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Same watts at 8 and 4 ohms?

I'm in the market for an integrated amp and trying to sort through tech specs. My understanding of the tech aspects of hi-fi gear is limited. Looking for some clarity in regard to watts-per-channel specs.

It is my understanding that wpc at 4 ohms is typically 1.5x -2x the wpc at 8 ohms.

But I'm seeing a number of respectable mid-fi integrateds with the same wpc for both 8 and 4 ohms. The NAD 388 is one and I think this is true for several of the Cambridge Audio units at a similar price point ($1500-$2000).

The NAD features make a point of saying " 4-ohm stable for use with a wide range of speakers". 

Would appreciate any insight to what these specs mean and what 4 ohm stable really means to me. My speakers are 4 ohm speakers.

Thanks,

George
n80
cakyol's avatar
cakyol
940 posts
 
atmasphere,

You are right in saying that the internal impedance of an amplifier must be way less than the speaker impedance, in order to deliver power indirectly proportional to the speaker impedance. I took that as a given, since that is the case with most amps these days. However, if the supply line starts collapsing under the extra load, it will never be able to deliver the extra power, no matter what other parameters are tweaked.
georgehifi's avatar
georgehifi
10,312 posts
 
This statement is false
This ’doubling down’ thing is mostly marketing and **waaaaay** overplayed.
This is the false statement, and is the typical statement of amp manufacturers that can’t double down with their amps.

However, if the supply line starts collapsing under the extra load, it will never be able to deliver the extra power, no matter what other parameters are tweaked.
Not just the supply, but the whole output stage as a well.

Use this comparison analogy
A 3000w Behringer https://djcity.com.au/product/behringer-nx3000-power-amp-with-smart-sense/?gclid=EAIaIQobChMIsLTX0viJ6wIV3sEWBR0v2w9eEAQYASABEgK3DvD_BwE
Verses
Old 25w ML2 monoblocks, https://img.usaudiomart.com/uploads/large/2229206-5c605986-mark-levinson-ml2.jpg
Both into a pair of the worst speaker loads known, the Wilson Alexia, but still very efficient at 90db, just a horror load.

To a given volume level the 25w ML2 will walk all over the 3000w Behringer for sound quality, control, image and depth.

Cheers George
n80 OP
2,116 posts
 
Well, the Bryston sold. So at this moment I’m listening to the 6Ts in a bizarre little system.  Sonos Connect into Classe’ AV preamp into old Onkyo home theatre amp. Amp and pre on bypass. It is 75w into 8 and god-knows-what into 4.

It is certainly a reflection of my lack of audio sophistication but it doesn’t sound bad to me. Bass remains quite good. The main difference I notice is that the midrange seems thinner and less lush.

So far just listening at modest volume and the amp isn’t ‘hot’.

This will have to suffice until I get off the fence or win the lottery.
invalid
1,190 posts
 
I doubt any amp can really double it's power with halved impedance. Most of the amps that say they do are actually underrated at the 8ohm impedance.
georgehifi's avatar
georgehifi
10,312 posts
 
I doubt any amp can really double it’s power with halved impedance.
If you take literary then no, it would like perpetual motion then "impossible"

"Almost" double, it’s wattage is the operative word, 8 to 4ohms, 4 to 2ohms and in the ML2’s case 2 to 1ohm

Cheers George
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