Considering A Build, And Want Your Help!

[Eskii]

Show us some pics of how the cars interior looks. I'm from Aus, so dunno wat it's like!

[Sniper]

I'm gonna get the pix on here hopefully by the 14th of November (my b-day, im buying a new cam with my cash )

we're not gonna see serious build status until about December anyway, thats just how it is, I can prep the car all I want, but that still leaves me about 500$ short of where I need to be, basically saying, its gonna be a month if im lucky before I can start the main build process, im already talking to the person-in-question about the RE, and I have told him my status on the money and me and Dan are getting the cash ready by next week, give or take a few days, in other words, I should be seeing this stiff legged monster in about 3 weeks if I play my cards right.

And, I have a b-day party-meet-thing coming up on November 15-16, so who ever wants to slam out here for the bass-heads I hang with, you should, and as soon as I figure out when the local competition is for this year, I'll definitely run for it ^^ (maybe some will join )

[Torres]

with a 1ohm load on it, set it to the 1200 mark, which will be 120V if its the right amp

whoooooa...unless i read the post wrong...setting the gain that high (if it will even read that high) would kill the amp. with 1200 watts @ 1 ohm, you should get a reading of ~34 volts. 34.64 to be exact. 120 volts would be over 5k watts...

[Sniper]

eep, thank you for the correction, I could have fucked my amp and sub up, I owe you one!

[wL<3bass]

.boon,

i know you are very intelligent and knowledgeable but i have an 18" MT on a Sony 9001GTR and it FUCKING SLAMS!! only around 500 RMS

im not saying im doing 150's but i am in the low - mid 140's @ 30 hz

Doubt it, and why do ppl buy killer subs just to underpower them by less 1/4 of there RMS?

[Sniper]

wL<3bass, you've never heard his system, its the sensitivity of a driver that determines how loud it is and will get at any given power, and + you dont know what his box is in, what its tuned to, and how much space is available in the car as the listening zone and how his test was taken, or if it even is, so of anything I'd just nod and agree.

I could pull 125db at 35hz with a 50w Acoustic Research AR-3a speaker from the late 60s, whereas it takes a logitech 250W+ Z5500 to hit 126db in my room at the same frequency. and before you call bs, i suggest you look up alnico speakers, they have an outstanding spl of 105db 1w/1m.

the trick is QES, QMS, and QTS, then the box tuning freq, knowing what your response graph is gonna look like at a given tuning frequency, most people dont know woofers perform better at lower powers, 35% lower power on any driver can show performance increase in both cone control and coil heat dispersion,

now for the people that say a coil will just sit there and melt with lower power, thats BS. Its distorted signal that kills speakers, not low power, who ever told you that was smoking crack, speaker builders such as TC will tell you that's BS, EV woofer builder Paul Clark had this to say when I told him about this thing known as underpower killing, he said it would only happen with the thermal handling being passed that the coil melt.

Remember, its impossible to break a window with a feather.

And some more info, running a speaker at more than its rated power will make the coil leave the gap (passing its rated XMAX) or it will move less (it will) and heat up quicker than it can disperse. And with the above stated leaving of the voice coil to the gap will let the coil stay "out-of-bounds" long enough to build up a little heat before the suspension forces it back down, and for each stroke, more heat is gained, for a beast like a RE MT, it would have to last long enough for the full coil to leave the gap, and as we all know, the RE MT has a massive 4" coil (a little bigger than a can-o-pop) that is 8-layer, meaning it'd have to stay out of the gap for about 3m per increase in power (dependant on the ratio of how long its out and what the power is), hense why you can wallsocket a RE MT and have it last for on upwards of 48 minutes, the idea is to keep it in the gap, now before someone says "why are you posting this?",

well to tell ya the truth, im just tired of stupid people, it gets on my nerves, and besides that, I broke my toe, so I have to take it out on someone, and frankly its who ever decides to be stupid, most of you are cool, and some are stupid, but Meade is my god, Dr. DB is my god, Big Oki is my god, and the rest, many are my favorite bassers, one of them being BigPimpin91 who's music I slam everyday (the actual reason I sold the spare set of MTXs, the neighbors called the cops! ROFL) and want to meet up with when ever I can (judging if its even to ohio for a competition)...

Now people, lets stop bickering like 5 year olds and figure out the next step for this ride.

--

onward to something worth talking abot

--

Daniel bought 3 16ft dayton audio shielded EMI RCA cables, now why did he buy 2 sets more than needed?

So I can run a Mid amp and a high amp of course!

[Boon]

Blech...

Have you got the MT yet?

If not, you won't have noticed that it has several EXTREMELY stiff spiders. You seem to know plenty about speakers so you'll probably know that this is to help control the cone at very high power levels.

It has a high sensitivity rating primarily because it's an 18 inch sub. I suspect that they extrapolate the sensitivity from what the sub does with a few thousand watts because I just don't see it doing what they claim at 1w. Similar to any high power-handling SPL woofer - the sensitivity is often rated at 90+dB @ 1w but I suspect it's extrapolated because when you can't move the cone pushing down on it with 2 hands you're sure as hell not going to move it much with 1wrms.

The reason 'low power' is going to kill your woofer is because the power you currently have means it will not really get up and boogy like it should (due to the actually relatively low sensitivity)

Now if you use a rediculously large box and enormous port (so the sub is just about free air) then you may get enough cone movement to properly cool the coil.

If you look at the MT motor you'll spot 2 things about it - 1. no pole piece vent (as I have mentioned about 1000 times) 2. extremely narrow gap

Then we look at the coil itself. It's basically just a big complex mess of copper clad aluminium - much like the heatsink in your computer in many ways.

With your computer's heatsink, you'll notice it has a big fan on top. That's because forced convection cooling is much more effective than plain old convection (transfer of heat to air)

With the fan on your heatsink you should be able to run that CPU for hours on end at 100% load and it'll be fine because there's enough airflow to dissipate the heat.

Now imagine if you took your heatsink and put it inside a very very small metal box (kinda like the inside of a subwoofer motor...) without the fan on top.

If you kept the load on the computer very very very small it may just manage to keep on ticking because the heat would be able to dissipate fast enough on it's own but as soon as you put a small load on that CPU it would overheat and the computer would crash or reboot from it's own thermal protection.

Let's transfer this to a subwoofer, if you haven't seen where I'm going yet.

When you have low(ish) power to it, the coil is hardly moving in the gap so there's very very little airflow around it. Basically you're slowly just warming up the same little bit of air. Once the ambient temperature gets high enough (Newton's law of cooling) there will be virtually no cooling and then it's only a matter of time until the magic smoke comes out.

Subs like the DD9515 or DC Level 5 aren't so prone to it because they have bigger gaps and pole vents. This does result in a slightly less efficient motor but they compensate for it by using a very large motor.

When you wall socket an MT, the sub is basically running xmax-to-xmax so there's an enormous amount of air flowing around the very large voice coil which makes for very effective cooling. Which is why they can last for ages.

As long as you're banging the crap out of them you're fine.... for all the reasons above.

It's when you CAN'T get the cone moving, due to lack of power, that you're endangering the sub.

Long story short, you're going to have to build a simply colossal box to try and get the cone moving enough. At least you're only running 1 18 in a wall so this is fairly feasible. The problem with that is when later on you get a proper amp for it, the box is way too big for the new setup, the sub unloads all the time and your cone comes away from the former

[Sniper]

basically your saying if I underdo it im fucked, but if I get it set for the underpoweredness then get the good amp on it im gonna fuck it up in the longrun?

also, you should see dwrights vid with his setup on 500wrms, it kicks very very nicely and flexs the hell out of his truck.

[Boon]

basically your saying if I underdo it im fucked, but if I get it set for the underpoweredness then get the good amp on it im gonna fuck it up in the longrun?

In a nutshell, yes

If you're sneaky you could make the box big enough for _2_ MTs with an assload of power on them (Say 10 cubes?) then when you get some proper power, maybe 6kw, you can get another MT or 2 BTLs or whatever and it will wang hard. That's what I would suggest, just remember to make the box so you can rip the baffle out without fucking the box

[Sniper]

damnit, killed my Kenwood amp today... the line-in for RCA was loose, and my stupid ass tightened the screw while it was running.. it shorted the amp out, and now I cant get it to turn back on... god damnit... 40$ down the hole..