Jeff, nice to see you have bought a UR Pulley as being it's in your sig. Now you just need to make an appt. at a local shop to have it installed then to the dyno .

Rick

 

Jason, I'm sure the RT cats are awesome--I may get them at some point. But your statement about humans starting to notice loudness differences at 3dB is patently false. Humans with good hearing can notice loudness differences at a fraction of 1 dB.

Keep in mind that if X is 10dB louder than Y that means it is TWICE as loud. So 80db is twice as loud as 70dB.

--Steve

 

Those of you into car audio can learn something from this when it comes to your amp's power and getting more "volume" out of your system.

(I went to school for audio engineering and spent 2 years in audio technology and acoustics classes...)

From the article "dBs Made Simple" by Herman Burstein in Audio Magazine January 1975

from the = "How loud is a Decibel?" section

For most program material, such as rock, pop, or classical music. a Power increase of 1dB - to 1.26 times its starting level - tends to be inaudible. It has been observed that volume must be increased about 3dB in order for the human ear to have a definate impression of an increase in loudness. Even so, a 3dB volume increase produces only a slight rise in apparent loudness.

Yet 3dB represents a doubling of power. The lesson is that great increases in power are required to produce substantial increases in apparant loudness. If one considers a 30 watt amplifier to have insufficent power and replaces it with a 60 watt amplifier of otherwise equal quality, one can achieve but a slight rise in maximum undistorted sound level. For a hefty lift in sound level, one might have to go to an amplifier of 300 watts or more. This would amount to a 10dB increase over the 30-watter. yet still would not permit a "great" change in apparent loudness. A rise of 10dB sounds to the human ear more like a doubling of the sound level than like a multiplication by 10.

The decibel appropriately describes how the human ear responds to changes in acoustic level. The ear interprets equal increases in decibels as approximately equal increases in apparent loudness. Going from 1 watt to 2, from 2 to 4, and from 4 to 8 - in each case an increase of 3dB, or doubleing of power - tends to sound like a series of equal increases in loudness. But going from 1 watt to 2, from 2 to 3, and from 3 to 4 - in each case an increase of 1 watt - would sound like successively smaller increases in loudness. The increase from 3 watts to 4 might well be inaudible. Not long after an increase of 2 watts would be in audible; then one of 5 watts.

 

Well I ordered the Ur pulley and in the next couple weeks its the Crawford Plenum or Random Hi flo's....still unedecided.