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Posts by stv014

Measuring the output voltage of the O2 while playing a tone at the preferred listening volume settings at 0 dBFS level should be a good way to find out the peak voltage. Once you know that, you can calculate the average level with or without weighting by analyzing the tracks with software.   Note that some multimeters have a limited frequency range for accurate AC measurements. Try measuring at a few different frequencies (e.g. at 60 Hz and 1 kHz) to see how much the...
 It requires ~4.7 dB higher voltage according to measurements (DT770-600 vs. HE-6). Although in practice this number is likely to have a few dB of random sample variation, and the perceived loudness can also be affected by the frequency response. Low impedance by itself does not guarantee low voltage requirement, it only does if the efficiency (dB/mW) is the same. The HE-6 has rather poor efficiency, that is why it needs more voltage than more efficient higher impedance...
 Actually, the HE-6 also requires high voltage, a few dB more than the DT770-600.  The voltage requirement does not change as a function of impedance vs. frequency. Most headphone drivers perform best with a zero impedance source (which allows for the maximum possible electrical damping), and that implies a voltage source. The frequency response measurements you can find at innerfidelity.com and other sites also assume a near-zero source impedance, that is, they show SPL...
It would be somewhat more difficult to build due to the increased number of components, and not using a PCB would be less practical. Obviously, it would also need power.   For adding a bass boost to the previous passive filter, here are some quick examples: This does not use an inductor, but the gain at 1 kHz is now reduced to about -10 dB, and a 47 uF bipolar electrolytic capacitor is needed. The frequency response is also quite different from the original...
Using passive components only, a bass boost is easiest to implement before the amplifier as a low shelf filter, rather than a peak at 40 Hz. This requires two resistors per channel, and a capacitor in the few uF range. The disadvantage of filtering the amplifier output instead is a few dB more loss of power, and having to use a (bipolar) electrolytic capacitor. For a peak, a rather large inductor would be needed as well, so it would be more practical then to build an...
By the way, if power efficiency is an issue (due to the < 0 dB gain, and lower impedance load presented to the amplifier), an alternate solution could be to connect parallel RLC circuits in series with the ER4S.  It can matter because the impedance of both the load (headphones/IEMs, or amplifier line input) and the source (amplifier or line output) affects the frequency response. Also, although it might not be an issue with the Sansa Fuze, a line output may not like...
  This still needs some tweaking, especially if you actually want a different frequency response from what is shown in the previous post. R1, L1, and everything else to the right is the approximate model of the ER4S (based on goldenears.net and innerfidelity.com measurements), and obviously should not be built into the circuit. V1 is the source (amplifier), if it has a known significant non-zero impedance, then that should be subtracted from R3. The same applies to...
By 1.1 BW, do you mean Q = 1 / 1.1 ? If yes, the frequency response would look like this: Is the above graph correct ?
Make sure that any input (especially microphone) is muted, and that the output resolution is 24 bits. But if you do not really need the smart volume, you may want to disable it anyway to avoid dynamic compression.
 Medium width and narrow width are not quite exact. Do you have the Q values, or a frequency response graph ?
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