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Skeptico Saloon: An Objectivist Joint - Page 45  

post #661 of 1671

Oh man... another amazing comment in the Oppo thread. A fella with a lot of technical knowledge points to three headphone frequency response charts, all with the exact same curve to within 4dB and says those all sound completely different... and then compares two cans with a 15dB difference on the whole bottom half of the frequency range and says they sound the same. When I ask him what he's looking at in the charts he posted to make those determinations, he says it's "driver loading". Now I'm no expert, but I'm guessing that means the direction the sound comes out of the driver to go into your ears. I can't imagine that throwing half the frequency spectrum off by 15dB and make three headphones with identical response sound totally different. Does anyone know just how big of an impact "driver loading" has? (in dB) I would guess it would be easy to measure with tone sweeps by ear.


Edit: OK, now they say a 15dB difference in the heart of the treble is "measuring the same". I don't understand this at all. Why even bother with specs if they don't represent the sound?


For what it's worth, now that I've seen the "officialish" frequency response chart for the Oppo PM-1s, it pretty much accurately depicts how they sound- stone flat throughout the key frequencies. The only area I'd question is their measurement of the boost at 9kHz. I showed that at 6kHz on two different sets of PM-1s, and it was about 8dB less of a boost. That's a quibble that wouldn't really affect the sound much though.

Edited by bigshot - 4/18/14 at 10:38pm
post #662 of 1671

I don't see the part you are talking about, deleted again? You should try a HE-500, its even flatter in freq response (in terms of treble anyway) and cost 2x less than the Oppo


post #663 of 1671
Originally Posted by bigshot View Post

That graph is made using a microphone, so you have to apply a correction curve. If you determined the response by ear using tones, the sound of the tones would be even all the way across... no correction needed.... measured flat vs audibly flat. If you graph audibly flat, it's a straight line- correction built in.

I always EQ by ear, so Fletcher Munson and ear canal shape doesn't matter. All of that is already incorporated into my hearing. Simpler that way.

I might be a bit late for this but...

I think you can be dismissive about equal loudness curves because you don't actually EQ by tone sweeps (you EQ by music listening correct?)

I actually EQ by tone sweeps and I do need to dial in my equal loudness curve before EQing any headphones.

A simple illustration should suffice to show what's going on:

From left to right: EQ I dialled in on a pair of earphones (in this case the Philips SHE3580), EQ I dialled in to compensate for the equal loudness curve (swooping up and up in the bass), and finally the program I'm using to produce tone sweeps.

Tone sweeps at a reference loudness (reaching what I'd call an average musical volume for me at 1kHz) have to pass through both a headphone correction EQ AND an equal loudness curve EQ to have a consistent loudness throughout the range. Here's my equal loudness curve this year, as accurate as I can make it using reference earphones EQed to best musical performance for reference:

Note that the upslope in the bass is nowhere near as steep as an ISO standard equal loudness curve--it's interesting that this slope seemed to go down as I got more used to listening to tone sweeps--but it's still over 10dBs. The upslope on the right shows my age redface.gif even with this slope I have to give up on targeting equal loudness after 11.5kHz or so.

I think the issue is complicated by the fact that people who try to EQ by tone sweeps without an equal loudness compensation curve "learn" that a bass tone that sounds weaker is actually "just as loud" as that 1kHz tone until their brains' perception of equal loudness tones changes to one that is actually almost equal power throughout the range. Or they EQ with this skewed equal loudness methodology and deem the resulting sound to be natural. Or some combination of the two.
post #664 of 1671

I don't use tone sweeps myself. My buddy who is a sound engineer does. I did a pass using my EQing to music method with an equalizer and took note of my corrections, then he came in and did tone sweeps by ear. 


My friend did two passes of 1 1/2 octave sweeps from low to high. The second pass was louder than the first. Probably peak listening level. He tweaked the EQ at both volume levels, then let me check an octave and a half at a time. I didn't pay attention to how he did the final pass, but it involved comparing different parts of the frequency range. By the end, he was doing huge sweeps across large chunks. He might have a sense for loudness compensation built into his head.


When we compared our notes, he was able to find more tiny bumps of 1 or 2dB in the treble than I did, but the two large bumps (in the range of 4dB if that can be called large) at 3kHz and 6kHz were on both of our notes. The fact that we both used different means and ended up in the same place made me think we did something right...

post #665 of 1671

After following the Stax thread for a month, I no longer have an antipathy for audio snake oil salesmen. The average hobbyist has no interest in the science contained within his music, equipment, and listening. We demand to be able to dump our money!


My highlights of the thread:


  • A complete evasion on the limitations and requirements of electrostatic amplifiers. Pages of wittering on the topic and nothing to show for it. Like a pack of dogs being fed peanut butter. Even the one or two who have designed electrostatic amplifiers do not care to authoritatively answer what should interest them. A far cry from another forum I frequent about displays, where experts always throw in for serious questions. That forum is no conservatory either; ownership has just as many commercial interests as this, too.
  • Stax developed their own diffuse field equalisation for their headphones, and I have the exact parameters! My convolution engine is compiled and poised for action. I won't even have to listen to sine sweeps to get a linear response. However, users tell me either that it sounds bad, or EQ adds IMD.
  • To get around this, people irreversibly butcher modify their two thousand dollar headphones to change the sound signature, always for the better I am told.
  • Another option is to simply sell and purchase new headphones constantly, for life, even though the model they have now is distortion free and reasonably linear, making it perfectly suited for EQ by even one parameter alone.
  • We need to work on our interconnects. I'd call them morons but my post would be disappeared.
  • The new model sucks. This is what really disgusted me. You have to either buy vintage or one of the big toys. Were it not for Rin Choi's work showing far more similarity than difference between models thirty years apart, I would have made a concession on this.



By and large, we are talking about bumbling and incurious people owning three thousand dollar systems. I would be offended by the behaviour of my customers if I were operating a serious sound company.

Edited by dripf - 4/19/14 at 1:55pm
post #666 of 1671

About electrostatics though, do they have the lowest amount of distortion for a headphone?  Does dynamics have most?  Anybody have a link that goes in depth of information on different types of drivers and their characteristics?

post #667 of 1671

dripf wins the prize for best post of the day!

post #668 of 1671
Originally Posted by SilverEars View Post

About electrostatics though, do they have the lowest amount of distortion for a headphone?  Does dynamics have most?  Anybody have a link that goes in depth of information on different types of drivers and their characteristics?



Examine all the headphones you have interests in and you can draw conclusions to your questions.

post #669 of 1671
Originally Posted by SilverEars View Post

About electrostatics though, do they have the lowest amount of distortion for a headphone?  Does dynamics have most?  Anybody have a link that goes in depth of information on different types of drivers and their characteristics?


The primary difference is the absence of rising low frequency distortion usually present in dynamic models. Otherwise, the best models of all technologies seem to float at 0.1% THD+N. Is this the detection limit?


Decay characteristic is where electrostatic and isodynamic regularly obsolete the dynamic offerings. You often see resonances in CSD plots for dynamic models. Problem is, there seems to be poor agreement between results. The importance and perceptual effect of resonances isn't well explained either.

post #670 of 1671

Anyway, thanks for the info guys, it's a fantastic reference.  I want to thank Tyll with his efforts to provide this info.  Yes, dynamics have low end increase in distortion.  It's apparent in the square waves for low frequencies.  I do like the Hifiman measurements, and also the Sony EX-1000 which I thought sounded well.  I have the LCD-2 the THD is leveled under 1% and also there is no resonance with it as it's purely resisitive load from what I've heard.

post #671 of 1671

What do people say the resonance causes to the sound?

post #672 of 1671

Closed sounding, main difference between open backs and closed from my knowledge

post #673 of 1671

Ok, there is a distinction between electrical resonance and sonic resonance.  Electrical resonance is clearly showed on the impedance graphs, but in regards to sonic resonance I would think it's the echoing effect on closed area from lack of decay of the sonic waves.  I've heard about this on hearing aids with small bore size where the user would fix the echo by enlarging the bore.  Also, for closed backs this would make sense since it's enclosed.


I still wonder what the electrical resonance graph would portray sonically.  I would think it would be the drivers moving ignoring the electrical control like a spring example.


Also, another thing that should be considered regarding Tyll's graph is what kind of source he was using for these measurements. 

Edited by SilverEars - 4/20/14 at 10:11am
post #674 of 1671
His measurement gear is described here.

As for what the electrical measurements show that is audible, I don't see what they show besides phase.
Edited by briskly - 4/20/14 at 10:54am
post #675 of 1671

I was at RWA's website checking out the Isabella Amp.  http://redwineaudio.com/components/isabella-re


And something perplexing I've run into.  This amp is run on a battery to elimate AC to DC conversion stage.  He writes this about how low internal resitance of the battery is better for SQ and doesn't explain why.  Here's what RWA says


State-of-the-art technology. Delivers improved sound & added convenience compared to alternative battery types.

LiFePO4 (LFP) battery packs have much lower internal resistance (compared to SLA), which translates directly into better sound. And only Red Wine Audio offers premium LFP battery packs for an entire line of hi-fi components, resulting in:

  • Great dynamics
  • Tight, resolved bass
  • An open and extended treble response
  • The most environmentally friendly battery technology available
  • 5 times the cycle life compared to sealed lead-acid (SLA) batteries
  • No loss in cycle life when batteries run to complete discharge
  • Built-in, custom-designed cell management, optimizing battery performance and reliability
  • Ease of replacement, with no special skills or soldering required

And, I've read comments on the forums of people saying all batteries are not created equal for portable music players, and the more expensive stuff has better power stage after the batter?  Really?? Can it really be that better?

Edited by SilverEars - 4/20/14 at 6:10pm
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