18" Audiobahn Subwoofer + Custom ported Box!

6 years 6 months ago #1 by Andy
A customer of mine purchased an Audiobahn 18" subwoofer from my shop, it had been sitting on the back room for years, so we did it cheap ;)

Specs are kinda hard to come across, but basically its got dual 4 ohm 4" coils, with a combined power handling of 600wrms.

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The vehicle is going in is a Hyundai Accent hatchback, with the rear seats removed. The box i designed is 5.8 cu.ft. after sub and port displacement, on the larger side but those who know me know i like to build em big :laugh:

So here's the final result, only 16mm thick but have added bracing inside......if i find its flexing too much i'll add another layer to the baffle.

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Ports are 200mm deep with a tuning of 48hz, so about 52-53 in-car (SPL). Once he plugs one of the ports up with a towel etc the tuning comes down to 37hz, so about 41-42 in-car (musical) . Box will be firing up, but i'll do some testing on the TL in his car and get the best configuration.

He's only got about 1000wrms on tap, maybe a touch more......im hoping for mid to high 140s, possibly 147s.....with such a large sub and not alot of power im abit skeptical on DBs, should go hard with music though :rock:
6 years 6 months ago #2 by Tezzating
Thats a pretty box man, looks like the sort of box I used to make :P

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6 years 6 months ago #3 by zion187reigneth
I like the box aswell
6 years 6 months ago - 6 years 6 months ago #4 by Andy
Thanks guys, see how different a customer's box comes out compared my own personal boxes. The sub sits off to one side mainly to keep as much "meat" as possible on the baffle, i always knew it was gonna be like Swiss cheese :whistle:

Wonder where i learnt my box building skills Steve? :lol:

Took it for a quick listen in my car tonight, sub is still very tight but it sounds promising, definitely gets low and loud already.
6 years 6 months ago #5 by Tezzating
Those old 18"s get amazingly loud with not a lot of power. I remember being beaten once by a guy running an 18 in a Civic and 500WRMS. I had the three Magma's and a D2 ! haha. It might surprise you once its in the customers hatchback.

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6 years 6 months ago #6 by amcinstaller
yea, that box does look nice. i remember when those subs came out around here. i dont think i was even driving yet :laugh: but i wanted one sooo bad
6 years 6 months ago - 6 years 6 months ago #7 by Andy
Whacked it in the customers car today......damn its loud, he's only got 600wrms but its easily 140s at the moment, apparently he has a Soundstream mono coming, about 2,000wrms. Should be interesting anyway.

He's got this idea of running 2 x 12s sealed as well, hopefully i can get it working ok by applying a low-range high pass filter (or high-range sub sonic) around the 60hz mark, idea is the 18 plays below 60hz whilst the 12s play 60-120hz or so.....dont know if its gonna sound like ass or not, never used 12s for a "low midbass" application before, its either going to fail or win :laugh:

Hmm, wonder how old this sub really is then? Just the hour i spent listening to it on the way to work this morning has loosened it up alot, hopefully he dosent fry it before its fully worn in :unsure:
6 years 6 months ago #8 by zion187reigneth
I reakon the owners better going for some light weight 10".

I did the whole big midbass thing in Goriila nuts1. Although the output of 10"+ woofers was great i found that box size and extra filters,amps etc just made to many variable, and infact the only time i got close to SQ was when i would independently turn the volume down on my bandpass big Mids.

Thats when i found 3 way fronts to be the ultimate, and i didn't skimp much as i had a 9" ;P

The last time i was planning something like what your client wants , i came up with the idea of using the rear passenger foot-wells with fiberglass bottoms and steel grills, it was for my mates commodore, but i was looking at some mid spec 8".
6 years 6 months ago #9 by Andy
Hmm interesting Zion,

To be honest, the guy isnt completely there if you get me......im working with him (and his ideas) to create a system so wont fry gear (he's blown countless subs and amps). This guy is more about pure volume, almost ear bleeding stuff.......if i mentioned sound quality to him he wouldnt have a clue :whistle:

He's dead set on running 2 x 12s somewhere in the rear, there's still plenty of room in there so i reckon two small sealed boxes (0.7-0.8 cu.ft. each) probably firing forward into the front seats i suppose, should give him a nice tight kick.....something the 18 "should" lack once its worn in, at the moment it sounds more like a 10, seriously my Pioneer 12 sounds more like the 18! haha.
6 years 6 months ago #10 by amcinstaller
oooOOOOooooohhhhhh, one of THOSE guys. :lol: had a few of those through the shops ive been in too. they saw some guys system that had like 4 different sizes of subs and theyre dead set on having it. yea, youre probly right on the plan with the crossovers, id almost be tempted to let the 12s play to 50 and the 18 play 50 and down though, but if itll work better and the 18 wont get too sloppy, take it to 60
6 years 6 months ago #11 by Tezzating
I can appreciate the idea.. I bet he thinks going from the 18" down to 6"s will leave a frequency gap. He might be right, but only an RTA can tell us whats happening there. Fitting yet more subs to cover the gap probably wont help, just make the sub bass peakier and not help the mid range bass spectrum.
If you could subsonic the 18" at 30hz and lowpass 70hz, then use a 12" woofer thats most efficient between 80hz and 150hz, and band pass it there, then step up to 6" then OK you might find some more SQ.

But by the time you're done with the aggro you could have just spent the extra money on a good front end which isnt lacking between 80 & 150hz :P

Or, you could throw in the 12"s and just make some money off him.

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6 years 6 months ago - 6 years 6 months ago #12 by zion187reigneth
And just to keep the discussion going :P

I always found rear mid bass to be detrimental to the sound envelope(SQ again sorry guys :P )
But i can see a visual of this guy and theres not much else to do but slap in a couple of 12" :beer:

Although ccss i know you still have the SQ touch. Does your shop have a set of custom sealed boxes with 8-6.5"
The idea being that the shop has a set of small boxes made for some mid spec 8" or nice 6.5" woofers. You tap into the rca, add a 2ch amp with remote volume/ HP fliter.
The shop owns a nice little extra crossover box and using the LP filter you bandpass to whatever you want.

The goal is to tempt shop surfers into custom front installations of your choice, but to do that you need to prove that midbass and subbass transition from the front is very desirable, and in fact its treasured.

So the shop has some boxes made up for the floor , the 2ch amp, crossover and jumper cables for all connections.It takes less that 10 minutes to set it up in the shop surfers car.You play his music and without changing any of his system , you tune in the required band pass range to produce the dramatic effect needed.In 20 minutes you have not only proven to the guy that you know your stuff , but i guarantee that this shop surfer will always come back and as you know, when you have someone in front of you in the shop there's a opportunity coming :P

The boxes are to big and bulky to drive around so your not trying to sell a 3 way custom install , but your created proof that you know what the car is lacking and you can create the same effect by using a set of 6.5". This setup will work on almost everyone who does not have nice 6.5 with good designed door installs.
6 years 6 months ago #13 by zion187reigneth
But wait theres more :P

You hire a couple of school kids friday afternoons and you attach subwoofers to the heads and give them a shop Tshirt each.

You send them into the city and knowing the by-laws your students are not allowed to hand out flyers , but if talking to by standers they can offer the flyer as information if the by stander agrees..
The students only need to say as they go along the street "Custom Car shop knows that Sound quality and SPL is achievable in your car, would you like to hear more"The student offers the flyer with all relevant info and keeps walking.
6 years 6 months ago #14 by zion187reigneth
but still theres more :P

owwww im bored :whistle:
6 years 6 months ago #15 by Andy
Hmm, youve got a few points there Zion.....unfortunately 99% of customers that walk into our shop are just after a $100 set of 6.5" 3 ways, sometimes they can be convinced to go with splits, but never top end stuff.

As im the fitter and im backed up with 2-3 weeks of work, i cant really spend alot of time with potential customers. I do have a very, very good salesman that has a alot of understanding when it comes to the installation side of things, which makes things easier. But yeah, i still like to get out and have a chat with the 1% of customers who are serious about their audio......im still yet to build a nice SPL system, just goes to show how popular SPL and big bass really is i suppose.
6 years 6 months ago #16 by amcinstaller
yea, big time spl does seem to be on a bit of a decline here too.
6 years 6 months ago #17 by zion187reigneth

C.C.S.S. wrote: ...unfortunately 99% of customers that walk into our shop are just after a $100 set of 6.5" 3 ways, sometimes they can be convinced to go with splits, but never top end stuff.

I hear ya, but a huge convincing part of the audio bug is to hear the before and after effect, this leads to further mods.The only part of car audio that could almost always be guaranteed in any car is the lack of quality midbass/subbass transitions from the front, i and all of the SQ competitors spend all there time looking for it.
When a shop surfer hears it in a demo car it doesn't mean much , when they hear it on the board it doesnt mean much,when they hear it in there own car at the flick of a switch they take notice.
I would not say it is for all shop surfers , but i think 30% of them will end up buying an extra amp, nice splits from somewhere in the following years.And i know theres atleast 10% of the monthly surfers that a salesman would identify as having buying potential.

When you mentioned that you are working with this guys ideas i remembered that there is a way to show him without having to explain it, a shop could use these tools to provide an experience that supersedes the big board retailers.
6 years 6 months ago #18 by pronuts
Big board retailers you mention zion?
Having the same attitude about Home audio sales i remember many years ago a smaller shop offered to come around to my place and set up the unit that we had been discussing about purchasing.
These guys know there Home Audio and could guarantee that the experience was going to leave me with a positive feeling.
Much like what your explaining i guess.
6 years 6 months ago - 6 years 6 months ago #19 by zion187reigneth

amcinstaller wrote: oooOOOOooooohhhhhh, one of THOSE guys. :lol: had a few of those through the shops ive been in too. they saw some guys system that had like 4 different sizes of subs and theyre dead set on having it. yea, youre probly right on the plan with the crossovers, id almost be tempted to let the 12s play to 50 and the 18 play 50 and down though, but if itll work better and the 18 wont get too sloppy, take it to 60


I figured the same approach and its do-able. Although the pain of it is the resources put into maybe 40hz of bandpass.Even when trying to bandpass to 90hz LP, the kick is from the back and this part of the system is now considered maxed out, maybe with great woofers and box design you could get a linear 50~120hz, but again thats the limits as its from the rear. Plus again i always thought 24db crossovers made the sound transition from the bigger sub a bonus.12db didnt seem steep enough and caused some peaky glitches.TA created the uniform kick effect i needed to blend the higher hz from 6" fronts to the bigger rear mounted midsubs

The 2 size sub setup was only appreciated when i had the digital processor wired in, but man that was alot of $ and hardware to keep that system in check.
I think a better sound can come from high quality sub and amp combo, something with 24bd crossover, 1band variable EQ, and as mentioned many times box design tune time.
6 years 6 months ago #20 by Tezzating
I'd bet the response curve for that 18" shows it peaks around 50-60hz cos thats what the kids want and has some retarded Vas to ensure its nice and peaky.. if the things infact around 10 years old, that'd be the norm for a speaker of that vintage. I swear old subs were just PA speakers with a lower impedence.

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