DIY K1000 style phone- *Updated 11/29*
Nov 5, 2008 at 12:16 AM Thread Starter Post #1 of 70

Punnisher

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I'd like to build myself a K1000 style headphone, in which the speakers will be placed .75"-1.5" away from the ear.

What kind of driver is well suited for this? I'd like the impedance to be rather high (to reduce any hiss that is present in many amps, healthy or otherwise).

I want the driver to be large enough to be able to put out an acceptable level of bass. I hear the K1000 is a bit light on the bass. I'd like it to be well balanced.

I want the driver to be low-profile enough so that it doesn't look like I have miniature speakers on my head. (The Duggeh picture comes to mind).

What do you think?
 
Nov 5, 2008 at 12:48 AM Post #2 of 70

Uncle Erik

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A few months back, I came across a bunch of small drivers in either the Mouser or Digikey catalog. I think it was Mouser, but not 100% on that. But they were under $10 each and looked great for experimenting.

I've been thinking of doing something similar with ribbons. Poke around for DIY ribbon microphone plans and maybe pick up Justus Verhagen's book at Old Colony Sound Labs.

Another avenue to explore would be the DIY electrostatic panels detailed at Headwize.

And I think Duggeh looks rather fetching in the Phonodome.
 
Nov 5, 2008 at 1:22 AM Post #3 of 70

Punnisher

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Thanks for the info. I stumbled on a manufacturer that makes many styles and sizes of speakers. CUI Inc - A Solutions Provider Of Electro-Mechanical Components For OEM Manufacturing


They are available through Digikey and other suppliers. They might have been the ones you were looking at.

I have another question: Does the advertised frequency response for small speakers go out the window when they are being used for a headphone application? I'm sure some of these are meant to be heard from a distance where the frequency range will be much less than when it is right next to your ear. If it's right next to your ear, you'll definitely get better bass response, most likely lower than than advertised.
 
Nov 5, 2008 at 1:55 AM Post #5 of 70

Punnisher

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That stuff is way too expensive, especially since I have no idea what this headphone will sound like. Under 30 dollars a driver is more my price at the moment. Once I find something that sounds good, I might go all out on a similar high end speaker.
 
Nov 5, 2008 at 10:45 AM Post #7 of 70

bidoux

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Actually AKG sells K1000's drivers but they are 600$ for both...
frown.gif
 
Nov 5, 2008 at 5:30 PM Post #9 of 70

Punnisher

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Thanks Germania, those do help quite a bit.

I found a speaker at Mouser that's 600 ohms and 40mm. The frequency range is 20hz-20khz. Most of the other ones on mouser have a lousy range. Then again, who knows how those frequency responses are measured. Here's the 600ohm one:

25CE500-RO

My question is how AKG managed to get a balanced frequency response with a relatively small driver that is placed away from the ear. In the manual they mentioned circuitry that modifies the frequency response. I could use some circuit that puts an emphasis on the lower frequencies to balance out the sound.

Another question: Do you think I should be using a somewhat large driver for this? I am thinking 50mm at the least. It's going to be difficult for a smaller driver to really convey any amount of bass from a distance.
 
Nov 5, 2008 at 9:23 PM Post #10 of 70

-=Germania=-

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I saw those drivers a while ago and always meant to go back for them.

The Freq response looks decent. Grab those drivers and tell us what you think. I am always itching for franken-phones.
 
Nov 5, 2008 at 9:55 PM Post #11 of 70

nikongod

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The K1000 has the circuitry to “counteract” some funky ear VS driver resonances when the headphones are worn “flat” against the head. It may be placebo, but a few head-fier’s reports of k1000’s with the circuit board removed says it keeps its flat frequency response. I think AKG designed the drivers as best they could, and went from there. With a design that uses pre-made parts the will to build a small crossover network to fine tune the headphones is a good idea.

For driver size: I would not worry TOO much. Take a pair of grados and spread them good and wide so the drivers are a few inches from your ears. The bass is a little lower, but still there.

The REALLY fool-proof solution would be to design the “holders” for the drivers to accept various drivers so you can experiment with minimal rebuilding. If your first attempt dosnt work, you have the platform to literally drop something else into. Perhaps mount the drivers in little boards, like lenses on a large-format camera.
 
Nov 5, 2008 at 10:46 PM Post #12 of 70

Punnisher

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My plan is to use a mesh screen as the surface to mount the drivers on. I might use a stand-off piece to give some room between the driver cone and the mesh.

I will leave the backs completely open so that changing drivers is easy. I will be buying a bunch of drivers to experiment with.

I would like to build a small crossover to reduce the volume of the high end, but not filter it completely. This way more low frequencies will reach the ear.
 
Nov 5, 2008 at 11:15 PM Post #13 of 70

Duggeh

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An adjustable slope filter would be better than a fixed notch for raising low end and attenuating treble. There are downloads for Quads rather good implementation of such circuits. You'd have to have that external to the headphone though, it'd be too cumbersome to mount into the housing.
 
Nov 5, 2008 at 11:29 PM Post #14 of 70

Punnisher

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That sounds like what I need.

I just tested this with my 880s, lowering the high frequencies and boosting the bass a good amount. It sounds very good actually. The possibilities for soundstage are pretty amazing.

Perhaps I could just use normal headphone drivers, instead of drivers meant for a full size speaker amp. I get plenty of volume from my 2move. Though, with those 600ohm drivers I may have problems...
 
Nov 6, 2008 at 1:36 AM Post #15 of 70

Punnisher

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After some more testing with my 880s, held so the drivers are about 1"-1.5" away from my ears, I can begin to see what will be needed in terms of frequency response.

I have my EQ in winamp set to a downward flat slope. The lows extremely boosted and the highs extremely attenuated. When held away from my ears, the equalized result is extremely similar to the frequency response I get when the EQ is flat and headphones worn normally. The main difference of course, is vastly wider soundstage and slightly less warm sounding (no boominess, absolutely none). The result is an open and free sound with little constriction in terms of soundstage.

I hope that the housing of the 880 is not contributing a significant amount to this sound. The DIY1000 housing will be completely devoid of obstruction. I don't think it is though, because no seal is being applied to the pads. We shall see.

Though I'm going to need some guidance for this filter. I hope it's not too terribly complex. Reading electrical schematics has never been my strong suit.
 

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