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Old 22nd November 2013, 03:20 AM   #3581
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Quote:
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Is there a single vendor with a complete BOM?
Audio Poutine - diyAudio from Canada

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Old 22nd November 2013, 03:21 AM   #3582
Davey is offline Davey  United States
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JDS Labs - Objective2 DIY Kit
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Old 22nd November 2013, 05:44 AM   #3583
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I'd prefer to buy from Digikey or Mouser. It's about $30 from Digikey, and the shipping is free.
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Old 25th November 2013, 04:41 AM   #3584
lhalha is offline lhalha  Australia
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Default Advice needed for using a toroidal transformer with the O2

Quick question - Can I use this 12V toroidal with an O2 - simply wire up one of the secondaries to the J1 inputs?

12V-0-12V 300VA Toroidal Transformer - Jaycar Electronics
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Old 25th November 2013, 02:25 PM   #3585
agdr is offline agdr  United States
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Originally Posted by lhalha View Post
Quick question - Can I use this 12V toroidal with an O2 - simply wire up one of the secondaries to the J1 inputs?
That would work as long as you have fairly high mains voltage and a light headphone load. One half of a 15Vac-0-15 would be better.

The problem is the dropout voltage across the voltage regulators. If the mains voltage is low (here in the States 105Vac - 110Vac) that reduces the voltage going into the regulators. If the headphone current draw is high, the increased regulator current increases the dropout voltage requirement. 14Vac or above takes it all into account just fine regardless of mains voltage or headphone load. But at 12Vac you are more restricted.

For what it is worth, NwAvGuy who designed the amp posted about the issue once that in his view it didn't matter if the regulators go into dropout on some 12Vac setups since the power supply rejection ratio (PSRR) of the op amp chips is so high. I never quite bought into that, especially since it is a half wave power supply with a relatively rough ripple voltage waveform. So YMMV.

Last edited by agdr; 25th November 2013 at 02:33 PM.
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Old 25th November 2013, 03:00 PM   #3586
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I used a small toroid on my own, one 15v tap directly to the O2, the other 15v goes though some linear regs down to 5v to feed the ODAC.

I worked on the basis the input voltage to the regulators should ideally be at least 2v higher than the output (12v). So 12v + 2v + diode drop = ~ 15v. I think mine measured ~18v unloaded which is also below the advised maximum which was something like 20-22v. Hence 15v was the magic number i came up with.
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Old 5th December 2013, 03:17 AM   #3587
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Default Some help please

Hey guys, i need a bit of help with my o2 amp, after checking the voltage on it i am not receiving the 11.7 and -11.7 volt at u4 (no sound at output also).. everything else is fine 12v at D1 and 23v at D3, Q1 and Q2 have power also.. followed this o2%2520voltages%2520all%2520ICs%255B7%255D.png (image) will upload photos if asked, any help would be awesome!
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Old 6th December 2013, 12:43 AM   #3588
agdr is offline agdr  United States
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Originally Posted by Salvolts View Post
Hey guys, i need a bit of help with my o2 amp
Do you also get the -12Vdc on D5 that he shows in that diagram? What voltages do you get on all 8 pins of U2? Be careful not to short across pins when measuring the chips.

Last edited by agdr; 6th December 2013 at 12:49 AM.
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Old 6th December 2013, 05:04 PM   #3589
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Hi guys, I also have a big problem with my O2 since I shorted one of the gain resistors to ground (amp was in perfect working order until I shorted it), my technical skills are very limited and would be eternally grateful if someone could help me fix my amp, I emailed HeadnHifi asking for advice just now but thought I might get a bigger audience on here so if anyone could spare a little time to help me then that would be great. Here is a little background: The LED does NOT light any more and amp doesnt sound healthy at all with headphones plugged in, a deep BURRRR sound, I only checked with cheap IEM's luckily. I am pretty sure I shorted R19 to ground and now the amp is sending 11VDC out from the two inner most pins on 'P2' instead of the very small voltage that should be present. My circuit tracing skills are very limited but I have checked the voltage across C15 and this seems to be perfect (23.5VDC) so I think the power side of things is ok but I am also getting the same 23.5VDC across 'C10', should this not be lower? my electrical skills are very basic so I don't know if 'Q1' and / or 'Q2' could potentially be damaged, what do these components actually do? Literally any help would be most appreciated
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Old 6th December 2013, 05:09 PM   #3590
Mooly is online now Mooly  United Kingdom
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If you can post a link to a clear circuit diagram of this amp then I'll take a look a little later
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