How low can you go?

[thisSNsucks]

I'm talking watts here, and mainly comparing Tube v. Solid State. Lots of these All tube amps dont really put out nearly as many watts as the Hybrid and Solid State amps do.

Examples:

All tube:
Ampeg SVT Classic - 300W
Fender Bassman - 300W
Orange AD200 - 200W

Solid State
Aguilar AG500 - 500W
Gallien-Kreuger 2001RB - 1080W

Hybrid
Aguilar DB751 - 750(@4ohms)

Theres obviously a ton more, but this seems to be the basic trend.


I'd like to know if there really is a difference between these Tube and Solid State Wattage ratings.

And also, how little wattage can you use in a gigging band?

 

[link wray]

Power ratings of all amp are typically at 1% THD ("distortion").
A tube amp is typically used at more than 1% THD, so it will put out more than its rated power. In tube amps the THD rises lineair with rising power levels. Transistor amps are almost never used at levels above their rated power because their distortion rises exponentially above onset.

 

[EricF]

Power ratings of all amp are typically at 1% THD ("distortion").
A tube amp is typically used at more than 1% THD, so it will put out more than its rated power. In tube amps the THD rises lineair with rising power levels. Transistor amps are almost never used at levels above their rated power because their distortion rises exponentially above onset.

In addition, SS amps generally sound crappy when pushed to clipping. Tube amps sound yummy.

 

[RickenBoogie]

As to the "minimum gigging wattage", well that's subjective too. Depends on the band, the venue, the type of music, etc. For me, in a 4 pc hard rock band, 300 watts and a 2x12 is as low as I'll go, but for actual gigs, 1100 watts and a 2x15 is my standard. Both my heads are hybrid's, btw.

 

[Balog]

Interesting, so watt ratings are where distortion sets in, but most tube amps are used above this level?

 

[EricF]

Interesting, so watt ratings are where distortion sets in, but most tube amps are used above this level?

Yes. This is why people claim that "tube watts" are louder than "solid state watts". A watt is a watt. However, a tube amp is very usable when pushed well above the point of distortion. The sound of moderately distorting power tubes is generally considered to be a very musical sound.

 

[Mat_F]

Being from a Hi-Fi and Home Cinema background, I've learnt that the rating in watts of any amp doesn't really mean much at all when judging it's capabilities. I won't go in to the technical boring stuff, but it's more down to the current and how the amp uses it.

There are different classes of solid state amplification and they all work in slightly different ways, producing varying results. A 50wpc Class A amp (the highest quality of solid state amplification) can easily control and drive a speaker far batter than a 500wpc Class D amp. Tube amplification is very different and a 5wpc tube amp can easily outperfrom a 50wpc Class A amp.

 

[alexclaber]

There are different classes of solid state amplification and they all work in slightly different ways, producing varying results. A 50wpc Class A amp (the highest quality of solid state amplification) can easily control and drive a speaker far batter than a 500wpc Class D amp.

The Class A/AB/B/D/G/H/etc designations of power amplifiers are not related to quality but to how they work. A well implemented Class D power amp will far outperform an equally nice Class A amplifier if the power requirements are such that the maximum clean voltage from the latter is insufficient. And in a live sound environment it will be hard to tell a clean running Class A from an AB, G, H, or D, except in the amount of heat it gives off!

Alex

 

[premiumplus]

The Class A/AB/B/D/G/H/etc designations of power amplifiers are not related to quality but to how they work. A well implemented Class D power amp will far outperform an equally nice Class A amplifier if the power requirements are such that the maximum clean voltage from the latter is insufficient. And in a live sound environment it will be hard to tell a clean running Class A from an AB, G, H, or D, except in the amount of heat it gives off!

Alex

Agreed. Power, in watts, equals volts times current. How you get there is determined by the class of amplifier. It's all in the details...and how you choose to measure the performance of a given amp.

 

[unclejane]

Interesting, so watt ratings are where distortion sets in, but most tube amps are used above this level?

Er...
The tube amps are just simply lower power designs, has nothing to do with how hard they're driven or anything like that. Reason being, the restrictions on tube designs are more practical than anything else:

- power tube availability. These days, we've got only a few choices and their power dissipation ratings are generally pretty low. That's why you need 6 or more of them just to get a couple hundred watts of power output. Your only other choices are RF transmitting tubes but these are expensive, gigantic and require LOTS of input power to operate.

- cost. What power tube designs we do have available are expensive compared to solid state devices. It used to be the other way around but not anymore.

- efficiency. Far more electrical power is thrown away as heat in tube designs, for instance you need an entirely separate power supply just to run the filaments on the tubes.

-size. Because of the inefficiencies and space requirements, a high-power tube amp is simply going to be huge and weigh a ton. There's just no way around this. The power transformer gets enormous as the power input requirements go up. Most tube power amps require an output transformer too (due to the normally high impedance of tube power amplifier output stages) which adds more size, weight and cost. Then you need a big cabinet to house the tubes, allow for ventilation and etc.

So to sum up - size, device limitations and power requirements are the main limiting factors on tube amp power. There're good reasons that, say the markbass tube amp only puts out 300W but is the size of a house, weighs a ton and costs $2500.....

LS

 

[unclejane]

Being from a Hi-Fi and Home Cinema background, I've learnt that the rating in watts of any amp doesn't really mean much at all when judging it's capabilities. I won't go in to the technical boring stuff, but it's more down to the current and how the amp uses it.

There are different classes of solid state amplification and they all work in slightly different ways, producing varying results. A 50wpc Class A amp (the highest quality of solid state amplification) can easily control and drive a speaker far batter than a 500wpc Class D amp. Tube amplification is very different and a 5wpc tube amp can easily outperfrom a 50wpc Class A amp.

I'm not quite sure what this means.....

Power output and amplifier type kind of don't have anything to do with each other. The class designation more or less refers to the amount of time throughout the signal's waveform the output device is conducting. Class A amps theoretically have the output device biased "on" throughout the full 360 degrees of the signal waveform. Class AB less than that (I believe between 360 and 180 degs), class B 180 degs and class C less than that.

The difference influences efficiency, linearity (i.e. fidelity of output waveform vs input waveform) and duty cycle imposed on the output devices. It doesn't have anything to do with overall power output or damping factor or etc., beyond the general issue of the thermal/power limitations of the devices you're using.

What's sometimes called "control" refers to damping factor, or the tendency of the amplifier to look more like a short-circuit to the speaker. High damping factors allow less overshoot (or "ringing" you might say) from the speaker which leads to higher fidelity reproduction from it.

Tube amp designs are notorious for having low damping factors simply because of the fact that they require impedance-matching, usually through an output transformer, to work with the typical low impedance 4 to 8ohm speaker. So they often have a kind of "loose" sound in the bass.

Personally, I can't think of any reason to prefer a tube amp over a good solid state as I haven't heard a tube amp whose sound I like. But as others have said, that's kind of an artistic judgment and a tube amp can be worth it for that.....

LS