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Need feedback on Bluetooth adapter design

post #1 of 7
Thread Starter 

Hi Everyone,

 

I'm currently working on putting together a module that would allow you to stream audio over Bluetooth to any set of headphones from 32 to 600 ohms impedance. I couldn't find anything that was relatively cheap, with good audio quality, that worked over a standard Bluetooth connection, so I thought I'd try to make something myself (I'm an engineer with a background in electronics and circuit design, so I like this stuff :D) Since I wouldn't describe myself as a "real" audiophile, I thought I'd get some input from you guys on whether you'd want something like this, and if so what features you'd want.

If you could take the time to answer a few questions, I'd really appreciate it!

#1. Would limiting the frequency range to below 20khz be a problem for you?

 

#2. Would using a lossy codec (albeit high quality, as in > 500kbps) be a problem for you?

#3. How much battery life would you expect from a product like this?

 

#4. Would you mind mounting it on your headband?

#5. Is mobile capability critical for you (as in, would you need it to work with your cell phone/PMP)?

 

#6. Lastly, kind of an open question, but are there any features you'd love to have on something like this? (Track skip controls, optional noise cancellation etc.)

If you're interested, I'll post some proposed specs and details for you to tear apart.

 

Thanks,

JT

 

*EDIT: Changed title to more accurately reflect what post is about.


Edited by Psilocybe - 10/24/13 at 11:43am
post #2 of 7
Thread Starter 

Bump, if I can get any feedback! Also, is 11~12 hours of listening time enough?

post #3 of 7

Don't know how it sounds but there is this i found 

 

http://www.antecmobileproducts.com/product_detail/148

post #4 of 7
Thread Starter 

That's an interesting find. The main problem is the codec it uses--given that it doesn't list anything like AptX or AAC, it almost certainly uses the standard Sub-Band-Coding codec, which is the main problem with Bluetooth audio products. Also, I shudder to think of the amp that lies inside T_T Thanks for the reply!

post #5 of 7

I use the Fiio W1 and it does a great job of transmitting any format...   including uncompressed FLAC

post #6 of 7
Thread Starter 

Aha, very nice, but not exactly portable...

Anyone have any input on the questions I posted? :D So far the PCB is looking pretty good. Hopefully I can get to testing an amplifier configuration soon.

post #7 of 7

Hi,

You and I need to talk.  I'm currently working on modding this unit:

http://www.ebay.ca/itm/Wireless-Bluetooth-Audio-Music-Receiver-3-5mm-A2DP-For-iPod-iPad-iPhone-MP3-PC-/290920955046?pt=Other_Tablet_eReader_Accessories&hash=item43bc3d7ca6

 

(DL-LINK TS-BT35A01)

 

It is based on the OVC3860 chip with a 250mAh 3.7V Li battery.  Unless you are designing a surface mount board with those tiniest of tiny resistors, it will be difficult to get smaller than that unit, which is light enough to fix to the side of or inside an full size can.

 

As for your question, if you are planning on using A2DP, then that I think automatically cuts off below 20Hz anyways.

The module above uses A2DP, which is lossy as it is, I believe, using AAC.  You can also get APTX boards off ebay.

 

Once I figure out why this module I bought sounds like crap (looks like an extraneous HPF cct and probably extraneous IC amp circuit), will post in DIY.

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