Car that Goes Boom - Part 1

Today's post is about acquiring, and mounting an amplifier to power the speaker box I built over a multiple month period spanning from last summer to this winter. I will get to the wiring and test firing in a subsequent post. While Oliver, the MGB, will probably not quite "Boom" like L'Trimm describe, it will deliver some Phil Bombs.

Bassline

Sony MEX-M70BT

I started down this audio journey for Oliver, the MGB, simply: I wanted sound. I recognized that seeing the little LED screen when I had the top down would be difficult, so I found a stereo suited more for a boat than a car. I figured that a boat had similar issues as a convertible: moisture and glare.

I settled on a Sony MEX-M70BT, where the BT stands for BlueTooth. This plays CD's, has a microphone for hands-free phone calls, had 2 USB's for other playthings, etc. Based on the details at Crutchfield (product link here), it has an estimated running wattage of 17 watts with a peak output of 55 watts. It delivers with pre-amp outputs (at 5 volts) and a bunch of other features that made it slightly better than or on par with the other widely available boat stereos. Car stereos have more features, and usually have greater graphics, but I intend to be driving, so I don't need a light show coming from my dash. I need easily readable print regardless of light level. The simple red or blue back-lit buttons and grey/black main panel fit perfectly with my dressed-down interior. Unlike most of the other boat stereos on the market, there were 0 complaints about product failure. None. That made the decision.

For speakers, I had an old set of Polk Audio 6x9's and 6.5" rounds. I don't remember what their peak wattage was, but it's in the 200 watt or more range. Regardless, the stereo was not going to blow them out with a wimpy 17 watts. I installed all of this stuff into Oliver in posts (Get Sound 1 and Get Sound 2), including mounting the 6x9's into the rear firewall and the 6.5 rounds into the foot wells.

JL Audio 10W0v3-4

With little actual testing, I did some research into which frequencies disappear when a convertible top is lowered. Similar to a boat hitting speed, the wind rips the lower frequencies away. I had expected the high frequencies to disappear, thinking that the lower frequencies would be helped regardless by simply resonating against the body of the vehicle. I had even gone so far as to start investigating small 3 inch speakers to boost the upper end when I found that Crutchfield did tests (link here). They proved that the low end falls away. That was when I picked up a JL Audio 10W0V3-4 10 inch sub (details from Crutchfield) to address that.

I considered the math at this point. 4 speakers each capable of handling 200 watts plus a sub capable of handing about the same, and I have a stereo pushing out pretty much 17 watts. That did not add up, so I started thinking about an amplifier.

Channels and Selection

Picasso Nano

Once I made the tiny step into thinking about amplifiers, I discovered just how little I knew about it. Yes, I understood the concept, but the market and distinction between various things is fairly confusing. I considered 2 options: a single channel amplifier just for the sub woofer and a 5-channel amplifier for all of the speakers. The single channel probably would have made more sense for a system that produced more native power. 17 watts just was not going to cut it so I was probably going to need an amplifier for the regular speakers anyway, that is, if I wanted sound that wasn't totally distorted. I found this article which helped justify my thinking and then shifted to which one, what class, etc.

Because of the tiny size of the car, I narrowed my choices down to "class D" amplifiers. Between reviews on Azn, Crutchfield and anywhere else I could get reasonable feedback (blogs, Google, etc), I settled on the Picasso Nano PN5.640 (details from Crutchfield). This thing is tiny. It is so tiny, I can fit it inside the cockpit and hide it so the controls are within reach but it is out of sight... unless you look around for it. It sits 12 inches long by 5 inches wide by 2 inches deep (~300 x 125 x 45mm for everyone not in the US). One drawback is that it requires routing wires on both ends. I suppose it made the small footprint possible. Anyway, the inbound signals enters the front panel through 6-pin flat clips: one clip each for front / rear / sub for a total of 3. These clips can be routed through RCA cables to the pre-amp outputs or direct-wired into the speaker wire outputs from a stereo if you don't have a pre-amp.

front support from below

Locating
First, I wanted to find a mount location that was near the occupants so the levels could be easily adjusted. Also, I had already run lengths of speaker wire from the radio head unit to the various speakers, so putting the amp near the stereo would reduce the rework there. Last, I had some higher quality RCA cables, but they were each about a meter long so if I could use them I'd save probably $100US just in cabling.

Another consideration is human comfort. This car is small. There are not many spare inches available, especially on the driver side, so I went looking on the passenger side. With the seat adjusted so a passenger is reasonably reclined for a drive, with feet mostly extended (slight knee bend for comfort), I found that there was a reasonable amount of space under the glove box. If I crossed my ankles, so one knee was higher, there was still enough space to fit the amp without that knee bumping it. Anything more aggressive might, but this amp only adds a couple of inches... so, I chose to mount it under the glove box, off center towards the transmission tunnel.

Front Support

rear support with mock

To hold the end nearest the engine up, I re-used two bolts that pass through from the engine compartment. I test fit with cardboard templates or mocks for the amplifier and then for the supports I needed to make. I found a piece of flashing and shaped it to fit around the oil pressure hard line, fit the 2 bolts from above and have 2 small bolt holes for the "rear" panel of the amplifier. The 2 bolts required (as usual in this car) fine-thread nuts. I grabbed a pair of washers while I was at the hardware store getting that pair of nuts.

To mount the amp to the support, I threaded a pair of cabinet pull bolts through the support from above and then tightened nuts tightly against it. I passed the bolts through the "rear" slots on the amplifier and passed another pair of nuts onto the bolts. I intend to leave the support attached to the amplifier for any future maintenance, choosing instead to remove the nuts from the re-used engine compartment bolts instead, if I can. They are much easier to get to, and will need to come off when one of those bolts needs to come out for under bonnet service work around the sub-systems they were originally installed to support.

Rear Support

rear support from below

Holding the rear end or amp "front" is more of a patch-together solution than I'd intended. I removed the glove box and mapped out a plan that involved strips of steel mounted to the crossbar that runs under the glove box. I guess, ultimately, that is what I built. Reference the picture to the right and above. I started with 2 small angle supports and a pair of steel straps with holes in them. I marked off where I wanted the supports, using the cardboard amplifier model, and then drilled holes through from below. From above, I dropped 2 more cabinet pull bolts, but longer ones. Yes, I do have a lot of those bolts. I threaded on the one-bolt-per-side angles from below and then torqued down a nut per side. I took the 3-inch-long steel straps and bent the last inch 90* and attached one 2-inch end to each angle I had just bolted on. Last, I suspended another (you guessed it) cabinet pull bolt through the one hole in the 1-inch side of the bend strapping. I threaded on a nut and torqued it down. I then threaded on another pair of nuts, and then attached the "front" of the amp before adding a final pair of nuts. Why so many nuts this time? The extra pair of nuts allows for the "front" of the amp to adjust slightly up and down. Any more significant adjustment would be handled by shifting the straps up or down. This combination created a fair amount of adjustment.

rough install lit with flash

I left it like this and took a test drive. No, it wasn't hooked up. In fact, you can see from the picture to the right that I did not even bother to put the face plate back on the radio. This was the best test I could think of for making sure the amplifier mounting was viable. It held tightly; did not budge at all. Next, I climbed in to see how it felt to a passenger. While I'm not the biggest guy in the room, I am about the same size as my wife, who will be occupying that seat most. So, if it was okay for me, it would be okay for her. Check. Last, I asked Boo to come take a seat. She didn't even notice it until I pointed it out. She had to twist her neck a little bit to make out the knobs, so I think the location is perfect. Of course, there is not room for K2 to put his 40# backpack at his feet, but there really wasn't room for that backpack before. That will just need to ride in the trunk when he rides with me.

Like always, this got long, so I'll continue it next time with wiring and test firing. Thanks, as always, for following along-

New Seat, What a Treat - Headrests

This is the final installment of the seat reupholstering effort. I have stripped down, sanded, rust-treated and painted the original seat frames (in Part 1). Onto those frames, I have installed the seat webbing (Part 3), new hard-backs (Part 2), foams and covers (Parts 2 and 3). The seats have been installed back into the little car, with head rests, but I have not yet talked about that upholstery effort for those. I will cover that today.

Headrest Extraction

First, you need to separate the headrest from the seat. Obviously, but it's not that easy. With a convertible, moisture gets everywhere. In the Pacific Northwest, moisture gets everywhere. Add those together, and moisture truly gets everywhere. Even into the headrest tube, and enough of it to rust through chrome. My driver seat was easy, but I had to resort to these more drastic measures for the passenger seat: with the top down and the seat still bolted to the floor, stand behind the seat, place one hand on either side and lift as hard as you can. If you are lucky, it will come flying out, bang against the ceiling and not hit you in the head on the way down. If you are unlucky, you may just hurt your back, and the head rest is still stuck. Seriously, these buggers can be that stubborn. Use your best judgement, but it needs to come out to do the seats at all, so if you cannot get it free, forget about recovering your seats.

Old Cover Off
Once in hand, look at the underside of the headrest. There is a plastic strip that runs along the bottom which is held on with 2 Phillips head screws. Mine were really rusty (so I ultimately replaced them) so I needed to take care coaxing them out. If you keep yours, it may be worth soaking them in vinegar to get them rust-free Set the plastic strip aside for cleaning with dish soap and grab a thin slotted screw driver and a pair of needle-nose pliers. The plastic strip covers up staples which hold the cover on. With the screwdriver, work the staples free enough for you to grab with the needle-nose pliers and then pull the staples out. If you are not concerned about the old cover, you can tear the cover off and pull the staples afterwards. I prefer to not destroy things, but everyone is different.

With the staples out, the cover is only holding on through friction. Pull the cover and the foam off of the head rest stem. Do this whether you are reusing the foam or not. If it is original foam, I strongly encourage replacing it, though it can be hard to locate for some cars. I found the MGB headrest foams at Mirror Trim in the UK, and while the cost is a little high, it was worth not having the old foam disintegrate while installing.

Repair and Rust Treat
In my case, there was rust on the square metal head rest "head" as well as down near the bottom of the chrome post. The wood into which the staples were driven was shattered in the driver-side headrest (passenger side wood was in great shape). So, there was some repair and rust treatment needed. First, I taped off the top 3 inches of the chrome post with painters tape. This part of the post on both headrests was in decent shape, and I was opposed to painting them. Once taped, I sanded the "head" thoroughly and scuffed the rust off the chrome below the taped off section. I felt this chrome would not be seen, but needed to be clean for the head rest to work better. Then, I shot the "head" with some gloss-black Rustoleum and removed the tape. The wood strips in the driver head rest needed to be replaced, so I took one piece that was still intact and used it as a pattern. From my woodpile I found a strip of cabinet edging that was the right height and width, and cut two pieces to length. Before I started re-assembling, I cleaned the plastic strips with dish soap and found 4 Phillips head wood screws which would fit through the holes, sit flush once installed and were about the same length as the originals. I used "size 6" thickness, 3/4 inch long wood screws.

Re-Assemble

The headrest foam and cover are not uniform. Both are side specific (front and rear). The nicely tailored edge is on the edge from the front while the un-hemmed edge runs from the rear, and under the front, hemmed edge. The foam is thicker in the front than the rear, but that part is a little more obvious. Similar to stuffing a pillow into a pillowcase, stuff the foam into the cover, making sure that the corners are in the corners and the edges align with the edges. The foam is way bigger than the cover, so I used my thighs, arms, and abdomen to get the foam into the cover. Then, it was a considerable finger exercise to get everything aligned. Once set, though, you will see a slot in the foam for the "head" of the headrest to slide into. With the glossy paint, it slides right in. On the passenger head rest, I found I spent more time fiddling with the head rest post to get it at a depth I liked, but you may not have that issue, as I did not with the driver side. Shrug,

Staple and Screw
Before you grab your staple gun, I suggest that you take your nice and clean plastic strips and test fit them. Similar to the foams, the strips are not mirror-images, the rear side is thicker, but the distance from the post to the screw hole is the same on either side. So, consider where the screws will go, and then plan your staples. Remove the plastic strip, pull the rear flap forward, and under the front (hemmed) flap and hold it in place with your finger. I held it in place where the screw hole was so I would not lose track of it while stapling. Check that you are centering over the wood and place at least 1 staple on either side of the screw hole. There were 2 per side originally, so I did the same, making sure that the amount of stretch across the headrest was uniform as I did. There is a lot to keep track of in order to make it look good and lots of ways you can lose focus so it looks bad. Just do not staple until you are sure.

Once the staples are in, the hard part is over. Slide the plastic strip back into place and screw it to the "head" with rust-free screws. If you ever wanted one of those seat belt keepers (like these in the picture), now would be the time to install them. I do not like losing my seat belt, reaching around for it nor having it bang against the car when I take it off. These little plastic keepers really help, though getting access to a parcel stowed behind the seat is not as easy.

Re-Install
This should be straightforward. In my case, the seat foams were manufactured without holes for the head rests. Perhaps the seat foams were developed to span many years, including years without head rests. Regardless, If you did all-new foams like I did, you will need to find the rectangular hole with your fingers and cut the foam. Take care as you align the cover, the foam and the head rest post. Do not simply grab the chrome lip on the seat cover and push/pull. The chrome lip will easily separate from the cover if you do that. Once you find alignment, trim what little foam you need to and slide the head rest into the seat. I took an extra minute and applied some PB-Blaster brand white lithium grease to the post so it would move more freely in the future. I also applied this grease to the cleaned-to-the-steel seat rails and workings so the seat would slide forward and aft more easily. These little final touches really made a difference in the usability and perception of the seats once you were sitting down in them. I highly recommend taking the extra few minutes to apply the lithium grease.

So that's it. Over the course of about 2 days per seat, they are completely renewed. New foams, new webbing, new covers from top to bottom. The headrests are more functional, the seats tilt and move more freely. Most importantly, they are comfortable. Now that they are installed, I will either finish the wiring of the seat heat, put some effort into the amplifier for the speaker box or carpet the trunk. I will see how I feel when I get to the garage.

Thanks, as always, for following along.

Hapy B-Day to Me

So.. no real post this week since I'm celebrating my birthday with a once-in-a-lifetime / first-time-ever trip to Hawaii. I may post on what happened or not. Not really sure. As of right now, though, I'm in HI, enjoying the not-freezing (82*F daily high temps versus ~45*F daily high temps). Being thousands of miles from my projects, all I can really do is watch the waves.

I need to call out how grateful I am that Boo encouraged the idea, underwrote a large portion of it and really helped drive this, uh, home. It started with one of those internet /InstaFace things where you indicate the states you have visited. I realized that I had visited all but 3: Hawaii, Alaska and Louisiana. We decided the next big birthday (one that ends in either a 5 or a 0) we would knock one off the list. Hawaii in February sounds like a better idea than Alaska, so that was picked. I don't know which will be next. I guess it depends on how much it costs, and whether it is hurricane season (Boo b-day is in August) or winter again when we get to thinking about it.

When I consider how much money this trip is costing, it gives me pause. Normal people just can not afford to do this so it is no wonder that this is my first and probably only time. We have been saving since Summer (just saying we're normal people and that is how we managed to make this happen). For posterity, the cost breakdown is pretty severe, with an almost perfect balance of around $1200US each for flights, a condo rental and a rental car for a week for 2 people. The true math is more like $3500, and then I added my 2 boys (T and C) for another $1200 in flights. Costs for things like food and gas are much higher on the island too, so once I do the full accounting of just the grocery store and the gas station this will easily top $5k for a week in Hawaii. That is some serious scratch and that number just goes up when we think of places we went, lunches we grabbed, etc. This topic is way too heavy for this view so I am going to think about something else.... like drinks at sunset this evening... on the beach... in my flip-flops.

The money will solve and while it does we will dine at home. But that's for when we get back. I'll get back to the regular stuff next week. Enjoy this picture of the beach in the meantime...