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The Objective2 (O2) Headphone Amp DIY Project
The Objective2 (O2) Headphone Amp DIY Project
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Old 30th January 2018, 09:23 PM   #5141
Christian96 is offline Christian96
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Hi,
I got another question, unrelated to my last one.
What do I have to do, to use the "Audio Out" on the ODAC and not the "Line Out"?
I want to try the ODAC with another Amplifier, thats why.

The amplifier is working, tested with an onboard soundcard, the ODAC is recognized in Windows and should be playing music, tested on different USB ports.
Is there a jumper or something that I am not aware of?
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Old 31st January 2018, 04:29 AM   #5142
ammel68 is offline ammel68  United States
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The Objective2 (O2) Headphone Amp DIY Project
Quote:
Originally Posted by Technical Petting View Post
For the record, Mel, my Alps RK27 doesn't have any channel imbalance. It never has, and it never will, because it isn't possible! You think you're so smart, but I bet you can't even figure that much out without copying the answer from someone else.

Your prejudice against opamps is cute. I bet you copied that opinion from someone too. Perhaps you can elucidate us by explaining the difference, hmmm? If opamps suck so bad, your favored discrete amps must be very, very different! Do they add a lot more distortion? That would certainly be different.

Maybe they come with built-in lighshows! That would be awesome! Someone would be like "check it out, my new Laserdream has a 1 watt eximer," then Mel sashays in and strikes a dramatic pose. "Mine's got FIVE one watt lasers. Q-switched. You've never seen real detail until you've seen five lasers."

I guess I was wrong about you Mel, anyone who has that many lasers on their amp can't be completely despicable
Maybe the o2 does suck. I always liked it before, but recently I've really been noticing the lack of a laser.
You're sooooo funny Petting!
You get my vote for this site's best comedian.

ANY carbon film pot is subjective to channel imbalance issues at lower volume levels. To state that it's "isn't possible" is truly ludicrous.
I own several commercial integrated amps and preamps that use the RK27 and they ALL have channel imbalance issues at lower volume settings.
If those big, blue ALPS pots are so superior to stepped attenuators, then companies like Gold Point would've gone by the wayside years ago.
Yes, a Gold Point is considerably more expensive than an ALPS, but it'll outlast several ALPS and have zero issues with channel imbalances.

Ahh, another happy ALPS user without imbalance issues:
Need affordable stepped attenuator | Head-Fi.org

Not sure what in the hell "light shows and Laserdreams" have to do with this thread or HAs in general. It's totally meaningless and juvenile...but then so is your whole post above.

By the way, the name is Ammel, not Mel.

Now...let's bust out the moonshine and bunch of those good ole' NJM4556s and build a 02.
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Old 31st January 2018, 05:13 AM   #5143
ammel68 is offline ammel68  United States
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Quote:
Originally Posted by CHiroshi View Post
Just in case you missed it, most of the music you listen to probably already passed through dozens of opamps. That's what you're listening to, 5532s and the likes, and probably even some TL072s hahahaha!

No, I haven't missed anything. Personally, I could care less what the music has already passed through.
I DO care about what it passes through NOW, though.
Hahahaha! Thank you for such a funny post!
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Old 31st January 2018, 07:07 AM   #5144
Mooly is offline Mooly  United Kingdom
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The Objective2 (O2) Headphone Amp DIY Project
Quote:
Originally Posted by Christian96 View Post
Hi,
I got another question, unrelated to my last one.
What do I have to do, to use the "Audio Out" on the ODAC and not the "Line Out"? .............
I'm afraid I have no idea on the ODAC. Hopefully someone who has experience of it can advise.
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Old 7th February 2018, 06:00 PM   #5145
AriSa85 is offline AriSa85
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Hi everyone,

I'm about to order parts to build an O2 amp for desktop use only so I will omit the batteries. I'm also going to buy a bigger aluminium case and I will wire all the connectors and switches. I have a 12VAC 600mA power supply and I measured that even with 500mA output current to a resistive load the output voltage was around 13VAC.

I'd like to ask few questions before I make my order so I won't mess anything up.
I'm going to use Tasker C286 (or similar) to wire the volume pot, RCA-connectors ans 1/4" jack. I believe that's suitable wire for the job.
I was thinking that I would use a DP3T 3-position slide switch (Mouser 629-G128S3011) to control gain. My idea was that in position 1 there is no connection to ground and gain would be 1x. In positions 2 and 3 signal would go through resistors R17/R21 or R19/R23 to ground and that way I would get three position gain control. Is this a good idea? Does the swith quality matter? Can I use six (or five) single conductor hook up wires (like awg20 or awg22) and twist them together or should I use a shielded wire?

I know the D7 Led can't be changed to another color. If I still wanted to use e.g. a green power led separate from the PS-circuit, how do I do this correctly? Can I just connect the led and a resistor between the ~+12v line and ground line right after the power switch? If I do this should I use a equal load between ~-12v line and ground? Does this make any difference? Please let me know if this is a bad idea.

I was also thinking if I could fit tiny heat sinks to the voltage regulators (see Mouser 567-274-2AB). I was thinking if I could fit these to the regulators, if I don't mount the regulators so close to the pcb and bend the legs a bit. Thoughts?
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Old 7th February 2018, 06:14 PM   #5146
Mooly is offline Mooly  United Kingdom
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The Objective2 (O2) Headphone Amp DIY Project
The LED can be changed... in fact tying the design to specific parts is not good practice. If you want a brighter power on LED then just reduce the value of R6.

You need to read my notes on fault-finding the 02 (link at the bottom of post #1) where I suggest a method to allow different LED's to be used but if your mains only then it doesn't really matter as long as the comparators are in the 'on' state.

You shouldn't need heat sinks as the current draw is so low.

The gain switch is important because it is in the audio path, however it is configured around the 'earthy' end of the chain and so a short run of single core wire should be fine.
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Old 7th February 2018, 06:32 PM   #5147
CHiroshi is offline CHiroshi  Sweden
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Mooly, when are you going to build your O2?.. It is a neat and good sounding little amp, all things considered!.. The Objective2 (O2) Headphone Amp DIY ProjectThe Objective2 (O2) Headphone Amp DIY Project
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Old 7th February 2018, 07:16 PM   #5148
Mooly is offline Mooly  United Kingdom
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Mine is here

GERMANIUM Single ended Class A Headphone Amp.
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Old 7th February 2018, 10:29 PM   #5149
pukanetz is offline pukanetz  United Kingdom
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Default O2 P1 and P2 pinouts

Can someone please tell me what the pin outs for P1 and P2 are, I know the front 2 on P2 are ground and the middle one on P1 is ground, however which is the right and the left channels, also what is the benefit of the two grounds on P2

Thank you
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Old 8th February 2018, 09:24 AM   #5150
Mooly is offline Mooly  United Kingdom
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The tip of a 3.5mm plug is normally left channel and so that would indicate pin 3 of P2 is left (going off the diagram and assuming its drawn correctly).

That would mean pin 1 of P1 is left input.

Two ground pins simply reinforces the ground connection. Is it an admission that one pin may be suspect in itself...... ideally all connections should be soldered imo apart from where you must have plugs/sockets such as the headphones and inputs.
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