AtomBoy
100+ Head-Fier
- Joined
- Apr 22, 2005
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Quote:
ROTFL!
Originally Posted by mono Conan, run! |
ROTFL!
Originally Posted by mono Conan, run! |
Originally Posted by rsabo Your 5V wallwart actually provides +/- 2.5V to the chip. |
Originally Posted by tangent I don't know why you think this is significant. +/-2.5V is 5V, from a different perspective. The fact that the LM4881 wants a 5V supply doesn't mean it wants a +/-5V supply...that would be 10V, which would probably kill the chip instantly. |
Originally Posted by rsabo I think I see what you're saying, apparantly I didn't read the LM4881 datasheet correctly. 5V/ +/-2.5 is still too small for the OPA134, however, correct? |
Originally Posted by ozshadow KSC75's, while good, are still kinda low on the ladder. Grado's will open up the details more, but also be careful, because starting with something like the SR-80, in short order you start to realize your incredible headphones are suddenly lacking in certain areas and you want to spend more money on moving up the ladder. |
Originally Posted by rsabo 5V/ +/-2.5 is still too small for the OPA134, however, correct? |
Originally Posted by tomb Note that TI uses a "±" in specifying their opamp's voltage range, but National does not. Unless National specs their chips differently than TI (that would confuse Engineers), then perhaps they actually mean "±2.7V to ±5.5V", too. If that is the case, the OP's 2.5V would be even worse for the National chip. |
Originally Posted by tangent Not necessarily. Supply voltage requirements vary depending on load. If you're not trying to drive too much power into the load, the 132/134 family can indeed work at 5V. Used as a headphone driver, 5V won't be enough, but if it's the line output stage of a CD player, 5V might be fine. This assumes that the signal is centered nicely between the rails. If not -- as in the CMoy amp -- then that eats into the voltage swing range, so the supply voltage must go up in that case, too. You're overthinking it. +/-2.5V is 5V, as far as the op-amp is concerned. An op-amp doesn't see ground directly -- there is no ground pin on an op-amp. It only cares about the difference between its V+ and V- pins, and what the signal voltage is relative to those supplies. Ground is irrelevant from the op-amp's perspective. As circuit designers, we care about it because it affects how the signal is biased going into the chip and what it's referenced to coming out, but the op-amp itself doesn't care. The reason some datasheets use +/- numbers and others simple voltages is mostly one of tradition. If a datasheet gives its values in +/- terms, they're implicitly saying that the chip is designed for split supplies, which implies relatively high supply voltages. It doesn't imply either that the chip won't work on a single supply (or virtual ground scheme), or that high supply voltages are necessarily required. It just gives you some indication of what the chip's designers had in mind. Contrariwise, a chip specified with just a simple voltage usually means it's meant for single supply operation, which in turn implies lower voltages. And again, it doesn't mean you can't run it from a true split supply, and it doesn't necessarily mean that it can't tolerate higher voltages. The term "single supply op-amp" is tied up in this, too. All op-amps are single supply, and all op-amps are dual-supply. The term signals the chip's design characteristics, which suits it to some designs more than ohers, but it doesn't actually force you to use one power supply configuration over another. |
Originally Posted by regal There is a guy who will pay you $10,000 if you can hear the difference between two amps outputing the same wattage without clipping. In other words he believes a watt is a watt (the first law of thermodynamics.) You probably can't hear any difference because there isn't any. A $40 amp putting out .5W sounds the same as a $2000 amp putting out .5W. |
Originally Posted by philodox How did you achieve a line out from the iPod? Do you have an adapter of some kind or did you just volume match?Give me this guys phone number!!! |
Originally Posted by Qsilver2001 condescending image |
Originally Posted by philodox Give me this guys phone number!!! |
Originally Posted by rsabo Too small in this case, then? |
I guess it's time to start reading Op Amps For Everyone or something. |