Sennheiser HD201 wireless/wired mod

[azkay]

After weeks of waiting for parts, I finished my bluetooth HD201 mod.

In the left cup I have the usb port + battery + charging circuit from an old Sony mp3 player, which also has 16gb flash on the board so the headphones are also a flash drive now.

Right cup has a 3.5mm socket, fiio e5 amp, bluetooth receiver.
I tested it for around 8~9 hours of constant music before turning them off to go to bed, so I'm not sure what the battery life is but I know it's at least 8 hours. Leaning towards 10~15, I'll find out one day at the worst possible time, I'm sure.

I put the 3.5mm socket in so I can still use them wired if the amp/receiver/charger/battery dies.



Pictures: http://www.azkay.com/headphones
Video:

You Tube

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Feedback/suggestions?

[CrowdAds]

[epithetless]

Wow. What an awesome and ambitious project -- and a successful one, to boot! I take it the USB port allows everything (the cannibalized Sony player, FiiO amp, and Bluetooth receiver) to charge at once? How does having all that stuff crammed into the rear chambers of the cans affect the sound quality?

[azkay]

The Fiio and receiver both use a single battery that used to be in the mp3 player which is charger by usb, yeah. Seems the battery still outlasts both the receiver+amp if I had them both using their original batteries.

I havn't noticed any difference in sound quality, still sounds really good- but that might just be me. If I turn the fiio amp right up I get some humming and such, I think if I turn it up to the maximum it also pulls too much power from the battery because the receiver starts giving out these annoying "battery low" beeps every few minutes, I thought it was faulty until I turned the volume down the next day and didn't get the beeping anymore. I was getting the "low battery" beeps for 8 hours throughout the music, so I was sure the battery wasn't low. I guess the receiver just wasn't getting as much power as it wanted.

The only difference is it probably leaks a little more sound out, as I had to take out the plastic back covers over the speakers. But at the same time, they're covered in PCB and battery now. So who knows.

It works, though. That's the main thing.
I thought I did pretty well for my first mod of anything that went successfully. I was surprised I got the usb port hole pretty much perfect, everything was done with a knife, hobby knife, pliers, screwdrivers, drillbit.

The only other damage I did was near the end, soldering the connector to the 3.5mm, I accidentally leaned the iron on the right cup so the edge of it has a slight round burn, but it isn't too bad.

The only thing the sony parts are used for are the battery+charging+flashdrive, it doesn't actually play anything anymore.

[azkay]

Fixed the beeping "low battery" warning by soldering in the original receivers battery in parallel with the old one, both 3.7v.

[Tecneeq]

Originally Posted by azkay

Fixed the beeping "low battery" warning by soldering in the original receivers battery in parallel with the old one, both 3.7v.

I wouldn't do that, you might ending up charging one battery with the other, reducing lifetime of both batterys. I would use the one with the larger capacity and add an electrolytic capacitor to smooth out the current peaks (wich i guess are the problem).