A better OPAMP or a better ... "design"?

[videocrew]

well yeah, the ideal amplifier would do absolutely nothing but add gain to the input signal and feed it back out to the output. the only problem is, this leads many people who have never heard an amplifier to reason that the sole benefit of an amplifier is higher volume. the argument i heard most often in the car stereo world was "i don't need an amp for my speakers, its loud enough if i turn it all the way up already"

i can take my iPod, crank the volume all the way up, and drive my A500's to unlistenably loud levels. however, is this to say that i will gain nothing but volume by adding an amplifier? of course not. there is a whole litany of benefits to adding an amplifier, from more solid bass, to better extended highs, and a better midrange. the fact is, the headphone amplifier in most devices is lackluster at best, and probably close to being overdriven by the time a listenable volume is reached. so while a headphone amp makes things a lot "louder" it also lets all of the circuits in the signal chain operate in a region they are a lot more comfortable with, thereby producing 'better' and not just 'more' sound.

as an analogy, would you prefer to have a car that made 250hp at 9000 rpm or at 3500 rpm? if you ask me, everything else being equal, i'd like to keep everything much closer to a comfortable operating range to obtain the same result.

in a nutshell though, isn't it a lot more concise and less misleading to a headphone amp rookie to explain that an amp will make his headphones sound better and not just louder? i think so, and therefore i stand by my previous statement in the context in which i said it.

 

[philodox]

Quote:

Originally Posted by videocrew In a nutshell though, isn't it a lot more concise and less misleading to a headphone amp rookie to explain that an amp will make his headphones sound better and not just louder?

In that context the answer is perfectly acceptable... I'm just picky and felt like delving a little deeper. Now if someone reads this thread they will either get a quick answer or if they read further they will have that answer, but will also understand what it means. But mainly I was just being picky...

 

[SnoopyRocks]

It's great when consumers make the effort to educate themselves. Audiophiles seem to be pretty good about this in general. However, things get a bit hazy when they, or anyone really, try to read too much into technical details that really don't say much about the sound. As with most things, it's all in the details. If a group of electrical engineers (lets even assume that they were all audiophiles with golden ears) were asked rate the sound of a list of amplifiers just from technical information, even schematics, they wouldn't be able to differentiate the sonic qualities of the various designs. There would have to be blatantly obvious differences to make any judgements. My point is that only crititcal listening should matter. Who cares what's actually in the black box as long as it sounds wonderful?

To clarify a misconception about opamps...
They do not have to be monolithic, on the same die, like the AD8610 and OPA627. The Gilmore dynaX amps are really opamps, discretely implemented, but opamps nonetheless. Seeing the forest (functional block - that magic triangle) through the trees (transistors, leds, resistors, ...) reveals that the aforementioned gilmore designs are simply noninverting negative feedback amplifiers, just like a cmoy. The distinction lies in what the triangle actually contains.

 

[Cyrilix]

Shimage, excellent response!

Thanks a million.

Quote:

but apparently it oughtn't to be used as a preamp.

If the Pimeta shouldn't be used as a preamp, what other kinds of amps are there? Doesn't preamp simply mean that it comes before the headphones or is there a "post-amp" as well?

 

[MisterX]

The "post amp" in a headphone rig is your brain.

 

[shimage]

Quote:

Originally Posted by Cyrilix Shimage, excellent response! Thanks a million. If the Pimeta shouldn't be used as a preamp, what other kinds of amps are there? Doesn't preamp simply mean that it comes before the headphones or is there a "post-amp" as well?

I'm glad you found it useful! To clarify some vocabulary, "preamps" go between the source and the power amplifier. Audiophiles (you know, the ones that won't touch headphones) see them as expensive volume knobs, since power amps don't always have their own (volume knobs). Hence usage of the so-called "passive preamp". Aside from volume control, active preamps provide voltage gain and serve as a buffer between the source and the amp. They tend not to be as useful with modern sources being what they are (another reason for using a passive preamp).

Headphone amplifiers often make excellent preamps, so people that listen to both headphones and speakers will often have their headphone amp pull double-duty. You can't use an active ground in a preamp since many power amps short the signal ground to the power ground. Amps with an active ground can be modified to serve as a preamp, but then you're wasting a large portion of the circuit. That said, it's been done, though I haven't seen many comments on the quality of such a preamp. My guess is that it should be fine, but I don't have any experience with it yet (hopefully, I will soon, though). I've read that the Gilmore amps are amazing preamps but I've never even heard one with headphones, so I can't really comment.

 

[MKAL]

Would amps that only have inputs and headphone outs work as preamps? If so, does the SR-71 have active grounds?