stratman50th
November 17th, 2006, 12:44 PM
Tube amps do SOUND louder regardless. What we're talking about is not power but loudness, which we percieve with our ears. There are two factors at play here... the first is summed up nicely here (quoted from Geofex, a great amp/effects site).
"...the tube amp does indeed sound louder to your ears, in opposition to what the meter is telling you. Why?
It's tied up in the sensing instrument - that is, your ear. The way the human ear works is that it is very sensitive to the harmonic content of a sound. A tube amp is less linear (that is, has more distortion) at signal levels below clipping than a solid state amplifier. The distortion will increase slowly, and then more rapidly as the amp starts to clip. In fact, the distortion increases so gradually and is of such a benign nature that the onset of audible distortion has no easily defined threshold. The solid state amplifier on the other hand has no such gradualism. It is almost perfectly non-distorting right up to the point that it clips, and then it clips HARD. It's easy to hear the threshold.
This sudden onset of distortion is also composed of relatively harsh sounding distortion, not like the subtle second and third harmonics of the tube amp. The human ear hears the sudden harsh distortion as clipping and harshness. It interprets the low order distortion of the tube amp as a louder sound, not as distortion. In effect, the tube amp fools the ear into thinking that its early distortion is more loudness. They therefore sound louder or more powerful than the actual measurements show are really there. "
So, basically the tube amp as you turn it up adds harmonic distortion which we hear as more volume, where the solid state amp doesn't sound any louder, just more distorted.
The second factor is this... the speakers. Usually tube amps are paired with much more efficient speakers. The classic example as mentioned earlier in the thread is the vox ac30. The reason those are so loud, aside frm the fact that they're tube amps, is that the speakers are extremely efficient.
When you double the power of an amp, you get a potential gain in volume of 3db. A 100 watt amp is potentially 3db louder than a 50 watt. So, if you take the same 30 watt AC30 head and put it through a speaker cabinet that has 3db less efficiency, you have effectively cut the loudness the same as if you'd went down to a 15 watt amp. Likewise, if you get a speaker that is 3db louder, you have increased the volume the same amount as if you'd went up to a 60 watt head.
One of my favorite amps I ever built was a 5 watt single ended Champ clone. I put an extremely efficient 12" speaker in it and as a test, everyone who played on it had to guess the wattage. Without fail they guessed between 30 and 50 watts. Why? Because it was as loud as a 30 or 50 watt amp to their ears, and it was. It was still putting out 5 watts of POWER, but the loudness was much greater than you'd expect, and that same little amp was MUCH louder than say a Roland Cube60 or similarly powered solid state amp.
You generally have to have 3 times the power in solid state amps to equal a tube amp in volume. That's why there are so many people who buy 100+ watt solid state heads and can't hear themselves over a drummer, while people like me and many others here gig with 20-30 watt tube amps.
Another thread for Trade Secrets. Thanks JimmyBlood! :thumbs:
"...the tube amp does indeed sound louder to your ears, in opposition to what the meter is telling you. Why?
It's tied up in the sensing instrument - that is, your ear. The way the human ear works is that it is very sensitive to the harmonic content of a sound. A tube amp is less linear (that is, has more distortion) at signal levels below clipping than a solid state amplifier. The distortion will increase slowly, and then more rapidly as the amp starts to clip. In fact, the distortion increases so gradually and is of such a benign nature that the onset of audible distortion has no easily defined threshold. The solid state amplifier on the other hand has no such gradualism. It is almost perfectly non-distorting right up to the point that it clips, and then it clips HARD. It's easy to hear the threshold.
This sudden onset of distortion is also composed of relatively harsh sounding distortion, not like the subtle second and third harmonics of the tube amp. The human ear hears the sudden harsh distortion as clipping and harshness. It interprets the low order distortion of the tube amp as a louder sound, not as distortion. In effect, the tube amp fools the ear into thinking that its early distortion is more loudness. They therefore sound louder or more powerful than the actual measurements show are really there. "
So, basically the tube amp as you turn it up adds harmonic distortion which we hear as more volume, where the solid state amp doesn't sound any louder, just more distorted.
The second factor is this... the speakers. Usually tube amps are paired with much more efficient speakers. The classic example as mentioned earlier in the thread is the vox ac30. The reason those are so loud, aside frm the fact that they're tube amps, is that the speakers are extremely efficient.
When you double the power of an amp, you get a potential gain in volume of 3db. A 100 watt amp is potentially 3db louder than a 50 watt. So, if you take the same 30 watt AC30 head and put it through a speaker cabinet that has 3db less efficiency, you have effectively cut the loudness the same as if you'd went down to a 15 watt amp. Likewise, if you get a speaker that is 3db louder, you have increased the volume the same amount as if you'd went up to a 60 watt head.
One of my favorite amps I ever built was a 5 watt single ended Champ clone. I put an extremely efficient 12" speaker in it and as a test, everyone who played on it had to guess the wattage. Without fail they guessed between 30 and 50 watts. Why? Because it was as loud as a 30 or 50 watt amp to their ears, and it was. It was still putting out 5 watts of POWER, but the loudness was much greater than you'd expect, and that same little amp was MUCH louder than say a Roland Cube60 or similarly powered solid state amp.
You generally have to have 3 times the power in solid state amps to equal a tube amp in volume. That's why there are so many people who buy 100+ watt solid state heads and can't hear themselves over a drummer, while people like me and many others here gig with 20-30 watt tube amps.
Another thread for Trade Secrets. Thanks JimmyBlood! :thumbs: