The Objective2 (O2) Headphone Amp DIY Project

If you download the BOM from NwAvGuy's(RocketScientist) website, you can copy the parts list and upload it to Mouser with their Import BOM tool that's under the Services & Tools Tab. No typing required..
I could not get the Import BOM to work on a Linux computer. Instead I read the XLS file with Gnumeric, swapped columns to show part number followed by quantity and saved as a CSV file. Then I used a text editor to finalize for Mouser's format so I could copy-and-paste into the Mouser web page. No sweat... yeah sure.
 
I could not get the Import BOM to work on a Linux computer. Instead I read the XLS file with Gnumeric, swapped columns to show part number followed by quantity and saved as a CSV file. Then I used a text editor to finalize for Mouser's format so I could copy-and-paste into the Mouser web page. No sweat... yeah sure.

Hmm.. I used OpenOffice in Ubuntu, and just cut and pasted the two columns out of the file as is, and it worked for me..
 
From Nav Guy's O2 Details Blog, "There have been several suggesting higher voltage supply rails for various reasons. Some have dredged up rare discontinued headphones that need more than 7 Vrms to hit 115 dB SPL"

Are K240M's rare? Oh well, I guess I'm beat!

Well, rare might be debatable, but discontinued? yes. The K240MkII which replaces it (or the K240Studio) both have an impedance of 55ohms, which is realistic with the O2.

From AKG's website, under the K240M details: "600-ohm impedance for special studio applications". So it sounds like they are setup to be used with electronics that are less likely to be found outside of a studio...
 
From blog:
Maximum Gain = 7 / Vin(max) and on batteries it’s 4.5 / Vin(max)

On a totally separate note, I have just noticed I wired my TRS jack completely backwards: I wired the left channel on the board to ground on the socket, the right channel to the left channel on the socket and board ground to the left channel. I am even more confused by the fact that I have been listening to it and both channels seemed fine :scratch:
 
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This has been discussed earlier in the thread(sorry you'll have to dig for it).
The headphones you are talking about are outside the operating parameters of the O2 and trying to do what you want to do is unlikely to work very well.

You'll need something more powerful, like the previously mentioned "The Wire" or the Twisted Pear Ventus (unfortunately out of stock at this time) which both use the LME49600 buffer.

It's disappointing that, with my current headphones, I can't take advantage of what promises to be a great portable amp in such well presented diy package. Looking at "The Wire", I think I'd be out of my depth, there (ie; SMT). I'll go ahead with the O2 in the meantime, thanks MrSlim :)
 
Hey RocketScientist.

Have you come any further with the audio-widget guys on the DAC?
I have bought the 9023 DAC to see if I can help the community to tweak it to be an all purpose one at least up to 24/96 if it shows that we are good doing what we are doing 24/192 shouldn't be a problem.

Brgds
 
I'd like to buy x4 from you...( + P&P of cause) if possible

Hi olli1324.

I'd like to buy x4 from you as well - so pile up please :)

Brgds


I've been thinking about this since I posted that and I really don't have the time at the moment to organise it. The batteries are on special offer until close of business on Monday so if someone else wants to jump in and buy a bunch you have until then.

Sorry I can't be of more help!

(I can't remember if I have posted the source already but it is: Rechargeable NiMH batteries Hi Watt AA, AAA, C cell, D cell PP3 batteries)