O2: High Performance Portable/Home Amp

[hentaisan]

Hey guys, just as a prelude to starting the DIY project, I'm looking for a DAC recommendation here (so as to not make a new thread, and with the previous discussions about there being many budget DACs on the market that perform well). However, I'm after a DAC with optical input. Are there any that fit well with the O2, and has all the characteristics of being cheap, performs well, measures well, etc?

[jmwreck]

[The Larch]

That O2 would fit right in a Western movie.

[Tapion]

thats awesome O_O

[WalkGood]

jmwreck, Very nice distressed look

[El C]

Finally got all the Mouser parts resolved now and will order tomorrow. Though I'm shocked at the $99 shipping for two $11 enclosures from boxenclosures.com, going to get it somewhere else.

[jmwreck]

Originally Posted by The Larch

That O2 would fit right in a Western movie.

Originally Posted by Tapion

thats awesome O_O

Originally Posted by WalkGood

jmwreck, Very nice distressed look

haha, thank you, now charging for the first time

[t2t]

Originally Posted by maverickronin

If that's the right plug size you're good to go. To busy to double check that one right now.

2.1mm is the correct size of the barrel connector on the power supply. Sadly, my Triad died at about 2 months of use. I'm now using one from Radio Shack that's sold under the "Enercell" name. The one I initially purchased can be adjusted between 9V - 13V AC. The price was about $22.99. However, they also have an 18V / 24V AC adapter for $24.99. I'm going to go back and exchange mine this evening after work.

Fortunately, the Radio Shack adapter comes with the 2.1mm barrel fitting in place. Otherwise, one would have to purchase the right sized "tip" for another $6.99. However, I will say that the RS supplies do have some weight to them ... especially compared to the $5.55 Triad. It still kind of burns me a bit in regards to spending extra bucks at the retail level, but the shipping on one or two AC adapters wouldn't be worth it to go the Internet purchase route.

Edit: One quick note regarding the Enercell power adapter from R.S. With mine, I noticed that while comparing the barrel plugs between the Triad, they both seemed to be equal diameters. However, the R.S. Enercell would arc a bit if the power supply line was jiggled a bit and my iPod classic (the the metal back plate) would spark a bit, too. I took of the metal front trim plate and applied a small layer of adhesive around the inside of the drilled hole for the power supply. I let the adhesive dry and the next day, it acted like a great insulator for the issue I had. I'm not sure if anyone is experiencing any issues with the Triad supply and arcing with the plates from the group buy. I realize I could have also gotten the drill out and bored the hole slightly larger, too. Oh, one final point on the Enercell adapter. It features a right-angle plug so you can plug the adapter in and swing the cord around the left side of the case -- making it barely visible. Sorry to sound so much like one of those nerds that work at R.S.

[jmwreck]

[El C]

Sexy!

I just got the parts today (still waiting for the board/enclosure), so I can start assembling mine soon

[t2t]

Just a quick update on the "Enercell" AC power supply from Radio Shack. I was headed to their store following work and planned to swap out my model that went as high as 13V AC for the next one up in the food chain: 18V / 24V AC. Sadly, the 18V / 24V AC model doesn't have the built-in barrel connector of the right size. This means you have to buy the adapter for $25.99 and then pay an additional $6.99 for the proper tip for your device.

Being in this situation made me think a bit. I've seen posts on various forums where some people have been posting the actual voltage readings from some of the various power adapters. The Enercell when placed in 13V mode -- or, at least in my case, puts out 16.09 volts! This was confirmed both by the meter the guy at Radio Shack used as well as my own test with my volt meter upon getting home. Needless to say, I'm quite pleased at where this reading fell.

I hope that this supply can last at least a few years for me.

Good luck to all of you out there with the O2. It's a fun amp to own. I usually take mine to work with my on a daily basis. I can't survive the day without it.

[dcteague]

So I've been reading this and other forums to determine if its something I should invest the time to build, and at this point, I've decided it is going to be my next project. I'm by no means an engineer, but I've been able to assemble pretty complex electronics as long as I can figure out the location of everything. I'm obviously not going to try and modify the circuitry, but I may try to alter the location of a few items to make it a true desktop amp - since I have no use for a pocket amp.

If I were to simply panel mount the inputs and power to the rear by running some sheilded wiring, would it impact sound quality? I already purchased a pcb and the components, but given the low cost, I'd probably opt to purchase another board if its ready (just didn't think I had seen one published yet as selling).

Also, I'm going to run this with a set of K702 AKG - any specific alterations one might suggest to the gain controls or other components to optimize this for these headphones? I also run all my sound through a Nuforce preamp, if you know this and have suggestions, I'd appreciate some input/recommendations. If I posted in the wrong place, please feel free to move this.

And NWAVGUY - thank you for the incredible and generous effort!

One other thing - I discovered the Objective 2 at the same time as the RW Audio headphone amp - both pretty close in cost once you add in the case, power etc (in DIY state). So I ended up buying both. Once I'm done building them and breaking them in a bit, I'll post info on the 2 from a pure listening experience (sorry, no tools to do much else).

[Sorensiim]

Any of you guys still looking for a source might want to read this:
http://nwavguy.blogspot.com/2012/02/feb-1-update.html

ODAC + O2 = USB DESKTOP AUDIO JOY: The current ODAC revision is designed to fit inside the O2 if you remove the batteries. This works even with the slim B2-080 standard enclosure. It’s not a plug-and-play modification, but anyone with a soldering iron and some DIY skills shouldn’t have any problem. The O2 will need to be powered from the AC wall adapter and the ODAC is self powered from USB. It will require a rear panel modification for the mini USB jack.

That would give you a one-box 24/96 solution for your desk... I'm pretty damn tempted to go this route, despite already having a Fiio E10 and HRT HeadStreamer. (And seriously looking at the Ibasso D7)

[Limp]

Originally Posted by dcteague

If I were to simply panel mount the inputs and power to the rear by running some sheilded wiring, would it impact sound quality?

A better option would be to move the pot and output to the back, wired in twisted pairs, and use that as the 'front'.
Messing around with the power socket can quickly get ugly, as the AC will corrupt anything it runs parallel with. If you take a look at the PCB you'll see that great care has been taken in this regard, rectification occurs immediately after the power socket.

[dcteague]

Originally Posted by Limp

A better option would be to move the pot and output to the back, wired in twisted pairs, and use that as the 'front'.
Messing around with the power socket can quickly get ugly, as the AC will corrupt anything it runs parallel with. If you take a look at the PCB you'll see that great care has been taken in this regard, rectification occurs immediately after the power socket.

Thanks. Maybe that'll be a better option then. Thought I had read somewhere in the documentation not to move the pot but maybe I'm wrong.

[Lcomry]

Will the O2 power the Beyerdynamic DT-770 600-ohm headphones with a bit of headroom left, or will driving these phones up to "live" listening levels be at the upper limits of the O2's capabilities? Note: I will not be using batteries, just AC. (I've tried to follow the math at NwAvGuy's blog, but I cannot figure out the power requirements for the DT770/600 @ 110-115 dB SPL.)

I ask because I'm either going to purchase the pre-built O2 from JDS Labs now, or wait for the ODA if the O2 will not be able to power the 600-ohm Beyers fully up to "live" levels without clipping or falling short on current/voltage, etc.

I apologize if this has been asked and answered elsewhere. I appreciate any feedback! Thanks!

[Lcomry]

Regarding my post above, would going with a slightly higher-power AC adapter be the way to insure I get the most out of the O2 with 600-ohm Beyers? The AC adapter that JDS Labs sells with their pre-built O2 is the 533-WAU12-200. On NwAvGuy's blog, he also lists a couple of other choices that work with the O2, including the 533-WAU16-400 and the 533-WAU20-200.

For the best match with the O2 driving 600-ohm Beyerdynamic headphones, would the WAU16-400 (more mA) or the WAU20-200 (more voltage) be the better choice? Or is there another that is even better for driving high-impedence phones on the O2?

Thanks for any assistance, I really appreciate it!

[Lcomry]

bump

[maverickronin]

The regulators turn that extra voltage into more current and the 600 ohm Beyers don't need much current so you shouldn't need the higher voltage adapters.

[Lcomry]

Thanks for the response, maverickronin!