High current amp search

My philosophy is that since it is the speakers that shape a system’s end sound, they come first.

Selecting speakers based on impedance is like picking a movie based on which snacks the theater’s concession carries. Go that route and you may see a great movie, if you’re lucky.

You may find that the speakers whose sound pleases you most have a nasty impedance curve. Don’t go oh snap and look for different speakers; just limit your  amp auditions to suitably powerful candidates, and add a generous margin for headroom.

@atmasphere you are right about power vs current, of course. Ohm’s law tells us that I=V/R, (current equals voltage divided by resistance); therefore if a) voltage is constant, and b) impedance (resistance for all intents and purposes) drops by half, then current has to double, and so on.

So, if I’m not mistaken, if you’re pushing, say, 50V into an 8 ohm load, that’s 6.25A of current and 312.5W of power. That would amount to about 100 dB SPL from a 85 dB (in)efficient speaker.

50V into 4 ohms: 12.50A and 625W

50V into 2 ohms: 25A and 1250W

50V into 1 ohm: 50A and 2500W

Note that loudness is the same in all four examples above.

The rise is limited by how much current the power supplies are able to deliver.

There are high-current amps out there. Here is a quote from the Stereophile review of the Krell FPB-600:

Driven on a toneburst equivalent to peak program duty at 8 ohms, it reached to touch the 1kW line, while at 4 ohms it attained 1.85kW, and for 2 ohms 3.53kW. And for 1 ohm—wait for it—an amazing 6kW! These are single-channel results, but, measured as short-term ratings, they should be available from both channels simultaneously.

The complete measurements are here. The numbers are so insane it’s worth the read.

https://www.stereophile.com/content/krell-full-power-balanced-600-power-amplifier-measurements

Benchmark AHB2.  Stable down to 2 ohms at 259 WPC.  Amazingly clean neutral sound.  New for $3499.  

I have the krell fpb 600 and 700 cx and they are great

They do need to be gone through every 7 to 10 years and that's the only drawback. Happy hunting. The hegel h 30 is up there as well but so is the price

I don't get where people associate a speaker's efficiency with being a benign load or easy to drive. You all need to read more test bench reviews of currently popular speakers. For instance, Wilson Audio who's speaker's garner well above average efficiency ratings but are egregiously difficult to drive and require very stable high current amplifiers because their impedance drops to 1ohm or less in the bass. On the other hand, you could look at an ATC SCM19 v2 which about 83dB efficient but because of it's design has a very flat impedance of about 5 ohms across it's frequence range with the exception of a very large peak of about 50ohms at it's bass resonance. You would think it's very easy to drive. Another example would be any speaker from the Klipsch Heritage series who's impedance in the bass routinely drop to 2ohms or lower and have very notable rises and drops further up the speaker's frequency response but for the fact their efficiency is so uncommonly high they don't impose an undue demand on amplifiers. We're talking microwatts here to achieve very high sound pressure levels!  

You might want to look into an Anthem P2 amp it will drive any speaker and it goes down to below 2 amp loads with no problem.