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A question about perceived loudness.

B

BassMan7530

May 2, 2009
117
0
#1
This has been on my mind recently, and I'm curious as to what the answer would be. I want to compare two hypothetical setups.

Imagine that you have two rigs. The first rig consists of an amp that puts out 500watts at 4 ohms and a 410 cabinet rated at 4 ohms. The second consists of the same amp, but has two 410 cabinets both rated at 8 ohms each (assume that all cabinets in this example can handle the wattage safely). So the way I see it (correct me if I'm wrong) is that the wattage is equal, but the second rig has twice the amount of speakers putting out that wattage.

So, if both rigs are putting out similar wattage and all other variables (such as EQ, the bass used, etc) remain constant:
A.) The first rig will be perceived louder than the second.
B.) The second rig will be perceived louder than the first.
C.) Neither setup will sound louder than the other.

More speakers makes me think that the answer would be B. Then again, it IS the same wattage, so I'm leaning mostly towards C being the correct answer. What does everyone think?

Thanks in advance for your input!
Brian
 
#5
Rick Auricchio said:
+1

Remember, it isn't just wattage that creates loudness. Sound is created by speakers moving. If you had a single speaker that could take all 500w, it would never be as loud as a pair of 410s.
Click to expand...

Not strictly true, as the speaker efficiency would come in to it. If the 10" speakers in the 410 were incredibly inefficient, and they were going up against a very efficient 15" speaker, then the single 15" would go louder.

But yes, as a general rule of thumb, the loudness of a rig is proportional to the total surface area of speakers.

S.P.
 
#7
If you assume that:

A) All speaker cabinets are the exact same other than the impedance difference (i.e. same efficiency and response etc.).
B) All speaker cabinets can handle the power given without reaching their limits.

Then the setup using two 4x10s will be ~3dB louder.

It will seem louder still to you because it will also be closer to ear level.
 
#8
stylonpilson said:
Not strictly true, as the speaker efficiency would come in to it. If the 10" speakers in the 410 were incredibly inefficient, and they were going up against a very efficient 15" speaker, then the single 15" would go louder.
Click to expand...

Granted, but I'm assuming reasonable speakers, not comparing crap against great stuff.

There's also the cab design, but in the absence of all these details the general rule-of-thumb applies: More speakers = more loudness.
 
#11
An approximately equal-loudness scenario would be 500 watts into a single 4x10 vs. 250 watts into two 4x10s (assuming identical 4x10s). Actually in this situation several factors would play against one another, but I think the 250 watts into two 4x10s would be louder real-world mainly because the single cab would compress and/or fartout.

Most amps I'm aware of that deliver 500 watts into 4 ohms actually deliver about 300 watts into 8 ohms.

Anyway the question was 500 watts into a single 4 ohm cab vs. 500 watts into two paralleled 8-ohm cabs. In that scenario the latter would be about 6 dB more efficient [edit: mohawk is correct; should be "3 dB more efficient"], and at high levels compression and/or fartout of the single cab would make the maximum output difference even greater, perhaps as much as 8 dB [should be "5 dB'"] real-world.
 
#14
"perceived loudness" Changes with how loud something actually is.
http://en.wikipedia.org/wiki/Equal-loudness_contour

When things are quiet - your ears are less sensitive to bass frequencies.
When things start getting loud - things even out more across the frequency band until you go deaf. But you will not get to turn up when things are quiet. The first thing anybody will complain about is the bass is too loud.

"Percieved loudness" also depends on how far away you are. Think about being outside 1/2 mile away from a band. You'll hear the bass. When you get audience position it will sound evenly mixed. Bass pressure waves are more resilient to distance than higher frequencies that get absorbed. Mids and highs have controlled dispersion in the first place, focused in front of the band. The majority of the times bass players complain they can't hear themselves it's because the mids are beaming by their legs and not getting to their ears.

If you were getting equal SPL and frequency response out of one cabinet, and another rig with two stacked cabinets - the two stacked would be perceived louder because you have mids up closer to ear level.

In the end "perceived loudness" is how it sits in the mix. You're going to have to trust the sound engineer out front, or your musician audience friend letting you know how it sits in the audience. If you've got some other instrument walking over the frequencies you're trying to carry - your loudness is going to be affected. It depends if you're playing by yourself, or in a band and with what instruments. KB players, and 7 string guitarist always get in the way.
 

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