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O2 Headphone Amp - Complete Kits (UK only)

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I thought I'd try a different variation on a group buy, by purchasing the parts first, and offering complete kits of parts only once everything is available to send out - so no waiting around, everything is ready to ship and will be despatched within one working day of receiving payment.

Sorry - all kits have now been sold, this group buy is now closed.

If there is a lot of demand for this service, I may consider repeating the offer at a later date, and will keep a 'reserve' list of anyone who is too late this time.
 

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Received the kit today so that's about 3 to 4 days after ordering, started putting it together this afternoon and its playing as we speak.
Wasn't fond of the input and power to be on the front so I modified that and made some cinch connectors and a powerjack in the back. I`ll post some pictures later on.

But for it all to fit because as usual I manage to not pay attention to the height of the little box that came with it I had to remove some PCB that was in my way, also I ignored that there was an "up and down" to the little faceplates, I managed to get the back one the wrong way around :X
O well you can't really see that anyhow ;)

I also still don't know why I soldered on the 9volt clips in the wrong order to desolder them later on and resolder them in the correct position, even though I`m never going to use them..... o well extra wasted time.

Printed out the frontpanel available on the site, I found it strange the bolt holes where so crocked *cough* anyhow used that as a template just put some spray adhesive on it and stick it on then use a counterpunch to make some pilot marks then drilled it all up to size.

Plugged it in and had a listen, its pretty silent awesome stuff! Highs are a whoooooooooooooole lot better defined then my previous little diy amp they really sparkle, I have the O2 amp hooked up to my Moodlab DAC that's connected to my pc where I do all my audio stuffs (lossless FTW)

Cons (if they are any): If anything the highs are a bit.... high it's as if I'm lacking bass, the high is really crisp and loud, compared to what I was used to. Also the volume control is rather sensitive and will easily change to a non comfortable listening level, perhaps changing to a LIN

Any ideas on that? Using a Sennheiser HD598
 
Cons (if they are any): If anything the highs are a bit.... high it's as if I'm lacking bass, the high is really crisp and loud, compared to what I was used to. Also the volume control is rather sensitive and will easily change to a non comfortable listening level, perhaps changing to a LIN

Any ideas on that? Using a Sennheiser HD598

Decrease the gain, read about it here and here. All you need to do is swapping a few resistors. Also the potentiometer you recieved is a linear one, the one you are looking for is logarithmic.

/Max
 
I have modified the postage cost to EU countries - it's now £3 more than UK shipping, but includes a UK-EU power adaptor, so the supplied UK PSU can be used immediately. If you want a kit sent to an EU country but don't want the adaptor, no problem, I'll leave it out and it'll be £1 cheaper.
 
I still feel its lacking bass

The O2 is pretty transparent, and I've heard great bass through mine, which would suggest that any lack may be down to your source or your headphones. What are you using?

I`m confused by the so called hi and low power

Do you mean the high and low gain switch? This lets you select how much the O2 amplifies the incoming signal - default values are 2.5x on low gain, and 6x on high gain; the amp will run the batteries down faster if it's on a louder setting.
 
The O2 is pretty transparent, and I've heard great bass through mine, which would suggest that any lack may be down to your source or your headphones. What are you using?



Do you mean the high and low gain switch? This lets you select how much the O2 amplifies the incoming signal - default values are 2.5x on low gain, and 6x on high gain; the amp will run the batteries down faster if it's on a louder setting.
Well i read something about high power and low power so that got me confused, so thats all to do with Gain then, its currently set to 1x gain.

I`m using a Sennheiser HD598 the O2 is connected to a Moodlab DAC thats connected to my PC,

Previously i was using a modified , indeed hybrid tube amp, it had a lot more punch to the bass, I do like the transparant sound of the O2 but i feel its missing bass :X
 
Does your PC source have any type of EQ? The overall sound balance will be different for different recordings, maybe the bass just needs turning up on some of your material. RocketScientist provides response curves for the O2 on his blog, do you have similar curves for the tube amp?
I've always found that the O2 just amplifies what it's fed without adding anything, or taking anything away, after that I guess it's up to the listener to adjust the rest of their system to their personal taste.
 
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