I'm not familiar with headphone electrical science, how does the source impedance factor into this exactly?
Quote from: jerg on January 13, 2013, 07:17:16 AMI'm not familiar with headphone electrical science, how does the source impedance factor into this exactly?This question has several answers.Firstly... the drivers are probably LEVEL matched as impedance matching says absolutely nothing about the drivers efficiency.The efficiency depends on: magnet field strength, distance between 'coil' diaphragm and magnets, current through the coil, (voltage across it divided by the impedance, resistance in this case), number of 'windings'.What is weird is that there is such a spread between the resistances. It might be due to the production method but personally think it is odd.Given the fact that they measure different yet sound equally loud says that the efficiency of the drivers is not under tight tolerances and they 'match' drivers probably by measuring them and selecting drivers closely level matched.This could mean the impedance (due to variances in the production process) could vary.This is not a problem when a low output resistance amplifier (source resistance) is used but due to voltage division COULD cause L-R balance issues when driven from a higher output R amplifier.A non- issue really as planars should be driven from low resistance amplifiers anyway.The resistance you measure = impedance for planars. It is different for 98% of all 'normal' dynamic headphones though.In this case the measured DC resistance is the lowest impedance and in general will be above that value .
Thanks for the explanation. So it seems that the impedance imbalance would be fairly benign under normal use then.
Interesting. Seems like these are seriously dark/muffled/cupped with the stock leather pads. Kinda similar from memory to my older DT1350, except way better everywhere. Especially the 1800 Hz hole affects the sound, making for weird behind-the-head soundstaging.Have a yummy correction curve. Of course my pair of HE-500 is not yet burned in as per manufacturer's recommendation, but this shouldn't change anything major.With or without the correction, there seem to be no audible resonances. Well maybe there's some slight extra grit with electric guitars and low trumpet overblow, I'm not entirely sure. Could be something near 4k.Bass is hard hitting and not really distorted at all, very fast. Treble has very nice body to it yet is not lacking sharpness at all. Mids are just superb, best I've heard out there. Generally powerful presentation but not lacking in finesse and micronanodetail when equalized. It makes TWFK and old Beyer T70 sound like a gritty mess. Modded equalized RE-ZERO are somewhat close, but far longer delay, reverberated and not as powerful bass impact.I'll follow up with velour and quite a bit later with home-made Jergpads.Reference 500 Hz, matched loudness vs the IEMs, calibrated as usual using a set of radio voice recordings (approx. 40 sones at -6 dBFS = not loud). Driven off Leckerton UHA6-mkII, OPA2209, gain switch on, dial around 2/3 position.I'd love to send them in for the measurement, but I want to compare them head to head vs Paradox first.On another note: Hifiman cannot make cables. The HE-500 cables are horrible PVC or PET (or some other crud stiff transparent plastic) that causes nasty plasticky microphonics, aggravated by the braid. It is also very long. Fortunately unlike IEM's it's replaceable.
More experiment: now with Beyer T70 velours. (same as T1 and DT990 I think) Had to trim the mounting plastic ring using nail scissors to accomodate these.These velours are made of thicker cloth, are softer and flatter (thinner). Not to mention they don't have the dust protection screen.The sound has a body inbetween leathers and velours. Lack of the dust protector improves air quality quite a bit. (The eq boost actually now can bring them to flatness. Previously I had to cheat in a slow rolloff.) Way, way sharper than even TWFK, but this isn't fake sharpness - does not sound like odd order harmonic distortion. It isn't overly liquid smooth like leathers, but doesn't have the slight grit of stock velour either.Sound without equalization is quite similar (from memory) to GR07, but way, way more refined and airy.Lower mids and bass have a bit more body with these than with stock velours. Soundstage is slightly narrower in a good way, forward positioning is better than leathers or stock velours. No slight shout or reverb unlike leather pads.With equalization, these are the winner for now. Equalized the sound is like equalized modded RE-ZERO, but even more neutral and much better note weight and power. Less reverb, more precision. Here's the correction curve. The very narrow notch is quite dependent on placement on ears in all cases. This one at 8500 Hz is with the headphones pushed slightly forward on the head. Ranges from 8200 to 9500 Hz, but is trivial to reproduce reliably on the head.The notch is probably the acoustic shadow of sorts of the huge mounting wire in the middle front of the driver.Huh, these are now merciless vs mastering issues and encoding artifacts, a true monitor quality. They do keep all the qualities of the recording now.
