Two identical amps twice as loud as one?

[Dacious]

A qualified yes. It still depends on a number of different things - speakers, preamp configs etc. But two Deluxe Reverbs played together should be roughly as loud as say a Pro Reverb - both scenarios have 2 x 12" speakers, around 40 watts. The second reverb tank in the Deluxe would make a difference by introducing some 'fullness'.

[ac15]

Originally Posted by Dacious

Doubling speakers will provide more output - not quite double but pushing more area will project more.

Another way is: if you had a stock worn original speaker, fit a more efficient new speaker. A 33 watt Vox AC30 with two Celestion Blues is as loud or louder than a 100 watt Twin Reverb with Emis - the Blues are 105 db SPl, the Emis maybe 95. You get 10db with the Blues, = 3 times the power.

Running a pair of DRs with Cel Blues would be loud - probably louder than a Pro or Vibrolux Reverb with stock ceramics.

This is why very high efficiency speakers are so expensive. Even some Emi 12" alnico low-wattage, moderate price speakers are very efficient, up around 98-100db. They'd kill old Utahs or Oxfords for output. Same with EVs or JBLs - they increase headroom too, because they don't break up with low wattage through them.

You aint kidding. I recently took the Celestion Blue out of my Vox extension cabinet and put it into my Carr Mercury (an 8 watt amp). It now seems to sound 3 to 4 times louder than it did with the stock Eminence speaker. In fact it seems almost as loud as my 38 watt Mesa Blue Angel (although I'm sure it's not, but it sure seems in the ballpark) And it puts out great tone.

[Tim Armstrong]

Originally Posted by postjob62

I can also grasp why using two 1x12 cabs with an amp is not louder than the same amp with one 1x12 cab (just more dispersed).

Oh, if you add an another speaker, your amp WILL be louder, just like if you swap a smaller speaker for a larger one. In either case, you have more speaker surface area moving and creating soundwaves, so you're physically moving more air. A 50 watt (or a 5 watt, or a 500 watt) amplifier is louder through, say, a 4x12 cab than it is through a single 12" speaker, and an amplifier is louder through an efficient 12" speaker than it is through an efficient 6" speaker.

Remember, "50 watts" is a power measurement, not a volume measurement (that would be in decibels). It's like horsepower in an engine, and the speakers are like the transmission and drivetrain. A tractor-trailer with a big, powerful engine isn't as fast as a (relatively) small sports car, despite having much more horsepower! Same with amplifiers.

Cheers, Tim

[postjob62]

Originally Posted by Tim Armstrong

Oh, if you add an another speaker, your amp WILL be louder, just like if you swap a smaller speaker for a larger one. In either case, you have more speaker surface area moving and creating soundwaves, so you're physically moving more air. A 50 watt (or a 5 watt, or a 500 watt) amplifier is louder through, say, a 4x12 cab than it is through a single 12" speaker, and an amplifier is louder through an efficient 12" speaker than it is through an efficient 6" speaker.

Remember, "50 watts" is a power measurement, not a volume measurement (that would be in decibels). It's like horsepower in an engine, and the speakers are like the transmission and drivetrain. A tractor-trailer with a big, powerful engine isn't as fast as a (relatively) small sports car, despite having much more horsepower! Same with amplifiers.

Cheers, Tim

Thanks Tim, that's good to know.

I obviously knew that a more efficient speaker is louder than one less efficient, but I was always under the impression that other things being equal, a 2x12 wasn't louder than a 1x12 with the same amp but just somehow had a different (smoother, more presence, better dispersed?) presentation from the stage. Theory being, I suppose, that the available power hadn't changed and was just didvided between two speakers instead of going to one. I guess this would assume the two cabs were as similar in design as possible.

Good to know.

[Tony474]

Originally Posted by maestrovert

let's say you have a 50 watt amp turned up a bit and you're getting a measured 90db....
if you then add an identical amp, at the same settings and pushing the same 90db, the resulting
volume increase would not equal 180db....

First of all, because of the logarithmic nature of the decibel scale, a doubling of loudness is equivalent to a 10dB increase, for example from 90 to 100dB, not 180.

Secondly, a doubling in power output represents a 3dB increase. So by running 2 DRs you'd be putting a notional 44W into 2 12" speakers, which might sound a little louder, but not by a lot, and probably a bit fuller.

On the other hand, other things being equal, if you're splitting the output from your guitar between two amps, each one is only going to be getting a reduced signal, so each pre-amp will have less input to amplify.

Experience tells me that, especially if you put one amp on the floor and stand the other on top of it, the sound will almost certainly be fuller with more low-end, but not necessarily any louder. BUT if you then attenuate the bass to compensate you should be able to advance the volume controls further before running out of clean headroom, or for the same amount of breakup.