Total Sound Makeover - Sound Deadening, Speakers, Processor, Amp, and Subwoofer

Phase I – Sound Treatment and Speaker Swap-Out

Shortly after I picked up my Plug-In Prius in April, I posted the following on this forum:

I'm upgrading the sound experience incrementally, tackling the challenges in order of those that have the greatest effect to the least, while progressing roughly from measures that have the biggest bang for the buck to the least. At the point I get the sound I want commensurate with the money I've put in, I'm done, so the project will probably not make it to Step 5:

1. The listening room. Far and away the worst thing about the listening experience is noise. No point plowing a lot of money into electronics to battle the noise without first doing everything reasonably possible to get rid of it. The largest part of the upgrade budget will be devoted to professional installation of resonance damping panels, acoustical isolation/insulation foam, and mass loaded vinyl sheeting. It is getting installed now.

2. Speakers. If sound treatment alone does not improve the sound adequately (and I suspect it will not), I'll next be swapping out the factory speakers for reasonably inexpensive component speakers in the front (Alpine SPR-60C - $170), and coaxial speakers in the rear door (Alpine SPR-60 -$120). My guess is this is all I need, and I'll quit here.

3. Sound Processor. Whatever aftermarket speakers we choose to put in these cars, they cannot match what the head unit was designed to power, so the next step would be a processor to adjust equalization, phase problems, and time delay. Several products seem well reviewed, but should the speaker swap-out alone not do it for me, I will be installing a JBL MS-8. It does a lot for $565

4. Amplification. I seriously doubt that I will have any use for power in excess of the 18w per channel put out by the MS-8, but if I do, it will be a 5 channel Class D amp - probably the Alpine PDX-V9. 4 x 100w plus 1 x 500w. Why the 500w 5th channel? Just in case I need...

5. Bass. I listen to music, and have no desire to annoy cars next to me at stoplights, so the mention of "subwoofer" makes me cringe. Still, there are limitations to what a 6 1/2" woofer can cleanly output at any power level. If I'm not happy at this point, I'm very comfortable working with MDF and fiberglass, and will fabricate a very shallow (~ 4" - the sub only needs .35 cu ft.) enclosure in the cargo area behind one of the wheel wells to house an Alpine SWR-T10.

The project is now complete. Some of you asked for updates, so here we go:

First off, I think I was right assuming that the greatest improvement to the sound was to be gained by getting rid of undesired noise. There are numerous posts on how to use commonly available single product sound treatments such as Dynamat and its many clones, with satisfying results, but I was looking for a more comprehensive solution. The multi-tiered approach employed by http://www.sounddeadenershowdown.com/ made sense, as it’s damping product (CLD Tiles) was better engineered to solve the resonance problem, and the addition of closed cell foam and mass loaded vinyl were far better suited to blocking the low frequency noise (road, tire, wind, and engine noise), than single product solutions were capable of dealing with. The total material cost was around $700, and it was the most cost effective part of the project.

Bare Metal


CLD Tiles Installed

Thinsulate Acoustic Insulation Installed

Rear seat and floor area treated with Closed Cell Foam (CCF) - gray, and Mass Loaded Vinyl (MLV) -black

All layers of CCF and MLV were installed with Velcro in order to facilitate removal for maintenance




A typical buildup of CCF and MLV - these folks do great work















Front seat floor and footwell area

Another complex geometry build up in the right rear trunk area















Door Treatment





















Don Sambrook, of SoundDeadenerShowdown was willing to work with and oversee the installation by Hampstead AutoBody in Manchester, Maryland, so that was my first stop after picking up the car in D.C. They gutted the car down to bare metal, and did a fantastic job of applying the layers of material and putting it back together just like new.


Post job follow-up was excellent as well. I highly recommend both of these companies. I live in Georgia, and will probably make the long drive to use their services for my next car.

The result was incredible. I’ve never experienced this kind of quiet, not even in high-end luxury cars. The only noticeable sound is now environmental noise coming through the only untreated surfaces – the windows.

Since the car was already gutted, I had the shop run 12ga speaker wires and replace the speakers. I had them route all of the speaker wires through the storage bin behind the traction battery, in case I later wished to add sound processing and amplification. I fabricated tweeter brackets from 16ga steel using the attached file (Prius Squawker Mounting Plates.pdf), to help expedite the installation.


Total material cost to this point was about $1,000 (Speakers $300, Sound Treatment $700), and achieved about 95% of the sound improvement I was looking for. It would have made sense to stop here, as the law of diminishing returns hits hard. Next post will outline how I blew roughly $1700 getting that last 5%.

Phase II – Sound Processing, Amplification, and Subwoofer Installation

The sound from the upgraded speakers, along with the incredible sound treatment drastically improved the listening experience, but I wanted better equalization and more accurate bass than the stock electronics and replacement speakers could provide. The biggest challenge was adding bass, particularly fitting a subwoofer into what I wanted to be as unobtrusive an installation as I could manage. My goal was to minimize intrusion into useful space, while mitigating the eyesore of a sub enclosure as much as feasible. I chose the Alpine SWR-T10 for several reasons (sonically matched to the other Alpine R Series speakers, appropriate power handling and frequency range) but mostly because it was the 10” shallow mount sub driver that required the smallest enclosure space (.25 to .5 cu. ft.).

Before getting into the subwoofer enclosure construction process, first let me strongly recommend that any Gen III, non Plug-In owner order either a completed sub enclosure, or a plug from mgb4tim. See http://www.morspeedperformance.com/priusRight.cfm. They appear to be of the highest quality, will save you a great deal of time and effort, and are very reasonably priced. His products will not fit the Plug-In because the charging port intrudes on the right wheel well space.

I chose the left rear cargo space because it is smaller than the right, I did not need much volume, and it would free up the larger right rear space for useful storage. Also, it allows much easier access to the battery.

I fabricated all unsupported parts of the enclosure out of MDF or plywood in order to minimize resonance, so all visible surfaces were constructed that way. All hidden surfaces would be in contact with the trunk carpet, with much of them tightly radiused, or consisting of compound curves, helping to dampen any resonance, so they were a reasonable application for fiberglass.

I used aviation fiberglass materials, simply because I am used to working with them. Epoxy resin and Bidirectional cloth. They have the advantage of being incredibly strong, odor free and non-flammable, but are expensive. Total material cost was about $100 for all cloth, resin, ratio pumps, application tools and materials – probably double the cost of standard materials.

First step was fabricating the MDF rings, mounting the driver, and prototyping the placement based on enclosure volume. I measured volume with packing peanuts, and it worked out that at the point that I had about ¼” clearance between the sides of the driver and the enclosing carpeting, the volume was .29 cubic feet – lower than the preferred .35, but within the acceptable range of .25 - .50. Adding polyfill will increase the apparent volume to approximately .36, so all is well.

Next, I masked off the area, placed a nut can cut on a diagonal to create a recess for the terminal mount, placed aluminum foil (as a release), and applied four layers of bidirectional fiberglass cloth to create the rear of the enclosure.

Initially using cardboard templates, I then cut and shaped ½” plywood sides, and shaped the final exposed part of the box to resemble a leaf on its top and front profiles. More trimming fit the MDF/Plywood exterior box to the fiberglass rear shell.


One layer of bidirectional cloth to secure the inside of the fiberglass shell to the exterior of the MDF/Plywood box completed the initial assembly.

Cutting the terminal mount hole at this point helped greatly to see inside for the sanding, filling, and fiberglass work to follow.


Filling irregular voids with “micro” (a mixture of epoxy and microscopic glass bubbles) inside of the enclosure created a smooth surface to apply two layers of bidirectional cloth joining the inside of the MDF/Plywood box to the inside of the fiberglass shell.

Not a fan of heavy subwoofer assemblies accelerating toward my head during a collision, I placed a couple of plywood disks using flox (a strong mix of cotton fiber and epoxy) and two layers of bidirectional cloth. Sheet metal screws will bear on these to hold the enclosure tightly to the car’s frame.


I covered all areas exposed to the trunk with at least a single layer of bidirectional cloth to protect from chipping. I also coated all MDF not exposed to abuse with at least a single layer of epoxy to seal against moisture – a few drops of water can disintegrate any unsealed MDF fabrication. Next came a lot of sanding, filling (large voids with micro, small ones with auto body filler), sanding, filling, priming, sanding, filling, priming, then painting



Smarter folks than I have found it impossible to match the carpet color, so I did not try. It was very easy to match the paint color. After some experimenting, I found a reasonable texture match to the car’s plastic parts by stippling a thick mixture of flat paint, and lightly sanding with 220grit.

A tap test revealed some unwanted resonance on the flatter parts of the fiberglass shell, so they were treated with Dynamat. CLD tiles work better, but Dynamat was all I had on hand at the time.


Mount the terminal, run the speaker wire (8ga), screw the enclosure to the car’s frame.

Get polyfill from Wal-Mart rather than a speaker part supplier. Same stuff, 1/5 the price. I attached it to the top and bottom with 3m 77 spray. Nothing on the sides, as I now have less than ¼” clearance from the driver to the wall. Press the final back polyfill in with no adhesive, so it can easily be removed to access the installation screws.

Mount the sub, grill, and trim piece, and voila.


I don’t know which I like better to finish the job. I like the way the black WeatherTech mat makes the sub less visually obnoxious,


But the carpet just looks nicer. It cost the minimum job fee ($20 in my case) for a local carpet shop to put a nice edge treatment on the cut carpet edge.


With the speaker wires already running through the rear storage area, installation of the sound processor (JBL MS-8) and amp (Alpine PDX-V9) was simple and straightforward, taking only a few hours. Distribution block (lower left), fuses (upper left), processor, and amp were all mounted using Velcro, for easy access.


Those concerned about temperature buildup in this area damaging the equipment need not be. I used a recording thermometer to measure the temp during a recent drive in 95 degree outside air temps, and the highest it got was 99. There is plenty of airflow back there – it is right next to the traction battery fans. The area also gets hot during charging, but again, never over 100 degrees, and the sound equipment is not operating while charging anyway.

After setup and calibration of the MS-8, I could not be more pleased. The sound is incredible. Was it worth the expense? I look at it this way. The difference in price between the base and advanced Plug-In models is $7525. Of the upgrades, only two appealed to me – garage door controls on the mirror, and an upgraded sound system. The mirror only cost me $168, leaving $7357 left to improve the listening experience. I spent $1000 on stuff that was necessary, and $1700 on stuff that was not, so (using logic you may find twisted) I am not only $4800 ahead, but have a much, much better overall sound experience than the advanced model could have hoped to provide. Yeah, it was worth it. I cannot begin to describe the joy I get from driving a car that is everything I hoped it could be. It is all at once the world’s most efficient electric car, most practical gas car, quietest luxury car, and surely ranks amongst the best sounding music entertainment cars on the planet. Thanks to all of you at PriusChat for the info to make it possible.

Holy shit! What a great job and write up!

Just wondering if you had an estimate how much weight the deading added? Plus the 15 lb sub and amps. I guess you didn't have a baseline, but I was curious if you lose 2 mpg. I guess with a prius you don't have to worry about the large cabling going up to the battery in the engine bay.

I do wonder though about adding a lead acid next to the amps to handle large current surges because the prius 12V can't handle a lot of current at once (if they are still using pseudo-AGM in the 2012). You could put in the 2nd 12V in parallel with the prius 12V and use a high current relay to turn it connect it after the car is started. Also when you are driving it, the DC-DC in the front is providing the 13.5V back to the battery and amps (the current comes from the HV batteries). I wonder how much wattage that connection is designed for since typically the 12V battery doesn't need to provide a lot of current.

Approximately 120 lbs for the sound deadening materials, 27 lbs for the sub and enclosure, not sure about the amps, but the wiring probably weighs more. All told, basically the weight of a passenger. I did not have a baseline, but am satisfied with over 100mpg so far. The way I see it, it still weighs less, burns less fuel, and sounds better than a Mercedes S Class.

I thought this issue through while researching the project, and ended up reasoning that it is not about how much power the system can handle, it is about how much is does handle. I listen to music at roughly the same volume that I did before the install, so roughly the same acoustic energy is generated by the drivers. Perhaps there is somewhat greater loss due to the additional electronics, but it is likely offset by the use of Class D amps. Bottom line is that in everyday use, I'm not drawing significantly more electrical power than I did using the stock head unit alone, and saw no need to add batteries or capacitors. Again, my preference is music. Not looking to annoy folks at stoplights.

If I'm wrong and do trash the battery, I'll replace it with an Optima Yellow top and add a capacitor rather than an additional battery.

Fantastic job!

Ok, I was just curious if anyone knew what the cabling from the DC-DC to the 12V battery looked like. I'm sure it is ok under 20A, I was just wondering about running 500W from back there if it would be a concern. I don't think the AGM or 12V battery is really at risk because when the car is on the majority of the current will come from the DC-DC.

I do highly suggest throwing a small motorcycle 12V battery there and/or maybe a large cap to even out the current spikes. The DC-DC is using a large buck converter and seeing how I see lines on the MFD in a Gen1 when it is struggling to charge up a low 11V range 12V battery, I do wonder about the control issues and power factor stuff.

ie. hypothetically someone could damage their DC-DC by putting large amps or too much reactive startup current. It's a lot more complex than simple alternator plus battery situation.

You may want to put a little voltage display that you plug into the 12V cigarette lighter than will show you the 13.5V or 13.9V when the car is on, or temporarily plug in a voltmeter to monitor it (especially if it has a frequency mode) and see if turning up the volume makes it drop to say 13.1V. Or alternatively if this car still allows for the Diagnostic screen and the Vehicle Signal Check menu, you could drive around in this mode and experiment with the volume levels.

I don't know what kind of 12V they put in there. The Prius C might now has a larger 50Ah, so maybe it is somewhere from 38Ah to 50Ah. At any rate I might be careful about running the speakers loudly for an hour with the car in ACC, because I'm not sure the 12V battery would last many years doing this. So make sure you are in ON and using the LiIon.

Quite thin, actually. I would estimate it to be approximately 6-8 guage.

Thanks for that. It is precisely the sort of advice I was looking for when researching the install. I come from an aviation background, where simpler is better, and it is all about a simple alternator and battery situation.

Good idea. Can you recommend a product?

Regarding operating the system for an hour in ACC - not gonna happen. I only listen to tunes when driving. I will heed your advice, however, when considering loaning the car to a teenager, and remove the fuse powering the whole thing.

I'm unable to find out more technical details of the buck voltage regulator for the 12V system.

There is this from EEtimes

So one tip might to not run the electric A/C compressor with the amps pulling a large current or you will be compounding the heating on the heatsink for the 12V regulator stuff. At least this give you the best shot at not damaging things, but they should have temp monitors and probably a current sensor on the 12V regulator to shut down things if the 12V is trying to draw too much current.

According to this source:

If Bob Wilson comments he appears to know a lot more at least in the Gen 1 it is a 100A connection to the battery and people have run 1000 watt inverters (true for Gen 1/2)

He also appears to have made the measurements:

Code:

13.94 V., 1.1 A. with inverter OFF
13.94 V., 1.7 A. with inverter ON and no load
13.83 V., 50.3 A. with heater on lowest setting (~ 700 W)
13.75 V., 71-74 A. with heater on medium setting (~ 1 kW) 

So you should have no problems running the amps at full power but you should get a TIS account and download all the Toyota Prius Electrical Wiring Diagram for the 2012 PIP and confirm the fusable links and current going to the battery so you know. If the inverter design is the same, the electrical A/C heat sink is shared.

Finally for a battery safety thing, since it probably is safe to run the amp loudly as long as the car is in READY, I think you should see if there is some type of "key on" 12V signal you can use nearby (ie. only on when the HV stuff is running) and use that for the power on signal to the amp. (To prevent it from running in ACC mode)

I would still highly recommend one utracapacitor mounted close to the amp to reduce spikes in current for playing loud dynamic music.

I also recommend getting some smaller fuses for the amp (20A?) so you can safeguard the current from the DC/DC and never have to worry about things. (ie. the amp goes silent and replace a $1 part instead of the ECU shutting down while driving because you happened to lower a window with A/C and power steering at night, or something like that)

Before running at max power I guess you'd need to research on the 2012 what current the headlamps, the electric water pump, a power window motor, the electric A/C and the electric power steering use, as well as the ECU overhead (and the heater and the window defrost). It's probably in the forum somewhere, but I'm guessing you can run 500 watts easy. I personally would avoid having the DC/DC stay up near it's max current rating (90A? 100A?) for extended time, and it would be worthwhile getting a cheap bluetooth OBD to keep an eye on the 12V voltage and the inverter temp.

That was a fantastic job and write-up. It is way more than I care to do but an interesting, educational read.

Joedirte, thanks a million for all of this advice. I don't know what I'd do without all of you helpful folks at Priuschat.

I've downloaded Torque to my phone and have a PLX Kiwi ODB2 bluetooth adapter on order, so will be able to monitor voltage and (if I can find it) inverter temp in a few days.

Swapping the main fuse from the battery to the distribution block for a 20A fuse is pure genius. I'll do that right away when I get home Sunday. I'll also plan to install a 1 farad capacitor close to the amp.

I just subscribed to TIS and am downloading the manuals now. Should make for a good read. I believe the power sensing lead used to trigger the processor (which in turn triggers the amp to power up) is already tapped from a non ACC source, but I'll recheck. The wiring diagrams should help me locate a better source if I'm wrong.

Thanks again.

Well assuming the DC/DC is the same in the 2012, you can get away with at least a 50A fuse (probably even more if you monitor the 12V voltage and see it drop under 13.7V). I was talking about the two 40A fuses in the amp might be cheaper fuses to swap out for like two 20A or 30A. But yeah, you could do the whole distribution, but the processor is only like 100W at most. Anyways, you can check the ACC now just go to radio mode, (one push) and see if the amp turns on.

Look on ebay or amazon for ultracaps, some of them are really cheap, but if you can find a cheap 1F audio type cap with low ESR, that will help with switching noise from the amp regulator as well current surges from burps and turn on and loud dynamic sounds. Maybe I'm wrong and ultracaps aren't a good idea. Most of them are only rated to 2.7V.

But six 1F ultracaps (put them in series ie. end to end) are like $12 at most, and you can put them in series. But the giant audio 1F caps are only $20 to $30 anyways.

I used to run two large amps in my GenII totaling 1900w (Diamond Audio D9800.2 and D61500.1) and never had a problem with voltage drop or any of the other issues common to high wattage stereo installs. Now I may not have been getting the full current require by the amplifiers at peak output but for regular listening sessions this was never a problem. I think the OP will do just fine with his system.

1900W rms / peak? At 10% volume?? The point was more of building in safety so as to not damage a fusible link or exceed the DC/DC regulator, which WOULD be damaged if you tried to pull too much current on the 12V.

So 1900W is 135A at 14V.. So NO, you did not run 1900W. And people should pay attention to max current instead of just putting in 1900W and turning it up and going, well nothing broke, so it's ok.

I'm sorry. You mistake me for a noob. Please do your research before you pop into forums and make such assumptions. If you are not familiar with the pieces I mentioned then your knowledge of car audio must be very new. Again, do your research.

How's the FM reception with this setup?

I would love to run new shielded antenna wire to the stock 2011 antenna to see if it would help.
I am afraid to remove the liner and put it back looking crappy.

I have a graduate degree in brute force engineering, so I'll put it to use with a little experiment. I just bought a hand full each of 20, 30, 40, and 50 amp fuses, and will do a little experimenting when I get some time at home (probably a couple weeks from now - I travel a lot). After installing the capacitor, I'll put in a 20A fuse and crank the volume until either the fuse blows or my ears bleed, whichever occurs first. If my ears remain intact, I'll progress through the 30, 40, and 50, stopping when the volume level reaches the point that I would never consider listening. My guess is that it will be a lower amperage than most of us think - Important point to note is that the fuse assembly is located upstream of the cap, so if the capacitor is doing its job correctly, the amp itself could very well see transient loads of nearly 80 amps, while the battery upstream feeds the capacitor a consistent current of well under 20 amps. That is the brilliance of your recommendation - most folks think about fuses to protect downstream circuits, but your out-of-the-box suggestion can, in effect, help to protect the far more valuable circuits upstream.

I'll probably go with one of the more expensive audio capacitors equipped with a power sensing lead, and direct wire connections that can save a few bucks on large gauge ring terminals.

Thanks again.

FM? What's FM?

Kidding, and sorry to be a jerk, but my dislike of DJ's, commercials, and the same 10 songs repeated again and again drove me to iPod (uncompressed CD recordings only), XM, and Pandora long ago. Sorry to say, I've never tuned an FM station since I bought the car in April. I'll do so when I get home Sunday and let you know how it sounds.

Awesome install.

Mike

I'm not an expert by any means, but my reading leaves me to believe caps add very little if anything. You're probably better off adding a better or additional battery. That said, at this point, it is probably a solution looking for a problem. Unless you are getting lower voltage to the amps or other 12V items in the car you shouldn't need to worry especially if the wires are fused properly. Your equipment (class D amp), coupled with the way you intend to use it, doesn't look like you are going to be drawing insane watts.

Here's a more intense install which doesn't appear to be having any issues yet: 2011 Toyota Prius by JT Audio & Accessories - DIYMA Car Audio Forum