Quote:
Originally posted by LTUCCI1924
iamdone
HI: How are you? The super mini is designed to run at max power 4.5 volts till the batt. are almost dead. Plus the V 5.28 up is designed to use max power with lots of enhancements that make the 3 AAA sound like way more power and last way longer till almost dead. Nothing batt wise comes close to the XIN batt technology in a portable amp. |
I read a post from tangent claiming that the s/m needed a min of 3v to run. If I can find his post, I'll quote it here. After re-reading his post, I misspoke about how soon alkalines will be able to last. Sorry for the confusion, please read the quote below from a real expert.
Here's his quote:
-----------------------
Alkaline 1.5V cells have a higher voltage only for about half of their lifetime vs. NiMH cells. That's because they drop steadily in voltage over time from a guaranteed minimum of 1.5V (can be 1.6V if the cells are really fresh) down to 0.8 to 0.9V. Therefore, they reach 1.2V or so about halfway through their total lifetime. If you must have more than 1.2V, you aren't going to use the cells' full capacity. When you've got to do that, you've got to do it, but one tries to avoid that kind of situation...
A NiMH cell, by contrast, charges up to 1.4V or so, but it drops very quickly in use to about 1.2V and stays there for most of its life. Then near the end, it drops off quickly to about 0.8 or 0.9V. So, let's say your absolute minimum operating voltage per cell is really more like 1.0 or 1.1V. In this case, a NiMH cell might actually last longer, since the bulk of its lifetime is above this point.
With the Supermini, the circuit is rail-to-rail all the way through; that means it can put out as much voltage to the headphones as you give it with the power supply. Most amps can't do that. The minimum operating voltage of the op-amp used in the Supermini is about 3V, maybe a bit less. Therefore, you probably can't drain alkalines 100% with this amp; the batteries are good down to 2.7V, but the circuit probably stops behaving properly before this point. 3V peak-to-peak output is equivalent to about a 1V sine wave, which is enough voltage for many headphones, but not all. With NiMH cells, the bulk of the lifetime for 3 cells is at 3.6V or above, which is enough for nearly 1.3V output, which is sufficient for more headphones, including ones like AKG K401s and Sennheiser HD-580s.
Another factor is the internal resistance. As alkalines drop in voltage, the internal resistance rises, making the amp sound progressively worse as the voltage drops. NiMH cells start with such a low internal resistance that even at their worst they're far better than alkalines at their best. So, even if the amp isn't yet clipping due to low supply voltage, you might choose to change out the batteries early because the sound has deteriorated too far for your taste.
So you see, whether NiMHs or alkalines give longer battery life depends on how you're going to use those batteries.
