2. amps-preamps
  3. 148643-116481

Conrad Johnson ART amps - Watts at 8 ohms vs 4 ohms

I had always thought of the ART150 and ART300 as being a 150 watt and 300 watt amp, respectively. Recently I noticed that on their website they are in fact rated as 150 watts into 4 ohms, and 300 watts in to 4 ohms. I've read that in many cases what puts out 200 watts at 8 ohms, for example, will put out 400 watts at 4 ohms, 800 watts at 2 ohms, 100 watts at 16 ohms, etc.
In this case, it would mean the ART150 generates 75 watts into 8 ohms (150 into 4), which does not sound right.
Can anyone shed some light on what these amps put out at 8 ohms? Would be appreciated. Plan on asking CJ directly as well and will certainly report back what they say, if it's of interest to anyone.

https://conradjohnson.com/art150-and-art300-amplifiers/

150 Watts rms per channel from 30 Hz to 15 KHz at no more than 1.5 % THD into 4 ohms (also available connected for 16 ohm loads)

300 Watts rms from 30 Hz to 15 KHz at no more than 1.5 % THD into 4 ohms (also available connected for 16 ohm loads)
gmercer

Showing 1 response by erik_squires

erik_squires
15,647 posts
 
The transformer is part of the issue. It boils down to effective output impedance.


Think of it as a resistor in series with the speaker. As the speaker impedance drops, more of the amp's voltage appears at the amp output stage, instead of at the speaker.


Solid state amps tend to be better by using lower output impedance devices, more of them, and feedback at the output stage.


Tube amps use output transformers because of the excessively high output voltages. In the hundreds of volts, vs. what's needed at the speaker.


I did read of a very interesting design, which used tube amps directly coupled to an ESL,which love high voltages.
More to discover