2. amps-preamps
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Driving 1 ohm

Hi,

I'm actually driving my recently refurbished Acoustat 2+2 electrostatic speakers with a Conrad Johnson MF 2500A. My Acoustats have been completely modernized with new more rigid frame, new electronics in the interface, Medallion transformers and other tweaks.They really get down low with a lot more dynamics than before.

A lot of electrostatics owners will often chose pure Class A amplifiers to drive the load these speakers command. The 2500A plays beautifully and doesn't get very hot at the task.

My question is : am I slowly damaging the amp without noticing it ?
andr
rwwear
2,904 posts
 
It depends on how loudly you play the amp.
andr OP
109 posts
 
Thanks Simon !

Rwwear, not very loud, we can still speak at normal level while playing music. Most of the time, below half the volume dial on the preamp. But.......even at a moderate volume level, on good recordings, the bass level will drop at a point that a vibration sometimes continuous, can be felt. Those speakers are really something else now. And it is specifically that kind of effect that makes me cautious about the amp.
bombaywalla's avatar
bombaywalla
1,958 posts
 
Well, depends.
Ask CJ if your amp is rated down to 1 Ohm &/or meant to drive 1 Ohms loads. Most amps in the market are not & even if they are, they sound like crap!
If it's rated down to 1 Ohm & meant to drive 1 Ohm then CJ should have provided adequate heat-sinking & an able power supply.
Otherwise, the amp would clip & the power transistors would saturate thereby degrading them over time.
Further, there are 1 Ohm loads & then there are 1 Ohm loads. How benign is your 1 Ohm load? Is there lots of phase shift in the 200Hz - 8KHz region? If yes, then your amp is being pushed pretty damn hard. If there is minimal phase shift, say, 10 degrees, then your amp is not being pushed hard. It's still driving a very low impedance but it does not have to provide too much power/current to drive the reactive load in the speaker x-over.
The amp-speaker interface is dynamic over 20Hz-20KHz so there is no fixed answer - all depends on how "nice" your speaker is being to the amp. Plus, as Rwwear pointed out, how loud you are playing your music.
spiritualized
138 posts
 
Check out FM Acoustics line of power amps.
andr OP
109 posts
 
Thanks Bombay,

Actually, I didn't ask CJ, but I saw a reply they gave a few years back to a same inquiry about an Evolution 2000. CJ answered it wasn't designed for 1 Ohm without beeing specific if it was damageable either. That is why I am first asking here.

Your giving me figures, I appreciate. I'll have to check it out with one of my buddies who is familiar with such specifications. But it doesn't clip, that is for sure. And it doesn't get very hot, but does this also means that I'm not overriding the power transistors.

I feel reassured about the answers, thanks to all !
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