Project Stupid

[Adrian_D 520]

You take 2 audio geeks, 2 cars with similar installs and 2 of the cheapest 10" speakers. Add some particle board, a huge port and try to lay the smack-down  

 

Here's how the box looks, 2 $20 subs, in a push-pull configuration. It's going to have to fit in the cargo area, initially designed for my car but my friend and I were both anxious to hear the thing before the wood glue cured and it's pretty awesome. The Honda will get a custom-fit box once I exhaust all the ideas in the Jeep. 

 

 

We even did 2 burps with a short port. Considering the end goal for the system is 142+ dB, how about some educated guesses on the actual score today? 

 

 

[ricksi30 923]

104db

 

 

Looks like fun!

[Adrian_D 520]

Are you lowballing me?

[jcarter1885 995]

Knowing you, I would say you surpassed your goal. Maybe a 143 or 144db :

Edited July 30, 2013 by jay-cee

[Adrian_D 520]

Not yet...but you're close  

[S.DeYoung 968]

At least one six zero....on half power

[Accuwave 11]

Tip: it's somewhere between 130 and 150db

[Adrian_D 520]

jay-cee was the closest so far  

[ricksi30 923]

142

[jcarter1885 995]

139db

[Adrian_D 520]

 

Second burp ever, X-over hurt the score higher than 44Hz, the gain was not dialled in right because we would have clear sound at volume 18 for instance and massive bottoming out at 19. 

 

0.1 from the class record. 

[jcarter1885 995]

Hell of a score, what's next?

[Adrian_D 520]

Test in the Jeep, since that's where I know exactly where to tune. Resin inside, resin outside, 2 speakers in a regular configuration, bracing, rounding the edges, aluminum tape on the top side of the box, polishing the inside of the box, subs close to the tailgate (to control excursion) instead of pointing up, MDF box.

 

A customer of mine left the garage with 147.0 and his highest score a few months later was 148.2 IIRC, part of the gain just by gimmicks like aluminum tape, more resin and polishing the box inside. 

 

The limit today was cone excursion. Plenty of power, just not tuned right. 800w @ 4 ohm amp  

[IDGAF 0]

Holy hell. That's awesome.

 

"push/pull"... do you mean it's iso loaded or just plain ol' push/pull with one sub inverted?

And what class is this?

[Adrian_D 520]

it's push-pull isobaric, works fine for now

i'm competing in an organization across the ocean, since i'm not from the us. the class is similar to street stock.

[Adrian_D 520]

After some testing in the Jeep I managed 142.2 dB, completely class legal, ie box in the cargo area, under the window line. 

 

Got the tuning right, I can barely bottom out the speakers but it peaks at 48 Hz, while with the BTL 12 it peaks at 50 Hz. During testing I managed to blow 75A worth of fusing on the Zapco and the coils have never smelled, motors are cold. 1.5" coils taking abuse

 

Jacob's Jeep does something similar, peaking at 48 with a bigger box. So maybe that's just how it works. 

 

The box is resined inside, it's nice and smooth, time for more testing next week. Really curious what the resin does, on an older box 

[Adrian_D 520]

Resin helped at least 0.4dB. 

 

142.5 without ductape around the speakers (helps 0.1) and 142.6 holding the rear quarter windows. So far so good, time to resin the outside of the box. 

[jcarter1885 995]

Slowly but surely climbing

[Accuwave 11]

we still have to tune it for the civic. Hoping for miracles.

[Adrian_D 520]

You've been listening to too much Sub Focus

 

We're doing testing in my garage, where miracles sometimes happen  

143 in the Honda today *fingers crossed* 

 

Biggest problem in testing is the coils heat up quick and it takes about 10 minutes to cool off and get the same score. First burp I can bottom out the subs easily. By the third burp I have no chance of bottoming out. Hot coils, high impedance, power goes down. If my reasoning is right, the 142.6 could be a bit more. 

[Adrian_D 520]

The Civic did 142.9 dB, twice within 5 minutes. All is well, also got the tuning right. 

 

After that we cut another speaker hole and went with a normal alignment. No more bottoming out, all that the Steg 800w @ 4 ohms amp could do, the little buggers took it and put up 142.8 dB. It's 0.1 less than the isobaric alignment, with more power. If they survive thermally they are going to be ok, I have a feeling that bumping the tuning higher will get us over 143.0 in the Civic.

 

Next step is bracing, then doubling up the bottom of the box and the baffle. Bracing is not appealing, I've had mixed results but who knows what's going to happen considering the box is made out of particle board.

[pmureika 31]

Nice job!!!!! 

[Aaron Clinton 2,372]

Love it how Adrian does not try to hide anything as he progresses.

[Accuwave 11]

We're being secretive on local forums. It's gonna be a big surprise...

[Adrian_D 520]

Yup, locally it is a secret, for memories of old times when everybody was secretive. These speakers really don't have a good reputation so seeing scores as big as these is going to be a shock. 

 

Having the info here allows easy reference to see what works and what doesn't