sparky3

Which do you guys prefer for accurate bass? Which seems to cause less car vibration (all things being equal). I have a 6th order bandpass box that the local stereo shop built for me. It sucks for SQ, but pounds like hell at certain frequencies.


My sub setup (will be this weekend)

2 12" Eclipse 88120 DVC's, with a JL Audio 500/1 on EACH sub. Sealed enclosure, with 1.35 cubic ft. air space per 12".

Thoughts?

Shawn

Mean Gene

Shawn - I've played with my sub box placement & direction & here's what I've come up with. The best SQ seems to occur with the subs firing upwards thru the rear deck ( providing that U open up that area so that there's a clean shot into the cabin - eliminates cancellation as well ). The loudest was EASILY firing into the trunk - kinda like an untuned bandpass with the bass wave being filtered thru the open deck area. Unfortunately, it was also the most rattling design & my trunk's heavily Dynamatted! Didn't get much from the subs facing forward - had I removed the piece of leather behind the center armrest I'm sure things would've sounded better. I've seen/done 2 BMW's where I fired dual 12's thru their ski hole ( wedge shaped box ) & it was pretty boomy. Just experiment with your BP box & see what pleases YOUR musical tastes.

sparky3

Mene Gene-

What subs do you have, and how much power? Is your box sealed?
I have a sealed box on the way (5/8 MDF, 1.35 cu ft per side). If the guy who I bought it from measured correctly, I should be able to face it up, backwards or forwards. Backwards is out.

What type of music do you listen to? I think I want more of a rock & roll box that anything else.

Thanks for your replies.

Shawn

RON430

Mean Gene - Not to horn in but you really need to get the ordering info for the manual as a sticky at the top. Percy doesn't seem to be a moderator anymore so he can't make it sticky. Don't know if it is still current but your configuration is explained and showed in photos very well in the manual. At least it would let folks know a little more about your setup. And I really appreciate your comments again. Hard to figure out what all these different sub orientations really do to sound. Sounds like for us mere mortals that are out for SQ, even though we don't have Percy's refined auditory nerves, having the sub fire up into the opening is the way to go.

retrodrive

I had a chat with a couple of reputable stores in my area and they all say that with a trunk like that the sub would work best if it faces upwards into the hole in a rear deck. The sub should be mounted 6 inches below the deck so that the wave has time to develope. Just my 2cent

sparky3

Does anyone that has a box facing upwards know their dimensions off the top of their head? I may build one myself or pick one up locally. This of course all depends, especially if you're allowing 5-6 inch gap.

Thanks guys I want this to be "right" I'm already out the $300 from the shop that built me a !@#$$@#$ bandpass box.

Shawn

Mean Gene

Ron - I went back a few weeks & found another request to do the sticky thing so I'll see what I can do. I've got to apologize for not being online much lately but my home CPU is in the shop so I can only monitor things from work ( & U know how much employers love that!! ).
Shawn - I have a 2.84 cubic inch sealed box ( 3/4" MDF & plexi ) with dual 12" RF Power HX2's running in a 1 ohm stereo load ( 2 ohm DVC's wired parallel ) & feeding of a single RF Power 1100a2 ( RF birth certificate of 1344 watts into a 2 ohm mono load - same as mine ). Actually. I sing baritone in a local Southern Gospel quartet but I still listen to old fashioned rock 'n roll plus some R&B. Most of the time I shut the 12's down & rely on the Diamond Audio 8" midbasses in the rear doors for low frequency everyday listening - use the Symmetry to drop the crossover point for those times ( it has the ability to program up to 16 curves into it's memory ). I took much of the same info Retro said one step further - the top of my enclosure's about 4 inches from the rear deck but I used a weatherstripping "boot" from the local camper shop to totally seal the subs into the cabin area. U can see the gap in Percy's primer ( GREAT manual!! ) before I added the boot. FWIW - P said in the primer that I was "soon upgrading to Dyns" & that MAY well be true!:eek: I'm in the process of retooling the system ( like Retro & Percy say - is it EVER really done? ) so I'm shopping/demo'ing Dyns. Don't get me wrong - I love my Focals but I've just about had enough of the politics involved in competing so I might just redo things to please ONLY myself instead of making concessions for what judges look for. We'll see.

RON430

MeanGene - If you use an enclosure for a sub but want to mount it as high as possible it sounds like you should leave four or six inches between the enclosure and the rear deck. Is that correct? And what are the factors about whether to leave the gap free air versus sealing the gap to the deck as it looks like you have done.

By the way, anything informative in Griot's detailing book?

sparky3

I'm assuming you meant 2.84 cubic feet, not inch (LOL). Anyway, did you notice a difference before you added the weatherstripping boot? I have 0 plans to ever compete; I just want a hard hitting clear stereo with room to put golf clubs/groceries in the trunk. With that much power, did you have a 1 Farad stiffening cap or upgraded alternator?

Also, what did you NOT like about facing the subs forwards? Not enough low-end, or do the rear seats simply muffle the sound too much? I want SNAP more than anything else. Was it the same enclosure you now have facing up that was facing forwards? Maybe the box's depth wasn't enough?

Lastly, do you have any pics you care to share? I'm going to pick up Percy's primer when I upgrade the mids/highs later.

Thanks!

Shawn

Mean Gene

Shawn - The cubic inch screwup was another senior moment! I have two 1-farad Stinger caps on the bass amp ( rule of thumb is 1 farad/1000watts - doesn't matter if it's rms or peak, BTW ) & err on the high side. I also have a system-dedicated Optima Yellow Top in the trunk so if I stop competing, out comes that battery as it's an additional drain on the factory alternator ( 110 amp hot rating ) & I won't be playing the system much w/o the car running so the trunk power source won't be necessary. Might look into a Jacob's Accuvolt at that point - besides insuring 14 VDC to my amp, it cleans up the signal as well ( although I have no noise at present ). On the BMW systems I've done ( firing the subs thru the ski hole ), both of your comments were noted. The seats muffled & muddied up the bass. If U want "snap" in your bass, might want to go with dual 10" as they're more responsive & tighter than 12's. Remember that I basically have 2 systems in one - I play everything EXCEPT the 12's for the SQ portion of contests ( using the Symmetry to adjust my crossover points & EQ curves as needed to please both the RTA & the judges ) then I shutdown the front stage ( kickpanels & front door midbasses ) & rely only on the 12's & the rear door 8's for SPL - a best of 141.2 on a B&K meter. If I wanted more SQ from the enclosure I'd have made it smaller & for more SPL I'd go larger - all within the RF recommendations for these woofers, of course. 2.84 cubic FEET ( LOL!! ) was about as large as I felt comfortable going & still making the box fit the trunk ledge & still leaving the trunk 75% usable. Master P ( Percy ) has a small section in the back of the primer with alot of my system pics ( under construction ) & the finished product ( for now ) can be seen on my friend's website www.aceaudio.net under "Custom Installation".
Ron - I noticed that the bass seemed to tighten up a little when I installed that boot. Figure that some of the bass wave was being lost into the confines of the trunk - even picked up about .2 dB when I sealed it. The bass wave as it bounced around the trunk made for some resonation even with the Dynamat. If U can get the top of the box closer to the bottom of the deck lid ( maybe within an inch ) I venture to say that U won't need the boot seal. I didn't notice anything "super secret" in the Griot's detailing book. Most of the info is contained within his catalog already but the index provides a numerical listing of all Griot's products for quick reference. Not a bad little investment & it was one of the few automotive things my wife ever got me!! BTW - I did the "sticky" thing for U guyz - sorry it took me so long!!

sparky3

I get a fun filled evening of hooking up my 2 new amps and new Eclipse's! I bought a semi-cheap 5/8" MDF sealed box that I should be able to face forwards, up, and to the rear. Keep in mind that I'm really used to about 250 watts to cheap Kicker's, and now I'll have 1000 WRMS (1 Farad Cap on the way) with 500 going to each sub.

I can't wait! My parents live in the country south of Columbus, Ohio and I'll probably wake up all the "farmers" down there banging everything around! I literally can't sleep at night I'm so excited! I've been fortunate enough to literally quadrouple my salary in the last 4 years (I just turned 28) so having a really nice stereo is something I've always wanted.

Like you say though, there is really no "The stereo's finished". Next will come the mids/highs upgrades and a possible upgrade to the 3rd amplifier.

Thanks for everyone's help, and I will report my 8-24 hour testing and conclusions. I have about 50 square ft. of Dynamat Extreme left, so the objective is as little rattle as possible.


Sleepless in Columbus,

Shawn

sparky3

Well, where to begin. First of all, I must emphasize that 37 pound speakers are very heavy. Both of these in a 20 pound box (nearly 100 pounds total) in 28 degree Ohio weather 2 all-nighters in a row was fun. Let's just say there was a fair amount of swearing involved.

Well, I tried all sorts of different configurations (box foward, rear, facing up) and I honestly can't say I like the way it sounds facing up. I think the problem might be that the box, being 15" deep, is way too close to the rear deck when on it's "back". I currently have the box facing the trunk, and HOLY ***** is the bass responsive at low frequencies. I threw in the live version of "NO Quarter" from the "Song Remains the Same" (Zeppelin) and holy low bass, Batman! Although fun for awhile, the entire trunk rattles way too much and isn't tight and punchy as I'd like.

I also bought a 2nd battery for the trunk, as the 2 JL 500/1's were draining the crap out of the main battery. It's a nice gel? type deep cycle battery and fixed that problem.

The little Soundstream Rubicon A4 on the factory mids & highs is now very dwarfed by the big boomy bass. I won an EBAY auction for a new JL 300/4, as well as (I KNOW THESE aren't Dynaudio or Focals or Diamond Audio)
Infinity Kappa Perfect 5.1 (front) and 6.5 (rear). Both sets are in an unopened box and I got them SHIPPED to me for $425. I think that will be a heck of an upgrade over the factory speakers.

Anyone running these mids/highs?


Lastly, if anyone could give me their exact or close to exact box specification for dual 12"'s (L X H X W) I would gladly appreciate it.


Very lastly, before I put the back seats in (-15 DB for seats-LOL) and I played low hitting rap music it literally hit so low my ears were ringing....


Thanks for everyone's help! Again, please let me know about your box dimensions, as I have a guy locally that'll build me one for $50 carpeted. Should I port the box too?


Shawn