2. amps-preamps
  3. 181516-144057

Do Amps matter.. in an Amp?

I have Magnepan speakers, and have tried dozens of amplifiers. I do find they sound quite different with different amplifiers. Tubes, class D, and A/B may be where to see some trend but lately I’m stuck on amperage. Most product tout wattage, which I find misleading since the highest wattage amp I own has the least satisfying sound. My favorite amplifier claims >60 amps of current, and a few manufacturers state this measurement. But most don’t. Is it significant? What does max amperage mean compared to the damping factor or the wattage change into different loads? Seems like an easy engineering question but I don’t see it discussed very often. 

dain
fuzztone's avatar
fuzztone
5,638 posts
 

I would suggest reaching out to Chris Brunhaver for power/speaker interaction answers. Or Ralph. He answers the phone.

kijanki's avatar
kijanki
4,443 posts
 

Your amp would likely need that much current to drive difficult load, but 60A current thru 1ohm load produces 3600W  !!!   These numbers might reflect good power supply, but have nothing to do with reality.  As for damping factor - the easiest way to reduce output impedance is to increase negative feedback leading to, in extreme case, Transient Intermodulation Distortions (overshoot in time domain).  40dB of negative feedback will reduce output impedance 100 times.  Membrane motion damping is limited to DFmax=1.5  anyway, since speaker's resistance is in series.  We don't want to make it much worse, so output impedance should be at least 10x lower than speaker's impedance.   Output impedance might be important to produce constant voltage (voltage source) under changing output load, but again many tube amps have higher output impedance and sound fine. 

 
Assuming competitive market 100W amplifier should sound better than 200W amplifier if they cost the same and you don't need 200W.  Cost of larger heatsinks, bigger transformers, stronger transistors etc. can be used for better components and design.

erik_squires
16,554 posts
 

In theory, an amplifier with high current output capabilities is less affected by either the speaker or the music played before, but even this measurement can be greatly misleading. Is it peak current? Sustained?  Equal across all frequencies or only in the bass? 

 

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