I'm currently troubleshooting my amp and I have a serious discrepency at the power supply capacitors.
According to my readings,
D3: 23.4V
D4: -24.3V
But
C2+ : 11.58V
C3- : -35.7V
Is that correct?
If it is worth anything C2 has approxiamtely the same values as C5. C3 has approximately the same values as C4.
According to my readings,
D3: 23.4V
D4: -24.3V
But
C2+ : 11.58V
C3- : -35.7V
Is that correct?
If it is worth anything C2 has approxiamtely the same values as C5. C3 has approximately the same values as C4.
No.
Give the power supply section a good visual inspection and perform the voltage checks I described in post #3475.
U5:
1: 24.2V
2: 0.00V
3: 11.87V
I'm struggling to get accurate readings of U6 because I previously had to de-solder and re-arrange U6 and U5. I think in this process I damaged U6.
I pretty adamant that U6 is the culprit now as D5 and C7 Both read 1.2V while D1 and C6 (the U5 side) read 11.87V.
1: 24.2V
2: 0.00V
3: 11.87V
I'm struggling to get accurate readings of U6 because I previously had to de-solder and re-arrange U6 and U5. I think in this process I damaged U6.
I pretty adamant that U6 is the culprit now as D5 and C7 Both read 1.2V while D1 and C6 (the U5 side) read 11.87V.
XLR w/ ST/Mono switch
Hi folks, newbie here and I am going to build a couple of these O2 Amps intended for Live use.
First off, I would be utilizing Aux outs of professional consoles, dropping the balanced - leg and going unbalanced. IDEALLY I would love to add in a transformer to maintain a balanced input that can remain portable. I have searched and read a lot of this thread and haven't seen this mod to an O2. Can anyone help me out here?
Second, I want to add a ST/Mono switch in utilizing a DPDT switch, anyone do this mod yet? I have the idea in my head and in my head, it works. I will not be using the the JDS panel, even as nice as it is. I will be making my own panel to use an XLR input (either 3 or 5 pin depending on whether or not I can get the balanced input mod to work) and from there take L to off board input 1/R7 and also to one pole of the DPDT. Right will connect directly to another pole of the DPDT and then out to off board input 3/R3. Anyone see any issues with this? I will be trying to get a schematic up for visual soon.
Lastly, I want to add another input resistance level for flexibility. My thoughts include a 3PDT Switch and utilizing a separate breadboard using 3 stages of input gain resistance.
Please, I would love feedback!
Hi folks, newbie here and I am going to build a couple of these O2 Amps intended for Live use.
First off, I would be utilizing Aux outs of professional consoles, dropping the balanced - leg and going unbalanced. IDEALLY I would love to add in a transformer to maintain a balanced input that can remain portable. I have searched and read a lot of this thread and haven't seen this mod to an O2. Can anyone help me out here?
Second, I want to add a ST/Mono switch in utilizing a DPDT switch, anyone do this mod yet? I have the idea in my head and in my head, it works. I will not be using the the JDS panel, even as nice as it is. I will be making my own panel to use an XLR input (either 3 or 5 pin depending on whether or not I can get the balanced input mod to work) and from there take L to off board input 1/R7 and also to one pole of the DPDT. Right will connect directly to another pole of the DPDT and then out to off board input 3/R3. Anyone see any issues with this? I will be trying to get a schematic up for visual soon.
Lastly, I want to add another input resistance level for flexibility. My thoughts include a 3PDT Switch and utilizing a separate breadboard using 3 stages of input gain resistance.
Please, I would love feedback!
jcx posted some good information about that in another thread:
http://www.diyaudio.com/forums/head...ut-headphone-amp-possibly-o2.html#post3651995
He also discusses transformers in that thread - you may want to scan the whole thing from post #1.
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ordered a kit and extra board from head'n'hifi, hope its with me tomorrow for the weekend for something to do, i have been reading all the problems people have been having and hope i dont run into any, the more i have read about this amp the more i have though hmm should i have bought it, but oh well to late now, i got the extra board because i was going to use some highend parts like pr9372 resistors and nichicon caps and then use wima poly boxes on it, and then maybe have some off board output caps, i have a nice collection of mundorf and clarity caps aswell as a couple jensen and audio note i was given by a friend who was clearing his bench, a friend said it could add some warmth it lacks but then could do nothing and look pretty, oh well will keep me from being bored i suppose
Just take your time with the build.
The O2 is a quiet, transparent headphone amp. Don't expect any more or any less.
Does the LED come on when you have the A/C adaptor plugged in and the on/off switch on? Did your O2 ever work, or is this a new build you are trying to get running?
Measure the voltage from ground (metal shell of the gain switch) to pin 4 of U2. Pin 1 has the dot on the corner of the chip. Then do the same measurement between ground and Pin 8 of U2. Then do the same thing measuring pins 4 and 8 of U1 to ground. Be extremely careful not to short IC pins together when measuring.
If the power supply is working you should get somewhere around +/-12Vdc on pins 4 & 8 of U2. If the power management circuit is turning on you should additionally get around +/-12Vdc on 4 & 8 of U1.
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Hi all,
I am a bit late to this party but I have a question. If the O2 is built for desk top use without the protection circuit and without batteries, and if you leave the AC on all the time (like a wall wart) but switch the DC to the amp will you still get a big thump on turning on-off? I know that is not a plan suggested by the designer, but it would make for a much simpler build.
If the DC is switched and a snubber is placed across the switch will that soften the turn on-off thumps? Any thoughts?
Thanks.
I am a bit late to this party but I have a question. If the O2 is built for desk top use without the protection circuit and without batteries, and if you leave the AC on all the time (like a wall wart) but switch the DC to the amp will you still get a big thump on turning on-off? I know that is not a plan suggested by the designer, but it would make for a much simpler build.
If the DC is switched and a snubber is placed across the switch will that soften the turn on-off thumps? Any thoughts?
Thanks.
Yes you can bypass the Power Management. You can connect h/p after the amp is powered up & disconnect h/p before turning OFF, so need to keep them ON 24X7.
If your switch is of good quality, the amp will have minimal ON/OFF thump. My personal observation is "toggle" switches are better than "push" switches. As for snubbers theoretically they should help.
If your switch is of good quality, the amp will have minimal ON/OFF thump. My personal observation is "toggle" switches are better than "push" switches. As for snubbers theoretically they should help.
right have built the amp as instructed, worked fine for about an hour cased up, then went all weird and distorted and then stopped working all together, have gone though all the issues listed here and nothing works at all, the amp dont work unless the batts are installed aswell, seems like a utter waste of time and effort of a kit
Right, that would be the first of 1500+ kits that is not working (after decent troubleshooting)... and this are only the ones I sold during the last two years.
First thing to check would be if the power supply circuitry is working, you mentioned the amp works only with the Batteries installed? Can you post some measurements and high res pics of the board (bottom and top side)?
Thx, Stefan
Thanks for your reply, but what I want to know is whether keeping the power supply on 24/7 and switching (on or off) the DC supply to the amps at board level will minimize the thumps.
Yes it will itwill minimize the thump.
Case I
You keep PS AC adapter ON 24/7 & use FP switch to turn amp ON/OFF-minimal thump.
Case II
You turn AC adapter ON & use FP switch to turn amp ON/OFF-minimal thump (same as above)
Case III
FP switch is in ON position & you turn ON AC adapter- Loud thump, worst case is AC half cycle.Even if you plan to keep AC power supply ON 24/7 there may be situation of momentarily supply failure (lasting just under a second) or brown outs resulting in large thumps.
The batteries in O2 also act like "online UPS" to eliminate Case III type situation.C1(1uF) is also useful in reducing power ON thumps
The "minimal thump" will still be more than O2 using standard BOM.
BTW High impedance, low sensitivity h/p are more immune to power ON/OFF transients than low impedance, high sensitivity h/p e.g. IEMs.Other well designed desktop amps usually employ some sort of relay mechanism to connect h/p after the PS has stabilized & disconnect the h/p in case of supply failure/turn OFF/ DC at o/p type situation.
NwAvGuy: O2 Details
Attachments
![o2 turn on transient into 600 ohms[2].png](/community/data/attachments/342/342122-e9b473b57c9fbe44d8889c0ea8735aa6.jpg)
![o2 turn off transient into 600 ohms[2].png](/community/data/attachments/342/342131-9cebbd1184bcdd4b5b919593c4eb0779.jpg)
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availlyrics,
As a result of your reply I went to the schematic for a closer look. Silly me, I did not understand that FP meant Front Panel.
I assumed the O2 switched on and off at the AC input. I was wrong. It switches DC at the board level after the regulators/batteries. Exactly as I plan to do. But as NwAvGuy says, even doing that will result in large start up thumps without the protection circuit.
I am rolling my own PCB with no protection circuit and no batteries. I will leave it on 24/7 and use a snubber, FWIW, right on the board. Also, I will put a constant load on the regulators to keep them fully regulating when the DC is turned off. I hope the combination will moderate the thump on turn on and off. Of course there will be no protection for brown outs and power losses except for what the snubber might do.
Thanks
As a result of your reply I went to the schematic for a closer look. Silly me, I did not understand that FP meant Front Panel.
I assumed the O2 switched on and off at the AC input. I was wrong. It switches DC at the board level after the regulators/batteries. Exactly as I plan to do. But as NwAvGuy says, even doing that will result in large start up thumps without the protection circuit.
I am rolling my own PCB with no protection circuit and no batteries. I will leave it on 24/7 and use a snubber, FWIW, right on the board. Also, I will put a constant load on the regulators to keep them fully regulating when the DC is turned off. I hope the combination will moderate the thump on turn on and off. Of course there will be no protection for brown outs and power losses except for what the snubber might do.
Thanks
ok so i sent my board off to a friend for him to have a 2nd look to see if i missed anything and appears r14, r20 are wrong they are marked as if they are 10k but read 268r and 269r i am slightly confused with a wtf face i have checked the codes 56789746373823 times just to be sure and tested with a few dmm's and they all read the same, would these cause the amp not to work??