Watts and power

No two 200wpc amps are the same. It has to do with-current.  A
200wpc Class D amp may only put out 27 amps of current per channel, while a 150wpc Odyssey Class AB amp puts out 60 amps of current per channel.  Guess which amp sounds more powerful?

27 amps is 1500 watts into 2 ohms. 60amps is 7200 watts. 60amps would require a bus voltage of 120V at 2ohms, phase-angle aside. I think the number of speakers that drop below 1.5 ohm approaches a handful and even the number that drop much below 2 ohms are uber expensive and won't be matched with a $1,500 amplifier. 60 amps at 1.5 ohms requires a 90V bus voltage (approx). Odd of the odyssey amplifier having a 90V bus supply are pretty much 0. Given it's power rating, it is much more likely to be close to 35-40V.  That 60A specification is pretty meaningless ..... not to mention 60A would drag down the power supply capacitors pretty seriously, further limiting the practicality of delivering this much current.

Tube-amps sometimes "seem" more powerful as their distortion is typically more pleasant when they clip, but they are still clipping.

After a lot of listening and reading speaker specs here is what I feel to be true:

Amps, including solid state, are a lot more susceptible to low impedance in the bass region than we should expect by the common mathematical models.


If you have a speaker that dips below 4 Ohms in the 150Hz or lower region, that is a speaker I'd expect to come out as more "discerning" of amplifier gutsiness. You can also call that speaker more challenging, and less amplifier friendly. I've even seen speaker manufacturers deliberately make their speakers dip in this region, I suppose that the idea was that by dipping the speaker would be called more transparent, because you can hear the quality of different amps. I don't know why they did it, but i know they did.

I also think this is why cables seem to matter. Amps are more susceptible to variations in impedance than we think.

Most tube amps don't have "guts" in the bass due to low damping factor. You may prefer that or you may not and that will be room / speaker dependent. 


That dip in impedance is a factor of woofer electro-electromechanical properties and sometimes a 2.5/3.5 way folding in another driver. Crossover may shunt current from woofer to tame a peak.