Topic: Driving to "full potential" (Read 5670 times)

MuppetFace · « **Reply #20 on:** March 14, 2014, 02:26:28 PM »

Others here can do a much better job of explaining the technical underpinnings, but commenting from my own experience, the "proper amping" issue is a genuine one that has been overused to the point of becoming practically meaningless, generally by people who are being defensive about a headphone they like or trying to flex their e-peen.

That being said, it's just as common these days to run across posts that say all amps have to do is just make your headphones louder, that all amps sound the same, etc. In my opinion these are even more misguided in their own way.

The way I see it, an amp needs to be able to properly control a transducer---what some pirates have referred to as grip---and this isn't really a matter of raw power so much as providing a stable platform for it. The SR-007 is an obvious example. The voltage swing of the amp needs to be large enough to "wake it up," otherwise it sounds too dark and polite, the bass too flabby.

Just as important though is the amp's ability to convey complexities, low level information, proper timing, etc. There's a tendency for jargon to pile up quickly in this hobby, so honestly I just fall back on whether it sounds natural and musically satisfying to me or not. Yes, a totally subjective assessment that comes from listening. However many amps that are touted as wire-with-gain just sound dynamically flat, like all the rich musical nuance is compressed into a single plane.

A good amp to my mind needs to be able to let those complexities through without blunting them, and in my experience power is often totally beside the point. In fact a lot of speaker amps that put power first actually sound worse with headphones in my opinion. Purrin gave a reasonable theory as to why: because they're built with a different set of priorities in mind, and they can "get away" with using cheaper parts often times.

So yes, "driving to full potential" is a legit term for me, provided it's applied in the right context. It rarely has to do with raw power however and more often than not the quality of the amp in its ability to let the transducer's full potential shine. Obviously this will vary from one pair of headphones to another. The Sennheiser HD800 for instance is one picky mofo, and on a lot of amps---in all price ranges---it can sound flat, dull, and devoid of life. It's not about spending a lot necessarily: the Vali does a good job considering its price and competition.

dBel84 · « **Reply #21 on:** March 14, 2014, 03:21:26 PM »

This topic will remain a hot debate for as long as the hobby exists.

SD has nailed the technicalities of voltage swing and current drive for high and low impedance headphones respectively. There are many amplifiers that can play loud - this means very little. as MF states, it is how well it controls the headphone driver and translates the musical signal into a tangible experience. I too think the real factor is the quality of the gear and design - if the amplifier is designed to deliver exceptional performance ( not measured THD ) , it would have taken into consideration the headphone impedances to be driven and worked that into the equation. Often this equates to a higher capabilities in order to deal with both voltage and current requirements. ( higher voltage rails with higher current abilities just equate to higher power amps out of necessity )

..dB

N · « **Reply #22 on:** March 14, 2014, 04:46:52 PM »

Quote from: anetode on March 14, 2014, 08:58:57 AM

Damping factor & headroom pretty much nail it. I'd also throw in low noise floor, low enough to be inaudible with IEMs with 120db sensitivity. No hum, no click & pop on input change, adequate heat dissipation, no channel imbalance on volume changes, etc. Basically a well designed amp where you don't have to worry about any hypothetical "full potential" and simply enjoy the music.

What I find odd is that so many enthusiasts have strange deeply rooted predilections about amping and often sacrifice on features, noise, etc. for the sake of some ideal design. Just ask around about an amp for the HD800 or HE6 and you'll assemble the militant factions.

Threads like this are an awesome reminder for me to give less of a fvck.

Ultimately, I'm mostly consistent with this mindset.

My participation in a DBT in 2010 caused me to lose faith in ~~perceivable~~ my ability to perceive differences in upstream components with sufficient confidence (null result).

I did think the difference between a pair of stock and modified HD 800s was subtle. But from a O2 or Magni up to a Balancing Act (regrettably not yet the 2A3/Mk4), I have never heard the HD 800s "transform" as many seem to say. Sorry, but I'd rather take my old HE60 and HEV70 (!) over any of those HD 800 setups I've heard.

Darth Obvious · « **Reply #23 on:** March 14, 2014, 04:55:29 PM »

Quote from: N on March 14, 2014, 04:46:52 PM

I did think the difference between a pair of stock and modified HD 800s was subtle. But from a O2 or Magni up to a Balancing Act (regrettably not yet the 2A3/Mk4), I have never heard the HD 800s "transform" as many seem to say. Sorry, but I'd rather take my old HE60 and HEV70 (!) over any of those HD 800 setups I've heard.

No amp or DAC can transform a headphone into a completely different headphone... It's simply not possible unless the device is doing some sort of an equalisation or is overly distorting the sound. HD800 always sounded like a HD800 to me, on a warm tube amp as well as using a bright-sounding SS amp. Modded or unmodded. I agree that differences between different amps, DACs, cables etc. are better heard on the HD800 in comparison to other headphones... But it still was the same headphone.

CEE TEE · « **Reply #24 on:** March 14, 2014, 05:10:35 PM »

This may add to the thread, I just read this: http://benchmarkmedia.com/blogs/news/12838141-headphone-amplifiers-specifications-are-only-part-of-the-story

Solderdude · « **Reply #25 on:** March 14, 2014, 05:46:48 PM »

Quote from: Darth Obvious on March 14, 2014, 04:55:29 PM

Quote from: N on March 14, 2014, 04:46:52 PM

I did think the difference between a pair of stock and modified HD 800s was subtle. But from a O2 or Magni up to a Balancing Act (regrettably not yet the 2A3/Mk4), I have never heard the HD 800s "transform" as many seem to say. Sorry, but I'd rather take my old HE60 and HEV70 (!) over any of those HD 800 setups I've heard.

No amp or DAC can transform a headphone into a completely different headphone... It's simply not possible unless the device is doing some sort of an equalisation or is overly distorting the sound.

VERY possible I am afraid (says the cloth eared techie) but it is not the amplifier part itself but the output resistance that does the transforming due to voltage division with headphones that have wildly varying impedances in the low nominal impedance range.
MORE measurable than audible in most cases.

I also have to add that certain non-feedback designs that are bandwidth limited also can have some influence on the sound.

To some that is night and day, heaven vs hell, bliss vs horror, others might categorise the same differences as small, hard to hear or even negligible or non existent.

The white paper is flawed btw.
Well.. in that it is more of a marketing ploy than research with a good foundation.
They aren't really measuring a higher distortion, they are measuring the EMF generated by the driver.
More specifically the part of the generated voltage that falls over the (added) output resistor of the amp.
If they measured the THD coming out of the amplifier section (thus BEFORE the output resistor) they would have found that the distortion that is added by the amplifier circuit itself would have been the same and there is no increase.
What one is seeing in the plots is what the headphone driver generated working as a microphone NOT distortion added by the active electronics.
Of course if one looks at the output of a black box (which has an output resistor) than you measure a generated voltage across those terminals.
Would they have measured the actual (damping) CURRENT the differences would have been MUCH smaller.

It isn't damping, as much as people would like to see it this way cause it 'explains' things.

As correctly stated earlier by chetlanin a driver is damped by CURRENT and this is determined by the drivers Ohmic resistance + amplifiers resistance, number of windings and magnetic field strength.
Most damping for headphones is done by air surrounding the driver and membrane materials as well as membrane tension (in case of orthos).
Headphone membranes/diaphragms aren't comparable to heavy woofer cones.

Thujone · « **Reply #26 on:** March 14, 2014, 10:04:08 PM »

Thanks, everyone. I really appreciate and enjoy the discussion, both the technical and more subjective points of view! Thanks, CEETEE, for the resource!

Solderdude, thank you for spending the time to walk through this. I understand that any given amp's output power is dependent on the load (impedance) of the headphone as well as the output resistance of the amp. I also understand that voltage(squared) is directly related to power. For the sake of only using one word (and all amp specs are given in power), I'm going to just use "power". As I understand it, most of these power rating specs provided with an amp (hopefully provided as a chart/graph showing the difference in output with respect to impedance) are typically "peak" power ratings. Since these specs can differ between companies, let's just pretend we are only looking at Garage1217 graphs. As long as you have enough power to reach your comfortable SPL (using your headphone power requirement chart), can you not assume that you have enough voltage as well? What about current?

I'm also still a little lost on the point behind overhead power. For example, let's say I always listen at 105dB (

) on Project Ember. I would go to your chart and see the power requirement for my particular set of headphones at 105dB, then I would go to the power output graph for Ember at my particular headphone's impedance. Now that I've found my headphone needs XmW to get to 105dB and Ember provides YmW at the given impedance, all I got to do is make sure that Y>X in order to not have a clipping issue at 105dB, right?

Typically, Y>>>>X and the difference (Y-X) is what I'm referring to as "overhead power". Is this overhead power/voltage being used at all if the headphone is never turned up past 105dB? It seems to me that the only time it would be used is if you wanted to turn the volume up even higher. That said, having "overhead power" is just like having a safety cushion. While giving you the option of being able to turn them up even louder, you are also insuring that the amp is not operating at 100%, which is better for the amp. In this sense, I am very fond of Marv's metaphor regarding cars and HP. If you don't plan on turning it "up to eleven", having a ton overhead power is like having 400HP and driving like my grandmother, but at least you can tell your friends!

Now, as far as the subjective discussion goes, "driving to full potential" is completely based on your own preferences. Once you meet the power/voltage requirements you are more concerned with pairing, AKA quality>quantity. I have no problem with this at all. It's no question that amps sound different and that some will find one more appealing than another. I guess my whole issue with that phrasing is that "full potential" to most people in this hobby is only accomplished by have more quantity (i.e. higher power specs). The reason I don't understand this mindset is because, at a given volume, the headphone is receiving the exact same power/voltage regardless of the amp (provided it can actually reach these voltage levels at the given impedance), right?

From my own experience I have found that the mini-X did one thing better than the Vali or Ember on my HE-4's and that's bass impact (and possibly bass quantity). In all other cases (clarity, spacing, noisefloor, etc.), I would prefer the other two. Maybe this is the characteristic that Marv has experienced on speaker amps with HE cans, though I'm not sure what is accounting for it.

OJneg · « **Reply #27 on:** March 14, 2014, 10:22:06 PM »

No one listens at 105dB. That's painful. The rule of thumb (that I'm familiar with) is to have your system be able to hit 110dB (I've also heard 120dB) for dynamic peaks. The logic goes that if your amplifier can provide power at that high level continuously, then it'll have no problem delivering the music over small period of time. So that's where your amplifier's dynamic headroom would come into play.

But given that most music doesn't have more than 30-40dB of dynamic range, your listening level would have to be closer to 80-90dB. Which matches up pretty well with what most consider to be "reference" levels. Maybe it's my young ears, but I consider "reference" levels to be very loud, and tend to listen closer to 70dB. Especially with headphones; I find loudspeakers are a bit easier to crank up.

Should also be noted that most transducers start distorting way before the amplifiers do.

Thujone · « **Reply #28 on:** March 14, 2014, 10:25:53 PM »

I don't actually listen at 105dB

. Just making up an example. What would cause a dynamic peak?

fishski13 · « **Reply #29 on:** March 15, 2014, 01:00:10 AM »

"headroom" is a nebulous topic, and as Don said, will be debated ad nauseam. SD has a great article on HPs/amplification that i don't think he linked? i can't find it right now.

to muddy the waters some more - some mistakenly equate amplifier gain with power. you can have a more powerful amplifier with a lower gain, utilizing the full sweep of the pot, that will require more pot travel than an amplifier with less power but having a higher gain. in an amplifier that employs global NFB (most do), gain is set by increasing or decreasing the amount of NFB (less NFB=moar gain), and not is dependent on total V-swing or current delivery.

i'm not a big fan of "Watts" as a spec. i'd rather have V-swing, and Class A and A-B bias.

while it doesn't take a lot of power to drive HPs, even with "headroom", some output devices do like extra current bias or V-swing (moar power) to achieve subjectively better sonics and measured linearity, but this is entirely dependent on the output devices, implementation, and sonic preferences of the circuit engineer.

i would never outright reject an "over-powered" amplifier, nor a "barely enough" amplifier, provided both were quiet without clipping - i've had good luck with both. line level matching with a DMM won't give you an STD either.

Author Topic: Driving to "full potential" (Read 5670 times)

MuppetFace

Re: Driving to "full potential"

dBel84

Re: Driving to "full potential"

N

Re: Driving to "full potential"

Darth Obvious

Re: Driving to "full potential"

CEE TEE

Re: Driving to "full potential"

Solderdude

Re: Driving to "full potential"

Thujone

Re: Driving to "full potential"

OJneg

Re: Driving to "full potential"

Thujone

Re: Driving to "full potential"

fishski13

Re: Driving to "full potential"

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Author Topic: Driving to "full potential" (Read 5670 times)

Darth Obvious