ScoobyDoo555

The install is going well so far - I've still got the spare wheel (only got 16" ooer!!) in place. I've taken off the wingnut, and am replacing it with a 'normal' nut & bolt (another tool to put it the kit)

The 12" sub is mounted in an MDF floor. This floor dosen't have total floor coverage - about 7/8.

The problem is that the Scooby floorplan is SO uneven! Any ideas on how to 'level' it off?

I was going to use industrial velcro to fix the MDF floor to the car (enables access to the spare wheel).....

I'll post some more after I've put it all in :-)

Dan

ScoobyDoo555

Snow has beaten me back :-(

However, the amp and sub are in place, as is the power wiring (on the passenger side).

All I've got to say is, the 5dr is THE most ICE-install friendly car I have ever had :-)

Everythings gone in so easily. All that's left to do is:
1. Run the phono cable for the amp input.
2. Connect the remote cable to the stereo.
3. Connect the power to the battery.
4. Connect the earth to the body.
5. Screw the amp down.
6. Place on the speaker grille.
7. Tune it.
8. Further research into how to fix MDF floor to car.

Any comments? (Piccies will be posted soon)

Dan

RonaldoH

Sounds good

The MDF is a tough one. Your best bet is heavy duty velcro its strong but only use a little. Its proper strong.

Good luck, I know a little about stereos and installs should you need some advice

Ron

ScoobyDoo555

I've just got parts 1-4 completed (it's now dark & snowing)....

wow!! Sounds bloody great! :-)))

The wife heard it inside the house (thru double glazing!) oops! ;-)

Got to fix the amp and floor down tomorrow....

Dan

john banks

When I am doing ICE work I seem to attract bad weather, high winds, snow, rain etc. Today was no exception as I was putting ring terminals on my power leads - had some messy work before when done in a hurry - soldering iron just into full swing and then someone s*its a load of snow on me from nowhere. Retreated into the rear seat area with seats down and boot just open to get benefit of boot lights etc as darkness always descends like someone has set off a nuclear winter just when I get to the crucial bit! I have great sympathy with you Dan - we've got 6" snow here in Scotland! Not good ICE weather, but good ice, and I have missed the turbocharger for the last week - dying to try out these brakes/geom properly!

Perhaps I should get a garage next time I buy a house

ScoobyDoo555

Yeh we got about 4" here.... scary driving!!!My house came with a garage but because most architects these days must misplace the decimal point, the garage sizes are ridiculous!! I've built a great workbench in my garage for such jobs as you mention in your post - soldering station etc.... ONLY if the car isn't in there too. This garage is so tight that if I don't drive in properly, I've got to get out of the sunroof!!

My neighbour's got a 93WRX saloon that he REVERSES into his garage - fair play!!

The only shock yesterday with the install was when it came to putting the +ve lead onto the battery i.e disconnecting the alarm.

I thought that, yes, the alarm would go off when it was disconnected, but then go quiet whilst on battery backup..... WOW, it's loud!

Had to get wifey-type-person to man the key fob, "chriping" it every time whilst I put on the lead...... bloody thing - at least the theft thing works <grin> bet the neighbours were pissed off though. Reminds me of the first Xmas we moved in and the house alarm went off every half hour from Xmas Eve to Boxing day.....not faulty - the decorations set off the passive in the lounge!!! Cost a lot in apologies and bottles of wine!!!!

ScoobyDoo555

For piccies of the install so far, try this link:-

john banks

Dan, looks good. Are you velcroing the underside of the MDF and the top of the metal boot floor?

Edited cos I was going to say the piccies don't seem to load properly, but given enough time they do, but the IE globe had stopped spinning which made me think the page was fully loaded.

[This message has been edited by john banks (edited 29 December 2000).]

ScoobyDoo555

John wrote:<Are you velcroing the underside of the MDF and the top of the metal boot floor?>

Yep, that was the general idea, unless anyone has got any better suggestions?

Just need some time now to fine tune it all - preferably when nobody else is in (too much bass, heheh!!)

Dan

john banks

Yeah, it's a nightmare setting up your levels to the point of distortion and turning back a bit. I just leave my input sensitivities on max and can tolerate the head unit up to about 20/35 on a dynamic piece, although I don't think it distorts there - just damn loud - slightly less power than your system I think - 450W RMS total from amps and whatever the headunit does for rear fill - prob 25W total. Hopefully yours will be "Loud 'n' clear" once you've finished with it!

chiark

Could you put a bolt through the floor coming from the bottom of the boot to secure the box? Attach a bit of the box with wingnuts.

You *really* don't want to see the mess a sub box can make of the back and front seats when involved in an accident if it isn't secured properly... You may be OK as it's only a sub and sheet of mdf, but I'd really really look at a bolt of some sorts.

ScoobyDoo555

Hey Chiark!
Where would you recommend bolting the board?

There are 2 'holes' right by the bootlock mechanism - I've cut the board to fit over them. What about the front bit? Obviously, underneath the front board is the petrol tank - I won't be doing too much drilling there!!!

The front bit was where I was going to velcro - just to hold it down. The bolts at the back will really secure it....

Waddya think?

Dan

BTW HAPPY NEW YEAR!!!!!!

:-))

chiark

Dan,

As long as it's bolted in some way, it should be fine. Give it a sanity check that you've left enough wood around the bolting point so that it wouldn't just tear if the worst happened and you'll be happy.

Happy new year to all. Hope everyone had a good 'un.

Nick.

kryten

john, the levels on the amp should be set at the minimum possible to give an acceptable volume.

ideally, you'd probably want to be listening at 30/35 on the head unit: this gives you a bigger voltage going down the RCAs to the boot meaning an improved signal/noise ratio.

It also means your amps won't be working quite so hard and will run a bit cooler...

kryten

Dan, I think you may have misunderstood the idea of a 'free air' sub. Its true that it doesn't need an enclosure as such - the cone suspension doesn't need the help that an enclosure provides BUT:

If you don't seal the back of the sub from the front you'll loose output.

To make the sub work to its best you will need to seal (totally airtight if possible) that MDF floor so that NO air escapes from underneath it to cancel the output from the front of the sub. Otherwise you'll get all sorts of wierd cancellation.

You may find that the MDF sits tight enough to the floor for this not to be a problem, though as you've pointed out the boot floor isn't exacly even.

See if you can feel air escaping from around the edges of the MDF on a bassy track (a small candle, just blown out to produce smoke is also a good detector - just mind the fuel tank!).

I doubt you'll get a total seal and keep it removeable, but adding layers of the foam door insulator around the uneven bits may help

ScoobyDoo555

Hi Kryten :-)
Thanks for the info, but I'm not convinced about the 'free-air' explanation.

What you're explaining about the rear of the sub having to be air-tight, only applies if the you are building an 'infinite baffle' enclosure. i.e a loudspeaker enclosure.

From my limited research, albeit somewhat limited (I'll put my hands up!!), the free-air sub is designed to be a 'baffle/doublet' arrangement, thus the need for an air-tight rear (oo,er) is redundant......

The aim of a Free-air sub, is that the cushion of air acheived from having a air-tight enclosure, is not required....

This is also what the Hi-Fi guy told me when I bought it.

HOWEVER, I'm open to suggestions as to why this is wrong, as I have no wish to damage my Chrimbo prezzie!! :-)

Agreed though, the floor should be as flat as poss, so how about lining the base of the floor with rockwool? should also get rid unwanted noise.....

Eagerly awaiting response :-)

Dan

john banks

Kryten - the problem with setting the amp level for 90%ish as textbook is that I then have no headroom for quiet tracks or classical stuff - I have no detectable noise anyway apart from that on the actual recordings - none at max volume if CD paused - and the amps run cool.

Dan - how about a thick, wide, well-glued piece of foam on the underside of the MDF - circular shape - that pushes against the rubber of the spare tyre - would this give you a reasonable seal - if that's what you want?

ScoobyDoo555

Good point - hadn't thought of that :-)

Might give it a try, but 'technically' the sub shouldn't need it......


Might do some experiements this weekend...

Cheers

Dan

kryten

You're right in the fact that free-air mounting doesn't require an enclosure to aid the sub's suspension BUT you still need to ensure the back and front are isolated.

The ideal free-air installation is a speaker mounted on a baffle that is infinitely high and infinitely wide: that way the output from the rear of the speaker cannot interfere with the output from the front of the speaker.

As the rear/front output is 180deg out of phase you'll get significant cancellation if they are not isolated.

If you place a speaker on the floor with no baffle and connect it up you'll get almost no bass at all: its all cancelled out.

Put a small baffle on and you'll get a bit more bass, but when you seal front from rear there is no cancellation so the speaker works efficiently.

This shouldn't damage the speaker _assuming_ it really IS designed for infinite baffle mounting: what make/model is it?? (Given the HiFi guy got the info wrong, its worth checking!)

See

ScoobyDoo555

Nice one Kryten :-)

I'll have a look at the weekend - won't be able to make Dono - the wife's birthday......


Cheers guys!

Dan

kryten

Something I should have thought of before:

The spare wheel well really doesn't have much air space.

Assuming you get some sort of seal (even if it isn't 100%), it will perform more like a sealed box, than free air mounting.

I looked at putting a sub in there and reckon there isn't much more than 1.8 cu/ft of space if you remove the wheel. With the spare in place I doubt there's much more than 1.2cu/ft so it may be worth trying to change the sub for one that works in a sealed box of 1 to 1.5 cu/ft

Free air subs don't work at their best in a box as they are designed to have lots of air behind them eg an entire boot's worth if you're mounting on a rear shelf.

If you let me have the make/model of sub (with TS parameters if you have them) then we can take a look at the probable response plot....

Wife's birthday: guess we'll let you off then!

ScoobyDoo555

Hi Kryten,
The sub's a Kenwood KFC-303 12"....

What are the TS parameters?

I'll try a mate's 'normal' sub too.... in all fairness it shouldn't make THAT much difference - you'll probably get a better bass response compared to the Free-Air, but at the expense of durablilty (what with most drivers requiring an air-tight box.....

Turning into quite an interesting topic this:-)

Dan

chiark

Dan,

I don't think turning it upside down would help at all, as you're effectively using the same suspension for the driver but just changing the phase.

The proof of the pudding is in the eating. If it sounds good, don't worry about it .

No need to think about taking it back or looking for something else if you're happy, and if it was a pressie then it is of course so much the better.

ScoobyDoo555

I see what you're getting at now. I know what the TS parameters are (knew them as Theile Small), but never even thought to use 'em!

Yeh, agreed, the sub would be much better being mounted on the back of the seat, but it ain't gonna happen :-(
The sub was a Christmas present, and therefore can't be taken back now (no receipt!)
The only consolation is that it DOES sound good :-)
I'm sure you're not disputing that fact, but with the right environment, it COULD sound better...

The other option is to turn the sub upside down and mount it in the spare wheel - you'll still get all the boot air-space :-)))

Might be worth looking at...

<grin>

Dan

kryten

The Theile-Small (TS) parameters are what defines the characteristics of a speaker. From these, you can accurately model the response of a given speaker in a given enclosure.

You may have got a spec sheet with the sub detailing these. From a quick search on the net what I've found for it are:

Vas=62.5, Qts=0.28, Fs=37

Don't worry about what they mean for now.

If you go to the following page:

kryten

Dan, glad your happy with it. Of course, if your music tastes happen to include music that benefits from more oomph at 60-120hz then it works for you!

As chiark says, no point turning it upside down as it would just reverse the phasing.

Glad its all working: got any pics of the finished install?

All this reminds me I must get my kit installed soon.....