I think you mean P1 and/or J2? But yes, you can have both if you cut the traces under J2 as shown. Just don't try to use both at once (which would have one of your sources fighting with the other source--the O2 won't care but it won't sound very good and could even damage one or both sources).
@cusp et al, let's hopefully get back to the rational side of things here and leave CSA to his own self induced misery.
@jokener, I wouldn't take the "let's make a deal" bait. Your original deal was more than fair.
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I can't find the picture right now, but I'm sure we are quite a few around to take one for you
@RS: I must admit I am tempted. MythBusting has always been a fun thing to do.
And I am sure I can find them unicorns that you have mischieveously hidden in that particular unit.
But 80€ for a broken amp... 50€ was fair indeed. More than fair actually, it included the "lets drive a point across"-fee.
@CSA: what would justify the 80€?
I mean, shipping is $13, the parts are $30 and the PCB is $10... 50€ are equivalent to almost $70... ... ...
And I am sure I can find them unicorns that you have mischieveously hidden in that particular unit.
But 80€ for a broken amp... 50€ was fair indeed. More than fair actually, it included the "lets drive a point across"-fee.
@CSA: what would justify the 80€?
I mean, shipping is $13, the parts are $30 and the PCB is $10... 50€ are equivalent to almost $70... ... ...
Why don't we focus on the things we can all agree on . . .
and that CSA's headphone amp doesn't work very well . . .
and be done with this silly distraction ? ? ?
The O2 works fine when built to spec, sounds as good as anything out there, and is cheap and easy to build. CSA built something that isn't an O2 (which is why he won't post pictures) and is having problems with whatever it is.
That really should be the end of it . . .
and that CSA's headphone amp doesn't work very well . . .
and be done with this silly distraction ? ? ?
The O2 works fine when built to spec, sounds as good as anything out there, and is cheap and easy to build. CSA built something that isn't an O2 (which is why he won't post pictures) and is having problems with whatever it is.
That really should be the end of it . . .
It may be possible to use one of the "3B" jacks (no switch) for J2 instead and avoid cutting traces, if I'm looking at the artwork correctly.
STX-3120-3B-284C Kycon Phone Connectors
I found that 1x and 1.6x are where it needs to be to prevent a thermal meltdown in current-model studio-quality AKGs. It also provides enough range to make your favorite PMP's output turn into deafness.
Isn't it amazing how we all somehow still think that AKGs are hard to drive? I was very surprised when I found how loud the K272HD got. My laptop drives them too loud at 18% volume. My TouchPad, iPad2, and iPod Mini all have room to spare on their volume meters and the phones are loud enough.
We're entering a new era with AKG. They're releasing a new "closed" flagship the K550 with lower impedance and higher sensitivity. Their latest IEMS are 8Ohm 125dB SPL.
I'm still not exactly sure how I'd tweak an O2 for something like that. With 8 Ohm impedance there's such a narrow voltage window with low THD+N and I'm not sure it's even "acceptable." I'd like to see measurements. The DC offset would be higher than we'd want because we'd keep the damping maximized with low value resisters. The gain would have to be something wild like 0.5x to even dare plugging them in. And so on...
Fortunately, they're $1K so nobody has anything to worry about... until the technology gets commoditized. So we have some time to engineer.
You're forgetting that A) I initially was convinced by people (dogmatic types) that my amp was simply revealing how horrible and harsh my sources were. And that B) the performance of my first amp degraded over time. And that C) the performance of my second amp also degraded over time. That led me to the v-regs getting hot, something that was born out repeatedly. I tack soldered input bypass caps on both v-regs and U5 got cool but u6 got hotter, I decided to wait for the correct parts (tantalum caps) before proceeding further. The change in temps from adding those input bypass caps indicates that those were needed. But since I didn't have the right values or type I can't draw firm conclusions there.
@ethanolson, interesting. I wasn't aware of some of that. Some of the AKG changes might be the Harman influence. 8 ohm headphones are a bold move. I wonder if they're planning on their own amp/source to go with them?
I can certainly measure the O2 into 8 ohms at those sorts of levels. It might do better than you might think and the 0.5 ohm output impedance is still low enough. But lots of amps, even many expensive ones, are really going to fall on their face with an 8 ohm load.
I can certainly measure the O2 into 8 ohms at those sorts of levels. It might do better than you might think and the 0.5 ohm output impedance is still low enough. But lots of amps, even many expensive ones, are really going to fall on their face with an 8 ohm load.
Except that the O2 built to spec doesn't sound good with HD650's to my ear, it's kind of thin and harsh sounding. And both amps suffer a change in the character of their sound over time.
HD650's should be a little bassy and lush sounding right? That's what their FR curve would indicate. Most impressions are that the HD650 offer even more of that traditional HD6xx sound (big bass, lush mids, slightly rolled treble) than the HD600's even. To me it sounds like my HD650's are being driven by a lightweight amp. I'm probably being to much of a perfectionist, but then people like yourself hype it up by saying "it sounds as good as anything". I want to hear that, but I don't.
Well... I offered to find out what is wrong with your O2's.
I just won't spend 80€ on a broken piece of kit only to prove a point.
Not that everybody with a broken O2 comes here with wild accusations and the expectation of me buying their stuff and diagnosing it.
The 50€ offer stands. Take it or leave it.
On another note: I just ordered myself a Raacostat 6-3 (250 series) with 54 ESD-drawers.
That way I don't have to keep all them Mouser-bags around.
And the WAF (woman/wife acceptance factor) on the Raacostat has been tested...
Result: the Raacostat has a WAF of 0,8 while the cardboard box has a WAF of "2 days or it goes out", which is fairly close to 0.
I just won't spend 80€ on a broken piece of kit only to prove a point.
Not that everybody with a broken O2 comes here with wild accusations and the expectation of me buying their stuff and diagnosing it.
The 50€ offer stands. Take it or leave it.
On another note: I just ordered myself a Raacostat 6-3 (250 series) with 54 ESD-drawers.
That way I don't have to keep all them Mouser-bags around.
And the WAF (woman/wife acceptance factor) on the Raacostat has been tested...
Result: the Raacostat has a WAF of 0,8 while the cardboard box has a WAF of "2 days or it goes out", which is fairly close to 0.
@cheapskateaudio, everyone here knows where you stand. You don't like the O2's sound, so you "fixed" it, and now apparently it's even worse, overheats, fries parts, oscillates, etc. We're all deaf and clueless and you like the uDAC better. We got it. Given your views someone offering you twice the parts costs for your O2 board seems like a great deal, but that wasn't good enough for you either. So please stop cluttering up this thread with your redundant, and very unhelpful, posts or I'll take it up with the admins. Go listen to your uDAC if you like it better. Problem solved. Even Konga ended up not having a regulator problem at all. You're standing alone on an ever shrinking island.
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Here is a photo of the two amps:
The "modded" amp is on the left, and the now "partially modded" amp is on the right. I reduced the gain on that amp in addition to a couple other things I was trying out. They're not "final" which is why I resisted posting them, but since everyone is going berserk, here you go.
Looks like the link doesn't work so:http://www.flickr.com/photos/71466527@N05/
The "modded" amp is on the left, and the now "partially modded" amp is on the right. I reduced the gain on that amp in addition to a couple other things I was trying out. They're not "final" which is why I resisted posting them, but since everyone is going berserk, here you go.
An externally hosted image should be here but it was not working when we last tested it.
Looks like the link doesn't work so:http://www.flickr.com/photos/71466527@N05/
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Yup, it was just an optical illusion on my part (I thought it looked like heat sinks might be facing toward the back).
My CSA theory is that it's a canny businessman doing what he can to stop the O2 wave which has a fair potential to swamp the headphone amp world and take his investment with it.
CSA has cleverly 'modded' his O2 which means he avoids libelling the real O2 (or RocketScience) while also mixing in some eye of newt (personal smear) in to the cauldron to influence those of sensitive and nervous disposition.
With a smart use of SOE: CSA's strategy might have some effect. Better than doing nothing and seeing his investment go up in smoke.
I can see NWavGuy's blog being hit with copyright "Cease and desist" orders sooner or later. I've already copied the whole of his site using site copying software so that I have the build info I need in case it goes offline.
There are vested interests who can't be too keen on RocketScientist. If their investments are substantial then RocketScientist should take basic security measures and review his anonymity (which may be a good or a bad thing, I don't know).
CSA has cleverly 'modded' his O2 which means he avoids libelling the real O2 (or RocketScience) while also mixing in some eye of newt (personal smear) in to the cauldron to influence those of sensitive and nervous disposition.
With a smart use of SOE: CSA's strategy might have some effect. Better than doing nothing and seeing his investment go up in smoke.
I can see NWavGuy's blog being hit with copyright "Cease and desist" orders sooner or later. I've already copied the whole of his site using site copying software so that I have the build info I need in case it goes offline.
There are vested interests who can't be too keen on RocketScientist. If their investments are substantial then RocketScientist should take basic security measures and review his anonymity (which may be a good or a bad thing, I don't know).
Wow, this is hard...
Ok, the first one I built was *exactly* the BOM specified amp, I hated it. Thats why I got a second one with modifications, to start, it was solely improved parts with better specs. Within reason of course. About the only thing I splurged on were the WIMA coupling caps, which are $6 each. (Thats why I offered 80 euros)
Now I've modded them both to varying degrees.
Hi Jokener, if this is not just joke, can you please post photo of your soldering iron, especially tip.
Oh guys, come on please just leave it be, ok?
If this would be Amazon, there would now be one (or maybe a few more, I don't know) negative ratings against an overwhelming repsonse from all of the other buyers.
So cheapskate doesn't like his amp, ... that's ok. Maybe we'll never know if it was built according to spec or if he just doesn't like the sound. It really doesn't matter to me. I don't think anyone here was paid to post their reviews. But cheapskate you've made your point clear, and if you don't want to take Jokeners offer, please feel free to use an amp you like and leave us to our little O2s
It's just that this discussion is getting ever more bothersome for me to read, and I would like the admins to take a closer look at it, so we can stay on topic. Accusations of any kind don't fit diy-audio.
All the best, guys,
I think the postman tried to to deliver my O2, but I wasn't there at the time, so I'm gonna have o pick it up at the post office. I can't wait to start
If this would be Amazon, there would now be one (or maybe a few more, I don't know) negative ratings against an overwhelming repsonse from all of the other buyers.
So cheapskate doesn't like his amp, ... that's ok. Maybe we'll never know if it was built according to spec or if he just doesn't like the sound. It really doesn't matter to me. I don't think anyone here was paid to post their reviews. But cheapskate you've made your point clear, and if you don't want to take Jokeners offer, please feel free to use an amp you like and leave us to our little O2s
It's just that this discussion is getting ever more bothersome for me to read, and I would like the admins to take a closer look at it, so we can stay on topic. Accusations of any kind don't fit diy-audio.
All the best, guys,
I think the postman tried to to deliver my O2, but I wasn't there at the time, so I'm gonna have o pick it up at the post office. I can't wait to start