Need help understanding tube wpc

While it's true that watts is watts whether tube or solid state, the ear's sensitivity to different types of distortion is what's coming into play in a "tube watts vs solid state watts" discussion.

Tubes soft-clip; that is, they produce less high-order harmonic distortion when driven into clipping. High-order harmonic distortion is quite audible and objectionable even in fairly small amounts. Generally speaking, tube amps can play louder than equivalant-power solid state amps before the ear detects the distortion. This matters because usually the problem that's most noticeable in clipping is the distortion rather than the dynamic compression.

Given that recorded music can have an average-to-crest ratio of 20 dB or more (which would call for a 100-fold peak in amplifier power), clipping can and does happen more often than we'd probably like to admit. In theory enough reserve power to avoid clipping would be great, but I'm not sure that's always practical.

Duke

Tubes typically have FAR higher rail voltages than SS amps, which therefore gives them more dynamic headroom. Tubed amps also clip in a "harmonious" manner, making them less objectionable when overdriven. This means that a smaller tubed amp can play "louder" than one would think, as it has quite a bit of dynamic headroom and doesn't rip your ears / eyes out when it does clip.

The biggest problem with tubed gear is that it typically lacks current and is bandwidth limited, both on top and bottom. The lack of current is what gives most tubed gear that "round, tubby" bass that many folks dislike. At the same time, this "added warmth" tends to "fill out" many of the leaner digital recordings that we hear. The limited bandwidth up top tends to soften the treble response, making hard, bright and edgy digital sound smoother and more listenable.

Like any other amplifier, you want to look for a design that utilizes very large core transformers. With tubed gear, the output transformers are as important ( maybe moreso ) as the power supply transformer. As such, look at the build quality of the amp more than the actual power rating, as most tubed power ratings are "bunk" anyhow. If you applied the same standards for measuring distortion in tubed gear as one does to SS gear, most of these tubed amps would be rated at about 1/4 to 1/3 of what the manufacturer advertises.

There are obviously designs / products that fall outside of these basic recommendations i.e. output transformerless ( OTL ) designs, digital power supplies, etc.. These are all non-standard designs, so the "rules" are apt to be different for these products. In such cases, proceed with caution and just make sure that you're dealing with a reputable manufacturer. Sean
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PS... Buy more than what you think you need, as running tubes quite hard on a regular basis also means replacing tubes on a regular basis.

I like Sean,Rl,Viris comments and would ad that regardless of tube/ss when an amp is capable of X watts/ch RMS it is capable of a different number of watts for an instantanious peak. A better amp can do a peak perhaps 50-100% above the rated RMS power. This is based on a better power supply and design, etc. Music is peaks. Not steady. Then there are Class design differences too. There are a lot of factors involved. Good luck!

ET

watts is watts, which means if if you get more usable watts because of soft clipping then you got more watts!

Someone mentioned distortion, distortion can be percieved as being 10 times louder than it really is. Accepted practices of one percent distortion setting the standards for the amplifiers quoted power rating as Sean mentioned makes most 60 watt tube amplifiers like 20 watts.

But unfortunatley everyone missed the point and continues to miss the real reason tubes sound louder than solid state.

http://stereophile.com/solidpoweramps/806halcro/index4.html

See figure 9 on the link above.

Halcro DM88 Monoblock is playing at 100 watts and look at the complete lack of harmonic content with a 50hz input

Now compare.

http://stereophile.com/tubepoweramps/306yamamoto/index3.html

Yamamoto tube amplifier look at the harmonic by products which are ADDED to a simple 50hz signal, now these byproducts do not effect the voltage or WATTS, so in this case the tube 100 watts offer a great deal more sound than the SS watts.

The factor I just demonstrated with the comparison and the soft clipping has everything to do with tube watt sound like more than a solid state watt.

But depending on your speakers getting tubes may be a bad idea as speakers are not always compatible with two very different amplifiers. Many speakers are not designed well enough to have solid state run on them and the ones that are do not sound very good with tubes. So your speakers are going to determine which amplifier type is best for you.

Thanks for all of your input - getting a real education.
My speakers are Tylet Linbrook System 2 - 8ohm 89db are there certain tube design amps that would not work well with these. Have seen that Ty uses Jolida at times during shows?