. Also keep in mind ported enclosures lower distortion on the low end, as they limit cone movement near the tuning frequency.

On using all of the power, the difference between 600 and 1200 watts is only 3db. The difference between 2 different subwoofers could easily erase that difference, and the difference between ported and sealed definitely would. I would find the subwoofer you want, and then decided whether to go 2 or 4 ohms.

I've got two 2 Alpine 12s in a relatively small sealed enclosure. Hits nice and, yes, it was too much power. I wound up wiring them in series to bring the impedance up.

Regardless, it's all about the box and how much space you want. You can get great sound with a single 10 in this car. You can get better sound with a dual ported 12 but you'll have no trunk!

Make sure you budget in sound deadening - this car rattles like hell with bass.

Yes it does

You could always turn the gain down instead of wiring up to larger impedances. That way if you decide you want a bit more boom you could turn the pot instead of cracking open the box and rewiring. Also, most dedicated sub amps have a bass knob these days anyway, right?

They only problem you'll face is space, and every panel is going to rattle.
My current set up is MTX amp 300w @4ohms on a single Xtant 10" sealed .75 enclosure. That's enough to rattle the mirror, and any lose panels.
My amp comes with an adjustable gain control knob. So far my gain is set at 50% and I usually have my gain control knob at 25% most of the time.

Pretty much I say 300 watts on this car is more than enough. But go for it. You may just endup going with a single sub.

Shoot, a simple 50w Bazooka tube is enough to cause things to rattle in mine. lol

"How many watts does your car need"? A more accurate question would be how much SPL does your car need? A low efficiency subwoofer will need more watts than a high efficiency subwoofer to achieve the same spl.

I would not worry much about how much power your amp has. Instead I would focus on what your goals are for the system you want to have. Are you looking for high SPL competition one note bass? Are you looking for SQ accuracy where SPL is not important, but rather clarity and realism?

Your amp should work fine for most subwoofers provided you set your gains properly. Whether you go for a high spl ported setup or a high accuracy sealed enclosure, you can set your gains to deliver just the right amount of power needed. IMO, you are best oversizing your amps. You can always turn them down.

If you have a 600 watt amp powering a sub that is only designed for 250 watts, setting gains is easy provided you have a measurement microphone and software to record your response. I recommend Room Equalization Wizard (REW), which is free, and a UMIK-1 measurement microphone from MiniDSP for $75.

Turn your amp gains all the way down. Play pink noise at 0db (full volume) on the head unit. The sound coming from your subwoofer should be quiet. With the measurement software displaying the frequency response, pay attention to the bass response at the bottom end of the chart. Look around 25-30hz. What you are looking for is how much gain can you achieve before you start clipping your subwoofer. Turn up your gain slowly while noticing the curve on the frequency response. As you turn up the gains and the subwoofer gets louder, you will eventually begin clipping the lower frequencies. What will happen is that as you turn up the gains, the higher frequencies keep increasing while the lower frequencies stay the same. Lower frequencies move the subwoofer cone more and will clip the speaker first. So turn the system up until you no longer get any increase in the lower frequencies. Then turn it down slightly. Now your gains are set.

What you've done is limit your gains so that you don't clip your subwoofer even though it is being driven by an overpowered amp. So don't worry about what size amp you have. You can always turn it down. Instead look for what subwoofer you want and use the amp you have.

It's a myth that sealed is for accurate sq, and ported is for high output spl. As noted earlier, a ported enclosure lowers distortion at the low end of its response. Provided you have good enough eq, the only downside to ported is space requirements.

Actually I was thinking of the excess group delay you get when trying to play below the port tuning frequency. This makes it difficult to have a multi sub setup withouth causing dropouts due to phasing mismatches. Another difference is that ported enclosures roll off at 24db/octave whereas sealed enclosures roll off at 12db/octave. This gives sealed enclosures a large advantage over ported when played in cars.

The resonant frequency of a car is determined by the longest dimension. Typically this is the measurement from the front floor board to the back of the trunk. Below the resonant frequency, waves no longer fit and begin to rise in volume at a rate of 12db/octave. So the room gain of a car matches the 12db/octave rolloff of a sealed enclosure. If you are looking for a flat frequency response down to the speaker's excursion limit, then sealed is the way to go. The downside is that you get lower overall SPL and you don't get the typical midbass bump that many people prefer with ported enclosures.

All good points. That said, group delay changes with eq changes, and can mostly be negated by eq'ing the ported subwoofer to match the response of a sealed subwoofer, and it would have the added benefit of reduced distortion. Of course, this is provided you tune the enclosure low enough, which is why I'm a fan of llt ported enclosures.

That said, I can see also that it's kind of a moot point without parametric eq with fully adjustable centers and q.

Update:

So this past Sunday I built a small 1.3 cuft sealed box for my 12" Kenwood W3013PS, outer box dimensions are 13x12x18. I'm pushing 500 watts RMS and it's actually quite loud, maybe a little too much. When my volume is fairly low the bass is definitely covering up the mids and highs but at higher volumes it's all pretty much audible. Inside the cabin it's definitely loud but surprisingly you don't hear much of the bass outside of the car, unless both doors are open.

Conclusion: for such a small box, I'm fairly surprised at how loud it gets (inside the cabin, anyway). I like it. :)

https://s31.postimg.org/vnp4xtgln/P_20160630_082028.jpg

Nice

Nevermind