Sensitivity

[cLepto-bass]

I did trying looking to see if this topic had been covered but couldn't find a definative answer.

Basically can someone help me understand 'sensitivity' of cabs.

I'm looking into getting my self a small rig, maybe Aguilar GS112's or EBS Neo-112 etc but just want to make sure I understand what I am getting with regards to the sensitivity of the speakers and what is good or bad.

So if someone could explain the principle to me that would be greatly appreciated.

Many thanks

[Stylon Pilson]

Sensitivity is, more or less, the efficiency of the speaker cab in converting watts (electrical energy coming from the amp) into decibels (sound energy flattening the punters).

Edited to add: manufacturers' specified sensitivity levels are generally all a big pile of nonsense. Don't trust them.

Is this the answer that you were looking for?

S.P.

Edited October 29, 2009 by Stylon Pilson

[alexclaber]

You don't hear watts, you hear dB SPL. Sensitivity is the measure of how many dB SPL you get out for 1W input. With 10W input you'll get 10dB more, with 100W input you'll get 20dB more, with 200W you get 23dB more, 400W 26dB more etc. With a bass cab the low frequency (LF) sensitivity is determined by a combination of cab size and low frequency extension (-3dB and -6dB points). The larger the cab and the higher the -3dB & -6dB points, the more sensitive it can be in the lows - this comes down to physics and no amount of money will allow you to beat this. However the dominant limitation in the lows is the real world power handling (usually a fraction of the quoted power rating), so two cabs of equal size and LF sensitivity could have very different max LF SPL.

HOWEVER (and this is worth of capitals!) most manufacturers do not quote an honest sensitivity figure. Aguilar have been very honourable in changing the sensitivity spec on the GS112 to 95dB (after I pointed out to Dave B that their previous claim of 102dB was impossible) but many manufacturers persist with claims which are so outrageously far from reality that if they were true no-one would bother with big PA systems for stadium gigs, they'd just use a handful of bass cabs!

I've spent a looooong time trying to work about a good way of explaining my cab specs so they are transparent and the solution I've come to is to quote multiple figures - one for LF sensitivity (basically the sensitivity at ~100Hz), one for broadband sensitivity (basically the average sensitivity between ~200Hz and 2kHz) plus the two related power handling limitations (peak LF excursion-limited and continuous thermally-limited). If you look at my various models you see that those that go loud but are small compromise on the lows, whilst those that go lower compromise on the loudness, whilst those that are larger manage to be both loud and go pretty low. You can get deeper lows by adding bass boost on your EQ - but by doing this you are effectively adding extension by lowering sensitivity - no such thing as a free lunch!

Have a look at the attached chart to see how these specs interact.

Alex

Edited October 29, 2009 by alexclaber

[cLepto-bass]

Thanks alot guys. Your words of wisdom are appreciated.

That is just what I was after.