The future of preamps

The specs indicated in the manual for the Krell 700cx are 3.58 volt sensitivity (for its balanced input), 26.4 db gain, 700/1400/2800 watts into 8/4/2 ohms respectively.

26.4 db is a voltage gain of 20.89, based on db = 20log(Vout/Vin).
20.89 x 3.58 = 74.79 volts.
(74.79 squared)/8 = 699 watts into 8 ohms, corresponding almost exactly to the 700 watt rating.
Double that into 4 ohms (= 1398 watts), and double it again into 2 ohms (= 2796 watts). The results again correspond almost exactly to the rated power capabilities.

Ralph, I think you were right in the first place!

Concerning Keith's reference to "3.58 volts min," that is probably the result of a miscommunication. Sensitivity specs are usually neither min nor max, they are simply the (approximate) input voltage required to drive an amp to its rated maximum output power. And based on these calculations, that certainly appears to be the case here.

Regards,
-- Al

An additional point: The 700cx is spec'd as being capable of putting out a maximum output voltage of 84 volts RMS.

Based on the amp's voltage gain of 20.89x (see my previous post), that output voltage would be produced by an input voltage of:

84/20.89 = 4.02 volts.

Therefore if someone indicated to Keith that the amp can handle an input of 18 volts without clipping either what that person said was misunderstood, or that person misunderstood the question, or that person didn't know what he was talking about.

Regards,
-- Al

Keith- Meet Al, our resident technical analyst and voice of reason on all things electrical/quantitative. He's not a manufacturer or designer. He's kind of like our Spock but with a love of music ,a keen dispassionate "eye" for techno-babble, and a willingness to help all of use non-EE types understand some of the basic science, math, and engineering behind things audio.

Swamp, you speak for many of us on this site in regards to Al.
Charles,

Keith- I hope you were not offended. I know how foolish I once felt when I tried to explain to a client how difficult and expensive it would be to build a certain type solution to a coastal erosion problem he was facing, only to find out later that:
1. the guy was one of the most experienced and competent architect/builders on the northeast and
2. he had more $ than god!
3. he was too much a gentleman to tell me either.