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In Reply to: Re: Need help understanding/comparing Amps specs (Gain) posted by SteveLim on March 3, 2007 at 08:53:34:
...nor tell him how to do it correctly.Steve, the gain of an amplifier is usually calculated using only the input and output Voltages. This is actually a misuse of deciBel, which is a ratio of 2 POWER, not Voltage, amounts, but it's easy to do, and, more importantly, it works.
First the output voltages.
A. 200 Watts into 8 Ohms is 40 Volts (using the formula V(squared)/R. The ratio of Voltages is then 40/1.68, and 10 times the base-10 Log of that is 24.8, so this amp has 24.8dB of Voltage gain into 8 Ohms.B. 300 Watts into 8 Ohms is 49.0 Volts. The ratio of Voltages is then 49/1.8, and 10 times the base-10 Log of that is 25.8, so this amp has 25.8dB of Voltage gain into 8 Ohms.
So the prospective amp has 1dB more gain than your amp, which you may not even notice if your volume control is continuous and not stepped. BUT...it's going the wrong way if I understand you correctly...that you want to be able to use the volume control at higher rotational positions. Yes?
PS. I use an Excel spreadsheet to calc the Log numbers. You too can. :-)
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
Follow Ups:
Thanks. Very much clearer now about the gain differeces.Yes, i will be giving it an audition before i buy it.
Just that before i buy , i wanted to make sure the gain of the new amp isn't higher than the current amp. So i won't end up not able to use the amp with my preamp, and end up changing even more things. Thanks again. :-)
... and I was concerned that too much emphasis was being placed on the gain and not enough on how the two amps sounded. I've met too many people that have fallen into that trap and regretted it.So, if one believes that someone plans to jump off a cliff, is it wrong to point out a bench to sit on some 50 yards from the cliff-edge and better to explain to them how to jump off?
:-)
Thanks too Devil for your help and advise regards taking care of the sound quality by listening to it.
Yes, i have every intention to audition it.
Just wanted to make sure the gain compatibility was not worse off than my current amp , so that i don't end up cannot use it my my preamp and current setup. :-)
And of course gain has nothing to do with sonic quality, but we're not that far yet.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
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