Watts is Watts

[dragonworks]

If you have a tube amp that puts out 50 watts RMS and a solid state amp that puts out 50 watts RMS, they both put out 50 watts RMS.
So whats this 50 tube watts shit I keep reading?????

 

[Dakota]

Can you give an example of where you read this?

 

[AcidRain]

because of the way tubes distort, and the harmonics they generate, tubes have a higher percieved output. They sound like they're louder. Electronically they're not, and I'm not sure about SPLs...

 

[M.Brane]

My Boogie head puts out about 75 watts in Simulclass mode.

MY PA is 450 watts a side.

The Boogie is louder than the PA.

My 50 watt JCM800 is louder than either of 'em.

'Nuff said.

 

[dragonworks]

Can you give an example of where you read this?

In ads in mags, say Musicians Friend, I cant say exactly where but I have seen it more and more lately.

 

[dragonworks]

My Boogie head puts out about 75 watts in Simulclass mode.

MY PA is 450 watts a side.

The Boogie is louder than the PA.

My 50 watt JCM800 is louder than either of 'em.

'Nuff said.

You cant crank the PA due to feedback????

 

[M.Brane]

You cant crank the PA due to feedback????

Even with a direct source (no mics) the tube amps are louder than the PA. Of course the speakers probably play a role in that. The Celestion cabs are probably more efficient than my Peavey/TOA PA cabs, but it's still no contest.

Then there's the stereo thing. My McIntosh 240 is also louder than my Marantz 2230, and Harmon/Kardon A-401 despite being within 10 watts of the rated output.

I think AcidRain is onto something. I think our ears can tolerate more distortion from tubes than from transistors. I know speakers certainly can.

 

[Lt. Bob]

It has to do with power supplies actually. The ability to put out brief, large amounts of current. Even if an amp is rated at 50 watts, it might be able to put out 400watts for a milli-second or so. This creates a louder percieved volume. Since tube amps often have more robust power supplies because of the need to carry a high bias voltage......they often have a much higher percieved output because of their potent transient response.

 

[M.Brane]

Yeah, that would be another good point Lt. though the power supply in both my PA amp (Carver PM 1.5) and Marantz reciever are just as robust as any of the tube gear. The Carver in particular has quite a beefy PS for a SS amp. It's no slouch!

 

[shredfit]

Lt Bob is correct!

Tube amps work by placing a DC current between the plate and Cathode... electrons can jump in a rather linear fashion between the two elements(with the loss of heat). The tube has a grid...which allows much larger voltage changes between the plate and Cathode(think of a water valve only for electrons).

A transitor amp doesn't work in this linear fashion. So, a DC bias signal is added to the transistor to limit the amps dynamic range...(full DC throughput on these amps would be ugly for any speaker) this is why the dynamic range must be limited!

 

[Doug H]

tube amps go to 11

 

[Dakota]

I'm no expert here, being mainly an acoustic player, but isn't it the quality of the sound the reason why people prefer tubes? Going on what I've heard, solid state amps clip flat as soon as the peaks reach a certain level and the distortion sound harsh Tube amps have roll off or compress the peaks resulting in a warmer distortion or crunch.

 

[shredfit]

When a tube amp reaches the saturation point... That is, when the input signal is large enough that the DC output voltage isn't large enough to produce the required voltage... waveform distortion(clipping) occurs. The waveform is basically being cut off or compressed.

Tube amps pushed to the saturation point produce even-order harmonic distortion(which sounds rather musical and pleasing)

Transistors pushed to the saturation point produce odd-order harmonics(which are not very musical sounding and tend to be harsh)

Shred

 

[juststartingout]

Well, the cathodes can do this and the plate woltage can be that, but the bottom line is that the tube amp will sound a lot better at higher volumne.

Just go down to your local shop. Get 2 equal amps (1 solid, 1 tube). Run them clean, no boxes attached, and through the same cab. Crank them up and you will understand.

There is no substitue for a tube amp at high volumne. It simply sounds better. It will give you a cleaner, more managable overdrive (classic metal distortion).

If you want to run it at lower volumnes and run a lot of boxes, a solid state amp will be adequate. This is because your boxes are going to give you your sound. You are only using the amp to amplify the sound, not add to the sound.

 

[mcmd]

yes.... watts are watts, but remember one of the reasons why you bought that Denon or *other* high end Home Theatre Receiver....it's all in the %THD ( Total Harmonic Distorsion)...

Your $700 Denon or Onkyo reciever rates output power of 600W at a THD of maybe 0.05%?....
Budget buster receiver brand X rates output power at 600W and at a THD of 1%....and thus produces more distorsion.....
You get the same power BUT not the same quality...if you want to faithfully reproduce the signal, at a rated power level, you want a low THD spec...

I suspect that cranking a valve amp preserves much of the original signal and adds some harmonics....cranking a transistor amp adds lots of harmonics and turns it into a stomp box...

/Dara

 

[cstockdale]

just one example, I have a SS Fender Frontman 25R amp, 25 Watts, and a Garnet Mohawk, all tube, 7W. When cranked, the Garnet is louder than the Fender.

 

[Lt. Bob]

My other guitar player uses a Badcat which is only 30 watts and it is ungodly loud. Most of the time he leaves it on half-power. And we play loud! I use two different amps for different gigs.......a Fender Vibro-King (60 watts ) and ususally run it cranked. But lately I have been running an old Ampeg V-2 ( again, 60 watts ) thru the Vibro-King's speakers. So the speakers and everything else is identical and the Ampeg is WAY louder than the Fender. It's also heavier by far.....which is a consequence of that old heavy power supply.
So I resubmit that the thing that makes two identically rated amps have very different loudness levels is the power supply.

 

[acorec]

If you have a tube amp that puts out 50 watts RMS and a solid state amp that puts out 50 watts RMS, they both put out 50 watts RMS.
So whats this 50 tube watts shit I keep reading?????

1. A guitar amp has a severely limited freq range. It is like 50-3500Hz. A PA amp has an expanded range (like 30-20Khz for a good one). 50 watts on a guitar amp will sound much louder that 50 watts on a PA because the energy on the PA is spread out over a wide freq range. The guitar amp is concentrated in a 4Khz freq range.

2. "tube" watts is just a name they use to tell you that the guitar amp has a tube power circuit. There are a number of amps that have a tube pre-amp and a transistor power amp. An amp with 50 "tube" watts is an all tube pre-amp AND power amp.