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Creating custom headphones. I need help finding speakers.

post #1 of 9
Thread Starter 

I'm currently planning on making my own pair of headphones. Being somewhat new to the whole audio craze i don't know too much about it, but i have been doing my fair share of research. I'm going to be customizing these from the ground up, except for the speakers themselves, and there are a few questions i'd like to ask. So i'm thinking about using these speakers," http://www.mouser.com/ProductDetail/Kobitone/25CE500-RO/?qs=pO9a3qNHhpHhpCGAHh60Sw%3D%3D ," and my reason behind these is i'm looking for speakers that are preferably 40-50mm diameter, 15hz or 20hz to 20khz, and although ill be able to put out enough power with my amp for 600 ohms i'd like speakers with around 32-128 ohms. If anyone knows where i could find speakers like that, that would be amazing.

 

One of the things i'm confused about is in most headphones there is a circuit board in each cup, and i am confused as to what those are. I know that most cables are split into 3 wire where one is ground, one is right side positive, and one is left side positive, which transmit to a stereo audio, and when it comes to those circuits, do those circuits make a signal like a 5.1 surround sound or do they just deal with noise cancelling? 

 

Since i'm building these from the ground up, i am teaching myself how to use autocad inventor and that jazz, but i will be creating a complete 3d model of the whole thing. Also, i plan on making these out of wood, which i am very skilled with, and i know they may be heavy but i want to have some style to them. I would mostly be using these at my desk where i can plug them into my amp and there wouldn't be much background noise at all, but i might want to bring them somewhere every once in a while. With that in mind, should i create them as closed back or open back? My idea of these headphones are heavily inspired from this man's homemade pair- http://www.instructables.com/id/Wooden-LED-Synced-Headphones-from-Scratch/?ALLSTEPS

 

I feel like i rambled for long enough, but i needed to get it off of my mind. If you have any suggestions whatsoever, feel free to let me know. Thank you everyone!

post #2 of 9

I've been eye-ing those 600 ohm drivers.  They even come pre-soldered with 1.5" wire leads.  I have some empty / unused HD580 baffles that I think will accept a 40mm driver.  I'm not really in a hurry though, these 580 plates have been in storage since I blew out the drivers 7-8 years ago.  600 ohms is a perfect Z load for any of my tube amps, and my solid state amps all have more than enough gain too.

 

Some phones have resistor-capacitor networks to "EQ" or attenuate the output... some times the resistors are mounted on small circuit boards.  The Sony MA900 is an example of one phone with resistors inside to color the sound.  I can't recall though if its PCBA mounted or free floating inside.  One mod that people to is to bypass /remove the resistor network.

 

Headphones have internal PC board circuits for just about anything.  Bluetooth phones will have radio receiver, amplification, and battery-power management... for example.  The DT770 has a small single sided PCB that splits the ground from the left earcup over to the right.  Its basically a point to point wire.

 

 

post #3 of 9
Thread Starter 

I understand what you're saying for the most part, but when it comes to surround sound is that something that just kinda happens or is there something that the signals need to go though for that to happen?

 

And what you were saying about board mounted resistance, does that mean that i could take a driver with maybe 8 ohms, and make my own simple circuit that could add resistance to that to bring it up to 32-128 ohms?

 

Since i'm making this from scratch, ill be able to make my own driver mounts that could be pretty decently. And I still don't know if i should make them closed-back or open-back.

post #4 of 9

I am not familiar with "surround sound" headphones, or how they work internally.  They just never really caught my attention.  So it would be better for others to respond on that topic.

 

for your second question, the answer is no.  Adding a 100 ohm resistor in series with a 32 ohm headphone will not result in a 132 ohm impedance load.  Resistors in series increase resistance NOT impedance.  So you end up with a 32 ohm impedance and a 100 ohm resistance when you do that.

 

If it were me, I'd go for an open-air design... but that's just my preference.

post #5 of 9
Thread Starter 

I've only really ever had 2 pairs of headphones and the first pair was just a 10 dollar pair of philips and my second is a pair of turtle beach x11, which is a 60 dollar headset that was made for gaming and i have them set up so i have sound from my xbox and music from my computer going through them. In lots of games, "3D" sound helps a lot for situational awareness, so most gaming headsets have a surround sound feel to them, even though they only have 1 driver per cup. It might be going too far for just the headphones i'm making, but im interested in doing it. 

 

Quote:
"Adding a 100 ohm resistor in series with a 32 ohm headphone will not result in a 132 ohm impedance load.  Resistors in series increase resistance NOT impedance.  So you end up with a 32 ohm impedance and a 100 ohm resistance when you do that."

I know that increasing impedence means that you'd need more power, but would lessen the distortion. With this in mind, i'm guessing that adding resistance wouldn't lessen the distortion.

 

Thanks for the input, ill try making them open. I could just grab some $1 speaker grills from my local Axeman surplus, and i could cut them pretty small to have for the ends.

post #6 of 9

Yeah my amps most definitely distort more with lower impedance loads.

As near as I can hear, increasing resistance does not lower distortion levels.

 

Increased impedance does not necessarily mean you need more power.  I have turn the volume down a little going from my K701 to my HD650. (65 ohms versus 300).  Sensitivity is the key point here.  The DT880 (250-600)  is another example of a highly sensitive phone with a high impedance, that does not necessarily require more amplifier wattage.

 

fwiw these are my impressions with the following amps:

 

millet hybrid

larocco PPA

darkvoice 337

Earmax original


Edited by kramer5150 - 3/7/14 at 9:34am
post #7 of 9
Thread Starter 

Throughout the last 2-3 weeks that i have been looking into audio stuff in general, i haven't really understood or paid attention to sensitivity. So what you are saying is that if that there is a greater sensitivity, that it can sometimes still be better than drivers that have higher impedences. I'll have to look into sensitivity, but thanks help though.

post #8 of 9

i used sony mdr7506 drivers in my home built iphone stereo headset (see avatar).
40mm drivers. frequency response is 10-20kHz. impedance is 63 Ohms. sensitivity is 106 dB/W/m. power handling is 1000mW.
easy to find for cheap used on ebay, sometimes as low as $20.
easy to find new find new, usually $100 to $130 but sometimes as low as $80.
driver mounting is made simpler by just using the mounts from the headphones.

good luck!

post #9 of 9
Thread Starter 
Thanks for the advice. I've been really slacking off with this project, and money is one of my issues that is keeping me from progressing. I've been thinking of using drivers from a pair of superlux hd 681, and I found the set on amazon for approx. 30 dollars. I'm still in high school and I still don't have a job so money really is a big issue, and me getting distracted by other possible projects that I want to work on is not helping.
All the advice that all of you guys give me is helpful.

Whichever drivers that I do end up using, whether it be plain drivers or drivers scavenged from a pair of headphones, i will make a 3d model in autocad of a kind of mounting bracket for the drivers to sit in. My school has a 3d printer, so I will take that model and print it for the drivers to sit in. These brackets will be made to fit the headphones being made, so as to keep a structured headphone chassis.
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