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Posts by stv014

 It could affect the distortion of the HD600, though, as I have shown above. Unfortunately, those measurements at the site that cannot be named used the HD600 only for frequency response testing (which produced the results expected from the impedance vs. frequency plots for the HD600), but the distortion tests were performed with resistors instead.
 They are on a site - known for its CSD plots - that cannot be named here, but it was created by those who started this thread, if that helps finding out what site it is. Check the forum there, the Bakoon HPA-01 thread is a recent one and should be easy to find.
If you mean you intend to use two separate headphones connected to each amplifier, it is not a good idea, since the difference between the headphones (even if they are the same model) is likely to be greater than it is between the amplifiers. It obviously also makes fast and blind switching difficult.   Therefore, it is better to use a single headphone, connected to a switch box - preferably operated by someone else - to select one of the amplifiers, both of which are...
 The article is probably wrong, though, since an amplifier that acts as a current source effectively has (near) infinite output impedance, and eliminates the effect of electrical damping. You can see what happens to the distortion of a full size dynamic headphone when the source impedance is increased here, for example. Higher output impedance, which is closer to a current source, resulted in higher distortion. Although it is true that the current drawn by the driver from...
 It drops both, but to compensate, you need to turn up the volume, and that typically increases the hiss less than the signal (because noise that is added after the volume control is not affected by it), so you get better SNR at the same loudness.
Electrostatic headphones are more challenging to drive than others, due to the large voltage swing (even compared to loudspeakers) that is required in the range of up to hundreds of Volts, and they are a very small market, so it is not impossible that some of the few amplifiers that are available are not transparent. But it is hard to tell without detailed measurements, and sighted listening is not a reliable source of information.
Technically, you need a source with a known (and preferably purely resistive) output impedance, and measure its frequency response with and without the headphone load, then the impedance can be calculated from how the frequency response (including the phase response) changes. There are various software packages like ARTA that can do this, some may be available for free, or as a trial version. Also, the utilities linked in my signature can be used for impedance...
 Well, some of them might really have lower distortion at higher levels, it could only be found out for sure if InnerFidelity provided more information (i.e. THD (not +N) vs. frequency and/or FFT plots). But distortion that is higher percentage at low signal level (for example, crossover or quantization distortion) is usually "bad", because it does not benefit as much from masking (it is more like noise), and it tends to produce high order harmonics.  Louder generally...
 Actually, when the sample rate is a multiple of 44.1 kHz, the Xonar Essence STX has much lower SNR, "only" about 110-111 dB, which is of course still good enough for a line output. The advertised figure is at 48 (or 96) kHz sample rate, and even then it might be 118-120 dB in practice, perhaps depending on other parts of the PC. Lowering the volume on the card obviously reduces it further, since the volume control is digital.
 While the specs provided are not enough to explain to exact figure of 84.1 dB, the main reason why it can decrease so much is that the power amplifier is not run at its maximum output level (i.e. the 115 dB is very likely referenced to the highest voltage it is capable of without clipping, while the 84.1 dB is at 1 W power), and that there is significant gain after the volume control. If the volume control is in the pre-amplifier, and the system has excess gain (it would...
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