tube amp wattage

[mikegraveling]

i have heard that even though a tube amp that puts out only 16 watts still produces greater output than a new electronic amp that puts out 16 watts, my question is can anybody tell me roughly what a 16 watt tube amp would be comparible to in lets say a new style digital onkyo amplifier?

[AJ]

16W is 16W. It doesn't matter where it comes from. Because of frequency response irregularities tube amps tend to sound louder. This depends on the quality of the output transformer and the speakers used. Also, clipping and distortion sets in more gradual with tubes.

[Æ]

i have heard that even though a tube amp that puts out only 16 watts still produces greater output than a new electronic amp that puts out 16 watts, my question is can anybody tell me roughly what a 16 watt tube amp would be comparible to in lets say a new style digital Onkyo amplifier?

It kind of depends.
Transistor amps are usually rated at 1KHz into 8 ohms. Depending upon the amount of headroom a solid state amp has, it should be able to deliver even more power into lower impedance loads. But the real test comes when delivering full spectrum music power instead of just 1KHz test tones.
My mentor Henry Wolcott showed me what most solid state amps are not capable of. He tested them with pink noise into 4 and 8 ohm loads. Transistor amps typically have significantly less power than the "rated" power when using pink noise instead of single test tones. Not so when conducting the same test using tube amplifiers.
That is where tube amplifiers shine, excel in real world power. They have the advantage of so much higher power supply voltage, which means more Joules available instantaneously.
To sum it up, it's not that tubes really have more, but that transistors actually have less.
I mean, how much headroom could a 16 watt solid state (transistor) amp actually have?

One final note, tube amps usually clip gracefully compared to transistor amps. So it appears that you have greater power available.
With a tube amp you can continue to turn up the volume and the amp will keep playing. Tube amps are well mannered, they play nice and get along well with others when it comes to power output.
Unfortunately many tube amps are temperamental when it comes to frequency response, especially with reactive loads.

[gumert]

One final note, tube amps usually clip gracefully compared to transistor amps. So it appears that you have greater power available.

This ties in nicely with the following quote.

You can get a decent amount of sound from 16W but it really isn't fair to compare a 16W tube amp to a 16W solid state amp because the tube amp will distort much more gracefully than an SS amp when it clips. This is a key factor since most music has a very low average power content but high dynamic peaks and SS amps just chop off the top of the signal which leads to a lot of high order harmonics (an example is to take a sine wave and chop the top off which leaves a very sharp edge at the point where the signal is clipped which according to Fourier transform theory will lead to a lot of high order harmonics and the most extreme case of a square wave has the slowest decaying harmonic content). Tube amps tend to clip "smoother" with less high order harmonics so that even if it is clipping it sounds much less harsh and less detectable.

I think that pretty much hits the nail on the head. As I said earlier, my little 16 WPC tube amp really impresses me with its output capability when paired with an average sensitivity bookshelf.

[gumert]

It's also worth noting that doubling your power only gains you 3 dB. Sure, this makes a lot of difference when choosing between lower power amps (say sub 64 watts), the difference in output between amp A (say 75 watts) and amp B (say 115 watts) really isn't that much if both amps are rated accurately. You also meet a point where you get extremely diminishing returns in terms of $$ spent to gain output.

1 watt = reference sensitivity @ 1w/m
2 watts = reference sensitivity @ 1w/m + 3
4 watts = reference sensitivity @ 1w/m + 6
8 watts = reference sensitivity @ 1w/m + 9
16 watts = reference sensitivity @ 1w/m + 12
32 watts = reference sensitivity @ 1w/m + 15
64 watts = reference sensitivity @ 1w/m + 18
128 watts = reference sensitivity @ 1w/m + 21
256 watts = reference sensitivity @ 1w/m + 24
512 watts = reference sensitivity @ 1w/m + 27

[Æ]

This ties in nicely with the following quote.




I think that pretty much hits the nail on the head. As I said earlier, my little 16 WPC tube amp really impresses me with its output capability when paired with an average sensitivity bookshelf.

So you built one of those S5 16 watt amps? Do you have any pictures to show?
Did you see my 8 watt K-12M from S5?

[mikegraveling]

i dont' even have an amp yet, but i am looking at possibbly buying a 16L5 kit or a st-35 from one of the members here

[rudyjakubin]

Not suggesting you do this, but throwing my 2 bits in.
This is what I chose to do after reviewing kits and start from scratch in tube books and schematics available on the net.
I bought two guitar amps. The first pair were Bugera 125 watters using 6L6 tubes. $500 each and a pair of Peavey Windsors 100 watters for $250.00 each.
I bought the Peaveys after my son heard the Bugeras and had to have them.
Plus the Windsors looked to be more 'Mod' friendly. There's a lot of empty real estate.
The biggest reason to go this route was quick addition.
Nearly a $100 for each transformer. There is two - so $200.
Seven tubes aboard - about $50. So the rest is free. Resistors, caps, knobs, ratastats, plugs, fuses, fuse holders, metal case with holes pre-drilled.
With the Peavey comes a feature where you can twist a knob and go from class A amp (40 watts/channel) to AB1 (100 watts/channel).
Comes with a bias trim pot and test point. 2 circuit boards that seperate the preamp from the power amp except for the 12AX7 phase splitter.

[Æ]

Pictures of my 8 watt per channel K-12M from S5 Electronics.

[gumert]

So you built one of those S5 16 watt amps? Do you have any pictures to show?
Did you see my 8 watt K-12M from S5?

I did build one, a little over a year ago. I do have pictures, but they were taken with my crappy base power shot, which was literally the cheapest power shot money could buy a year and a half ago. My Nikon D40 is at my girlfriends house, so I can take better pictures if anyone wants them, but I can't do so now.

I must say that your base looks much, much nicer than mine. I built it mid semester last year and didn't have a lot of time to spend on cosmetics, so I just used the supplied piece of wood and didn't make any trim for it. Once it was done I was happy to have it done and never went back to make it more aesthetically pleasing.


Construction


Soldering


Completed and testing. The only thing that's changed since this picture is the gain knob - I updated it to something a little nicer looking.


I love the way it looks with the lights off.

I must say that I'm very happy with this amp. Sounds great and has more than enough power for what I've been using it for.

[cpcarter]

Other factors not mentioned are damping factor and current capacity. Transformer coupled tube circuits seem to do both really well.

I have an old 35W Fisher that is more "musical" than my 200W B&W ST3030.

I sometimes prefer it for Vinyl. Sometimes not. It's all subjective and varies with mood and the phase of the moon and the speakers being driven of course.

If it makes you happy...

Enjoy the music!

CC