5:25 Head no volume change with power switch?

Hi guys,
just purchased the head in subject, and I absolutely love it.
I have a doubt though: when I switch from 5W to 15W I clearly notice a slight volume boost, when I switch from 15W to 25W I don't hear any particular change. Volume remains the same.

Since I bought it yesterday I had no material time to test it out of my room and louder. The impression is, however, that from 5W to 15W there is a clear difference in volume (just by moving the switch I mean), while there is not the same boost from 15W to 25W.

Do you experience the same behavior? Is that normal? Apart from this concern, the head runs perfectly.

Thanks a lot.

Changing the power on an amp doesn't always change the volume-it's sometimes more of a tonal thing. Also it takes a lot of additional power to bump the perceived volume even slightly. Going from 5 to 15 watts is tripling the power so you will hear some increase. Going from 15 to 25 watts isn't even doubling it so any perceived volume changes are likely to be minimal. It would be more of tonal change, and even that would be more evident at higher volumes.

I don't think there is anything wrong.

If you play loud, you'll notice you will run out of headroom quicker running at 15 watts instead of 25. Which means as you turn up the guitar, it's going to start to distort sooner at 15 watts even with the amp turned up all the way. At 25 watts, the amp will stay cleaner a bit longer.

But... 15 to 25 watts is only a 40% increase.
5 to 15 watts, on the other hand, is a 300% increase. Mucho larger.

Here's something else to wrap your brain around:
If you want to be TWICE as loud, you need TEN times the power.
So, in order to be twice as loud as 5 watts, you need a 50 watt amp.

It works the other way as well.
5 watts is not going to be twice as quiet as 10 watts. Or 25 watts. Or 40 watts.

Science!

Thank you guys!
Lots of valuable considerations I did not think about as I should.
I just wanted to hear owners of this head are experiencing the same. The behavior sounds absolutely normal in light of your explanation.
To be honest my perplexity came also from another head I own ( H&K tubemeister 36). When I change the power soak settings I can always hear a clear increase/decrease of volume (I can go from 36w down to 18...then 5 .1 and viceversa)

Back to Mesa,maybe I should also take in consideration that, as the manual says, the change from 15w to 25w determines a change of efficiency as well (a/b class ..a class). When you say that I should expecf more a tonal change you probably refer to that as well. Right.

Nice to hear that my brand new Mesa is ok!

Len Rabinowitz said:

Going from 5 to 15 watts is tripling the power so you will hear some increase. Going from 15 to 25 watts isn't even doubling it so any perceived volume changes are likely to be minimal.

Click to expand...

Not only that, but the 5 watt SE mode will have a "softer" attack so the change will be more evident.

The change from 15 to 25 watts would probably be more evident playing with a band where 25 watts might feel like it has more punch.

Thanks.
Do you guys hear some rustle when you increase the master?
My unit does, at all power levels.
I think it is quote normal but you know...when you spend so much money you want to check again ans again that everything is fine the very first days.

More science: Doubling the power increases the perceived loudness by only 3 dB because sound pressure works on the log scale. 3 dB is generally considered the threshold at which most people can notice a difference in perceived loudness, some may be able to notice a 2 dB difference but not most. Going from 15 to 25 watts is only a 2 dB increase in perceived sound level, which is barely if not perceptible to most people. You'll notice as stated in other posts, that your clean headroom will go up, but the volume will sound about the same.

I have the Express 5:50+, and can barely tell a difference in volume when switching between 25 and 50 watts (a 3 dB volume increase), but there's a noticeable difference in clean headroom. There is a big difference between the 5 and 25/50 watt settings, however. 7 db increase going from 5->25W, and 10 dB difference going from 5->50W.

Jem7VWH said:

Thanks.
Do you guys hear some rustle when you increase the master?
My unit does, at all power levels.
I think it is quote normal but you know...when you spend so much money you want to check again ans again that everything is fine the very first days.

Click to expand...

Hey bud. That "rustle" is probably a slight scratchyness in the Master volume pot. My Electra Dyne has it pretty bad. Strike an open string on your guitar, then turn up the Master. Is the rustle more prominent than when it's quiet? If so, it's the pot. It's perfectly normal. It can be a little annoying (since it's a brand new amp), but nothing to worry about. You should be able to rapidly rotate the pot back and forth several times and that should get rid of it for a while. The only permanent solution is to replace the pot. That's up to you, of course. Mine is pretty bad, but it doesn't bother me enough to change it.