As I see it there is no problem with any brand of battaries - it's a design issue. The design does work in an ideal world which we are not part of.
Brgds
If i manage to get some more running time from these i will not even consider changing the batteries or the resistors. I can live with that. If i can't, i'll try something else. Thought Philips would be a nice brand of batteries though.
By the way, how should we charge the batteries, with amp on or off?
By the way, how should we charge the batteries, with amp on or off?
Manage to complete my first O2 portable case and it work on the first try (no battery wet). I'm listening to it while I'm typing this message and it sound really good. This was an easy build specially due to all the well documented process. "Chapeau" to NwAvGuy for this amazing amplifier. Thanks! (I'll be building the desktop model now).
Perhaps the most important characteristic of the BOM batteries is their 8.4V output, as opposed to the more common 7.2V. The difference will affect run time.
@sofaspud - afaik, 9v PP3 NiMH rechargables are either 7 cell, giving 8.4 volts, or 8 cell, giving 9.6 volts when fully charged.
As long as your AC transformer can handle the load you can charge the batteries either way, on or off.
Brgds
Left the amp charging the batteries all night and measured them with a dmm. BT1 is giving 9.77v and BT2 is giving 9.31v. I don't have a clue if this is normal.
Anyway, they are Philips Rechargeable accu 8.4V NiMH, 170mAh. They seem within spec regarding the BOM.
Any thoughts on this?
Thx for the explanation Turbon.
Anyway, they are Philips Rechargeable accu 8.4V NiMH, 170mAh. They seem within spec regarding the BOM.
Any thoughts on this?
Thx for the explanation Turbon.
NwAvGuy does include a brief on recommended batteries in the O2 details, though I might have imagined 7.2V types were more common.
raspunsen, I'm currently using the type shown below. With my Grado SR80s they'll run for only a few hours at most before needing a recharge.
I have a mod in the works that addresses run time no matter what PP3 is used.
raspunsen, I'm currently using the type shown below. With my Grado SR80s they'll run for only a few hours at most before needing a recharge.
I have a mod in the works that addresses run time no matter what PP3 is used.
Attachments
OK, PP3 NiMH batteries are available in 7.2, 8.4 and 9.6 voltages.
Given the number of 9.6v PP3 batteries available, why choose a 7.2v?
e.g. Powerex 200 mAH 9.6V PP3 Rechargeable Battery from mahaenergy.co.uk
and VTE220PP3
Given the number of 9.6v PP3 batteries available, why choose a 7.2v?
e.g. Powerex 200 mAH 9.6V PP3 Rechargeable Battery from mahaenergy.co.uk
and VTE220PP3
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7.2V pack is more common than 8.4V... but not at all for 9V/PP3 battery layouts.
I think everyone knew that.
Anyway, so what's killing off the batteries in the O2 faster than expected? What would the effect be of having added resistence in the battery circuit, in theory AND in practice?
I think everyone knew that.
Anyway, so what's killing off the batteries in the O2 faster than expected? What would the effect be of having added resistence in the battery circuit, in theory AND in practice?
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hello guys, I wanted to ask about this transformer: http://www.evernote.com/shard/s102/...fda580616a83/72735cbd9d3d3e3dda12874e98482e60
this is the one I have, if I assemble it, can I use it to power and charge my o2 ?
my concern is that I havent read VAC on the output
thanks 😀
this is the one I have, if I assemble it, can I use it to power and charge my o2 ?
my concern is that I havent read VAC on the output
thanks 😀
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I got a problem here. After I forgot to turn off it for over 24hr, it is heavily distord now. has anyone face this problem before? What you think is spoiled?
Thanks.
-coolhead
Thanks.
-coolhead
Further to Lorriman's heads up on the Superlux HD681 headphones, mine have now arrived - extraordinarily good value for money, comfortable to wear and excellent sound quality. Check out the discussion here Rock Grotto Audio Forum - For Headphones - Headphone Amps - Amplifiers - X-Can V2 - Musical Fidelity - headphone Discussion - Amplifier Discussion - DIY - Amplifier Kits - Projects - SCHA - Sennheiser - Beyer - Grado - Audio Technica - Headphone amp
- they definitely sound smoother after being in use for a few hours. A very good companion to the O2.
- they definitely sound smoother after being in use for a few hours. A very good companion to the O2.
Describe what it sounds like if you can, one or both channels, was it plugged into AC or on battery, etc...
How the O2 sounds
Over at Head-Fi the O2 review thread is really rather fun. Out of all the impressions from reasonably respected people with very high post-counts:
1) A couple of people declared it a wonderous wire with gain.
2) A few were more conservative and declared it "almost" up there with (INSERT EXPENSIVE AMP HERE)
3) A few more declared that was silly and the O2 wasn't even in the same league.
4) Another respected individual has just popped up and declared it is coloured and beaten by a CMOY modified to use opamps paralleled in the output stage.
Funny how nobody can agree on what the amp sounds like when the sound to be expected has not been suggested in advance!
Over at Head-Fi the O2 review thread is really rather fun. Out of all the impressions from reasonably respected people with very high post-counts:
1) A couple of people declared it a wonderous wire with gain.
2) A few were more conservative and declared it "almost" up there with (INSERT EXPENSIVE AMP HERE)
3) A few more declared that was silly and the O2 wasn't even in the same league.
4) Another respected individual has just popped up and declared it is coloured and beaten by a CMOY modified to use opamps paralleled in the output stage.
Funny how nobody can agree on what the amp sounds like when the sound to be expected has not been suggested in advance!
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Head-Fi just stripped my signature by themselves and shot me a PM about it. My blog link was not acceptable so I turned my back on my Head-Fi affiliation and, after some thought, wiped out my blog as well since it wasn't turning out like I had hoped. It's funny how quickly things can change, yet how little impact it really has on life.
well tbh as much as i dont always agree with what happens over there, using the fact nobody can agree on what something sounds like is hardly a valid criticism. people often dont agree about things that are very black and white, right the way to how good eggs taste. so expecting a consensus on sound is a bit ridiculous IMO considering we all have a different idea of what neutral is, well worse than that neutral/flat ear response IS different for everyone, forget it when you throw in different source, different headphones, different music, different taste, different experience, different language, different vocabulary, different mood. so its a bit of a cheap shot IMO.
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@MrSlim, they didn't like that my signature linked to my former blog, which had reviews of audio equipment and steps I've taken to improve the sound. My latest article discussed the need or lack of a need for a headphone amp and got technical about it to prove that sometimes (because of headphone efficiency) the only thing a well designed amp, like the O2, actually does is fight distortion and improve damping... neither of which are amplification, but compensate for poor design. Many of that I've learned here following the O2 thread and at the nwavguy.com blog.
I don't think Jude took the time to read my blog, but he may have scanned some of it. He stripped my signature completely and CC'd joe and currawong.
I don't think Jude took the time to read my blog, but he may have scanned some of it. He stripped my signature completely and CC'd joe and currawong.
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