|
Bronze Member Username: BabaUnaIndia Post Number: 26 Registered: Mar-05 | just wondering we have amps giving out 75w per channel, but when we read the specs, 1. signal to noise ratio one says 92 db, other says 76 db, ( any rule of the thumb as to which is better). 2. in high/low pass slope, one says 24 db/oct, whileother say 12 db/oct... again any hard and fast rules.. |
|
Gold Member Username: N2audioLawrence, Ks USA Post Number: 1268 Registered: Mar-04 | higher S/N is better, theoretically. But those numbers really don't tell you much unless you know how they were taken. They can be taken at 1w, they can be taken at rated power -- for all we know they could be made up. What it comes down to is - there's not an amp out there with an s/n low enough to be an audible issue. Slope is the rate at which the crossovers "roll-off" power. 24db is steep, 12 would be more of a medium slope, 6db is a relatively gradual roll-off. Let's say you have a 24dB/oct high pass filter set at 100hz, meaning below the crossover point the power is reduced quickly. At 50hz (one octave below 100hz) the power would be reduced to a small fraction, almost nothing if my math is right. At 75hz (1/2 octave) it would be roughly 1/16 of the power at 100hz+. With a 12db/oct hpf at 100hz. Power at 50hz would be 1/16, power at 75hz would be about 1/4. For that to really mean something to you you'd just need to do some listening tests. The differences would be subtle. Personally I can't distinguish much difference between 12 and 24. Besides, by adjusting the x/o point a bit you can get just about the same result from the two. Mathematically it seems drastic, but audibly it doesn't amount to much. |
|
Bronze Member Username: BabaUnaIndia Post Number: 27 Registered: Mar-05 | you right end of the day let the ear decide... know any good places in NY city to see some demo setups .... |
|
Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 11954 Registered: Dec-03 | S/N or Signal to Noise ratio reference links: http://en.wikipedia.org/wiki/Signal-to-noise_ratio signal-to-noise ratio (SNR): The ratio of the amplitude of the desired signal to the amplitude of noise signals at a given point in time. SNR is expressed as 20 times the logarithm of the amplitude ratio, or 10 times the logarithm of the power ratio. SNR is usually expressed in decibels (dB) and in terms of peak values for impulse noise and root-mean-square (RMS) values for random noise. In defining or specifying the SNR, both the signal and noise should be characterized, e.g., peak-signal-to-peak-noise ratio, in order to avoid ambiguity. The sSNR of car amplifiers today is below the threshold of human hearing, so this emasurement is of little use when comparing amplifiers. Factors such as slew rate, damping factor, and power supply voltage are more important in determining the quality of an amp. in regards to slope on crossovers (12/24dB) the steeper the slope (higher #) the faster the sounds drops off beyond the crossover frequency. see www.bcae1.com for crossover basics. |