I think this is about an earlier post (#2647) about the desktop AC-only version I built? (apologies if not)
On the O2 circuit diagram there's a dotted line around BT1, BT2, D2, D6, R1, and R2, with the text 'Battery Power (omit for AC only operation)'. If there aren't any batteries, then R1, R2, D2, and D6 aren't in circuit so can be safely left out.
All of the power management section (U2, Q1, Q2 etc) is present - if it's left out there's a big switch-on transient, as described by NwAvGuy (and it's true - I tried it just out of curiosity).
One thing I did notice in my earlier post - I said that the gain switch S2 and associated resistors were left out because I was running with a gain of 1. I must have been on autopilot when I assembled the board, because although I left out the gain switch I actually put in the default gain resistors R17, 19, 21, and 23 as you can see from the picture I posted. They have no effect because the switch S2 is absent, and the O2 runs with a gain of 1.
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The dotted line for both the battery and AC circuits both encompass R1 and R2. It makes it seem like they can be removed if the amp is battery only, or AC only, but need to be there if its built with both?
That is correct. R1 & R2 are current limiters for recharging. If built for battery only use you have to use primary cells or employ an alternate charging method for rechargeables.
Is anyone using the Audeze LCD-2 or HiFiman HE-500 on the O2? Is it a nice combo?
The gain resistors(R17 - R21 and R19 - R23). If i don't add any resistors there, then the gain switch wount work. But if I add:
133ohm to R19-R23 will the gain be 12x when I push in the gain button?
And if I add the 499ohm to R17-R21 will that give 4x gain with the gain button not pushed in?
The gain resistors(R17 - R21 and R19 - R23). If i don't add any resistors there, then the gain switch wount work. But if I add:
133ohm to R19-R23 will the gain be 12x when I push in the gain button?
And if I add the 499ohm to R17-R21 will that give 4x gain with the gain button not pushed in?
I use the LCD-2s as standard with my O2 and it sounds spectacular. The HiFi Choice reviewer tried the amp with his HD800s and again was nothing short of very impressed. The amp really can drive pretty much any headphones you can through at it (and well).
Any info on ODA progress?
Does anyone have information on the status of ODA, the desktop version, or the esteemed scientist himself? Rocketscientist's last blog entry was back in May.
I hope all is well.
Francois
Does anyone have information on the status of ODA, the desktop version, or the esteemed scientist himself? Rocketscientist's last blog entry was back in May.
I hope all is well.
Francois
Just checked my email history and realised I haven't heard from him in a while either. I'll shoot off an email and see if everything is OK.
As for the ODA, nope, no info...
As for the ODA, nope, no info...
After a quick check, it looks like he's posted in the comments of his own blog as of yesterday, so I presume he's still alive and kicking, doing alright. He's probably just busy with real life and/or finalizing ODA or ODAC-related documentation or design.
I'm kind of curious what the final O2 -> ODA changelist will be too.
I'm kind of curious what the final O2 -> ODA changelist will be too.
Yep, just heard back from him; he has just been having a busy Summer. He says that the ODA is a bit behind schedule but still coming... He didn't say when though, the tease!
Anyone know the difference between NE5532APE4 and the NE5532AP ? The APE4 costs a bit more AFAIK, but I want to know why...I am planning to use this one instead of the default NJM2068D. Thanks in advance.
and while we are at it why not use the NJM5532D instead as NWAVG/RS seems to prefer ICs from that company. The NJM part seems to have slew rate 8v/us instead of 9v/us for the same part from other companies.
Thanks for the quick responce Mr Slim 🙂 . I have indeed read that article; I should have probably explained better. I was planning to build an ODAC+O2 combo for a friend of mine who intends to use it with a DT880-600 Ohm and since the 5532 seems to perform marginally better at gains >5x, I thought it was a good idea. On another note I did find a note on NWAVG/RS blog (in the comments section) that he did test the NJM and did not find any significant difference between that and the NE part.
I've just finished building the O2 amplifier but how important is it to clean the back of the board to get rid of flux residues?
It's not critical. I used to be anal about it, but you are more likely to cause problems with flux getting into the switches or the jacks by trying to clean the board.