2. amps-preamps
  3. 159074-115924

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
 
invalid,

Of course you can get more power.  It is ludicrous to think otherwise.  An amp is like (bit of an exaggeration to get the point across) your mains amplifying a 60 Hz signal.  If you connect a 120 ohm load to mains, you will get 120 watts, if you connect a 60 ohm load, you will get 240 watts, if you connect a 30 ohm load, you will get 480 watts, etc, until you blow your fuse.

AS LONG AS YOUR MAINS DOES NOT COLLAPSE AND YOU DO NOT EXCEED YOUR CURRENT LIMIT, you WILL get more power.  It is virtually the same in amps.  It is like supplying a 60 hz continuous signal.  As long as the power supply can supply the needed current, it will keep on supplying more power.  The limitation with amps is the heatsink/output stage design (transistor current limits), the maximum internal impedance and its stability at different frequencies.  The ideal amp (again, an asymptotic exaggeration) will even handle a short cirtcuit across its speaker where the current will be limited by only the internal impedance of the output stage.  This obviously will blow the transistors but you get my point.

invalid
1,208 posts
 
No amp can do that it's virtually impossible.
cakyol's avatar
cakyol
940 posts
 
invalid, georgehifi,

This is the spec page from D’Agostino Relentless welding machine.

https://dandagostino.com/products/relentless-monoblock.php

Please show/indicate to me where the ’incorrect’ or ’misleading’ information is.
georgehifi's avatar
georgehifi
10,312 posts
 
invalid, georgehifi,
Please show/indicate to me where the ’incorrect’ or ’misleading’ information is.

No need to get your knickers in a knot, the only way to prove it is with independent testing, and not believing the manufacture

Like I said bet the 8ohm is under quoted just like his Progression Monoblocks are below.

Progression Mono:
D’agostino specs
8ohm- 500w
4ohm-1000w
2ohm-2000w

Stereophile tested specs
8ohm-595w
4ohm-943w
2ohm-750w (went into turn off protection mode)

It’s impossible to double exactly there are always losses, if it did it would be saying it’s like inventing perpetual motion.


Cheers George
invalid
1,208 posts
 
The bigger the power supply and the bigger the output stage the higher the wattage into 8 ohms. They may spec an amp at 1500 watts into 8ohm but if it's actually measured by a independent 3rd party they always come up with a higher wattage than the spec sheet from the manufacturer says. Take my krell amp for instance it's spec says 300 watts into 8ohm but stereophile measured it at over 330 watts.
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