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New Physics

#4
A couple of things: although the watts of amplifier power output and the electrical watts consumed are directly proportional, they are not equivalent measurements. Also, a guitar or bass amp isn't typically used in such a fashion that it is operating at it's maximum output level continuously--in fact it probably is rarely consuming its maximum available power. For that reason, it wouldn't be unreasonable to assume some reduced level of power consumption as compared to its maximum available continuous power. That leaves plenty of room for creative marketing and specs-manship. I doubt the manufacturer is under any legal obligation to divulge how it arrived at that 4-hour figure, but it wouldn't surprise me to learn that it's at some de-rated continuous power consumption...perhaps as little as 1/8th to 1/4th.

If you really want to get annoyed about the alternative physics of the marketing world, try to figure out how you can plug a shop-vac rated at 6 HP into a 15-amp, 125-volt AC outlet. :D
 
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#6
Here's how the calculations work for this...

Battery capacity is 4WH x 8 = 35 WH total available energy.

Amp power is 25 watts (RMS presumed) and assuming 85% efficient would consume about 30 watts at rated power.

For average consumption, the figure generally calculated at 1/8 rated power, so .125 x 30 watts = 4 watts.

Divide 35WH by 4 Watts and you get 8.75 hours.

Therefore in practice, I would expect the claim to be a reasonable one.
 
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#7
agedhorse said:
Here's how the calculations work for this...

Battery capacity is 4WH x 8 = 35 WH total available energy.

Amp power is 25 watts (RMS presumed) and assuming 85% efficient would consume about 30 watts at rated power.

For average consumption, the figure generally calculated at 1/8 rated power, so .125 x 30 watts = 4 watts.

Divide 35WH by 4 Watts and you get 8.75 hours.

Therefore in practice, I would expect the claim to be a reasonable one.
Click to expand...

As ever, I have learned.

It does mean that my hope that this was a way to create free energy and cascade these to run an aluminium smelter of 8 AA batteries have been dashed!

I'll look at the 45W version too. It's an acoustic instrument amp so I'm looking at it more for something clean for ABG, acoustic guitar, and electric guitar with speaker sim for jams and on stage monitoring. It's a 6.5 inch speaker so I doubt the SPLs are a big number.
 
#8
When designing for low power applications, there are things that can be done to improve speaker sensitivity if low cost is not the sole determining factor.
 
#9
agedhorse said:
When designing for low power applications, there are things that can be done to improve speaker sensitivity if low cost is not the sole determining factor.
Click to expand...

Indeed, but I would assume it's likely to be of lower sensitivity unless I can find some specs.

It's pretty cheap as it's not a primary usage for me and I'm pretty cheap too :) It would be purely for secondary applications so it's low priority so I'm not minded to spend a lot. I have powered monitors although I've not bonded with my IEMs. An acoustic amp would like nicer at a low loudness coffee shop gig with an acoustic than a black wedge, though.

If I could get a hi-fi sound out of the old tweeterless Trace Elliot Commando I'd use that. I doubt I could even find a coaxial tweeter speaker with reasonable TS parameters with which to butcher it. That would work better for low level bass monitoring for me, though, as I'd prefer something relatively hi fi I can modify with a speaker sim when I need to.
 

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