dB estimate

ive gotta 12" HE2 Fosgate with a 401s Fosgate amp. Its in a sealed box, pushin 400 watts RMS, any body have any clue what kind of spl that might have, even though its punch series?? just guess at my dB, thanks

Have it measured. Somebody more experience than I might be able to tell you, but they'll want to know what kind of car and probably some other stuff.

Below 98db for sure. the speakers are not efficient enough.

Julian59

walty220  

      Ok here are the specs,  no guessing  just the facts! The Rockford Fosgate HE2 (RFD3212) it's efficientcy is only 87db@ 1watt / 1meter  Power Handling (RMS) is 400  Max is at 800 at 4 ohms. If you max this out at 800 watts you'll only maybe get an increase of 4 db. The numbers don't lie, always do the math before you buy.  Sorry if this isn't what you want to hear.

Julian59 

Julian, not to knock you at all but do a little more research into the math involved. If It generally assumed that a doubling of power is a gain of 3db, then we need to check the math. If it is in a ported enclosure, then add 3db as well, add cabin gain, this is pressurizing a small airspace, not a big room. A factory stereo with no sub can play above 100db. I stand firm that the system should play above 115db and probably close to 125db. Please let me know what you think on this if you have or I have any misconceptions.

1 watt = 87db

2watt = 90db

4watt = 93db

8watt = 96db

16watt = 99db

32watt = 102db

64watt = 105db

128watt = 108db

256watt = 111db

512watt = 114db

Forbidden

       Thank you for the heads up, but I'm sorry to say that's not right. The speaker in question is rated at 87db @ 1 watt / 1 meter. There is no way this speaker will ever come close to those figures you have. It doesn't matter what type of enclosure this is in. Rule of thumb is in order to gain 3db is to increase the power no lell then 100 watts. You will gain SPL but no more then 3 dbs +- .05.  I hav't read the MECP manual in about 10 years. but I do know that's this is in there. Check it out.  The key word here is DBs. 

Thx

Julian59 

Exactly what does the efficiency rating mean. I was told it's the sound level that a sub is most efficient but that sounded odd.

This "spec" has a real meaning, it however does not tell you how something will sound or how it will react in a vehicle or enclosure. It is a measurement of how loud the speaker plays as compared to all others. This "spec" is also one that has an agreed upon standard in the industry. In general terms this is what it is.

The speaker is mounted in an anechoic chamber (a dead room - no reflections)

The speaker is fed pink / white noise (think of a dead channel on a tv)

The speaker is fed exactly one watt of power.

The speaker has a microphone exactly one meter away from the speaker.

The microphone measures how loud that speaker "plays" the test signal and records it in decibels.

Thus the speaker is given a "spec" of in this case 87db/1w/1m

A speaker that is more efficient, say 92 db will play much louder with the same amount of input power, a speaker that is less efficient, say 82 db will play much quieter with the same amount of input power.

forbidden is right.  The speaker isnt even in any box..its just sitting there.

jpranwez wrote:

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Exactly what does the efficiency rating mean. I was told it's the sound level that a sub is most efficient but that sounded odd.

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Well it means diffrents things to some and a lot to others. OK lets say you have two 12" subs, if these speakers are rated at 89db @ 1 watt/1meter and you have an amp that rated at 200 watts your basiclly getting 92dbs out of it (not SPL) now if you have a pair of 12" speakers that are rated at 101db @1watt / 1meter with a 2 rated amp at 75 watts each you'll get 101dbs. Yes I know these guys don't agree with me. That's cool. Here's something you will agree with. If you shop around for the most efficent speakers you can find you'll need less power to run your system,  that mean less money spent for Amps(power) and less money spent on a huge charging system to run all that raw power that you need for your boom,boom. You can have a system that powered with under 500 watts and sound like 1200 .

There is another power test for speakers (using spectrum specifed in EIA Standard SE-013 Section SE3)

30 ft. at .001 watt input = ?? dbs      54dbs

10 ft. at 1 watt input  = ?? dbs           93dbs

4 ft. at 200 watts input = ?? dbs       124.5dbs

the 2nd dbs is the rating of my sub speakers. My 1963 Chevrolet Impala SS Convertible has tested at 120 dbs and has an SPL of 132   8 speakers. 2 -15s, 2-mid mids, 2 high mids, 2 tweeters.  total power of 420 watts  

yeah, Forbidden has it the way i was taught by the experts.

87db (or whatever your particular subs ratings say)  is its output with 1watt input.

Julian, ya gotta understand, double the power  =  +3dB.

double the input power is 2watts, giving us 90dB. Double again is its expected dB at 4watts input, etc.

1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 watts RMS.

outta curiosity, at 121 dB.. am i going to be heard from a block away??

Only if you keep the windows rolled down, and in this cold, I wouldn't think it wise (you might catch a cold) .  No but seriously, you do turn it down when you enter a neighborhood or pull up to a light, right?  In a properly dampened car with the windows rolled up, even with the system up a good rate, it's noticable outside the vehicle, but not very loud.

most small neighborhoods yes..well ATT, i love att. I just want to be heard coming, enough to turn a head,if  this set up is incapable... then im sorry for puttin you in the position to break it to me lol, dont feel bad, im learnin, its not gonna hurt my ego.

The efficiency rating (a percentage) is not to be confused with the sensitivity rating.