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Headphone outputs : lots of measurments and one ABX

Discussion in 'Sound Science' started by pio2001, Jun 15, 2009.
  1. Pio2001
    I didn't try to ABX the original with the others, because they involve a DAC and an ADC in addition to the heaphone amplifier.

    The original is level-matched, though, and time-aligned too. The top graph shows that the playback and record system quality is good.

    The fact that the sample rate is not the same is the main difference, because when you listen to the samples, there must be a short delay for the DAC to switch between the sample rates. Unless you have a soundacrd that resamples on-the-fly. In this case, the quality of the resampling can be questionned.

    If you are using Foobar, load an SRC DSP, set on 44.1 or 48 kHz, and see if the difference is still there (if you want to try the ABX again, you must check a box for the DSP to be loaded in the ABX module).

    Edit : I can't record at 44.1 kHz with my deck, and I wanted to use the deck as ADC in order to avoid any clipping.
  2. xnor
    Hmm, I converted the org. to 48 kHz using foobar2k (resampler ultra mode) and still can hear a very, very subtle difference. I did make errors at the ABX this time, but still reached a 95% confidence level. (9/11) .. this sample really is fatiguing xD not going to play this again anytime soon :p
    anyway, ymmv
  3. xnor
    Based on the FR charts we can actually rank the hardware in terms of flattest FR:
    Pro-ject > Marc2 > Arcam > Marantz

    If we take a look at the headphones, it seems that a flat impedance curve is desirable, because flat means it's much easier to feed with "neutrality".
    low HD's > high ones

    is it as simple as that? [​IMG]
  4. royalcrown
    xnor: a flat impedance curve is only desirable insofar as that makes the transducer easier to drive. It's not unlikely that Sennheiser compromised efficiency with the HD800, and to a lesser extent the HD650 and so on, for performance. Sennheiser probably assumed that whoever would buy the HD800 would be feeding it with a low output impedance, from a dedicated headphone amp or the like.
  5. Pio2001
    The impedance curve of the HD600 reaches twice its lowest value (300 x 2 = 600), while the HD555 reches more than 4 times its lowest value (50 x 4 = 200). From this point of view, the red curve is flatter than the green one.
    But the amplifier output impedance has to be taken into account too. So the result is difficult to predict.

    Also, ask yourself if you prefer listening to the Marantz sample on a HD800, or to the original sample on a HD485. The intrinsic quality of the headphones is much more important than its impedance curve.
  6. xnor
    @royal: I agree

    @pio: Yeah on a logarithmic impedance scale, red would look flatter.
    But I don't know what I'd prefer. [​IMG]

    By the way, do you also see the similarities between your FR charts and the headphones' FR charts?
    Compare this with your HD600 Marantz chart: There's a "bump" from 40-300 Hz, 3k-4k, a very small one at 8k ...

    Maybe the "quality" isn't so important after all?
  7. Pio2001

    Originally Posted by xnor /img/forum/go_quote.gif
    By the way, do you also see the similarities between your FR charts and the headphones' FR charts?

    Not really. In my charts, 1 kHz is a minimum, and everything goes up above. And the 100 Hz peak is narrower. My FR charts are rather an image of the impedance curve.

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