1. 140's easy or no??

i know this is such a stupid question to ask everyone but i'm still gonna do it. is hitting 140 with 2 or maybe 3 15"s running of either 750wrms total or around 1000watts total depending on if i have 2 or 3 15"s and easy task to accomplish?? i know so many factors come into play but let's just add in i drive a jimmy custom box built right, over 100ft of dynamat xtreme would 140's be easy to get on the dash??

keep it thumpin,

2. Even with 2 15's and 750 watts, 140 should be easy enough. I say should because you never know until it goes in and gets metered. I say yes as long as you had a big *** box with a lot of port. Hell, maybe even 145, but to do better #'s, I would get more power instead of more subs, but if thats not an option, why don't you just get 4 12's instead of the two or three 15's. That way you could get the full power out of your amp if you really want the Blueprints. Probably cost close to the same too.
Last edited by JTz62; 06-22-2002 at 01:45 AM.

3. Basic dB formula This formula is assuming that all things are perfect.
It is a LOGICAL “Guessimate” that is ALWAYS within 3 dB of actual!
That voltage is near 14 volts/plenty of battery/alternator
Using at least 1/0 Ot guage wire
Some kind of Line Driver is being used
1st things first
Start off with sensitivity of the “raw” driver
Then total power of the amplifer (peak AC volts measured with a volt meter)
2nd thing
Calculate the total efficiency of the woofers
Add each woofer as + 3, doubling of cone area equals double output
For example: Take a CC-D1200, connected to 2 SS-12 (a load of 1 ohm)
You’ve measured the Ac volts out into this speaker load as 42 volts,
which calculates to 1764 “peak” watts. A/C volts squared (times itself) divided by
the impedance equals power. So.....42 X 42 = 1764 divided by the impedance, which
is 1ohm in this instance, so its still is...1764!!! We now know the REAL power
(cause you measured it into a REAL load...............The Concept SS-12 woofer)
The Concept SS-12’s are 87 dB 1W/1M (typical of ALL small box woofers *
Lets do the dB Log:
1 woofer = 87 dB
2 woofers = 90 dB
4-woofers = 93 dB
4th thing
Add up the special “side deals” Like is the boxed sealed (no extra dB), hatchback or coupe? Etc.
Use the following to get “close to the REAL DEAL in SPL.
Transfer Function (sedan) = 12 dB
Transfer Function (hatchback with woofers aming towards the rear glass) = 16 dB
Sealed box = No extra dB
Vented box = 3 dB (UNLESS you have an odd order alignment)
Vented box = 6-9 dB (IF an odd order alignment - Big *** box )
BandPass Box = 6-10 dB (depending on how small the enclosure is)
Mic Placement = 6 dB for DB drag dash/window mic placement
125 dB
3rd thing
Do the “dB log” starting with the total subwoofer (s) efficiently (which is 93 in this instance)
93 dB = 1 watt
96 dB = 2 watt
99 dB = 4 watt
102 dB = 8 watt
105 dB = 16 watt
108 dB = 32 watt
111 dB = 64 watt
114 dB = 128 watt
117 dB = 256 watt
120 dB = 512 watt
123 dB = 1024 watt
126 dB = 2048 watt
Obviously we only
have 1764 watts
so we’ll “split the difference”
So.... this car will play
Now lets total it all up 125 db - basic “dB log”
+12 dB - standard cab car with a direct facing woofer box
137
But the woofer box is vented in something other than “optimum” or flat
+ 6 dB
143
+ 6 dB DB drag dash/window mic placement
+ 6 dB
149 dB (+/- 3dB)

4. Hope that confuses, I mean helps you a little.

5. how's about a simple YES OR NO 140's should be easy on this one wesleysh???

keep it thumpin,

6. sounds like u should do it easily to me.

J

7. Yes.

8. well look at it this way, i 'm hittin 140 with 1 15inch type r, got me a nice second place trophy it did

9. Originally posted by wesleysh
Basic dB formula This formula is assuming that all things are perfect.
It is a LOGICAL “Guessimate” that is ALWAYS within 3 dB of actual!
That voltage is near 14 volts/plenty of battery/alternator
Using at least 1/0 Ot guage wire
Some kind of Line Driver is being used
1st things first
Start off with sensitivity of the “raw” driver
Then total power of the amplifer (peak AC volts measured with a volt meter)
2nd thing
Calculate the total efficiency of the woofers
Add each woofer as + 3, doubling of cone area equals double output
For example: Take a CC-D1200, connected to 2 SS-12 (a load of 1 ohm)
You’ve measured the Ac volts out into this speaker load as 42 volts,
which calculates to 1764 “peak” watts. A/C volts squared (times itself) divided by
the impedance equals power. So.....42 X 42 = 1764 divided by the impedance, which
is 1ohm in this instance, so its still is...1764!!! We now know the REAL power
(cause you measured it into a REAL load...............The Concept SS-12 woofer)
The Concept SS-12’s are 87 dB 1W/1M (typical of ALL small box woofers *
Lets do the dB Log:
1 woofer = 87 dB
2 woofers = 90 dB
4-woofers = 93 dB
4th thing
Add up the special “side deals” Like is the boxed sealed (no extra dB), hatchback or coupe? Etc.
Use the following to get “close to the REAL DEAL in SPL.
Transfer Function (sedan) = 12 dB
Transfer Function (hatchback with woofers aming towards the rear glass) = 16 dB
Sealed box = No extra dB
Vented box = 3 dB (UNLESS you have an odd order alignment)
Vented box = 6-9 dB (IF an odd order alignment - Big *** box )
BandPass Box = 6-10 dB (depending on how small the enclosure is)
Mic Placement = 6 dB for DB drag dash/window mic placement
125 dB
3rd thing
Do the “dB log” starting with the total subwoofer (s) efficiently (which is 93 in this instance)
93 dB = 1 watt
96 dB = 2 watt
99 dB = 4 watt
102 dB = 8 watt
105 dB = 16 watt
108 dB = 32 watt
111 dB = 64 watt
114 dB = 128 watt
117 dB = 256 watt
120 dB = 512 watt
123 dB = 1024 watt
126 dB = 2048 watt
Obviously we only
have 1764 watts
so we’ll “split the difference”
So.... this car will play
Now lets total it all up 125 db - basic “dB log”
+12 dB - standard cab car with a direct facing woofer box
137
But the woofer box is vented in something other than “optimum” or flat
+ 6 dB
143
+ 6 dB DB drag dash/window mic placement
+ 6 dB
149 dB (+/- 3dB)

NICE!!!

10. I knew that looked familiar http://www.conceptcaraudiovideo.com/...%20formula.pdf and yes you can get a general idea of how loud you would be, but read the top part again. In a perfect world, with the voltage near 14, and a line driver. And you're still at +/- 3 db. and thats a lot of difference. Probably more like +/- 6db but still a good way to get a general idea of what you could hit. Only one way to find out for sure though.

11. I wouldn't doubt a novice with little to no knowledge of car audio would have trouble with it. But as much time as some of us spend on these boards if you couldn't at least "tweak" your way to 140 with two 15's something is wrong. I still have fresh in my head a whole thread where beginning SPL guys were hitting 140's with one 12" IDMax. Now if your talking about mid to upper 140's that's a little different, but I think the Jimmy (and Adam) can pull it off.

12. yeah i'm pretty sure i can considering the fact that i have had people take there guess at what my car hit's right now with just 2 12" HE2's in a pre-fab box and they have all gone to comps and i just let them guess and that's typically a decent way to get a decent # and they all think i'm doing 140's on the dash now. but i want to get it metered and i might tomorrow at my friends bbq i think they have a meter but not totally sure, you better believe if they do i'm going to get it tested.

keep it thumpin,

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