Suitcase Sub...

[Dangermouse]

I have a small suitcase which is shaped to fit the rear luggage compartment of a Beetle; I am considering converting it into a subwoofer box for maybe a 10" speaker. How would I best go about this? It's constructed of a quite light cardboard like material; would I have to make it completely rigid inside with MDF or would it be sufficient to completely line it on the inside with some kind of acoustic deadening material?

[sideshow]

A speaker box tends to be fairly rigid, how about making an inside shell from fiberglass? That way you can have a nice MDF mounting point and use the case as a grill.

[volkdent]

Put Dynamat or similar over all the other interior surfaces of the case besides the speaker mounting surface. Cut the mounting hole in 3/4" MDF then laminate it to the speaker surface from the inside using fiberglass resin and filler material powder(get it from TAP plastics, it makes the resin fluffy so it is very viscous) . Let that set up till it's very tacky, then close the case and start building up layers of mat, letting each cure as you go. When its over 1/4" thick you could consider stopping. When you wrap it with your knuckles it should thud, not ring at all. Then fill it full of water if you can to make sure there is no leaks, or kitty litter or sand to measure the volume, that will be your total interior volume. You then can select a speaker that is suited to that volume. Drill a hole and seal in your speaker wire with silicone. I would probably add fiber fill(pillow filling material) before you install the speaker. Make sure it's sealed well and your rockin.

Jason

[Soul]

There was a real cool one on another forum a while back.

http://forums.vwvortex.com/zerothread?id=4366550

[Dangermouse]

Well, in the end I opted to go for an 8" sub as I thought a 10" in a beetle was just silly. I got a JBL GTO804 and built a sealed enclosure to suit out of MDF... My woodworking skills are pretty rudimentary at best but the volume is close to spec and it's all caulked up internally so should be pretty airtight.





Planning to use it with a (6V!!! ) 600W amplifier and a pair of three way speakers in kickpanels up front.



I think it turned out pretty well; hope it sounds good

[volksbugly]

2 years later I reply.. sweet setup... you still running it? how did it end up sounding? anything you would change?

Personally I would have mounted the sub directly in the box.. secured the box to the suitcase, cut the hole for the sub like you did in the suit case, then build a nice speaker grill into the suitcase.
using something like this
guitar amp speaker grill cloth




you could still do that
Cheers,
Bugly

[Dangermouse]

Yep, still running it. It sounds great; nice and punchy. I'm really surprised how good the acoustics can be inside the cabin of a beetle. Quite interesting when the floorpans and pedals pick up the vibration and you can feel the bass through your foot...

Appreciate the suggestion about the grill cloth but as the speaker is hidden from view and well protected behind the back seat, I'll leave it as is. I did consider adding a rigid grill over the front of the speaker for protection but never got around to it in the end. Here are some pics of the finished sound system I added a volume control knob and power toggle to the amp, as well as foglight and fanfare horn switches, to an accessory switch box underneath the dash

[Dangermouse]

Some time later…

Been using and abusing this stereo setup for some time now and it’s been all good. But this week I find myself in need of another switch (to control an accessory fan) and out of switch position options. At present, the stereo amplifier is controlled by two switches, an on/off toggle (power) switch and the line level (volume) controller in the middle. It seems to me that I could free up the power toggle switch position if the volume controller included on/off switching in the old rotary style. This seems more elegant to me anyhow.

I’m thinking that this might be done using a dual gang potentiometer (which I’m pretty sure is all that is actually inside that LC-1 box anyway) incorporating on/off power switching to the amplifier and a pair of dismembered RCA Y-cables, largely as described at http://www.mobilesoundscience.com/f13/d ... -bucks-49/



Finding a dual gang pot with on/off switching locally is proving surprisingly problematic but I did find these on eBay which look like they might fit the bill -



Any electronics wizards able to comment on whether this might be suitable for what I’m suggesting or suggest appropriate alternatives? Linear or log taper on the pot? 10K, 50K, 100K?

[volksbugly]

Not sure about what your doing specifically, but I am also not sure why you have a switch. Your head unit, or ignition wire can turn your amp off and on. You can also use that to power a fan via a relay. If your wanting to control the speed of the fan use PWM.
http://www.dalewheat.com/store/

sells a very cool PWM dimmer. I personally have bought about 40 of them. I use them for all kinds of projects.

[Steve Arndt]

Test your old pot with an ohm meter. That way you know if it is linear or log taper.
What amount of current does the switch need to handle?

[Rodek]

What great setup! I was at my local audio shop the other day....I was shopping around for a small footprint amplifier that was fairly light weight and provided decent output power. I chose a Sony amp as well. Is the XM-GS400. Nice 4 channel amp that provides 70 x 4 RMS. Its bridgeable and surprisingly fan cooled...or shall I say "air cooled". LOL! When it comes time to upgrade your amp, I can say that it sounds great on a pair of Pioneer 6.5's on the front channels and a 12" Rockford Prime R2 sub in a sealed enclosure.

[Dangermouse]

Not sure about what your doing specifically, but I am also not sure why you have a switch. Your head unit, or ignition wire can turn your amp off and on. You can also use that to power a fan via a relay. If your wanting to control the speed of the fan use PWM.
http://www.dalewheat.com/store/

sells a very cool PWM dimmer. I personally have bought about 40 of them. I use them for all kinds of projects.

I wanted it switchable because it's all running on a 6V system and I wanted to retain control over all of my millivolts I didn't want it on all of the time as it does draw a tiny bit of power even on standby. As for the fan, it's just there to waft cool air up my shorts in summer so also needed to be independently switchable (via a relay).



It all worked out nicely in the end I got the pot and got it all soldered up and installed; works a treat (for the record it's a 10K stereo audio log cmoy metal shaft dual gang potentiometer switch)





Of course now I need to find a spot for yet another switch, a 6V booster fan I want to plumb into the heater system to act as a windscreen defroster on cold winter mornings. Hmmm...