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Testing audiophile claims and myths - Page 110

post #1636 of 2910
Quote:
You EE chap(?) is wrong. I have measured the output levels from 3 different DAC and/or CDP combinations there can be anywhere up to a 0.5V difference in line levels !  Also look at some StereoPhile measurements on digital components they frequently show big variations away from the nominal !

 

Correct me if I'm wrong, but isn't level matching at one frequency (as the EE pointed out) incomplete as far as the listening test is concerned? I would think it is.

post #1637 of 2910
Onlymif the frequency response isn't flat, and that's what you're doing the listening test to determine.
post #1638 of 2910

So testing at one frequency is the norm as far as level matching source components are concerned?

post #1639 of 2910
Quote:
Originally Posted by Yahzi View Post

So testing at one frequency is the norm as far as level matching source components are concerned?

 

The DAC or whatever is being compared is supposed to have a flat frequency response, so if the levels are matched at 1 kHz, they should be matched at other frequencies, too (except maybe some minor roll-off at the ends of the audio frequency range). If the frequency response is not flat, the result of the test will be positive anyway.

post #1640 of 2910
Quote:
Originally Posted by Yahzi View Post

 

Correct me if I'm wrong, but isn't level matching at one frequency (as the EE pointed out) incomplete as far as the listening test is concerned? I would think it is.

 

 

I measured the average across the audible frequency spectrum

post #1641 of 2910
If both of the two DAC's don't have flat frequency response, then they very well may sound different!
post #1642 of 2910
Quote:
Originally Posted by Speedskater View Post

If both of the two DAC's don't have flat frequency response, then they very well may sound different!

 

Though the deviation from flat would have to be pretty large (anywhere from 1 to 3 db in parts) and fall into the category of badly engineered or tweako. Some manufacturers (such as Wadia) do alter the FR or have sets of filters to have a HF roll-off that can start as low as 5Hkz and reach as much as -6db at 20Khz. Some may find this pleasant to listen to but high fidelity (accurate) it is not - some manufacturers manage this inadvertently - that falls into the category of gross incompetence.

post #1643 of 2910
Quote:
Originally Posted by xnor View Post

>45 dB increase at low frequencies according to benchmark when going from an output impedance of 0.01 ohms to 30 ohms using an MDR-V6 (60 ohm) as load. That's only THD though.

 

do you think 0.3% THD at these lowest frequencies is audible?  here's what Douglas Self has to say regarding THD audibility (go down to #4): http://www.douglas-self.com/ampins/pseudo/subjectv.htm


Edited by fishski13 - 11/21/12 at 4:56pm
post #1644 of 2910

Probably not, but that was just a random example. Other amplifiers may have higher output impedance and higher distortion.

post #1645 of 2910
Quote:
Originally Posted by xnor View Post

Probably not, but that was just a random example. Other amplifiers may have higher output impedance and higher distortion.

i wonder what the change in THD would look like post transducer?  i currently have a 100R impedance adapter to use with my AKG K702/K601/K271.  subjectively, the FR sounds much more balanced.  i'm intentionally coloring an amplifier to make an inherently colored transducer sound less colored biggrin.gif

post #1646 of 2910
I would think the distortion created by the transducer dwarfs anything even the most mediocre amp creates. In general THD is no longer much of an issue in solid state electronics.
post #1647 of 2910
Quote:
Originally Posted by bigshot View Post

I would think the distortion created by the transducer dwarfs anything even the most mediocre amp creates. In general THD is no longer much of an issue in solid state electronics.

 

this makes sense to me.  

 

don't be afraid to adjust the FR of a HP with a series resistor in both channels.  i find EQing to be a pain in the ass.  line-level matching with a DVM when comparing components is a PITA, but necessary - if both components aren't matched in loudness, what's the point of comparing A/B or DBT?  

 

i'm really enjoying my K702/K601/K271 from the Benchmark DAC1, but with an 100R impedance adapter.  both of these components have the reputation of being itty-bitty-spitty in the upper-mids and lower-treble.  the 100R on the AKG702 results in a DF = 0.6...and it sounds great.  without the 100R dongle, it hurts to listen to music above 70dB.  the K601 is a champ as well.  

post #1648 of 2910
Quote:
Originally Posted by fishski13 View Post

i wonder what the change in THD would look like post transducer?

 

It is not an accurate comparison because the levels are different (106 dB SPL vs. 100), but here is the THD+N vs. frequency measured at the amplifier output with a damping factor of 10 (Benchmark), and the acoustic output with a damping factor above 150 (InnerFidelity):

 

    700

Of course, acoustic measurements are less accurate and reliable, and since it is not the same pair of headphones, random manufacturing variation in the transducers is also an issue.

post #1649 of 2910
post #1650 of 2910
Quote:
Originally Posted by stv014 View Post

Quote:
Originally Posted by fishski13 View Post

i wonder what the change in THD would look like post transducer?

 

It is not an accurate comparison because the levels are different (106 dB SPL vs. 100), but here is the THD+N vs. frequency measured at the amplifier output with a damping factor of 10 (Benchmark), and the acoustic output with a damping factor above 150 (InnerFidelity):

 

    700

Of course, acoustic measurements are less accurate and reliable, and since it is not the same pair of headphones, random manufacturing variation in the transducers is also an issue.

...(it was a silly question, I read one of the legends wrong)

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