True - true, as with all things there's always somehow to spend extra (18 laminate ply over 13, speakon over banana, t-nuts over screws, vinyl over paint, etc etc)
I've always really want to do an fg enclosure for one of my portable systems - but have never got round to it.
Postage would be a bit of an arse! I'd happily design one for you Nick - (design to order, shopping list, cutting sheet, assembly explanations etc) - just make sure whatever sub you do buy has readily available t/s parameters...



NB
Oh, and (back) on the subject of 6x9"s, I just remembered I have a pair of near-new JBL GTO 937 doing utter nothing in my equipment collection... if (or anyone else) is interested?

Have we forgotten that Nick drives? It's only an hour & a bit away



Classified forums? (you know the ones that people asked for then never use )

Thanks! What would be the charge? What I might do, if it's okay with you of course, is to have a go myself and ask you to cast an eye over it?



Perhaps okenobi might be keen?

That's spot on advice - but best to always ramp the amp down just a tad lower and do the test with the loudest recording you have - because you never really know (until it's too late) the dynamic range of every track you'll ever listen to...

It should be fine - a protection circuit will just cut power output and leave the unit in standby until a reset - they're pretty damn responsive so nothing to fret about - but something I thought you had best be aware of....

91db is v.good and the JBL's well serve you well - but for reasons stated I thought it best to keep trying to steer you towards components!

Don't worry about trying to achieve super-aural harmonics with over-blown claims of 25KHz upper limits - you won't notice them in a car environment.... and 65Hz is fine for low-end reach, cabin & door gain will add extra depth to them, but as you can probably guess, it won't reach to the scary wobbles of DnB & Dubstep - you'll get the "loud" bass - but not the bowel-unsettling back massage.... but then that's what the sub is for!


Good news! And remember - so long as the joinery is sealed airtight (no-more-nails etc) then carpet will hide all multitude of beginner-carpenter handywork!

Both true - but the latter is more a result of people using the generic off-the-shelf boxes and/or not heeding installation instructions correctly - but the best thing about DIY is that there's no harm building a ported one day, swapping out the driver and seeing how it changes your setup (this is where the SPL boys seem to get their kicks, extracting every last decibel out of variations in port length, internal finish, flared port mouths, flared port entries, adjustable port blockers, etc etc)

EDIT #01
No charge for a box design dude - seriously - especially not for a sealed enclosure! Remember, I play with 3D modelling ALLLLL day - it's fun for me! Of course, were you asking for the design of a multi-driver 6th order bandpass with finite volume restrictions and a desired SPL score then yes, then you'd be digging into your pocket... But sure thing, have a pop yourself and post it up here....

EDIT #02

Touche! But then I can't say I'm fond of the 1 week demise on the threads.

Touche! But then I can't say I'm fond of the 1 week demise on the threads. [/quote]

They only die if nobody posts anything, a bump would keep it alive. I can extend it but I wasn't sure how much traffic it'd get

Ok, well 6x9s are the best solution alongside 13s, but if you can't handle that, I might have to change tack and back Snowy on the call for comps

As for the Dynamat, you can get away with this for now:
http://www.caraudiodirect.co.uk/second-skin-damplifier-pack.html

It's not loads of it, but it's cheap and will easily do something for the place where you mount your coaxials (or mids ) The Damplifier Pro stuff is well regarded. It's not Dynamat Xtreme (which I swear by), but it's supposedly not far off. TBH though anything's better than nothing. Fair enough to leave the door skins and additionals for an upgrade, but I strongly urge you to put something around your speakers, you absolutely will not regret it.

Again I'll second Snowy on the JBL recommendation. 91db is good and they'll give you a very reasonable sound. As a side note, a friend of mine asked me about her EJ9 Civic last year and I recommended 16.5cm JBL comps. She bought those, some Dynamat, and that's it. Off a cheap JVC HU, it sounded (and still does) very, very good. That wasn't quite as much Dynamat as my Golf, but the Octy has less than that slightly as it's a more solid car.

Veato, please look into the Genesis 6x9 subs, that I posted about earlier in the thread. They're specifically designed to work in a decent MDF shelf without an enclosure and would be great partners to good comps up front. And yes, you really should sort the crossovers! The pic I posted earlier shows where I stashed mine in the Golf. In behind the kick panel. I just wrapped them in bubblewrap and stuff them in there!



The central panel here, you can barely see the bulge

Oh, and Nick, I don't need 6x9s thanks, I'm perfectly happy with my setup
I'll post some pics tomorrow if I get time...

Why don't home audio makers use the 6x9 format?

Elliptical drivers have been used in the hifi world before, Kef used them in some of the floorstanders of their Q range and B&W used them in both their 600 & P series (both mid 90's) - as for the whole co-axial thing, it was championed (and never bettered) by Tannoy in the 70's (continuing until the early 90's) & Kef tried to revived them in their Uni-Q range (which recieved great critcial success) in the mid-90's and still use them today in both their midrange hifi range and extensively in their professional range for home installs... and Cabasse are still making their monstrously exotic speaker using the same principle of aligned-drivers.... (there may be more)

The thing is "point source" doesn't sell to the masses; people still like the whole multi-driver appearance of speakers, that (and I guess more importantly) the R&D into singular components pays off more in terms of scaleability over these kind of hybrid units...

Right then. I've started thinking about the box.

I've been using this .pdf to get the figures. So far the only one I've used is the Vas which is the volume that the box needs to be, right?

The thing that's confusing me though, is that diagram in the .pdf for a sealed box gives the volume of the box including the driver displacement at 1cubic foot. Is this because the woofer will 'work' on an equal amount of air outside of the box too??

If so, then according to this tool a 13x14x14 (external measurements with 0.75" MDF) box will give just under a cubic foot, accounting for displacement.

Is it really as simple as that?

Those look pretty cool. My car takes 6x9s and in my last car, I had some Pioneer three way 6x9s and a Pioneer amp. I have the speakers in my current car, which is the same (but different engine), but haven't got round to installing the amp yet as it's such a PITA. When I finally get round to it, would I be better off having 6x9 subs like those you mentioned or normal ones?

The Gennys are superb and will offer you a cleaner, lower delivery and will also likely handle more power. That said, it really depends what you want them for. 6x9s make brilliant drivers, because of the surface area on offer for LF and mid and the fact that, as Snowy's been talking about, they are a "point source" driver. If I were to use them in a non-sub system, I'd probably high pass them at around 63-80hz and maybe fade them down a little. On the cheap they can't be beat. With more money, they obviously can. It's personal taste though really. Some people will straight away give it the whole imaging argument, and technically they're right. But on a budget, that falls down the priority list.

In your case, if you have decent comps up front and a four channel amp, I'd be tempted to run the Gennys and then you'll get imaging from the front and just plenty of weight from your shelf. Make sure you use at least 18mm MDF though.


Nick, I'm sorry, but I'm stumped at this point. I've always gone to a pro to custom make me a box.

Well, it's just a two channel amp, using the head unit to power the front speakers. I might consider a separate amp for the front, but wiring amps is such a PITA. It's a saloon as well, so no need for the MDF. The huge enclosure that is the boot is one of the reasons I thought it might be quite a good idea. However, I don't know if the metal of the parcel shelf would be too thin.

I would still make up some MDF to back the shelf. I don't know your car, but most of them tend to be a couple of mm at best and full of holes. Either 6x9 solution will benefit massively from solid, non-metallic backing.

If the fronts are 6" comps and not 5s I would amp them first and see what that sounds like. That said, if you cba with the amp (and I completely understand). Just put your existing x9s in and be happy

As have I!


The red & blue plots are as close I could get to the JBL-enclosures for sealed & ported; the orange & cyan are my variations on the same...

There's very little you can do with a sealed box to tweak it - their relationship with the driver is quite exacting - but note with a bit more enclosure volume you can drop the fs and increase the bottom output, whilst maintaining the steady curve (remember a flat line is best - although somewhat impossible) and by staying within safe excursion limits.

As for the ported box - the JBL design models with a bit of "peak" @50Hz which I have attempted to smooth out (at the expense of out-and-out output - reducing the dreaded "one note wonder" affect) in favour of lowering the fs and increasing the bottom-end output slightly... I've also used a different port design (slot rather than port) which would require a bit more carpentry - but note how it's lowered the vent speed considerably (the audible sound of air "chuffing" at port mouths)

I'm happy to model any of these for you - some dims from the boot (depth, height, width, angle of rear seat incline, etc) would help mind.

Wow thanks for that snowy!

I've now got myself sorted, amp wise. I'll be running two amps, which means that the sub will have it's very own power source - A Kenwood KAC-6201. I don't know if this will effect the box at all, but I suspect it may do - looking at your screenshot you have an input power figure of 250Watts, this amp will only pump 150Watts.

Thanks for taking the time to model those boxes for me!

There is one thing I don't quite understand though. Everything I've read has said that a ported box is better. But looking at those graphs, I can't see how??? Is it the cone displacement that is good?

The NAR graph seems to show that the ported is louder between about 30 and 100, but does that make it better?

I think it would definitely be best if you did model a box for me. Seeing those graphs has shown me that I really don't know what I'm doing!

I'll PM you some dimensions later.

Also, when it comes to cable, what do I need to know? I know they shouldn't be skimped on, and 10% of the budget is a figure I've heard before.

I've been looking at some wiring kits. Some of them (like this one [clicky]) look really cheap and nasty. I mean, a tenner for all that - it's got to be crap stuff!! There are others of course, but it seems quite hard to know what you are actually getting.