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- and + values with volume

 

Bronze Member
Username: James_the_god

Doncaster, South Yorkshire England

Post Number: 45
Registered: Jan-05
Id like someone to explain to me what the - and + values in volume mean. Ive seen in many shops on the amplifiers lcd display the volume which starts at 0 then can go up and down. I can't remember whether the + is a higher volume which logically I think it would be, but if so, then how can it go below 0 into the minus? Wouldn't this logically mean no sound at all?
 

Bronze Member
Username: Touche6784

Post Number: 90
Registered: Nov-04
the logic i think is that at level 0 you are getting the maximum wattage from you reciever. remember that sound loudness in measured in decibels(dB) which is a logrithmic scale meaning the actual difference between loudness of 12 and 14 is not by two but by 100 very much like the pH scale. so a decibel level of 0 can is actually 10^0 which equals 1, same with pH a pH of 0 actually means a H+ concentration of 1.0M. when you are raising the volume over 0 you are potentially going to clip the signal but the reciever can still push on. this is similar to recievers with just the dial, you never go over half volume, reason being that at about halfway up you are reaching the clipping point of the amp. i believe that at -20dB you are using 1% of your total wattage, i may be wrong though. atleast i think this is what applies to my reciever from what i understood reading another thread a while back. sorri about the chemistry analogies, i am a chem major.
 

J. Vigne
Unregistered guest

Numbers are just numbers and mean nothing other than being something the manufacturer gave you to amuse yourself with. The actual taper of the volume control is different from control to control. On a simple knob type pot, the taper can be linear or log scale. Most controls are log scale which gives more volume at the first half of rotation. This is great when the young listeners come into the shop in packs and look at the amplifer that is blasting away on the showroom floor and think, "Wow, that amp's really powerful; you only have to turn it up to 9 O'Clock and it's really loud." This idea is absolute trash since the log scale control will be out of usable volume by the time it gets to 12 O'Clock. A linear scale control gives the same amount of increase in volume over its entire range. This is a control where each click of a detent will amount to a 0.5dB increase in volume given a (typically) 1 volt input. The output votage of the pre amplifier is also dependent upon the input voltage to the pre amplifier. If one CD player outputs 2 volts max the pre amp will reach full output at a higher rotation than if a CD player that outputs 3 volts is connected. As long as the pre amp and power amp can reach full voltage output, it doesn't matter where the volume control is set to actually reach that voltage. LED type displays tied to a volume control are at the manufacturer's discretion as to what the numbers actually mean. Some manufacturers still like the idea that the group of potential young buyers will be impressed with the amount of volume a receiver can produce with the display reading -30dB. Another manufacturer will prefer to give themself some headroom and the amp won't reach clipping with a rated voltage input until the display reads +10dB. In either case the amount of volume is more dependent on the efficiency of the attached speakers. As long as the amp isn't driven into clipping it doesn't matter what the numbers on the front panel indicate.


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