Thanks for continuing this Neo 3 project. A couple more observations. I tried running a 20 hz sinewave through the neo 3 at a VERY low level with my ear right up to it. All I could hear was HD. It was pretty bad. It seemed pretty clean from about 50 hz and up. I also tried running my neo 3 "headphones" from the 2 ohm headphone output of my Ipad. It worked suprisingly well, but obviously had to low an output for this application.
I have always used resistors in all my planar designs, including my headphone designs (3) . You can match your amps, including headphones. Does anybody know why the headphone impedance is so high?? My KOSS-PRO4/XTC ARE OVER 100 OHMS!Never was satisfied with any "ear cup" I created. Eventually I gave up on the cup approach and went with something similar to "open baffle" by extending the boarders of the Neo3s with various types of materials to create a longer path for sound waves to travel around. This, of course, looks silly when worn on the head.However, it did sound nicer than any cup technique and material combination I could come up with.
In the future I intend to try the "H frame" technique seen in subwoofer design. After than, I'll try a simi-open-back* cavity with various amounts and kinds of filler (or lack thereof).
The biggest development in recent history is acquiring a DSP. I own the MiniDSP Balanced 2x4, and I'll attempt using it to create an ideal HRTF curve.
My only obstacle is something in the way of an amplifier. I still don't have one with a low enough noise floor. The voltage from my sound card provides enough "volume" for the drivers, but hooking a 4ohm load to my sound card makes me nervous and I don't want to do that to my DSP.
This may be silly, but can I just put a transformer between the output of my DSP and the 4ohm Neo3 drivers? I don't need more SPL, just something to handle the 4ohm load. Unless I'm mistaken, that sounds like a job for a transformer, not necessarily requiring an amp. Is that correct? A simple transformer would not introduce noise, correct?
*Just an enclosure with holes punched in the back
Of course! I'm more of a speaker guy, but whenever I think about headphones I can't forget the experience of the Neo3s.
I've driven them directly from my balanced soundcard with plenty of volume and headroom. The soundcard is nice because it has such a low noise floor, I can't hear it at all. Dead silence at unity gain even with the Neo3s. Can't recall if I mentioned it in this thread before, but it's the EMU 1212m. The THD+N (1kHz at -1dBFS) is -105dB
I'll try applying a HPF with my DSP. See if I can hear a difference.
I've heard resistors in series don't adversely affect planars. Something about planars being a purely resistive load if I'm not mistaken. Resistors would be easier than transformers. I'm not sure what impedance I'm trying to match. For that matter, I'm not sure what sized resistors to use either. I tried using resistors once with my Neo3s, but it felt arbitrary because I didn't know what impedance I was aiming for.
Headphone impedance can be as high as 300ohms! To my understanding, there is an advantage in amplifier design to higher ohm headphones. It seems to be an easier load to drive. I'm sure there is more detail than I am aware of.
Also, the resistance of the load effects the required gauge of wire. For headphones, high impedance means you can get away with physically smaller wire. This is desirable for obvious comfort and convenience reasons. Speaker Wire
I made a headset after reading the planar threads on this forum, thanks to all the guys who shared their planar projects here. (I'd never known the planar thing till I found Jamesbos's posts here, and it fascinated me all at once!) Really appreciate your sharing here!
Now trying to improve after my first try, however, I got some questions. My first headphones were way too clumsy (13cm*12cm, with 7 columns of 5mm neo magnets, two runs of foil between each two columns of magnet). Now trying to make a smaller one, approx. 8cm*10cm, I can only manage to install 5 columns of magnets, and lack of dexterity limits me to only one run of foil between each two columns. I'm concerned with low sensitivity due to reduction of magnets and coils runs. Impedance is also rather low, at only 1 ohm. Is that feasible? Anybody tried before?
I've also broadened the alufoil from 3mm to 7-8mm. Will the increase of mass have adverse effect on sound?
The project is still in process and I'm not sure whether this one will sound as good as the first. Any advice?
Now trying to improve after my first try, however, I got some questions. My first headphones were way too clumsy (13cm*12cm, with 7 columns of 5mm neo magnets, two runs of foil between each two columns of magnet). Now trying to make a smaller one, approx. 8cm*10cm, I can only manage to install 5 columns of magnets, and lack of dexterity limits me to only one run of foil between each two columns. I'm concerned with low sensitivity due to reduction of magnets and coils runs. Impedance is also rather low, at only 1 ohm. Is that feasible? Anybody tried before?
I've also broadened the alufoil from 3mm to 7-8mm. Will the increase of mass have adverse effect on sound?
The project is still in process and I'm not sure whether this one will sound as good as the first. Any advice?
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