Comparative power ratings for tube vs. solid state amps

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Whoopysnorp

Whoopysnorp

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The bass player in one of my bands has a really nice Ampeg 600 watt tube head. I've heard him and the drummer make declarations like "of course, 600 watts of tube power is equivalent to 1200 watts of solid state power". Now, I'm aware that, say, a 30 watt class A tube system (like a Vox AC30) will sound a lot louder than, say, a 30 watt solid state Peavey combo. But is there really that much of a difference factor between class A/B systems and solid state systems? I don't know whether his Ampeg is class A or class A/B, but it seemed a little simplistic to me to make a statement like "tube power = 2x solid state power".
 
Its the available headroom.Tube amps are useable right up to ten but solid state sounds best not turned up real high.My 2 cents.
 
It would depend on how honest the specs are on the SS amp. Many manufacturer's claimed output wattage are greatly exaggerated.

My PA is powered by a Carver PM 1.5 that is supposedly 600 a side at 4 ohms which is the load I run it at. My MKIII Simulclass head will easily keep up with it in class A mode (25 watts) and will go louder in simulclass mode (75 watts). Granted my Vintage 30's are more efficient than my PA cabs but thats still a big difference in power for the same relative volume.
 
To expand a little on what Tom said (and with the disclaimer that I'm not an amp tech), a tube amp distorts gradually the more you turn it up, whereas a solid state amp begins to clip at a certain point.

Tube distortion can be pleasing to the ear. Transistor clipping sounds like fried ass. And it can destroy your speakers as well.

I'm not really sure what Class A vs. Class A/B has to do with it, if anything. Maybe someone else can tell us.
 
Most solid-state amp power ratings (Ampeg's comes immediately to mind) are substantially exaggerated. That's one point.

Secondly, there's a real difference in perceived loudness between some solid-state and some tube amps at identical bench output. While a watt is always a watt, there are other factors (some extremely complicated) that contribute to the SPLs measurable at identical wattage output from different amps through the same speakers. Go to r.a.t or a.g.a for some lengthy and heated engineering debates on this subject!

Thirdly, a lot of high-output amps use low-efficiency speakers, so they are taking away with one hand what they are giving with the other.

Fourthly, there's a big bifference between amplification for different instruments. Getting bass to acoustically stand out in a band setting in the way that modern bassists wish takes a substantially greater amplification than guitar. The figure 3/1 is generally accepted. Personally, I think this is overkill, as does the guy trying to sleep a mile away who hears nothing but the basslines. :D
 
Most solid-state amp power ratings (Ampeg's comes immediately to mind) are substantially exaggerated. That's one point.
Click to expand...

Why is this?

Well, to answer my own question, "because they can."

If you have a tube amp with an output stage of, say, two 6L6GCs sitting right out there for the whole world to see, you can't advertise a 200WRMS @ 1%THD output for the amp, as everyone knows you can't get that kind of output from two 6L6GCs.

There are only a handfull of standard power tubes in use, and folks know the kind of ballpark output figures to expect from them.

Solid-state amps use all kinds of semiconductors that are usually hidden away inside a fan-cooled box, safe from prying eyes. If you have a solid-state amp you're advertising as 300WRMS, nobody's going to know what you really have until they do a serious bench-testing. Who's going to do that?
 
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