Stage volume: two 15 watt amps vs one 30 watt amp

[donh]

Printer2 just proved the texbook - yaaaa!

Double the power is +3db, and double the cone area is also +3db. Double both, and you are +6db.

The implication here is that given two identical 15w combo amps you go up 6db. And given an identical combo amp (heh) that happens to have 30w into one speaker you go up 3db. To go up 6db with our theoretical variable-power combo amp one must go from 15w to 60w.

Again, real world is pretty massively different. So you really really have to just set things up and play around for your personal joy. All the talk is only for a hopefully better understanding of how massive the variables are and a bit of underlying hard science.

If all watts were equal it would be a less interesting world. Last time I played electric out, some folks considered my 8-watt amp to be louder than both the 18w and the 30w one that were going on at the same time. Knowing a bit about the amps in question, if you reduce a few of the variables most people would rate the 18w one loudest, then my 8w one, then the 30w one. But any given single person could rate any of the three "loudest". Fun stuff.

[Laurent Brondel]

Printer2: how does your test relate to the OP's question about specific tube amps? I never argued the increase in volume when doubling speaker and cab surface, it is evident. My 2 x Deluxe Reverbs are louder when driving a 4 x 12 Marshall cab loaded with EV's and JBL's than with their suitcase cabs loaded with only 2 x EV's.

What I dispute, I'll repeat, is that 2 smaller tube amps will be as loud or louder than a single amp double the power.

Real-life examples: a single Deluxe Reverb will always be louder than 2 x Princeton Reverbs, equipped with the same speakers.
A single Twin Reverb will always be louder than 2 x Pro Reverbs, again equipped with the same speakers.
More dB's, more clean headroom, more bass response with bigger iron, this is an indisputable fact.

You can do all the tests you want with PA amps and meters, that still doesn't relate to the issue of design limitation concerning smaller and bigger classic tube amps, as we know them (Fender, Marshall, Vox and so on).
That's in real life.

[printer2]

I answered the OP's question,

Does using two 15 watt amps=the same volume as one 30 watt amp IF one assumes this comparison includes similar speakers and tubes? In other words do two Princetons=roughly a 2X10 Vibrolux (I know, not an exact comparison in wattage)?

And from my experience with tube amps I gave my answer. You said a 30W amp into one speaker would be louder than two 15W amps into two speakers (I was assuming the same type of speaker that the 30W speaker ran into). In that case the 15W amps into two speakers would be the louder. I just had the test showing a watt is a watt and contrary to some, yes they do sum together.

Taking exception to using a PA amp and some musical instrument speakers (which is where the Altecs were used previously) is of no concern to me. I could have done the tests with a couple of instrument amps I have in the basement and came to the same outcome. I used the Yamaha because it has calibrated meters and stepped volume controls. I did not want to leave any doubt in my methods showing what is fact as compared to opinions that are more fiction.

As far as tube amps and what they can do, I have seen my share and I have the test equipment and knowledge to work on them and have built my own designs with Fender amps being the starting point for most. I am well aware what each component is capable of including power and output transformers. And most of all I have done more than just throw two amps beside each other, set both volume knobs to 5, and declare one amp to be more powerful than the other. Since I know what ticks inside I tend to test apples to apples. If you wish to disagree with me I will not take it personally.

Have a nice day.

[stephenT]

Facts, tests and beliefs,.. it's difficult to let go of beliefs even in the face of facts.