My ideas so far are pretty basic, maybe fit one of these in the boot and run it via high level speaker cable input:

http://www.jlaudio.co.uk/car-audio-subwoofer-systems-amplified-microsub

Or fit one of these in the cutout, with an adapter, and add an amp:

http://www.caraudiodirect.co.uk/subwoofers/6-inch-subs-16cm/jl-audio-6w3v3

Powered by this:

http://www.caraudiodirect.co.uk/amp...io-mx300-1-mono-class-d-full-range-amplifier-300w-water-resistant-ultra-compact

 

There are 3 good 10 inch options from JL Audio. You have just under 14 inch clearance under back deck in trunk. Width is limited because of curves on the sides to around 25inches

1. C210LG-TW1 Fits nicely under deck filling the entire area. 22x11.75x7.3 Only comes out a little less then an inch past the deck. Looks good with two large JL TW1 subs. Best for those who want a lot of base and listen to mainly rap music. Two TW1's should really shake a little car like the Giulia. Most expensive option but still much cheaper than custom built box and will look almost like it was made for your car. Very close to custom fit when sitting in the car.
http://www.jlaudio.com/cs210lg-tw1-car-audio-power-wedge-subwoofer-systems-93316

2. CS110LG-TW1-2 Single 10 inch sub in 15x11.75x5.5 so fills a little over half of the space. Plenty of space to put almost any amp next to sub. Cheapest option also
http://www.jlaudio.com/cs110lg-tw1-4-car-audio-power-wedge-subwoofer-systems-93324

3. CS110TG=TW3 19x12.375 wedge shape with 4.1 inches on top and 6.25 inches on bottom. Uses better sub fits in area really nice tucked in behind seat. Can turn around and wedge fits right up against seat using even less trunk space but you lose view of driver when you open the trunk.
http://www.jlaudio.com/cs110tg-tw3-car-audio-powerwedge-subwoofer-systems-93302

As for amplifier's there are tons of options. I would look for one with auto-sensing turn on though so you don't have to look for a amp turn signal. Many small and very powerful clean amps available today at a reasonable price point.

I recently chose option 3 with a JL Audio 500/1 amp to fit in the trunk under the Styrofoam on the drivers side. Having it installed on Monday so will let you know now it sounds and fits. Should have taken pictures of the 3 options today when I sat them in car but wasn't thinking about it. We placed each one in the car. Option 1 looked cool but I really thought that it was going to be too much bass for me. I mainly listen to classic rock, contemporary, metal, and jazz music. Not much rap and would prefer the cleaner tighter bass from a TW3 then more power from two TW1's. But that is just personal preference.

Tried a few of the ported subs but none of the 10 inch ones really fit well. They are right at 14 inches tall and would not slide under the deck. Ported subs have louder sound, boomier bass and really hit on certain frequencies. Usually they are louder then sealed cabinets which have tighter and cleaner bass but not quit as powerful of a sound. I prefer the sealed cabinets but most salesman will push you towards the ported cabinets for the louder sound.

 

I'm going to follow your lead, but curious about option 1. I would like to have the sub be removable and you said it fills up the space nicely. Do you think it would come out easily if needed? I don't need much so maybe using the same one you chose would work.

Also wanted to know about the level control you put up front. How much work was it to fish that line up there?

Thanks!

 

Forgot amplifier I chose is JL Audio RD/500-1 and fits in compartment under Styrofoam just barely. Will post pictures later after install is finished. When finished not much should be noticeable except front of wedge which is only taking up a small amount hard to use space under the deck.

http://www.jlaudio.com/rd500-1-car-audio-rd-amplifiers-98618

 

Can't Styrofoam be modified to accommodate a larger amplifier? And how is cooling in that compartment?

 

Pcoates - really interested in seeing the pics! Good luck!

 

Yes stryofoam can be modified to make for a bigger amplifier. Technically you could cut out the entire bottom if you wish. There is a lot of space in that area. Few wires and a fuse box is all that fills that space.

As far as cooling not sure on that aspect yet. Will have to wait and see. It is in trunk so probably not much different then elsewhere in the trunk.

 

Yes stryofoam can be modified to make for a bigger amplifier. Technically you could cut out the entire bottom if you wish. There is a lot of space in that area. Few wires and a fuse box is all that fills that space.

As far as cooling not sure on that aspect yet. Will have to wait and see. It is in trunk so probably not much different then elsewhere in the trunk.

The other day when I opened that area and took out the styrofoam shelf, the plastic tub was super hot. I could barely touch it. I don’t think it will be a happy place for an Amp unless you vent it well. Maybe perforate the styrofoam and trunk liner a whole bunch.

 

My thinks this will be a popular thread.
My request to all that perform modifications:
Please post:
Images
Exact model numbers of components used
Information for local, and internet purchasing
Hints and tips and wisdom for trouble-free installation
Thanks,

 

Some really great ideas in this thread.

One thing I'd add with an external bass amp and sub enclosure is a remote bass control knob. This allows the level of the sub to be quickly and easily adjusted without getting into any clunky menu settings.

On front speakers-- has anyone figured out how to remove the tweeter pods in the dash corners? I've tried using interior trim tools and getting some leverage from the padded adjacent area by prying against another piece of plastic. I can get the pod up just a bit, but it is STUCK. Not sure if there is some sort of clip system or what? I'm afraid to try much more because the Quadrifglio padded leather can be easily damaged.

I like this: 10" JL Pro

The above sub will provide much deeper harder hitting bass at the expense of a little more space.

 

http://stereointegrity.com/product/bm-mk-iv-12-subwoofer/

Best shallow sub bar none IMO and so says many audiophiles. Only requires .5 cubic ft of closed enclosure. I have had the Mk III and IV where the performance and quality have been amazing. Check out the torture tests on youtube. The woofer has the highest stroke, flattest BL, most linear and low inductance, shallow subwoofer on the market. I imagine the Mk V just took it up a notch.

 

I'll ask my dumb question: with a relatively high efficiency speaker like this and and the passenger seat backs up, do you really need a separate amplifier or enclosure to make it work well?

I've also seen a suggestion of dismantling and/or replacing the center rear seat back and using it as a speaker mount/enclosure. It is perhaps a bit narrow for a large/high efficiency speaker but can avoid the loss of precious trunk space.

Don't forget, this car is already loaded up with electronics. You need to be careful that when you add an amplifier you do not disturb the operation of anything important. Reference the Jeffshul thread with his car stalling on the freeway and the speculation that his audio upgrade might have had something to do with it.

 

My Giulia's bass seems sufficient on some songs while lacking on others. Perhaps as much of an eq issue as a hardware deficiency?

I have never had a factory system that couldn't be improved upon with aftermarket upgrades but stopped pursuing making changes once I started leasing.

 

Yes you will definitely need a separate amplifier to power a sub. A single sub amplifier should not effect the electronics of the car. If it does then you have to seriously question the build quality of the vehicle. The alternator should be provide more thenenough to power for a single mono channel amplifier. Millions of people have done this for many many years on all types of cars without any issues.

Now when you install more then one high end powerful amplifiers then this can cause excessive draw and you may be required to install a high power alternator and sometimes a second battery to meet those demands.

 

If I add a subwoofer I would like to use the 8" free air sub that JL makes in their Marine line. The installation would require some clever adapters to mount the sub under the deck where the current sub is, and it would also be a more expensive installation, but on the plus side it would not take up so much space in the trunk. Sub's mounted in an enclosure are supposed to provide superior sound, but the free air sub mounted in my 2000 Nissan Maxima has always sounded really good, so I'm not concerned with making that choice.

 

Can one of you explain what an enclosure does that one does not get from a partition? I see calculations online, but nothing resembling an actual explanation. If the audio is dependent on the acoustics of an enclosure, won't it degrade with changes in altitude?

A large diameter "sub woofer" (12" +) can take as little as 1/100th the power to drive for the same sound level as a typical 8" unit (80dB/Watt for some 8" speakers versus 100dB/Watt for a high efficiency 12" speaker). The weight can be kept under control by going with a speaker with Neo magnets and an aluminum frame. I think the main issue is fitting it, as 12" (actual OD is typically 14") is pretty large and difficult to position in a car the size of Giulia.

The issue with the diameter of the speaker appears to me to be mostly mechanical; it is hard to move a lot of air with a small diameter speaker. Can a spacer-adapter between a large speaker and a smaller opening work?

 

I'm very interested in following this thread. @pcoates@drcoates.net please post pics of your install when it's done. This thread brings back fond memories of packing the trunk of my first car, an old Audi that cost $300, with $1,500 worth of stereo equipment when I was 16 years old. I had two 12s in a giant ported enclosure and only listened to rap music. My parents knew I was on the way home when I was still 5 minutes away because of the thumping. Now I'm a bit older and more restrained, but it'd be nice to replace the joke of a subwoofer that is in my QV.

 

Would it achieve worthwhile gains to simply replace the stock sw speaker with one of higher quality powered by it's own mono amp?
I would rather not reduce my available trunk space with a sw box.
Perhaps modify the rear deck panel to accommodate one (or two) larger sw speaker(s) and appropriate amplification.
Please, let's keep this thread going!

 

I have a buddy who seems to know his stuff. I know nothing about car audio (I am a home audiophile). He swears by Rockford Fosgate. I’ve been in his older e class merc and the sound is brilliant. No way I would put his system in my alfa for fear of jacking up the power supply to critical electrical systems as mentioned already. However, Crutchfield has some seemingly nice and affordable “base packages” that might be worth considering. They include an amp, enclosure, and a sub. All Rockford Fosgate (except enclosure), and some look fairly compact. What do our car audiophiles think of this?

 

Here is yet another silly question: are sweep frequency and white noise recordings available in a format suitable for use to play on a car sound system (uncompressed flash drive)? This would help separate some of the opinion from fact relative to the performance of the system. What about "missing tone" wide band test signals?

How about, are there any utilities or guides to generate test signals? I can easily write a program to generate the samples I want the system to put out, but those samples need to be formatted so that the audio system can process them.

While sound system components need to be evaluated in a very expensive anechoic chamber, the whole system should be evaluated in situ; no chamber needed. I believe the really bad things a system can do are nulls and peaks in the frequency response and non-linearities such as resonance induced rattles and either should show up with the help of such a system.

 

Here is yet another silly question: are sweep frequency and white noise recordings available in a format suitable for use to play on a car sound system (uncompressed flash drive)? This would help separate some of the opinion from fact relative to the performance of the system. What about "missing tone" wide band test signals?
.....

I use a Phonic PAA3. Comes with inbuilt test gen, and cd with test signals....
https://www.thomann.de/gb/phonic_paa3_personal_audioassistant.htm

https://www.mixonline.com/technology/field-test-phonic-paa3-portable-audio-analyzer-370275

http://www.phonic.com/?subcats=Y&pcode_from_q=Y&pshort=Y&pfull=Y&pname=Y&pkeywords=Y&search_performed=Y&q=paa3&dispatch=products.search

 

Seems to be a lot of people who do not understand a lot about subwoofers. Here is a basic summary.

First open or free air subwoofers perform the worst. They tend to use the entire space in then case the whole trunk as the box. Trouble is every subwoofer has a very specific amount of cabinet volume for optimum performance. The entire trunk is way too big and thus very little air movement and thus poor sound quality. However, they are used in most stock systems due to space and cost. They are cheap because no enclosure is required to be built around the speaker. In the Giulia replacing the sub with another open air sub may improve the sound a little but probably not dramatically. Since still no enclosure and without an external amp will push the sub hard enough to really make it move.

Second is the sealed enclosure. It requires the least amount of space but the space needed is different for each subwoofer. Newer subs now can utilize much less space than older subs. For instance the Jl 10W03 requires 0.65 cubic feet while the JL 10TW3 only requires 0.5 cubic feet. If your box is not the exact size you have a significant decrease in performance of the sub. Sealed subs typically have the smoothes curve and best overall sound quality.

Lastly is the ported enclosure. These are bigger boxes and a port which will make certain tuned frequencies much louder. They are usually tuned to have very frequencies in 18-40Hz perform at a high level. Thus giving 2-4x more output when those frequencies are played. They give more out more decibels and sound much louder. However, there is a small trade off in overall sound quality with a ported box and they are much bigger boxes compared to sealed boxes. They are very popular with rap music as they rattle entire car when those frequencies are hit.

So building a custom box requires a lot of math to make it work like it is supposed to. You can put a sub in any box and it will work but the sound quality will be poor. Factory made boxes that you can get to fit are an exact match the specifications the sub and thus have significantly better sound quality.

 

If I wasn't leasing I'd consider replacing the whole system, the premium sound is weak on power.

Maybe just the sub with a small amp, even an 8" sub with 100W would kick the crap out of what's installed. With auto on and the battery in the trunk, installation and operation would be a no brainer. All amps have an input adjustment and I'd just intercept what's already there (high level). But it would be awesome to scrap the whole thing and put in a new equalizing signal processor and high power multi-channel amplifers. Oh and the speakers too

 

Infinite baffle subwoofer installations do not have the acoustic efficiency of a sealed or ported enclosure but the driver can be controlled more precisely.

I found this as a possible option. This brand has good sound quality for the price, especially for home audio. One would need to make an adapter, probably out of mdf to fit the cut out. Based on photos, the magnet on this looks much larger than the hk sub.

https://www.parts-express.com/tang-band-w69-1042j-6x9-subwoofer--264-837

 

Thanks for the nomenclature, that helps a lot and is exactly what I had in mind.

From my perspective, the sound system is going in a sport-sedan not a concert hall, home theater or man-cave. My first priority is to control weight to keep the car sporty. The second priority is to keep the "sedan" functionality in place and not block off my ability to lay down the back seats. Being able to replicate the SPL of a rock concert does not even appear on my list of priorities. I wear ear plugs at the movie theater. I just want clean full spectrum sound.

I suspect that I am not alone with my priority list.

 

Here are pictures of the installation. Takes up very little of the usable space in the trunk. Looks very clean. Amplifier fit nice into compartment in trunk and styrofoam still fits over it.

After hours of playing pretty loud I took out stryofoam and amplifier still felt pretty cool. My concern in that location was over heating. Will have to watch this and decide if I should remove some styrofoam or put a small fan in there.

The ported 10TW1 box did fit and they really wanted me to get that one. It was a little louder. However, it took up more space and sounded boomier.

As for sound of the sealed sub, it is an amazing difference from the factory system. Incredible how much better it makes the stock system sound. The bass is clean and very powerful. You can feel it hit inside of you.

Back seat it punches you through the seat. Each best of bass hits you in back.

Up front bass can still be felt and steering wheel vibrates to the bass. Sound on rock is stunning. AC/DC feels like a concert at volume level 30. You can feel the bass in your legs. At low volumes it is very clean and fills car with nice full sound. Ozzy crazy train will drive you crazy when you the bass hits. Bon Jovi you give love a bad name has clean vocals to start with then hits your insides when the music and bass kicks in.

Jazz sounds amazing, the bass is a deep full sound that doesn't sound boomy or distorted at all. I turned down bass on head unit to keep stress and distortion down on other speakers since there is no crossover on these like you would have with a dedicated amp for all of the other speakers. I use bass dial to add bass from sub only. I had probably around 70% mark. All the way up and bass overpowers the treble.

Classic rock like Led Zeppelin whole lotta love sounds amazing with all the bass shaking the car. Haven't had time to listen to Rush but can't wait to hear classics like YYZ, Limelight and Tom Sawyer.

Contemporary music like Lionel Richie, Madonna, and Prince were all had very clean and powerful bass. Let's groove tonight by the four seasons sounded incredible with deep bass and no distortion.

Rap music it's getting hot in here by Nelly was so loud it sounded like a dance club. I turned it up in the parking lot at my tennis club and all of her tennis team started dancing to it. It can be heard from a long ways with the windows down. It is hard to believe that much bass can from one 10 inch woofer when you turn on rap music.

Overall, bass is extremely clean and very powerful. It takes a lot of stress off the other speakers if you turn the bass setting down so they play a little louder cleaner. Would be better if you could cross them over at around 100hz but only way would be to put passive crossovers in.

If I end up replacing any of the fronts or rears I will definitely add crossovers if I continue using stock amp to power them. Sub sounds so good it makes you want to upgrade other speakers. But I have to say I am way more impressed with stock speakers after hearing them with some good clean bass.

 

Looks good, which sub box did you actually go for in the end? I see there are several Micro sub boxes...

And does the signal come via high level from the existing subwoofer speaker output?

And the JL Audio amp auto senses the signal?

The control knob in the front is volume/bass control btw for whoever asked, plugs into the amp at the other end...

 

Thanks for sharing the photos.

Curious why the driver side trans tunnel interior shots are with the photos? Is that where they pulled the amp signal from?

 

Thanks for sharing the photos.

Curious why the driver side trans tunnel interior shots are with the photos? Is that where they pulled the amp signal from?

Is that a sub woofer volume control knob?

 

Yes that is bass control knob. I highly recommend getting this knob installed so you easily turn down the bass when you want because it is extremely powerful if left all the way up.

Sub box I choose was CS110TG-TW3 fit nicely up under deck and more then enough bass for me. This is a sealed box which gives a tighter cleaner sound.

They really wanted me to use the CP110LG-TW1-2 which is a ported box and they got to fit but was a tighter fit since box is bigger. Also being ported it was way more bass then I wanted when it hit the tuned frequencies of the port. If you are a big rap guy this will be the box for you.

As for weight the box I choose is 21.2 lbs and the amp is probably around a pound maybe two. So adds less then 25 lbs total to the car.

Lockem yes I agree not everyone wants there car to be like a music hall or rock concert, but many of us are looking to get the maximum performance and sound quality without sacrificing too much weight or space. Also with bass knob I can easily control how much bass I am getting even turn the bass all way off. Like you we want to be able to our car as a sedan. Not trying to be mean but if that is not you want sticking with the factory sub might be the best option. It is not terrible for a factory system. In fact compared to many factory systems it sounds quit good. Also, if you look underneath the factory sub you will see the speaker wires are actually built into the frame of the factory sub so this makes it a little more difficult to swap. I use parts express a lot and they make really good drivers for the money, but without an increase in power not sure how much better it will sound over the factory sub. Also you need to pay attention to that sub being an 8 ohm sub as most car speakers are 4 ohm. It is home speakers that are 8 ohm. Thus the stereo will have to use twice as much power to move it as the factory speaker. Luckily it is inexpensive and some one can order one and test it. In addition the optimum sealed size for that sub is only 0.25 cubic feet. So you could actually buy a small 6x9 pre made box online for under $15 to mount the speaker in and then mount the box where the old sub was located. Should be pretty easy to do. This will probably improve sound quality some as long as stock amplifier can push it. Might be perfect for those who want to keep everything same as factory. In addition parts express has a cheap hi level input auto sensing mono kicker amp for $139 which would for sure improve the sound but at an 8 ohm load even with "250w" amp it will really only provide 62.5 watts to the sub. This could even mount to the back of the box hidden under the dash Which would probably sound pretty good and would only be about a $200 upgrade.

 

I think swapping an 8 ohm speaker for a 4 ohm speaker will reduce the power that can be delivered to the speaker by less than 3dB (1/2). W=V^2/R and the amp acts like a constant voltage source in this case, since V is limited when R is increased. However, the amplifier has an internal resistance which should be 4 ohms. Thus for constant V value and assuming the OEM speaker is 4 ohms

W(OEM) = V^2/(4+4) = X Watts. V= sqrt(X*8)

W(8 ohm) = V^2/(4+8) = X*8/(4+8) = X*0.6666 -> 1.7dB loss in max power

However, a typical 6x9 speaker produces 85dB SPL/watt while a 10" high efficiency speaker produces about 96dB SPL/watt (12" produces up to 100dB SPL/watt). Of course SPL is what you hear, not watts so SPL is what we care about. Thus with this overly simplified arithmetic you should get 96-1.7-85 = 9.3dB more SPL with the 10" speaker compared to the 6x9. That is before factoring in that the 10" speaker has a lower low frequency cut off (roughly 55Hz versus 80Hz) and greater air displacement capability (several times) than the 6x9.

Even a neo magnet light weight speaker in 10" is going to take up more space and weigh more than the OEM ceramic magnet 6x9 (I think about 5-6 pounds plus an adapter ring versus OEM at 2-3 pounds), but some care in selection should yield a reasonable tradeoff. My main point is that a larger diameter speaker mounted in an "infinite baffle" configuration should negate the need for a heavy space hogging box and an extra amplifier (loss of a couple of inches of height along part of the trunk versus blocking off a whole section of the trunk and adding maybe 5 pounds total versus maybe 20-30 pounds for a box, amplifier, wires, fasteners, etc) and looks like a much better way to get more bass within my constraints. Note that it is probably more expensive than the amp and speaker box arrangement. Of course the "infinite baffle" arrangement won't work well when the rear seat is laid down, as the rear seats form the main partition.

There are lots of things in speaker specifications that are vague to me although they are probably precise if industry practice is fully understood.
For example the manufacturers provide R and L values for the impedance model and then an impedance curve that does not match said model. They provide frequency response and impedance curves but do not state the conditions under which they were measured (i.e. what kind of baffle/box?). Maybe R and L were measured on a stationary voice coil?

 

I'm interested to see an infinite baffle with a 10 in sub either with the stock amp or small dedicated sub amp. My car is a lease so I won't be digging into it but as an audiophile I'm interested.

Most driver spec sheets are taken in free air. Resistance and inductance, R and L are basically static values for audio frequencies. The overall impedance is dependent on frequency, 2*pi*f*L + R.
The actual audio frequency response of the driver is highly dependent on the enclosure and environment. Using the free air resonant frequency of the driver and other specs determine the enclosure volume needed to getting the desired audio frequency response.

 

I was thinking along similar lines, in theory a super high sensitivity larger driver would in theory work with the standard amp, but it would be a question of housing it! I mean, just look at what can be achieved with valve amps and the likes with modest power.

I do have an old Boston Acoustics 8" sub that is fairly high sensitivity, tempted to offer that up and amplify it once placed with an adapter inside the original hole, but that might look messy!

I guess at least by going for a box it won't mean cutting things about too much, no doubt it could be fitted infinite baffle neatly with some care.

In my QV the seats don't fold, so in theory I have a fixed, fairly rigid chamber.

 

The 10 inch JL Audio MX series Marine subwoofers should fit what you are both looking for. They are 4 ohm infinite baffle subwoofers that are efficient and have very good bass performance. They should be able to be mounted in same location as stock sub with minor modifications. They will use the entire trunk as an enclosure with seat up and stock radio should be able to drive them. Weight is only 6.5 lbs

 

Uh-oh, did you simply put your subwoofer box in the trunk, with the sound going through the rear seats? If so, for an infinite baffle design to work some kind of bass attenuating partition is required between the trunk and the rear seat backs.

I'll have to stare at it for a while to figure out how/if that can be done while still maintaining the ability to fold the seats down.