bass performance in cold climates

General question about subwoofer performance in certain or cold climates. I suppose this question could apply to any similar subwoofer and enclosure setup?

I have an Alpine Type R 10" shallow sub (SWR-T10) in a 0.42 cu ft sealed fiberglass / MDF enclosure molded and bolted directly in the factory sub location behind the pass side factory cargo panel in my 2004 Honda Pilot. Scroll down for pictures.This woofer has amazing sound quality and does achieve 127dB at 45hz with 300 watts RMS from an Alpine PDX-5.

I retired from the U.S. Navy in Sep 2011, then went to The Installer Institute in Holly Hill, FL near Daytona Beach till December 2011. I've been in Laramie WY. since June 2012 attending Wyotech.

I built and installed this enclosure while at The Installer Institute. I've been in relatively warmer climates ever since. Here in Wyoming, it started getting colder here in October, and for the past 2 weeks and it's been ultra cold here getting near or below zero in the mornings.

I'm noticing very diminished bass performance during extreme cold. After I play music for 10 minutes or so and the interior is warmer, then the bass performance gets better. If my enclosure was just a regular box in the cargo area, then this probably wouldn't be as noticeable. But since the enclosure is made of MDF on the front baffle and sides, but fiberglass on the enclosure rear molded to the outer body panel from inside the cavity and bolted directly to the vehicle.........could the cold effect bass performance or cause the fiberglass or enclosure to crack or have structural defects? The fiberglass is mated to the MDF using Duraglas on the inside edges.

Hey Toy, it may not be your Sub box. looks solid from the pics. in cold temp your battery will give lower amp out and your system (amp, head unit) need to be at a certain temp to run at peek performance. Most car amps are spec at 65-82 deg operating range. But i think sparky can give you a more detailed answer. Prob why after 10mins or so its back to normal sub sound. That's why we "warm up the car in the cold" as they say.... The best tool in my work shop, is my BRAIN!!!!

i have seen subwoofers crack in half because they were being used in extreme cold on the way to Minnesota. on top of that the soft parts of a subwoofer can become stiff in cold weather. cold wire has more resistance to electricity so you may actually be seeing less power from your amp. i believe thats the same reason why your battery has less output in cold weather which is why the CCA or cold cranking amps on a battery are usually less than the normal cranking amps.

hey soundnsecurity i don't mean to sound like a moron but your wire resistance doesn't have anything to do with weather. resistance in the wire would only be affected if it were cut, pinched or frayed where some of the wires inside were severed. all my instructors at college taught us that in basic body electronics and I live in northern Minnesota. however you are right about the woofer rubber surround becoming really stiff in cold weather. the loss of power to drive the woofers would be a battery or alternator issue. I have two alpine type r 12's and they don't hit nearly as hard when i first start the car in 0 or below, but that is why you keep it turned down until the cabin of the car is warm and the woofers have had a chance to make a little heat from running in the box. if you poly fill the box it will warm the subs up quicker but beware if you overpower them and smoke the woofer you may find yourself on the side of the road filling your box with snow to put out the fire.fabricating just for entertainment

I've also had trouble in the past with bitterly cold temps and very poor subwoofer performance at the start, well until after the subwoofer slowly warms up. I'm guessing that condensation is occurring between the voice coil and magnet from the heat generated during operation. So after the system is shut off for the overnight, the voicecoil either freezes up and/or the ferrofluid if any within the voice coil creates a heavy viscosity because of the frigid temperatures. As for Fiberglass cracking in the wintertime, I'd say maybe happening more so in a sealed enclosure than in a ported enclosure? Less pressure against the sides in a ported enclosure.Keep on Buggin'

To prevent fiberglass from cracking, I'd also like to add that you could try sandwiching rabbit wire (screening) between your fiberglass layers to add extra strength to your enclosure and/ or maybe use a can of rubberized undercoating over the top of that (inside the enclosure) to help kill the internal vibration?Keep on Buggin'

believe it or not but there is just as much pressure or more inside a ported box.

Well it seems to me that cold cranking amps are not your problem since you are using an Alpine PDX amplifier that has respectable output even at 12V (your car did start right?)and that you should not be noticing the level of diminished output that you describe since even if the amplifiers output was cut in half the output of the sub would only be down by 3 Db; not half. I didn't see anything in your post about resistance in the wires so let's forget about that because it's not a factor. Type R subwoofers don't use Ferrofluid so I really don't think that's a problem. I have never tried using rabbit wire in any of my fiberglass since the glass in my fiberglass is quite strong and the next hardest thing to diamonds, so I personally would not attempt adding any rabbit wire to your enclosure. I think that your reduced bass output is due to the cold suspension components of your subwoofer adding mechanical resistance to the woofer and consequently lowering the woofers tenancy to resonate at the lower end of its pass-band. Looking at your pics the enclosure looks very nice and well made, however I can't tell by the pics how thick the glass actually is and I wonder how you attached the front baffle to the enclosure (screw and glue?). In any event the problem would not go a way and then occur again if a structural flaw was the problem. I say if you are worried about the enclosure cracking then you should push the sub hard every day, rock out, enjoy it, and then repair or rebuild the enclosure as it should have been in the first place if it fails. If it never fails then you did a good job.

If the engine is running the battery CCA should not be an issue (not for 300W RMS output unless overall load is swamping alternator output, but a voltmeter will confirm that). And resistance reduces with temperature for typical components and loads so output power and speaker/sub power should be higher at lower temps. That implies cone rigidity (when cold) or air density etc, though increased density should increase volume (eg, bass & trains at night...).

It sounds like the compliance of the cone is the issue. Although the manual does not state the normal operation range temperature, I bet the low end is above near freezing temperatures. When cold the compliance of most materials goes up and vise versa when hot. Even though the voice coil is pushing with the same force the cone displacement is lower when compliance is high, hence lower output. If you think it is a power issue, you can test it with a meter and a low frequency source, such as a test cd or signal generator. When testing low frequencies make sure you disconnect all speakers except for the subs, otherwise you may fry their voice coils. With the test signal, you can measure the voltage and current at the amp output to calculate power. If you are getting a significant difference when cold and hot, the problem is probably electrical. That is lower power when cold. The measured power may be a bit lower at the same settings when the system is hot since resistance is higher with elevated temperatures. If the power output is the same than compliance is most likely the problem. Also don't play the test signal to get the system to normal operating temperature, you may damage something.This information is provided only as a reference.

All circuits should be verified with a digital multi-meter prior to making any connections.