Subwoofer install on a budget

[LaserWhisperer]

No, stays powered ON after door is opened (I should have clarified). Sub beats like a heart for a bit, as though a capacitor somewhere is slowly discharging.

 

[Stormy]

Nope. I still have the pop. I haven't gotten around to messing with it as I've been busy this summer. It's actually a little worse because I plumbed in a computer fan to cool the amp, which worked wonders, but now I sometimes get a series of pops and some feedback through the rear speakers when the car is off. It's definitely a ground issue but I don't know if it's the amp or the chassis ground. I am suspecting the amp since I'm definitely grounded to bare metal in the trunk and because you are having similar issues with that amp.

As for the other problem, have you checked it for power after having closed all the doors and armed the alarm? I think power stays on in the car until you lock it and the lights go out, etc.

 

[Stormy]

Ok, so major update. I got fed up with the little SSL amplifier... I put up with the issues for longer than I should have and that all changed today.

Issues:

1. The annoying ground turn-on/off pops - I tried a number of different grounding points and could not get it go away.
2. Overheating - It went thermal on me a couple times. I wired up a small computer fan which kept it cool but made the ground noise worse and caused a buzzing in my speakers.
3. Sad output - I didn't really have an idea about how bad this thing was until I put the new one in.

Resolution:

I picked up an MTX Thunder TC2002 amp on craigslist for $20. it was the perfect size to put under the driver's seat without encroaching into the back seat footwell or worrying about clearance (There's no room under the passenger seat because there's some kind of module under there). it was lacking the molex plug for high level inputs so I got a cheap line level converter from Best Buy and ran RCAs. I just tapped into my existing splices for the rear left speakers. The interface tucked in perfectly in the space at the base of the door jamb behind the trim. I ran the RCAs under the carpet, over the hump in the back seat footwell and around the corner then up through the carpet where the sensor plug for the driver's seat comes through. I shortened my existing power and remote leads and ran them under the carpet and up through a slit. There was a common ground point for a factory wiring loom under the carpet by the front left bolt hole for the seat rail so I grounded the amp there using a spade connector. I cut another slit to run the speaker wire through and under the carpet and into the trunk on the driver's side. I cut about 2 inches off the little air duct under the seat so it wasn't right up against the amp (after the picture was taken). Bonus, ventilation for the amp!

Results:

To say the difference is night and day would be an understatement. First of all, the pops are all gone. The amp still cycles on and off a few times after the car is turned off (I noticed the power light cycling) but there is no more noise. The SSL obviously didn't have silent off/on so this was worth the upgrade by itself. The bigger surprise is how much the sound has improved. I was thinking about upgrading my 8" to a Fosgate shallow mount 10" to get a little more output but that will definitely not be necessary unless I somehow blow the 8". The SSL was turned up to about 80% and output was...acceptable. I couldn't go higher because of heat and distortion/clipping. I started with the MTX at half gain, bass boost at 10db and the Low pass filter on and set at around 120Hz. I figured the MTX would sound noticeably better but the clarity and output were insane compared to before. I've built a lot of systems in the last 20 years) and the output of this cheap Boss sub is pretty shocking. That SSL was probably putting out all of 20 shitty watts and is going in the trash. The MTX is CEA-2006 certified so I am most assuredly getting the full 200 watts out of it. I had to dial the bass boost down to about 5db, gain down to about 40% and low pass down to about 80hz because the rest of the system couldn't keep up (yet the sub wasn't showing any signs of overexcursion). Bass on the head unit is up about 3/4 of the way so I can get some depth out of the mids in the doors, mids are neutral, highs are maxed (man our tweeters suck). Now I have it dialed in and it's still enough to rattle the rear and side view mirrors when in balance with the rest of the system, and I know for a fact that it has much more in reserve.

I paid as much for the "new" MTX amp as I did for the old one so I'm calling that a write off. The line level converter was $15 so I am still around $100 total for my install and the results are above and beyond the original iteration.

Line level converter

Common ground point

Amplifier wired.

 

[chicagoslick]

Nice job with the install.

 

[antarctica24]

***Update*** Jump to page 3 for detailed revisions.

Ok. Let's face it. The Sony stereo sucks. We all know it. It's poorly thought out and even more poorly executed. The sound is flat, even with the adjustments maxed, your arm blocks the drivers side tweeters if it's up on the window sill, the sound stage is too low and wide because the tweeters are too far back in the door, etc. etc. Most glaring of all is the lack of bass. There are lots of threads on sub upgrades around here but this is mine. A little background on me, I was an IASCA competitor and SQ judge back in the mid 90's with sponsorships from Streetwires and Oz Audio. I used to dump a lot of money and resources into cars to win trophies. This is not one of those systems. I am much older and, currently, much poorer. If money was no object I know all the things I'd do to make the cabina place of sonic euphoria but this is a test to see how much improvement in sound a minimum investment can make. Also, I wanted to have the entire system fit under the rear cover with room still for my road emergency kit, Get Home Bag, and California Car Duster. All this plus a cost of under $100. I knew I'd be sacrificing on some things, which kills my soul after what I'm used to running, but taking a hit on brand snobbery was worth it to improve my daily commute. So here goes...

Sub - Boss Audio CXX8. 8" subwoofer, "600" watts, 4 ohm SVC, seals in .35. cubic feet. $26 on amazon.
Amp - SoundStorm SMCM200. Monoblock, 2 ohm stable, 200 watt class A/B amplifier. $29 on amazon
Wiring - Boss Audio Kit Zero 10 gauge wiring kit. $10 on Amazon
Wood - 2x4' sheet of 1/2" MDF. $10 at Home Depot
Carpeting - Roll of black automotive carpet. $10 at AutoZone.

So, all in all I'm on the hook for about $85 in materials, about half the price of a cheap super shallow powered sub. Granted, I had other things like glue, fasteners, RCA block, etc on hand that would add to others' cost, so YMMV.

I used the calculator at carstereo.com to figure out my box volume. I made it just big enough to tuck in by the passenger side rear tail light. External dimensions were 17" x 10.5" x 5", giving me an internal volume of about half a cubic foot. This will give me the ability to upgrade a small volume 10" sub down the road if I want to upgrade. I constructed the box using Gorilla glue and an 18ga finishing nailer. I figure that this should be adequate for a cheap 8" and would save the risk of splitting the thin MDF with screws. If I move to a 10 I can always go back and pre-drill/screw it together between the nails then.

View attachment 10197

View attachment 10198

Tomorrow I'll wire up the amp and get it installed and we'll see what happens.

Very impressive sir on the massive restraint. Good work on the box, and should work pretty good to add some bass to the car.

 

[Stormy]

Thanks guys. I'm very happy with the end result, both sonically and aesthetically. I have a bass knob on order for the amp as well so I can tweak it on the fly. After that I think I'm going to try a tweeter upgrade. The stock ones are just so flat and lifeless.

 

[Stormy]

Update June 9, 2017 - I think I popped the sub. I have (had?) discovered crazy unexpected levels output from this sub and it still sounded clean. Rear and side view mirrors were shaking and it was kicking like a baby mule. Well I turned the car off and ran a quick errand and came back and no bass. It was hot out and I thought my amp had gone thermal but I checked it and it's still lit and getting signal as far as I can tell, and the fuses are all good. It cooled down and still so sound. Then I remembered that I put a 5 gallon bucket of paint Probably like 75 lbs) right on top of the sub. I am positive I crushed the cargo deck onto it and then cranked it up on the way to the next stop. The cone was pinned and I burned up the VC. That little Boss was better than I ever would have imagined and I could be totally happy ordering another one, especially now that they're only $20, but I have a little cash in my pocket so I'm going to upgrade to a Fosgate P3SD2-8 for $100. Better build, better brand, CEA Certified, and will have a little more room in the same box (seals in .25 vs .35 for the Boss) so I should get better extension. The cutout diameter is slightly larger so on the slim chance I don't like it I may not be able to drop another boss in the same box but I can just build another one. I should have the Fosgate in on Monday and I'll post an update.

 

[chicagoslick]

Your amp may have caused the blown woofer. MTX amps are known for putting out highly distorted signals. Get a tonal reference cd, a meter, and spend some time setting up the gains to ensure you are not clipping the amp. Best of luck...

 

[Stormy]

Update: It was definitely the sub. I verified it with a meter. No resistance. Anyhow, I put the Fosgate in and I'm back up and running. The bass from the Fosgate is much tighter than the Boss was. Output is about the same. I know some of that will change after some break in. The magnet on the Fosgate is bigger and the dish on the cone is far more shallow than the Boss, and overall it's shorter than the Boss. The build quality is clearly much better. I have it wired for a 4 ohm mono load (It's 2ohm DVC).

I haven't known MTX amps to have dirty output, at least not their better amps. The TC is CEA-2006 certified and I have the gain set conservatively so I'm pretty confident that the Boss just died a premature death because I crushed it with that paint bucket.

I still say that for the money the CXX8 is an absolute bargain and I would recommend it for anyone on a budget. It probably would have run forever if I had been more careful.

 

[chicagoslick]

Great job on getting the system back up and running.

 

[antarctica24]

Your amp may have caused the blown woofer. MTX amps are known for putting out highly distorted signals. Get a tonal reference cd, a meter, and spend some time setting up the gains to ensure you are not clipping the amp. Best of luck...

Ummm where are you getting this information? I'm glad he figured it out, but even if he hadn't the sub is definitely the problem. Boss is one step up from radio shack as a brand. It is right their with Craig and pb. Rockford is on the same level build wise as jlaudio in regards to subs. Mtx is on the same build level as pioneer and Kenwood. If you had a mtx amp that was distorted more than likely it was not installed correctly or it was being fed a junk signal.

 

[chicagoslick]

Ummm where are you getting this information? I'm glad he figured it out, but even if he hadn't the sub is definitely the problem. Boss is one step up from radio shack as a brand. It is right their with Craig and pb. Rockford is on the same level build wise as jlaudio in regards to subs. Mtx is on the same build level as pioneer and Kenwood. If you had a mtx amp that was distorted more than likely it was not installed correctly or it was being fed a junk signal.

Just my experience and others I have been friends with for years. All have stated they are "dirty" amps. Now, with that said, they have always been pretty powerful. Most speaker failures are the result of distorted signals, weak or stressed components, improper enclosure, or over / under amplification. Just my experience.

 

[antarctica24]

Just my experience and others I have been friends with for years. All have stated they are "dirty" amps. Now, with that said, they have always been pretty powerful. Most speaker failures are the result of distorted signals, weak or stressed components, improper enclosure, or over / under amplification. Just my experience.

I'm not questioning that assumption. Most amps don't create distortion on their own. Most of the time is due to the signal going to the amp. Amps for the most part do nothing more than take a signal and amplify it. Yes there are good and bad amps. But in this situation his problem started with what he bought as a sub. Boss is at the bottom of the food chain and the products they make are sub standard no pun intended. It seemed like your were going straight after the amp and looking at kickers low level line at 14.4 volts thd is less than 1% and signal to noise is a weighted at greater than 95db. These specs are normal for a typical class d amp. So while not perfect not junk.

For am amp to be responsible for damaging a sub on its own would be profound. Normally speakers can handle well about their rated power in peak situations as long as the signal is clean. So while it would have been possible that what he was listening to was distorted or the signal from the head unit to the amp was distored it would be like finding a mouse on the moon remote chance that the amp caused his sub to have a problem. Amps do go bad I have seen the catch of fire right in front me, but in this case it was the junk sub.

 

[Stormy]

Some pictures. Sorry about the mess, lots of home projects happening. I thought I post some comparison pics of the old vs new sub and a photo of the finished box. The trim ring for the new sub adds a lot of height so it's a very tight fit under the rear deck now but I think the lack of protection may have contributed to the premature death of the old sub. I had a 5 gallon bucket of paint in the trunk and I think it may have pressed the deck down onto the speaker surround. I had to take the padding off of the bottom of the deck cover to make sure there was a little bit of clearance but if I put something heavy in the trunk again it should help to keep the sub safe. I'll also be more careful not to bump it with a heavy load in the trunk in the future.

 

[chicagoslick]

I'm not questioning that assumption. Most amps don't create distortion on their own. Most of the time is due to the signal going to the amp. Amps for the most part do nothing more than take a signal and amplify it. Yes there are good and bad amps. But in this situation his problem started with what he bought as a sub. Boss is at the bottom of the food chain and the products they make are sub standard no pun intended. It seemed like your were going straight after the amp and looking at kickers low level line at 14.4 volts thd is less than 1% and signal to noise is a weighted at greater than 95db. These specs are normal for a typical class d amp. So while not perfect not junk.

For am amp to be responsible for damaging a sub on its own would be profound. Normally speakers can handle well about their rated power in peak situations as long as the signal is clean. So while it would have been possible that what he was listening to was distorted or the signal from the head unit to the amp was distored it would be like finding a mouse on the moon remote chance that the amp caused his sub to have a problem. Amps do go bad I have seen the catch of fire right in front me, but in this case it was the junk sub.

Actually, I was going after incorrectly set gains, not a bad amp. If gains are not set correctly any amp can blow a speaker. Again my experience and "my opinion" (just as many of my friends) is that MTX amps while powerful are dirty amps. I did not Google, like I'm guessing you did, the specifications on MTX amps. I am speaking from my experience, and as I stated my friends experience, alone. MTX amps are not bad amps. If the gains are not set correctly, the signal good or bad will be amplified or attenuated.

If the gains are not set correctly (high gains can cause clipping and / or distortion) with his amp the RF sub will be exposed to the same risk of failure.

 

[chicagoslick]

Hopefully you have identified your problem and will be good to go now. Great job...

 

[antarctica24]

Actually, I was going after incorrectly set gains, not a bad amp. If gains are not set correctly any amp can blow a speaker. Again my experience and "my opinion" (just as many of my friends) is that MTX amps while powerful are dirty amps. I did not Google, like I'm guessing you did, the specifications on MTX amps. I am speaking from my experience, and as I stated my friends experience, alone. MTX amps are not bad amps. If the gains are not set correctly, the signal good or bad will be amplified or attenuated.

If the gains are not set correctly (high gains can cause clipping and / or distortion) with his amp the RF sub will be exposed to the same risk of failure.

An incorrectly set gain control can absolutely cause a amp to distort. But that kicker has dirty sounding amps, I'm not a fan of kicker just disagree with the assessment of you and your friends on that brand of amp. I think it is more likely in the past the gains have not been set correctly on the kicker amps you were using and thus an assumption was made. And it's ok 99% of the people who install after market amps don't have the first clue how to properly setup the gain on an amp. And if you tried to do it without a volt meter you definitely didn't do it correctly. If send enough signal voltage to the amp you can turn the gain completely off then you don't have to worry about it. 😀

 

[chicagoslick]

Setting gains correctly was one of the main points of my post and we at least agree on that...

We can agree to disagree on the rest...

 

[Stormy]

The saga continues. I think I'm going to have to build another box for this sub, or at least try it in another box. I know it's still not broken in but I have far more flat spots in the spectrum with the new sub, and while it sounds good at moderate volumes it sounds like there some excursion when I try to push it. Per the specs it should play well in .25 to .5 cubic feet and the box it's in is around .35 so it should be ok but something's not right. The hole for the Boss was slightly larger so I may be leaking air despite being screwed down tight. Maybe it needs to be in .25 for better cone control. On the bright side, a smaller box will fit even better give more clearance above the cone, plus I can make sure the cutout is the right size. On the minus side, I have to build a new box. haha.

 

[chicagoslick]

The saga continues. I think I'm going to have to build another box for this sub, or at least try it in another box. I know it's still not broken in but I have far more flat spots in the spectrum with the new sub, and while it sounds good at moderate volumes it sounds like there some excursion when I try to push it. Per the specs it should play well in .25 to .5 cubic feet and the box it's in is around .35 so it should be ok but something's not right. The hole for the Boss was slightly larger so I may be leaking air despite being screwed down tight. Maybe it needs to be in .25 for better cone control. On the bright side, a smaller box will fit even better give more clearance above the cone, plus I can make sure the cutout is the right size. On the minus side, I have to build a new box. haha.

Sorry to hear you are still working through it. I'm sure you will get it finally.