[granodemostasa]

I don't care to discuss... sorry.

 

[ecclesand]

Your conclusions seem logical, however, I have heard several amps and can definitely hear a difference between them. Is my hearing screwed up? Possibly. Is this the dreaded placebo effect? Maybe. Do I care if there shouldn't be a difference based on some forumula? Not really.

I know what I like and that's it.

BTW...shouldn't this be in the AMPS section?

 

[Roam]

On why THD numbers do not correlate well with perceived sound quality (PDF file) This is a graduate level thesis which was passed and approved by Electrical Engineering professors. It's based on the prior art of tests conducted by the BBC labs decades ago, the results & conclusions of which have unfortunately become lost for the most part in modern hi-fi. To briefly summarize, it's not the THD number which is important, rather, it's the distribution of the harmonic spectra.

Quote:

Originally Posted by TheVinylRipper /img/forum/go_quote.gif And tube amps create far more distortion than do solid state amps.

I suppose you'll be citing proof for this assertion?
As in an actual test of a properly designed tube circuit under realistic listening levels.

Oh, and by the way, the distortion created by a decent modern headphone such as the Sennheiser HD650 is pretty close to the -80dB level. So much for "orders of magnitude more distortion".

In short, TheVinylRipper should quit using Wikipedia and Google, and pick up some real actual textbooks and testing equipment. Norman Crowhearst's papers would be a good place to start.

 

[elrod-tom]

I'd like to remind everyone that we do not ARGUE here, we discuss. Please try to keep this a friendly discussion, without a lot of loud one-upsmanship and gotchas. Thanks...

 

[Computerpro3]

Quote:

Originally Posted by Roam /img/forum/go_quote.gif On why THD numbers do not correlate well with perceived sound quality (PDF file) This is a graduate level thesis which was passed and approved by Electrical Engineering professors. It's based on the prior art of tests conducted by the BBC labs decades ago, the results & conclusions of which have unfortunately become lost for the most part in modern hi-fi. To briefly summarize, it's not the THD number which is important, rather, it's the distribution of the harmonic spectra. I suppose you'll be citing proof for this assertion? As in an actual test of a properly designed tube circuit under realistic listening levels. Oh, and by the way, the distortion created by a decent modern headphone such as the Sennheiser HD650 is pretty close to the -80dB level. So much for "orders of magnitude more distortion". In short, TheVinylRipper should quit using Wikipedia and Google, and pick up some real actual textbooks and testing equipment. Norman Crowhearst's papers would be a good place to start.

Excellent post. Sure, TheVinylRipper may be a pompous ass (which doesn't, by the way, mean he's incorrect) but responding to him scientifically instead of emotionally makes the thread a lot more informative and interesting.

 

[TheVinylRipper]

"Pompous ass"

I thought personal insults were not allowed on headfi?

I'm not impressed by those who throw them around without provocation.

As to the graph of distortion in the HD 650, I'm skeptical, I have spectrum analyzers, I have waterfall displays very similar to what submarines use for passive sonar to detect enemy vessels at great distances.

I have put together remarkably simple devices with which it is possible to listen to the entrance of meteors into our atmosphere by picking up of television transmissions from stations well over the horizon. This can be done day or night, in any weather.

In 1969 I went into the Marine Corps and made such a high score on the induction exam that I was trained to troubleshoot and repair electronic devices which I still am not at liberty to speak of.

The peak on the graph of the HD 650 is just a little too sharp for me to believe it to be accurate. In my extensive experience with transducers the main peak of the frequency display is always wider than that and spreads out at the bottom.

This is a graph of the frequency response of my AT440MLa phono cartridge playing a 300 Hz tone from my quite expensive test record which I bought specifically for this purpose. Note the broadness of the response. Note also that the THD is nearly two percent and that the harmonics are -50 dB for the strongest one.

 

[J-Pak]

Quote:

As to the graph of distortion in the HD 650, I'm skeptical, I have spectrum analyzers, I have waterfall displays very similar to what submarines use for passive sonar to detect enemy vessels at great distances.

You're skeptical of something published by Headroom?

 

[elrod-tom]

Quote:

Originally Posted by TheVinylRipper /img/forum/go_quote.gif "Pompous ass" I thought personal insults were not allowed on headfi?

They are not...and I don't want to see any more of them. We ALL need to remember that we ought to have respect for the opinions of others, even when we disagree with them.

EDIT: We ought also be mindful of the ways in which our own argumentative style might be needlessly irritating or provocative as well...

 

[MaloS]

Quote:

Originally Posted by J-Pak /img/forum/go_quote.gif You're skeptical of something published by Headroom?

There are reasons to be, although not without taking an hd650 and taking measurements to present here...

Ripper, so what point are you honestly trying to make? We do not evaluate amps via their THD, and THD is not that only description of an amp's tonality.

 

[slwiser]

Quote:

Originally Posted by Roam /img/forum/go_quote.gif On why THD numbers do not correlate well with perceived sound quality (PDF file) This is a graduate level thesis which was passed and approved by Electrical Engineering professors. It's based on the prior art of tests conducted by the BBC labs decades ago, the results & conclusions of which have unfortunately become lost for the most part in modern hi-fi. To briefly summarize, it's not the THD number which is important, rather, it's the distribution of the harmonic spectra.

Exactly....

We have a memory of what a true note sounds like and what true music sounds like. The difference between when that music is first made and what comes into our ears has many significant things that happens to it. First it has to be miked then it goes into a long train of devices to be pressed into a form to be reproduced by our home equipment which does its thing. What we finally want is a sound which matches what our memory has of what that sound should be. All our trials of which components we like best comes to which set makes the best reproduction of that memory.

There is a book called, "This is your Brain on Music" by Daniel J. Levitin that does a very good job of discussing in psychological and memory terms of what we look for in our sound reproductions. Harmonic and tonal content differ with equipment and how what we hear compares with our memory of how it should sound like goes a long way into what we determine what equipment should sound like. It is not about purity and distortionless sound reproduction, it is about the reproduction of what we think the music should sound like. The sterile distortion free reproduction of sound is not what I am after but a reproduction of music. That may be something useful in a technical lab but not between my ears.

 

[guttorm]

Quote:

Originally Posted by slwiser /img/forum/go_quote.gif Exactly.... The sterile distortion free reproduction of sound is not what I am after but a reproduction of music.

this is what i was thinking. also i would expect even a good cartridge to have more distortion than headphones because of its greater amount of fine movements, making precision more difficult.

 

[esuko]

Hi


Does anyone know at what SPL are those headroom distortion plots taken?

Can those plots be taken seriously. HD650 and Koss portapro having same level distortion

Atleast HD650 should have lower distortion bellow 300Hz which is not shown in the graph?

By curiosity which headphone is considered having the lowest distortion figures?

 

[Blueiz]

Slwiser..... GREAT POST!

 

[guttorm]

Can those plots be taken seriously. HD650 and Koss portapro having same level distortion

QUOTE]

well, not exactly but not bad for either:

plus, look at the frequency graph comparing the portapros and some other kosses:

 

[Mindless]

Quote:

Originally Posted by slwiser /img/forum/go_quote.gif Exactly.... We have a memory of what a true note sounds like and what true music sounds like. The difference between when that music is first made and what comes into our ears has many significant things that happens to it. First it has to be miked then it goes into a long train of devices to be pressed into a form to be reproduced by our home equipment which does its thing. What we finally want is a sound which matches what our memory has of what that sound should be. All our trials of which components we like best comes to which set makes the best reproduction of that memory. There is a book called, "This is your Brain on Music" by Daniel J. Levitin that does a very good job of discussing in psychological and memory terms of what we look for in our sound reproductions. Harmonic and tonal content differ with equipment and how what we hear compares with our memory of how it should sound like goes a long way into what we determine what equipment should sound like. It is not about purity and distortionless sound reproduction, it is about the reproduction of what we think the music should sound like. The sterile distortion free reproduction of sound is not what I am after but a reproduction of music. That may be something useful in a technical lab but not between my ears.

I agree. Herein lies the whole personal preference-issue. What sounds good to my ears, dosen't have to sound good to your ears.