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  1. j-curve

    dB per milliWHAT? Efficiency vs. Sensitivity vs. "How loud do they really go?"

    Denons spotted here (japanese font). AH-D5000, 25 Ohms, 106 dB/mW AH-D2000, 25, 106 AH-D1000, 32, 103
  2. j-curve

    "ER-4J"

    I hope this project isn't perceived as some kind of evil EQ attempt. The equivalent circuit of an ER-4 transducer is not so different from that of a loudspeaker, basically an inductor with a little bit of resistance and a springy bit in the middle. The objective was to take some of the bounce...
  3. j-curve

    "ER-4J"

    First Listen From past experience I know not to expect too much from modifications like this, and sure enough, there was momentary subjective disappointment as some of the all-too-familiar Ety "flavour" was effectively suppressed. This is especially the case when comparisons are made with short...
  4. j-curve

    "ER-4J"

    Here's a different way to drive any of the 4-series transducers by Etymotic. The idea is to reduce the driving impedance without sacrificing the treble/bass balance. This will improve the damping factor at the transducer's resonant frequency, to produce a more natural sound. Unfortunately...
  5. j-curve

    Mono/Stereo/Left/Right Headphone Switch

    Shorting the left and right channels together is not the most elegant way to achieve mono. Here's another approach:- SW1 is a 6P4T shorting (make before break) rotary switch, quite a rare bird. With 30 connecting tabs in two layers, figuring out which is which is also a bit of fun. Once...
  6. j-curve

    Independent Volume Control when Sharing a Source

    Connect two sets of headphones to a single source and gain control becomes an issue. Sticking an inline volume control on one pair of headphones can help, but often has the unwelcome side effect of causing the other person's headphones to get louder when you turn yours down. Plus, those things...
  7. j-curve

    The HISSBUSTER - for sensitive headphones

    Um, guys, that's a bit spooky. I'm writing this reply from the Head-Fi Twilight Zone... Glad you like the metal shell connector. I think I got it in Akihabara, in the rabbit warren of component stores under the railway station. Believe it or not, at the time I was disappointed that I...
  8. j-curve

    The HISSBUSTER - for sensitive headphones

    Quote: Bob_McBob: How does this affect the sound of Westone UM2s? I have heard most attenutators affect it negatively, but the hiss from my iPod is really bothering me. Wow, a Westone UM2 owner. Did you know that in the spreadsheet (see link in first post) they came up as the most...
  9. j-curve

    The HISSBUSTER - for sensitive headphones

    Bumpety bump. After a few weeks of use I can say this simple attenuator is a winner. All my hissy sources (soundcard, integrated amplifier etc.) are now hiss-free. They still have plenty of headroom too. My only concern is the packaging as I'm not sure it will withstand being squashed under...
  10. j-curve

    6x6 Matrix Stepped Attenuator

    OK, here's the circuit:- Parts List As mentioned earlier, S1 and S2 are 2P6T "shorting" (make-before-break) rotary switches. At the risk of stating the obvious, the circuit shows a mono attenuator so you need to duplicate for stereo using S1b and S2b. For the resistors, the calculated...
  11. j-curve

    6x6 Matrix Stepped Attenuator

    Hi Garbz, Thanks for the expression of interest. Of course you're right, anyone with some basic electronics should be able to draw up the circuit, but I'll prepare a graphic anyway and post it for everyone else. For the moment, a few words about the parts, and the unexpected difficulties in...
  12. j-curve

    6x6 Matrix Stepped Attenuator

    So proud of my new toy... Big knob for coarse control = 6dB/step. Small knob for fine control = 2dB/step. For those times when I need an in-line volume control, I now have something I can rely on, i.e. no crackling or channel imbalance, plus a nice low output impedance to drive...
  13. j-curve

    dB per milliWHAT? Efficiency vs. Sensitivity vs. "How loud do they really go?"

    Headphone efficiency has been quoted in dB/mW ever since headphones were invented, hasn't it? Probably a good idea too, because it was fairly easy to calculate how much power you were going to need. It also allowed manufacturers to compete on a meaningful basis, improving efficiency with better...
  14. j-curve

    Digital Volume Control Artefacts on the D-NE900 [warning: long and somewhat geeky]

    A couple of weeks ago I was listening to the sample disc from Gramophone magazine (February) when I noticed something odd from my trusty portable CD player - a subtle effect but definitely something there, which if I had to "give it a name" would be noise pumping. The track was the 2nd...
  15. j-curve

    Reducing Wind Noise While Bicycling (without headphones)

    Thanks Bangers, and you're absolutely right - if it's worth doing at all, then it's worth doing in style! edit: PS: So, did it reduce the wind noise?
  16. j-curve

    ER4P to ER4B schematic -- helpful for binaural recordings...

    Interesting. Unfortunately KPOT's thread seems to be missing some of its original content. I like the look of the 100 ohm & 220nF network but the 24 ohm resistor looks suspicious. Isn't that the previously mentioned 20 ohm resistor which forms part of the 4P cable but which doesn't belong in...
  17. j-curve

    false claim.

    "Closed" has always been a false claim. Almost without exception, "closed" headphones are vented. I guess the market has tolerated the misapplication of the term because "closed" is somewhat more descriptive of the typical product than "vented", and after all it is the opposite of "open"...
  18. j-curve

    File Comparisons of Recording CD Digital Outs

    Building on the above, here's the simplest IIR filter function I could find:- ET(n) = + 26403/65536 * ET(n-2) + 30334/65536 * P(n+2) + 12794/65536 * P(n+1) - 4093/65536 * P(n) where ET(n) is the Estimated Toshiba ouptut sample at time=n and P(n) is the Pioneer (or "pure" ) input...
  19. j-curve

    File Comparisons of Recording CD Digital Outs

    Quote: Wodgy: This is very interesting. Agreed. Almost too interesting. A warning lamp is glowing on the geekometer. Quote: jefemeister: Comparison of Toshiba to Toshiba: 100% exact. At least there is method to its madness... I had a quick look at those text files...
  20. j-curve

    Sony SRF-S84 Pocket Radio: Wow!

    For decent AM in a small package you pretty much need an internal ferrite rod antenna. This makes the body of the radio directional, which might seem like a pain but is actually pretty cool for nulling out interference from electric motors when you're on the train. Do any of these radios have...
  21. j-curve

    Passive EQ for STAX

    Anyone with access to a STAX Basic, Classic or Signature system and an equalizer may wish to replicate the effect of the Passive EQ shown above. Here are some recommended settings. For a Parametric EQ without bandwidth correction:- +4dB @ 3.4kHz, 1/2 octave -5dB @ 10.5kHz, 1/6 octave If...
  22. j-curve

    Audio-Technica's Open Phones and Drive Units

    Design "Type A", Voice Coil Diameter 22mm (approx.) ATH-L3000 (Nov 2003, 500 units) 48ohms 104dB/mW, OFC8N bobbin wound voice coil
  23. j-curve

    Sony Electronics cuts and headphones

    Firstly, if Sony did cut their entire headphone range and only 3 models (selected by Jasper994) were missed then wouldn't that represent an overall victory for the headphone community, the removal of all those mediocre phones from the market? When were the 3 good models originally released...
  24. j-curve

    Aren't those new ATH phones cute or what

    <checks calendar> Nope, it's not April 1st... The final nail in the coffin, I'm afraid.
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