[AtomBoy]

Quote:

Originally Posted by mono Conan, run!

ROTFL!

 

[tangent]

Quote:

Originally Posted by rsabo Your 5V wallwart actually provides +/- 2.5V to the chip.

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.

 

[ozshadow]

Have you tried Rockbox on your Ipod ? I hear that improves the soundquality, and also adds a 5 band EQ. The only Ipod I ever spent much time with only had presets which I hated.

Using Grados + and amp, some things I notice with the amp are the instruments in the background, if you listen closely, you will notice more things are audible with the amp than without it. Things like soft bass notes deep in the background have some impact, albeit soft as intended, but without the amp, you will not notice them. Rimshots with an amp make me open my eyes and think someones at the door, without it, they typically blend in. Instruments are clearer and more separated than before.

If you just listen to the song and enjoy it, you probably won't notice these things or have need for an amp. If your enjoyment in listening to the same song over and over comes from picking apart the details of the music, and noticing things like someone's using a rhythm egg shaker in the background you did not notice before, well then an amp can help you.

An amp can improve bass performance as well, but big boomy bass can mask the other details of the music. I prefer very tight, impactful bass.

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.

 

[rsabo]

Quote:

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.

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?

 

[jonnywolfet]

if you really want to hear the difference i recommend doing all your listening on one of the amps for a week or so before going back to the ipod, it is much easier to tell differences between sources when you have gotten used to a 'superior' sound.
Also, i couldnt tell any major difference between my dap and amp untill i upgraded from a cmoy to a mint, the differences between the two amps jumped out at me and caught me by surprise. as it happened, my cmoy had a very similar sound signature to my source.
give it time, you need to train your ears to be able to tell the differences.

listen out for these qualities:
instrument seperation/sounstaging, which amp gives more of a 3d feel?
vocal/instrument realism, which amp sounds more natural? female voices are good for this.
bass definition/impact/extention.
blackness, which amp is quiter during quiet passages of music? is there any hiss?
speed, which amp can keep up with frantic and faster passages of music better?
detail, listen out for micro-details in familiar recordings.

hope this helps.
jon.

 

[tomb]

Quote:

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?

TI lists ±2.5V as the minimum for that chip.

BTW, National just specs "2.7V to 5.5V" vor the LM4881. (http://www.national.com/search/searc...eywords=LM4881)

Whereas TI says "WIDE SUPPLY RANGE: ±2.5V to ±18V" for the OPA134. (http://focus.ti.com/docs/prod/folder...plicationnotes)

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.

 

[pddjsteve]

Quote:

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.

Yeah, the headphones matter a lot. My ER4Ps are night and day between the Nano's headphone out and a homemade dock to a cmoy (both with and without the ER4S convertor cable), while my girlfriend's headphones (some sony ones from best buy) sound no better with the amp, all it seems to do is muddy the bass (which sucked in the first place).

 

[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.

 

[tangent]

Quote:

Originally Posted by rsabo 5V/ +/-2.5 is still too small for the OPA134, however, correct?

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.

Quote:

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.

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.

 

[rsabo]

Quote:

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.

Too small in this case, then?

Interesting post, thanks. I guess it's time to start reading Op Amps For Everyone or something.

 

[philodox]

Am I the only one that thinks it is just the headphones he is using? No offense, as I think the Koss are a great budget headphone, but they don't really improve all that much with a better amplifier.

I am surprised that there was no audible difference when changing from a 5v wallwart to 9v batteries. In my experience that change would have a huge impact... which leads me to believe that either the headphones or the source material is holding you back.

BTW. How did you achieve a line out from the iPod? Do you have an adapter of some kind or did you just volume match? Quote:

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.

Give me this guys phone number!!!

 

[Qsilver2001]

Quote:

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!!!

 

[philodox]

Quote:

Originally Posted by Qsilver2001 condescending image

Ummm... yeah, that is what I meant by an 'adapter of some kind'. Are you Conan or Qsilver2001?

 

[rsabo]

Quote:

Originally Posted by philodox Give me this guys phone number!!!

Likewise...

 

[tangent]

Quote:

Originally Posted by rsabo Too small in this case, then?

Yeah, as I said, when you're using a 134 as a headphone driver, 5V probably isn't enough. See my numbers on that chip here. Keep in mind, those were done on a CMoy with an improved virtual ground, so when talking about a stock CMoy, the voltage requirements will be significantly higher.

Quote:

I guess it's time to start reading Op Amps For Everyone or something.

Hardly the worst thing you could do.