Jeff Rowland
Al is right (as usual). This amp most likely uses PASCAL S-PRO2 class D modules. Data sheet shows minimum load of 2 ohms or 4 ohms when bridged. Bridging might create problems with your speakers gaining only about 20% of loudness. Not worth trying IMHO. http://www.pascal-audio.com/downloads/S-PRO2_Datasheet-1_20.pdf |
Ricred1, I stated 22% loudness increase, but it would be true for 2x loudness. I forgot that bridging doubles the output voltage, thus quadruples the power. In such case you can count on (substantial) 49% loudness increase. Speaker's minimum impedance remains the problem. L=k^(1/3.5) where L=loudness, k=ratio of power. L=4^(1/3.5)=1.49 |
Bombaywalla, You are right - not many amps quadruples or even doubles power exactly. I don't even care for the one that does, since in order for this to happen amp has to have hefty power supply but also lots of negative feedback. On the other hand listed power specification is useful only if you listen to sinewaves. Music demands very little power on average, since half of the loudness is 10% of the power and music has gaps. Heavy orchestral pieces might demand more power but Jazz trio needs very little. Maximum current is perhaps more important. Power specifications are very vague. It can be FTC, EIA, CEA or no standard at all. FTC defines amplifier's power when both channels are driven over full audio band 20Hz-20kHz for 5 minutes after one hour preheat at 1/3 of power and meeting listed distortions. EIA requires test at 1kHz and 1% THD without preheat for one channel only (not sure how long). CEA test requires 5 minutes at full power at 1kHz without preheat, while other channel is driven at 1/8 of max power (why 1/8 ???). Most of class D amps would not even pass FTC test, having very limited power at high frequencies. The only class D modules manufacturer I know that specifies full power bandwidth is PASCAL but it is useless anyway since music demands very little power at high frequencies, not to mention size of the tweeters. Most of manufacturers don't even specify what standard, if any, they use for testing. For instance Icepower module in my 200W Rowland model 102 is specified at only 55W FTC power limited to 0-8kHz with explanation "The power bandwidth is limited due to the output Zobel network". Continuous module power is listed in datasheet as only 40W @ 25degC and 25W @ 50degC. Bel Canto specified S300 and M300 amplifiers as 300W with the same Icepower module (200ASC). These modules can produce momentary power of 290W at 10% distortion and only at 230V supply. Useless specification but 300W looks better than 200W on the paper. |
