[clipto333]

Originally Posted by low_bass_makker

Sir from where did you got to know this...

are you asking or doubting? no offence meant bro.

nura is absolutely right about this. boss google this and you will come to know

cheers
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[zucchero]

lbm you mean to say that the sensitivity of hertz 95 db is derived through some other parameters!!!!!!!.

[low_bass_makker]

Originally Posted by clipto333

then sir how do the manufacturers measure sensitivity? what you are saying is that the sensitivity figures given by hertz is not accurate? does ID gives the rating at 1w/1m?

does an increase of 3 db mean double loudness? i dont think so. for a 3db increase, you need double the power, it doesnt mean the loudness will be double as well. correct me if im wrong.

got to go, will reply later

cheers
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Clip this discussion has been done before...have a look here...

http://www.team-bhp.com/forum/ask-gu...a-civic-7.html

after post 98.

some thing more on sensitivity measuring..

Loudspeaker sensitivity vs efficiency

[low_bass_makker]

Originally Posted by zucchero

lbm you mean to say that the sensitivity of hertz 95 db is derived through some other parameters!!!!!!!.

Sir I did not got your question...the Hertz sub is not having 95 db at 1m/1watts this I am 100 % sure...

[zucchero]

i would like guru's to make it clear bcoz i doubt theirs any other way to calculate sensitivity.

[low_bass_makker]

Originally Posted by clipto333

are you asking or doubting? no offence meant bro.

nura is absolutely right about this. boss google this and you will come to know

cheers
clip

I thought he was referring to power...as double the power will yield 3 db gain...Nura is correct.

[low_bass_makker]

Originally Posted by zucchero

i would like guru's to make it clear bcoz i doubt theirs any other way to calculate sensitivity.

Zucchero are you doubting my method of calculating the sensitivity ?

And I am NO guru here...

[zucchero]

lbm with no offence bro,what makes you think that the hertz 15 does not have a sensitivity of 93.

[low_bass_makker]

Originally Posted by zucchero

lbm with no offence bro,what makes you think that the hertz 15 does not have a sensitivity of 93.

OK lets take it like this is Hertz sub is having 93 db senstivity at 1watt/ 1 meter.

Absolutely not.

[zucchero]

bro,agreed that it is not 93 db how come you came to the conclusion.are you trying to say that the company specs are fake or according to you their are no 15 inch subwoofers which have such high sensitivity ratings????

[low_bass_makker]

Originally Posted by zucchero

bro,agreed that it is not 93 db how come you came to the conclusion.are you trying to say that the company specs are fake or according to you their are no 15 inch subwoofers which have such high sensitivity ratings????

Hmm the company is not stating all the specs for the consumer to compare two products look for your self you will not find all the detail...Like I said it is not 93 db 1watt/1meter but it can be at 1watt/0.5 meter which will yield 6 db gain as the distance is half, Now you can say it as marketing or fooling the customer.

I am adding some more info on the same as I know you will not agree with me here..

Originally Posted by Bass&Trouble

In what different way is Hertz measuring? Did you understand exactly how different? Let me try and explain.

Normal home audio standards has it to supply 2.83 volts to any driver/ system for sensitivity measurements. A lot of guys do exactly that for car drivers. Which is wrong. While home drivers/ systems 'usually' (not always) have a nominal impedance of 8 ohms, this means that 2.83V across it produces 1 watt of power. The same voltage applied to a 4 ohm speaker will produce 2 watts of power. There are some brands that will still refer to this as 1 watt of power as per standards (not in real terms), however absurd that may be.

In reality, this should mean that, if measured with 2.83V, a 4 ohm driver should show 3dB more than what the actual sensitivity is, on account of doubling the power. This seems the case with Image Dynamics (atleast 2 of the subs that you mention here)

My interpretation of the Hertz data is that, in the case of the SVC model (ES300/ 380) it's a 0.5m reading. Since distance is half of the legit 1m, there is a 6dB higher rating than what it should have been.

In the case of 300D, both voice coils have been fed one watt each, in addition to measuring at 0.5m. Hence 3 dB more on account of double power, and 6dB more for the halved distance. So the published spec is 9dB higher than actual.

Besides that, the sensitivity numbers have been rounded off to the nearest whole numbers.

Now you know what Dan was talking about.

http://www.team-bhp.com/forum/286845-post112.html

Also there can be 15 inch subs which might have 93 db sensitivity, Care to share if there is any...

[speedzak]

It seems like the guy who started this thread got tired and ran away! Why argue on something which was discussed and argued earlier?

@Gill. What have you decided? After reading your responses, I still can't figure out what car you're planning to put the subs in. More info from your side will help you reach an amicable solution.

[ScarySkulls]

Yup SpeedZak. Sub has been decided and ordered.
Lets wait for the install to happen :-) and then we can share the specs and the pics.

[zucchero]

@st7677
image dynamics idq12v2-website says 90.2,calculations shows87.4db
image dynamics idq15v2-website says94.2,calculations shows91.2
in my opinion both the readings are correct.sensitivity is simply a spec that tells us how loud a speaker will play given a standard amount of amplifier power.the industry standard is to present an 8 ohm speaker with a 1 watt(2.83) input signal and measure it output in an ANECHOIC CHAMBER with a microphone at a distance of 1 meter.these chambers are specially designed room which completely absorbs sound.BUT some companies gives us IN ROOM measurements.if we measure the same speaker in a room,then the boundaries(walls,floors,cieling) increases the output by 3db thus a lodspeaker which measured 89db in anechoic chamber will measure 92 db in room.this is what i think is ROOM GAIN.
ofcource what b&t bhai said is absolutely true.we will have to subtract 3 db if the impedance increases from 8 to 4 ohms.
i personally think that 90.2 db is the in room measurement and 87.4 is what it produces in chamber.it may be possible that HERTZ 93db rating is what it does in practical aplications though in any a ways is not the correct figure to disclose.
just my opinion.please correct me if i am wrong bcoz i am here only to LEARN.

[low_bass_makker]

Originally Posted by zucchero

@st7677
image dynamics idq12v2-website says 90.2,calculations shows87.4db
image dynamics idq15v2-website says94.2,calculations shows91.2
in my opinion both the readings are correct.sensitivity is simply a spec that tells us how loud a speaker will play given a standard amount of amplifier power.the industry standard is to present an 8 ohm speaker with a 1 watt(2.83) input signal and measure it output in an ANECHOIC CHAMBER with a microphone at a distance of 1 meter.these chambers are specially designed room which completely absorbs sound.BUT some companies gives us IN ROOM measurements.if we measure the same speaker in a room,then the boundaries(walls,floors,cieling) increases the output by 3db thus a lodspeaker which measured 89db in anechoic chamber will measure 92 db in room.this is what i think is ROOM GAIN.
ofcource what b&t bhai said is absolutely true.we will have to subtract 3 db if the impedance increases from 8 to 4 ohms.
i personally think that 90.2 db is the in room measurement and 87.4 is what it produces in chamber.it may be possible that HERTZ 93db rating is what it does in practical aplications though in any a ways is not the correct figure to disclose.
just my opinion.please correct me if i am wrong bcoz i am here only to LEARN.

Sorry sir but your theory is 100 % wrong here...I am no GURU here but this formula is the simple method to compare two subs when we have the specs and no chamber or room.

The following write-up was posted in ST thread before by me...

SPL is one of the most misused and maligned driver parameters out there today. Because most know that SPL has something to do with the loudness of a driver, they think bigger is better. And in general, it is... But recently, some manufacturers have taken to using unusual steps to "rate" the SPL of a driver. These can range from using non-standard drive levels, to measuring at 0.5 meters, to using in-room calculations. And unless they tell you what they used, you're out of luck! Or are you... Actually, no! There is a way to actually CALCULATE the efficiency of a driver. That is, you can run some simple equations, and come up with measure of just how efficient a driver is at converting electrical power to acoustic power. And from that, you can easily get to SPL. So now, you can actually "level the playing field" by removing any bias from the manufacturer's numbers...To start with, we'll need some of the basic Thiele-Small (T/S) parameters. I assume you can at least get these. If not, then take EVERYTHING that manufacturer says with a HUGE block of salt! If they aren't going to give you the absolute basic parameters about your driver, well...
Anyway, what you'll need is: Qes, Vas, and Fs. Yes, with these three little parameters, you can calculate the effective efficiency, and subsequently the SPL, of a driver. Here's how you do it:

Efficiency = 9.64 * 10^(-10) * Fs^3 * Vas / Qes

where
10^(-10) is ten to the minus ten power (0.0000000001)
Fs is the resonant frequency of the driver, in Hz
Vas is the equivalent compliance of the driver, in liters
Qes is the Q of the electrical system of the driver

This will give you a number, usually called n0, or eta naught. And, it's usually expressed as a percent, so multiply by 100.
Now, n0 is a measure of the efficiency of power conversion of the driver. That is, it tells you what percent of input electrical power is converted to acoustic power. Thus, you can calculate the output acoustic power by multiplying the input power by n0.

Now, don't be scared of a number down below 1% (0.01)! Rather, this is VERY typical of most subwoofers. Yes, drivers are inefficient, but that's what we've got to work with... So, how do we calculate the SPL of a driver from n0? Use the following equation:

SPL = 112 + 10 * log(n0 )

Where
n0 is the efficiency calculated above
log is the base-10 logarithm
SPL Calculations 2

So, let's run an example. Say, our Shiva subwoofer driver. For starters, we have: Fs=21.6 Hz, Vas=136.6
liters, Qes=0.3996. So, the n0 would be:
n0 = 9.64*10^(-10) * Fs^3 * Vas / Qes
n0 = 9.64*10^(-10) * 21.6^3 * 136.6 / 0.3996
n0 = 0.0033 or 0.33%

Now, let's put that into SPL:
SPL = 112 + 10 * log(n00 )
SPL = 112 + 10 * log( 0.0033 )
SPL = 87.21 dB SPL @ 1W, 1m

That's the 1 Watt, 1 meter sensitivity of Shiva. Go ahead and run your own favorite driver, and see if the manufacturer's being straight-up with you!

The above stand correct in comparing two subs, bring any sub you want.And I am 100 % sure on that.

If you wanna try do it on Adire sub, Fi subs and on DLS subs and let us know the results....