hOW tO gET eDUCATED: sPEAKErS = sound

[Joe Louvar]

Any one have a good link or reference that explains the whole speakers, amp, sound and loud thang? I was reading the "are two 100W amps louder than a 200W amp post and still not tracking with the feedback.

Actually, is there a chart that describes the folowing:

Let's jst use 500hz as the source freq.
@ 1w a 1x10 = xx db
@ 1w a 2x10 = xx db
@ 1w a 4x10 = xx db
@ 1w a 1x12 = xx db
@ 1w a 2x12 = xx db
@ 1w a 4x12 = xx db
etc, etc.

The answer in no (as everyone said) and the reason why in laymen terms is because not all speakers or enclosures are built equal. Now if all thing were equal and the only difference was size then the larger speakers will be louder (because they move more air) and the more speakers you have the louder the SPL up to a point - then extra power is needed.

 

[fuzzychaos]

There are a lot of factors at play here, however, with equal speakers (i.e. all the speakers are the same brand, model, etc) each time you double the number of speakers the perceived loudness increases by 3dB. 3dB is considered the lowest perceptible change in loudness and a doubling of perceived loudness requires a 10dB level change.

 

[VitalSigns]

Subscribed for knowlage and humor.

 

[will33]

Don't know how many people caught that but it's now filed under-

Reaon for Deletion: in the interest of useful info rather than adolescent bathroom humor

 

[neptoon]

*wonders if 'loud thang' is one of the variables taken into account when calculating output for any given cabinet + driver combination*

 

[Joe Louvar]

This link belongs on TB - checkout the Bass Guitar Magazine articles by Barefaced.
Barefaced Bass - BGM Columns

 

[xed]

There are a lot of factors at play here, however, with equal speakers (i.e. all the speakers are the same brand, model, etc) each time you double the number of speakers the perceived loudness increases by 3dB. 3dB is considered the lowest perceptible change in loudness and a doubling of perceived loudness requires a 10dB level change.

So you've got an amp. (baseline <pun intended>)
Add a second identical amp. +3dB from baseline
Add a third and fourth identical amp. another +3dB from baseline
Add a 5th, 6th, 7th, 8th identical amp. another +3dB from baseline

You're on your 8th amp and you're at +9dB.

 

[will33]

So you've got an amp. (baseline <pun intended>)
Add a second identical amp. +3dB from baseline
Add a third and fourth identical amp. another +3dB from baseline
Add a 5th, 6th, 7th, 8th identical amp. another +3dB from baseline

You're on your 8th amp and you're at +9dB.

You'd need more speakers to connect all the amps to so that throws it off.

In terms of just power.....

Power x 2 = +3db

Power x 10 = +10db

Depending on the speakers, that only works up to 100-200 watts or so, then it's time for more speakers. More speakers gets you louder than more power does.

 

[bongomania]

Add a third and fourth identical amp. another +3dB from baseline
Add a 5th, 6th, 7th, 8th identical amp. another +3dB from baseline
You're on your 8th amp and you're at +9dB.

??? Each additional "amp's worth of wattage" adds 3 dB from baseline, or +24 dB in your eight-more-amps example. But then what about the speakers? In order to handle +24 dB of wattage, with no speaker failure, you'd probably need to have eight more speaker "units" as well. Each doubling of the speakers adds 3 dB. So by the time this thing played out in a complete idealized model, we'd be at +48 dB from the original baseline. It looks totally different if you use each successive doubling as a new baseline.

 

[billfitzmaurice]

So you've got an amp. (baseline <pun intended>)
Add a second identical amp. +3dB from baseline
Add a third and fourth identical amp. another +3dB from baseline
Add a 5th, 6th, 7th, 8th identical amp. another +3dB from baseline

You're on your 8th amp and you're at +9dB.

Assuming each amp has its own speakers you get 6dB for every doubling of the amp count, at least for the first 16 or so amps. Then things begin to level off, eventually setting in at 3dB per additional doubling of amp count. Not that it matters, most would stop at two.

 

[Joe Louvar]

3dB is considered the least amount of SPL gain the human ear can hear and it takes about 10dB to double the volume (SPL). If you have a 100 watt amp with one 12" speaker and you add another 12" speaker you will get the magic 3dB increase. You would have the same SPL as a 200 watt amp with one 12" speaker. To get the next 3dB increase you need to double the speakers again so you would need four 12" speakers. Having 4 speakers will give you a 6dB increase in SPL compared to 1 speaker. Then it gets more complex. If you double the 4 speakers to 8 speakers there isn&#8217;t a 9dB increase in SPL as compared to one speaker like you&#8217;d think, instead you only a 6dB increase compared to one speaker because phase cancellation comes into play. The distance between the speakers causes the sound to reach your ears from some of the speakers at a different time and this has the effect of canceling some sound so more speakers are better up to a point. Speakers, enclosures, power, impedance, etc also play a role in the SPL. Checkout the Bass Guitar Magazine articles by Barefaced Barefaced Bass - BGM Columns

 

[will33]

As an "exaggerated for easy understanding" example:

Let's say you have a 410 speaker and a 10 watt amplifier. Adding a second 410 will get you another 3db but so will running a 20 watt amp into the single 410 because the speaker can still faithfully use/reproduce the power increase used to get the extra volume.

When you get to the power levels common to most bass rigs, the speakers can not handle the power increase that would be needed to achieve the increase in output...so to get louder, you add more speakers.

You add more power for increased headroom and reliability so the amp has some power in reserve it doesn't need to get the job done. That's for handling transient spikes, making clean undistorted bass and having generally less wear and tear on the amp because it's not spending all night with it's foot on the floorboard at max output just to get the job done.

 

[greenboy]

3dB is considered the least amount of SPL gain the human ear can hear

People repeat this a lot around here, but nope. Generally it's accepted to be 1 (ONE) dB. (Of course that varies with frequency, but the phon is 1 dB at 1K Hz as I recall, and that's the general reference point.)

It's a good thing too! If we had to gain 3 dB each time we were able to hear the step upwards in general amplitude, we'd need to add a lot more speakers and a lot more amp to get significantly louder! ...Actually, 3 dB acoustically, may be thought of as a significant but not earth-shattering increase - one that's roughly akin to adding a separate identical cab on a tube amp that can deliver the same output to either a 4 ohm or 8 ohm load.

And we all know you can hear that change.

and it takes about 10dB to double the volume (SPL).

That is generally accepted.

 

[Joe Louvar]

Thank you for the info, I&#8217;ll give it a test when I&#8217;m in the studio - I doubt I can hear a 1dB gain at 1kHz, but ok.

 

[greenboy]

Since the 1 dB figure was arrived at in research that was done a number of times over decades, with a lot of people, in well-constructed tests, well - whatever you will find out will indicate something about your hearing, but not for the majority of people ; }

 

[Joe Louvar]

I haven&#8217;t seen anything about this in Mix, Sound Pro, etc and I&#8217;ve been using 3dB as a rule for years - I&#8217;d like to see the research papers. In fact, I know a lot of people who would like to see them, do you have a link?

 

[greenboy]

Just the tip of the iceberg. References lead to references lead to pre-internet publications lead to AES papers as infinitum.

Human Hearing: Amplitude Sensitivity Part 1 &mdash; Reviews and News from Audioholics

I'm pretty much with the author's experiential summary of the info cited above, having had quite a few devices that calibrate in half dB increments, and being able to hear that increment at moderately low levels on a decent playback system, when the signal is some sort of broadband musical experience.

 

[greenboy]

Doesn't hurt to apply a little common sense to this (in addition to the tube head with a second cab identical cab example I mentioned above)... We certainly don't do all EQ adjustments in 3 dB jumps and multiples of 3dB, do we? I sure hope not. Even with average-Q signals a lot of good mixing EQ moves get done with smaller changes than that - and that's not even addressing the entire broadband signal, but just a portion of it.

 

[billfitzmaurice]

Since the 1 dB figure was arrived at in research that was done a number of times over decades, with a lot of people, in well-constructed tests, well - whatever you will find out will indicate something about your hearing, but not for the majority of people ; }

The dB was invented, by Bell Labs, though it was first called the MSC, later the TU, finally the dB in 1928. They tested hundreds of subjects and what they found to be the smallest deviation that the average person could hear they declared to be one MSC. Where it gets sticky is the testing was done to fit Bell's major concern circa 1900, telephone transmission, so the power curve was centered at 500Hz and 75dB. As soon as you deviate from that it no longer applies, the threshold being different at every frequency and level.

 

[projectMalamute]

??? Each additional "amp's worth of wattage" adds 3 dB from baseline, or +24 dB in your eight-more-amps example.

Each doubling of power gets you 3 dB. Assuming a speaker system that can make use of it.

twice the power gets you 3dB
four times the power gets you 6dB
eight times the power gets you 9dB

To get 24dB on power alone would take 256 "amps worth of power".