Tube watts vs SS watts

[Sada Yairi]

Still being new to the whole elctric thing I'm trying to work out what the 'equivalence' is between the wattage of tube amps vs ss amps. Tube amps seem to go up to 5 watts for prac amps & jamming, and then from about 15watts upward for small gigs. I've seen it mentioned on some sites that ss wattage is equivalent to tube wattage multiplied by 4, 5 or even 10 depending on which source you happen to quote.

So what would a 5watt tube amp compare to in a ss amp in terms of volume? Something like 30-40watts?

[Eric]

Yeah, I guess like 25-30 watts. That's my gut instinct, anyway.

The thing is that with tube amps a lot of that power will be distorted, while all of the solid-state amp volume will technically be 'clean.' The reason I say that is that if the SS amp is actually clipping, it would be square-wave, nasty-sounding, and not a planned part of the amp performance. The clipping in a tube amp is a big part of the amp selling point.

Also, tube amps naturally add compression which has the effect of sounding louder. So if you want to look at it this way, a tube amp played at the same level of distortion as a SS amp would probably be roughly the same volume, but they're designed to operate in very different ways.

I probably just muddied the issue, so feel free to ignore everything but the first two sentences.

[piebaldpython]

I think this issue was discussed here previously. IIRC, one tube watt equals 3 SS watts......so a 10 watt tube amp equals approximately 30 SS watts. Tube amps will "naturally" start to overdrive when pushed.....it sounds wonderful. However, if you push an SS amps......it's anything but beautiful.....as Eric mentioned.

For the sake of an example......if a 20 watt tube amp will be sufficient for a gig, you go with the 20 watt tube and not a 100 watt tube because you can push the 20 into a natural overdrive. However, regarding the same gig as the 20 watt tube amp.......you would think a 60 watt SS would be ok.......but it wouldn't because SS amps don't want to be pushed. You'd be better off with a minimum of 75-80 SS watts, to prevent the amp from going into unwanted territory.

[Sada Yairi]

IIRC, one tube watt equals 3 SS watts......so a 10 watt tube amp equals approximately 30 SS watts.

That doesn't seem right to me. Lately I've been playing around with two amps - a 5watt class A and a 15watt ss. The tube is significantly louder than the ss, so a 1:3 ratio doesn't seem right. I'm just not sufficiently versed with ss amps above 15watts to know what the 5watt tube compares to. Seems to me 5watt class A has to be on par with at least 25watts of ss.
At the same time, what you say about pushing the relative amps is certainly true. Pushing a solid-state is not pretty.

[Ch0jin]

That doesn't seem right to me. Lately I've been playing around with two amps - a 5watt class A and a 15watt ss. The tube is significantly louder than the ss, so a 1:3 ratio doesn't seem right. I'm just not sufficiently versed with ss amps above 15watts to know what the 5watt tube compares to. Seems to me 5watt class A has to be on par with at least 25watts of ss.
At the same time, what you say about pushing the relative amps is certainly true. Pushing a solid-state is not pretty.

Scientifically speaking, Watts are Watts. P=IV Apparent Volume is another thing entirely.

Whilst I don't disagree with anything here, and I think I've covered this in detail somewhere before, 3:1 is NOT a rule. It's just a quick reference to indicate a tube amp with the same power rating as a SS amp will usually sound louder. There are also dozens of other factors at play in making one amp seem louder than another.

[Sada Yairi]

So all other things being equal, that is assuming the speaker, cabinet design etc etc are all the same, a 5watt Class A amp would equate to what wattage in a SS amp in terms of maximum usable volume (without either amp breaking up too much)?

[deeaa]

Yes, about so. But indeed it is more about perceived volume and low frequency content than just decibels. My modded 5w valve jr. Was about as loud as my 15w tube head for instance...sometimes wattage just provides general direction. My Ceria, when switched to 18w mode from 36w...no change in volume really, just much less low end. The 15w tube amp was loud enough with band but sounded like beehive, way too little low end power at those volumes. Id say around 40w tube and 60w ss is in most cases OK for band use with suitable speakers.

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