Which watts are the right watts in SS amps?


Hello Sports Fans!

More than a few people over the years on these pages have said only those SS amps which double down in output power as impedance drops are truly special or worthy amps. Eg., 200 @ 8ohms; 400 @ 4 ohms; 800 @ 2 ohms; etc.

Not every SS amp made does this trick. Some very expensive ones don’t quite get to twice their 8 ohm rated power when impedance halves to four ohms. BAT, darTZeel, Wells, and Ypsalon to name just a few.

An amps ‘‘soul’’ or it’s ‘voice’ is the main reason why I would opt in on choosing an amp initially and keeping it. Simultaneously , I’d consider its power and the demands of what ever speakers may be intended to be run with it or them.

I’ve heard, 80% of the music we are listening to is made in the first 20wpc! I’m sure there’s some wisdom in there somewhere as many SS amps running AB, are biased to class A Only for a small portion of the total output EX. 10 – 60 wpc of 150 or 250 wpc.

After all, any amps true output levels are a complete mystery when anyone is listening to music anyhow.

I suspect, not being able to actually measure true power consumption, the vast majority of listening sessions revolve around 60wpc or so being at hand with traditional modern reasonably efficient speakers.

Sure, there are those speakers which don’t fit into the traditional loudspeaker power needs mold such as panels or electrostats, and this ain’t about them.

The possibility of clipping a driver is about the only facet in amp to speaker matching which gives a person pause while pondering this or that amplifier.

I feel there is more to how good an amp is than its ability tou double output power with 50% drops in speaker impedance.

However, speakers are demanding more power lately. Many are coming out of the gates with 4 ohm ‘nominal’ IMPs which lower with fluctuations in frequency. Add in larger motors on larger drivers, multiple driver arrays, and on paper these SOTA speakers appear to need more power.

IMHO It is this note which introduces great concern.

I’ve read every article I can find on Vienna Acoustics Music. Each one says give them lots of watts for them to excel.

Many times good sounding speakers I’ve owned sounded better with more power, albeit from arguably a better amp.

I tend to believe having more than an adequate amount of cap power is indeed integral. … naturally the size and type of transformers in play possess a strong vote for an amps ability to successfully mate with speakers.

Controlling a driver’s ability to stop and restart is as well a key to great sound and only strong amplifiers can manage this feat. Usually this gets attributed to ‘damping’ factor, but damping as I read it is more a shadow than a tangible real world figure as it depends on numerous factors. Speaker cable length alone can alter damping factors.

A very good argument exists about those mega watt amps voices. Each 500 or 600 wpc amp or amps, I’ve heard have had stellar voices too, not merely more watts.

So is it predominately these mega watt power house amps souls or their capacities that fuels the speakers presentation?

Would you buy an ‘uber expensive’ amp based more on its voice or soul, than on its ability to output loads of watts, even if you feel the amp may be somewhat under powered for the application?

Choosing this latter option also saves one money as the more powerful amps do cost more than their lower outputting siblings.

Please, share your experiences if possible.

Tanks muchly!

blindjim
Sorry @georgehifi , what is EPDR? 

I looked at the Stereophile measurements (which I do trust, unlike the subjective reviews), and while pretty bad for a full-range dynamic speaker, I only see a drop to 2 Ohms in the bass, with a moderate phase angle:

https://www.stereophile.com/content/wilson-audio-specialties-alexia-loudspeaker-measurements

This is certainly an example of a hard-to-drive speaker however. 
From my real world experience, when I'm looking at the VU meters of my 250 watt/ch power amp, even at loud listening levels, they stay around the 2.5 watts to 25 watts range (MacIntosh MC 252), hovering more towards the 2.5 watt gradation. But my first amplifier, the Peachtree Decco, a 50/channel amp, had a lot of trouble driving my Dynaudio speakers (86db). The Dyns were much less efficient than my current Legacy speakers, but still, the Decco was struggling to drive them, so obviously it wasn't really able to output clean 50 watts peaks, or even constant 30 to 40 watts as that should have been enough to drive the Dyns in my smallish room to loud levels. That's why the stated specs do not matter that much, and how the amplifier is built matter a lot, IMO.
Nearly all nice analogue meters grossly underestimate peak power, however. The meters on the amplifier that Alan Shaw used in the Netherlands were digital  peak level meters. But of course, a lot depends on the combination of speaker efficiency, room size, desired level and musical genre.
Sorry @georgehifi , what is EPDR?


EPDR is short for "Equivalent Peak Dissipation Resistance"

It’s the combination of the speakers low impedance and it’s percentage of - phase angle at points of the frequency range. Which can give a far low impedance as seen by the amp, than just the impedance measurements alone.

It’s explained here on page 27 in the pdf from HFN Lab Test done on the Wilson Alexia (the page is slow to load give it time or refresh it)

https://www.absolutesounds.com/pdf/main/press/WA%20Alexia%20HFN%200313-4web.pdf

Also here's 3 pages from Stereophile  https://www.stereophile.com/reference/707heavy/index.html

Cheers George
Peachtree Decco, a 50/channel amp, had a lot of trouble driving my Dynaudio speakers (86db). The Dyns were much less efficient than my current Legacy speakers, but still, the Decco was struggling to drive them, so obviously it wasn't really able to output clean 50 watts peaks, or even constant 30 to 40 watts as that should have been enough to drive the Dyns in my smallish room to loud levels.

Classic example is your Peach Tree at 50w, if it had "good current" (almost doubling wattage for each halving of impedance) it would have been able to drive the Dynaudios easy, as the Mark Levinson ML2 monoblocks would have easily done it also with great sound (maybe not party levels).

Cheers George