Wall of Sunn

[JoeArthur]

First of all, individuals vary in their ability to detect volume differences. All of us vary in this ability depending on the frequency of the sound.

With that said, in general, one decibel is usually described as the smallest change in volume that can be detected - but since a decibel is a fixed unit, it ignores the frequency dependent nature of our hearing.

When talking about power, a 3db increase represents twice the power of the original reference and a 3db decrease represents one half the power of the original reference. A 10db increase represents ten times the power of the original reference, and a 10db decrease represents one tenth the power of the original reference.

Acoustically, we perceive a 10db difference as either twice or one half a difference in volume. So, if we want to double our perceived volume we need to increase the power output by a factor of 10. A 100 watt output sounds twice as loud as a 10 watt output. To sound twice as loud as the 100 watt output, we would need 1000 watts.

Can you hear a 3db difference? Barely. If you have an amp with 4 output tubes, take out two of them (the two outside tubes to make sure since pairs on the same side of the output transformer are usually arranged this way). Now your amp will produce roughly 1/2 the power - a 3 db decrease in output volume.

It won't be that easy to hear a difference. I have an Acoustic G100T that does this with a half power switch that cuts out two of the output tubes. Operating with four tubes sounds like the bass has been boosted very very slightly over two tube operation.

That's why instead of increasing wattage capacity, it's normally more effective (cost wise) to increase volume by using more efficient speakers. And why I personally avoid high wattage handling in my speakers - with those speakers that handle 300 to 600 watts, the trade off is a loss in efficiency requiring more watts to make up for it to keep the output volume the same. It's kind of like the dog chasing it's tail.

[Isaac]

Hey Isaac, can you explain once more about the Db thing. I have always heard that a 3Db increase is an apparent doubling of volume. Once you get up into the hundred Db range...twice the apparent volume is a large increase. One of the reasons JBL D series work so well for the 100 series Sunn amps is that they are at least 3Db more efficient than most any other speaker...so they sound much louder. I can tell the difference in volume that going from the 916SPL speakers in my 215 cabinet to a pair of 140's made. Hugh in my ears.
I know there are some major simplifications and very probably some cross connections that aren't completely valid. I seem to recall you wrote a great explanation a few months ago...but I can't find it now. In any case, I would think one could discern the 3DB increase easily. But then again…even at 52…I learn something new most every time I sign onto this site.

No, 3dB is a doubling of power. 10dB is an apparent doubling of volume, but it's also a decade increase in power: 10 times as much. 3dB was determined as a noticeable change in volume. More recent research shows that we can perceive differences as small as 0.1dB, using identical test signals, but it's perceived only as a difference, not as a difference in volume. interestingly, louder is usually perceived as better. That's why lots of stereo stores will kick up the volume on cheap, high-margin components. Being slightly louder, they're perceived as sounding better, and the store makes more money.

So yeah, an aparent doubling of volume really is a big deal, and can be hard to accomplish when the levels are already high. Ten times the power causes all sorts of potential problems, from power compression in the drivers to cllipping amps to burning out components. It was really tough in the old days, when 60 watts was quite a bit of power, and about all most drivers could handle.

[Isaac]

I once pulled two of the power tubes on my Model T, hoping to be able to crank it up for power tube distortion at relatively low levels. Couldn't really hear any difference at all. Hard to A-B, though, and I was looking for a big difference, not a subtle one.

I was disappointed, but, hey, I was young. I got over it.

[EdBass]

First of all, individuals vary in their ability to detect volume differences. All of us vary in this ability depending on the frequency of the sound.
- but since a decibel is a fixed unit, it ignores the frequency dependent nature of our hearing.

+1
And that, IMO, is the most important factor to remember. It's easy to get caught up in specs, but the human ear is NOT an oscilloscope, and the ear is what determines good from bad sound/tone etc.

[basiklybass]

So how come I am never satisfied with the way my rig sounds?

Oh yeah...because I'm older now and can afford to keep playing with different stuff...G.A.S. and it is. Someday I too will have a Wall of Sunn ...... and probably still not be satisfied with the tone. I got enough volume as it is....for these old ears. But tone...that ever elusive tone....maybe a new guitar.......maybe if I just could get my hands on a......or what if.....