Adding Bass to stock system?

[TOOSTUBBORN2FAIL]

Originally Posted by sly

Under powering a subwoofer almost always causes clipping because the lower powered amp doesn't have enough headroom to satisfy dynamic peaks. A subwoofer has a large moving mass and therefore generally takes much more power to produce the same SPL as smaller speakers. If you tune your system VERY carefully so that you never clip, you will probably find that you are having to turn your entire system down so much that it isn't listenable.


Article referring to dynamic headroom:

So if you are using an amplifier with an unclipped power output capability of 100w, and you are listening to music with a crest factor of 20db then the average output you would be able to obtain from the amplifier and avoid clipping the dynamic peaks is 1w. The same amplifier with a crest factor of 10db, the average output would be 10w.

What happens if we want to listen to our 20db crest factor music at a higher average level than just 1w of output on our 100w amplifier? Well, you certainly can.....but you will end up clipping the dynamic peaks. Going back to what we said before about the nature of music, it's very transient. Those large peaks will occur over very short durations of time and change rapidly. Due to various reasons our brain can handle some amount of clipping without negative audible effects. But it is also possible, depending on the amount of clipping, original crest factor of the music and frequency regions involved, etc, that this clipping could result in harsh or compressed sounding dynamics at higher output listening levels. This is because of the increase in distortion as a result of clipping, and due to the forced reduction of the level of the dynamic peak compared to the average level of the music. An undesirable result indeed.



---https://forum.audiogon.com/discussions/dynamic-headroom

Another thing... because a subwoofer has a lot of moving mass, an amp must be able to provide enough current to pull the cone back. True, while turning down a high powered amplifier decreases the wattage output, it does not decrease the amp's headroom capability. While an underpowered amp may be pushed close to clipping, the properly sized amp will be able to push the subwoofer and have enough reserves to account for any dynamic peaks. The underpowered amp will almost always go into clipping under certain transients and this clipping will cause distortion to the output signal.


Can you run a sub off an underpowered amp? Yes. Will it damage the sub? Not unless you clip so badly that you overheat the voice coil. Will it produce accurate waves, equal to the source of the audio? Not always. Depending upon how underpowered you are, you will have to reduce the gains of the overall system to avoid clipping the signal. Depending upon how underpowered it is, you may end up turning the entire system down so much that it is no longer enjoyable to listen to. Eventually, as always, someone will turn up the gains to get the volume they want and clip the amp. It's better to just buy the properly sized amplifier from the beginning. You can always turn a powerful amp down while keeping all your headroom. You can't turn an underpowered amp up though...

I can absolutely agree with all of that. My point was simply that under powering alone won't cause distortion. Its when you push it into clipping because its under powered that the distortion comes in to play. That's also why I said that you can't get accurate sub bass for the price the OP is looking for unless you just don't listen that loud at all. That's why I ran 1000w to the sub in my last setup.

I think we have the same view of this, just have different ways of saying it. Also glad to see someone else understand that clipping itself isn't what cooks a voice coil, that heat does.

[sly]

The only difference between a powered sub and an unpowered sub in a car is that the powered sub has the included amp mounted in the subwoofer enclosure and the unpowered sub needs a separate amp mounted elsewhere in the vehicle. You don't need to buy a separate amp in a powered sub. An unpowered sub needs an aftermarket amp added to make it work. The head unit is not strong enough to power it.


Both still need the same wiring. Both need power from the battery, ground and remote wires. Both need signal wires from the head unit. The only difference is that the amp in a powered sub is included with the sub and the amp used for an unpowered sub needs to be mounted somewhere and then wired into the sub. You have to supply the amp.

[sly]

Originally Posted by TOOSTUBBORN2FAIL

Also glad to see someone else understand that clipping itself isn't what cooks a voice coil, that heat does.

Thanks. If an amp simply clips it will not damage the sub. Possibly the amp but not the sub. But if you drive an amp so far into clipping that the sub is only putting out square waves, then you can overheat the voice coil because you are holding it at either the peak or trough of the wave without any cooling from the vented pole piece. Severe clipping from an underpowered amp reduces air flow to the voice coil and can fry it.


With that said you can definitely damage a sub from overpowering it if you drive it so hard you hit the excursion limit. If you slam a speaker forward with more power than it can handle, you can rip the spider right off the basket. Hitting the Xmax can also fry the voice coil for the very same reason as clipping from an underpowered amp. Speaker clipping also produces square waves and can overheat the voice coil...


Long story short, long duration square waves are bad for the voice coil. Don't under power and clip your amp and don't overpower and clip your speaker. Generally, though, I recommend buying an amp that is at the top end of what the speaker can handle. You can always turn it down and if you upgrade to a bigger sub in the future, you already have a more powerful amp to power it...

[TOOSTUBBORN2FAIL]

Agreed. Plus with more power than you need and the gain turned low the noise floor will be lower.

[Sonicp9]

This is the sub and amp combo that I currently have. It was in my old Jetta before I traded it in for the FRS.

http://www.bestbuy.ca/en-CA/product/...a7f2b992f7en02

I love these subs. Amazing sound for the price... but the problem is the box is too dam big for the FRS trunk. It literally won't fit. I now am in a bit of a dilemma, because I am not sure if I want to keep this sub and amp combo and build a custom box for the subs so it would fit in the FRS (would build myself with help from the father in-law), or just buy this smaller set:

http://www.bestbuy.ca/en-CA/product/...b2ac090884en02

I kind of want to keep a dual sub system, since I feel like the single sub will be less power. Does anyone have any suggestions as to what my best choice of action would be?

P.S. I have a 2016 and I plan on using the stock head unit with a line-out converter to connect the subs. The rear speakers are crap anyway.

[Mr.ac]

If your dead set on duel subs, you are correct, a costum enclosure is your best option.
Look up the sub specs sheets from MTX for the recommended enclosures.

[IceFyre13th]

Originally Posted by Mr.ac

If your dead set on duel subs, you are correct, a costum enclosure is your best option.
Look up the sub specs sheets from MTX for the recommended enclosures.

that will ONLY work for the MTX subs listed.......not other brands (edit: Just looked at the link, you are using MTX drivers so yes use their specs)

Boxes are designed around the speaker and its Thiel Small parameters, add in the acoustics of the space they are playing in as well.

Otherwise you get one note subs (just go thud at one frequency) or muddy sound (nothing sound right) or even speakers that blow for some reason all by themselves.....do it right, have someone design the box for you or learn how to do it (plenty of information on how to do this on the internet)

[Ashikabi]

I got the Rockford P300-12 add am open box from Crutchfield for about $175 another 45$ for a wiring kit so about $220... I can confirm it definitely solved the stock bass problem. Big enough to rattle the trunk, fender, and tail light. The Bespoke factory upgrade head unit has RCA outputs. Crutchfield said it wouldn't but it did.

[gramicci101]

I have a Kicker CWRT81 mounted in a Pioneer shallow mount box and powered by a Kicker PXA 200.1 (0.5 ohm stable, woot!). It takes up about as much space as a shoebox and is more than enough to fill the car with bass. I tapped off the signal wires for the door amp to get my signal, and I cut out a bit of foam for the sub amp to mount right next to the door amp, under the trunk tray. The sub amp is about as big as a pack of cigarettes. The box is secured with Velcro, so I can move it around or remove it completely if I need the trunk space.

[Chimera]

I broke down and bought the JL stealth box and an MRV-M500
hoping to get them in next week

[Mr.ac]

Originally Posted by Chimera

I broke down and bought the JL stealth box and an MRV-M500
hoping to get them in next week

Let us know how it sounds.

[Chimera]

Got it in today. Not installed just yet, ordered upgraded power from 8awg to 4, that comes tomorrow.

[YamahaR86]

Here's my setup I just finished installing last weekend. The 2013 Bespoke does have RCA inputs, I just followed a guide on here. I wanted to keep costs down.

Was originally going to build a fiberglass box to mold the trunk like oem audio+ and everyone else but the materials alone would cost me $70~. Plus, being new to all of this, I wouldn't know how to measure how big the fiberglass box would be since it has a weird shape and subs need a certain airspace to sound good. I've read about packing peanuts or water but the price of the materials and work involved turned me away. I might do it later on as a weekend project when I'm out of things to do.

So I went with a prefab box for much cheaper.

[sly]

Originally Posted by YamahaR86

I wouldn't know how to measure how big the fiberglass box would be since it has a weird shape and subs need a certain airspace to sound good. I've read about packing peanuts or water but the price of the materials and work involved turned me away. I might do it later on as a weekend project when I'm out of things to do.

I posted a thread on this at dslreports.com: http://tinyurl.com/h7qm8pq

Packing peanuts are too coarse to get an accurate measurement. Plus they compress which makes calculating the volume inaccurate. Water works but you had better give everything plenty of time to air out before you seal a sub to your enclosure. I used sand. Fill the box up with play sand and then pour it out and measure it. Wipe the dust out of the box and you're good to go. Use an online program to calculate your needed box size using the T/S parameters or go by the manufacturer's recommendations.


You don't need to get the box size perfect. Just get it close. If your box is slightly too big, add wooden blocks or some other material to the inside of the box to take up space. If your box is too small, add polyfill to make the box act as if it's larger.


I got it exact by using a clamp on amp meter and by running sine sweeps through the enclosure until I found the resonant frequency. The resonant frequency of the enclosure will pull the lowest amount of amps. If my target resonance was 52Hz and I was at 50Hz, then that indicated that my box was too large. I added a piece of 2x4 lumber to the box to take up some space. I kept trimming the 2x4 until I got the exact resonant frequency I wanted.


In short I would recommend making your enclosure slightly larger than needed. I measured the available space and calculated in the roughest way possible how deep the box would need to be to guarantee that I had enough volume. I made it slightly large as was verified by using the amp meter and then filled it in with wood until I got it exact.


Here's a picture of my subs' frequency response with no EQ. That dip at 87Hz was caused by my midbass subs and my infrasub being out of time alignment at the crossover point. I fixed the time alignment and the dip went away. :