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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

Showing 10 responses by willemj

willemj
1,036 posts
 
A flat frequency response is crucial for a natural representation of the music. You don’t want the system to artificially boost or depress certain frequencies, and hence change the sound from what it was. As has been remarked, there are two sides to this.
First there is the speaker. It should have a relatively flat impedance curve without deep dips. There are plenty of speakers that present an easy load (Harbeth are good, but there are enough others), but there are also speakers with a devilish load.
Second there is the load dependency of the amplifier. A good amplifier should not be too troubled by impedance swings. Tube amps have a harder time here, given their design with output transformers. The Prima Luna that Eric referred to, with its absolutely massive frequency swings, is an extreme example of how not to design an amplifier. Compare this to an affrodable Yamaha AS 500, tested here: http://www.avhub.com.au/product-reviews/hi-fi/yamaha-a-s500-amplifier-review-test-395710 Even under realistic speaker loads it maintained a flat frequency response within 0.05 dB, an amazing performance not matched by many amps costing ten times more.
Taken together, I think speakers that are not easy to drive and amplifiers that are load dependent are just bad engineering, and are to be avoided. If you succumb, you will suffer the dreaded synergy problem and all the audiophile Angst that comes with it.

The second problem is power output. Most good speakers are not very efficient, so you will need lots of power to drive them. If you don’t have enough power, you will suffer clipping distortion on dynamic peaks, with a ’dirty’ distorted and compressed sound as a result. Again, some people like this, but it does not meet the criterion of neutral and life like representation. So how much do you need, not for average levels, but for dynamic peaks? A few years ago, having moved to a larger house and having upgraded from the Quad els 57 speakers to the less efficient Quad 2805 I decided to replace the 2x45 watt Quad 303 by a 2x140 watt Quad 606-2. There was no diference on small scale music, but it sounded much more realistic on the large and dynamic repertoire. I began to realize that I now also played my music rather louder, because the sound remained so clean. Since then, I have concluded that even more power may well further improve the sound. As another anecdote, Harbeth's Alan Shaw recently demonstrated his big M40.1 speakers in the Netherlands. Even he was surprised that on dynamic music the big amplifier that was used was putting out more than 500 watt per channel. Fortunately these days watts are no longer particularly expensive.
willemj
1,036 posts
 
Most tube amps are the equivalent of a graphic equalizer - hence a no no for me.
willemj
1,036 posts
 
Well, it is a free world, fortunately. However, for me it is not the job of my gear to change the sound of the music - I am not the artist. What I want is simply what Quad once called ’the closest approximation to the original sound’. I accept that that is a very modest brief, and at least for the electronics part of the chain easily achieved (witness the Yamaha that I linked to). With speakers and room interaction it is a different story, unfortunately.
Shaping the sound to your liking can be done much more cheaply than by buying exotic gear and expensive cables - just use a graphic equalizer, or if you want to get fancy, use one of the modern plugins for recording studios: vinyl, a Studer tape machine or tubes on the cheap and without the hassle.
willemj
1,036 posts
 
Too late to edit my post, but see here: http://audiograph.se/
willemj
1,036 posts
 
Geoff did not read my earlier posts carefully enough, for my other speakers are no longer the LS3/5a (lent those to my son while he is saving for a pair of Harbeth M30.1’s) but the much better Harbeth P3ESRs.
As it so happens I once attended one of Peter Walker’s blind comparisons between his three amplifier designs. Those were the days when people began to claim that tubes sounded better, and he thought they were nuts. I subjected myself to the test rig, and did indeed think that I could hear differences. Peter was pleased no end when he could show me that I had been no better than completely random. And I learned a valuable lesson. The stricture is, of course, that amplifiers have to be designed properly. If you read the Stereophile test of his valve amplifier, you can see that Peter Walker’s own valve design does indeed perform quite well under a varyring speaker load (flat within 1dB): https://www.stereophile.com/content/quad-ii-classic-monoblock-power-amplifier-measurements That is much better than many other valve amplifiers.
It is indeed a legendary design, just like his later 303 and the more powerful 405 current dumping model that still lives on in the again more powerful 606, 909, QSP and current Artera models. As Peter told me, the only practical difference is that of more power. Since at the time I was using the ELS57’s that could not handle more than my 303’s 45 watt per channel, he assured me there was no point in upgrading to the 405. A true gentleman.
willemj
1,036 posts
 
An interesting way to look at the issue is to measure a so called power cube. The late Peter Aczel had the instrument to do that, and here is an example: http://www.biline.ca/audio_critic/audio_critic_web2.htm#pa
willemj
1,036 posts
 
Geoff, as so often you are peddling nonsense. You are not only wasting people's money, but also their time.
willemj
1,036 posts
 
You just confirmed what I said.......
willemj
1,036 posts
 
The conclusion is that good engineering demands speakers that are easy to drive and amplifiers that retain a flat frequency response under varying loads. Combine such units, and you are fine. Combine hard to drive speakers with most tube amps and you have a response that is all over the place.
willemj
1,036 posts
 
Well, my Harbeths are easy to drive and nobody will deny that they are very good sounding speakers. So it can be done.
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