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Power Amp Doubling Output at 4 Ohm

Hi, all,

Another random musing. From time to time, I see ads that mention such and such power amp can double its output from 8 ohm to 4 ohm (and even double again from 4 ohm to 2 ohm). To me, this does seem to be a highly desirable, quantifiable, quality. I don't know anything about the engineering behind equipment design, so here is my question. Is this an important parameter to you? If not, why not?

Thanks for your inputs.
millicurie999
gregm
3,410 posts
 
It is important in that it's an indication of a robust power supply (and PS are an expensive part of the amp).

However, please note that doubling is not really possible, for a number of tech reasons. This does NOT mean that manufacturers quoting doubling are fraudulent!

What you do is, officially spec your amp at 8ohms for less than max output, which will allow the arithmetic to hold true to specs. Please note that amps capable of dealing with difficult loads (i.e. low ohm loads) are considered good designs and trustworthy.
foster_9
1,638 posts
 
Is this an important parameter to you? If not, why not?
It only became important to me when I recently bought my first pair of inefficient speakers that are a difficult load. (4 ohm 82-87db). Before these speakers, I never paid much attention to amps that double power.
allenwright
17 posts
 
1/ Realise that this concept ONLY applies to solid state amps - a tube amp delivers it's maximum power into the rated impedance, and less as the impedance climbs or drops.

2/ If the SS amp is well designed, with a decent sized powersupply and enough output devices, it SHOULD double it's 8 ohm power into 4 ohms.

Regards, Allen (Vacuum State)
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