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Objective Desktop Amp.....A Version from AGDR - Page 3

post #31 of 40
Thread Starter 

Yes absolutely....contact AGDR at diyaudio.com under the headphones section, here is the link:

 

http://www.diyaudio.com/forums/headphone-systems/229934-version-o2-desktop-amp-oda.html

 

OR

 

contact him directly on his site at www.agdraudio.com

 

Alex

post #32 of 40
Thread Starter 
Hey,

After being on now for a few days here are the temps I have measured with a thermocouple:

Front Panel 3.5mm jack: 88 degrees F. Inside about 1/2 inch its 90 deg F

Front Panel RCA Jack: 86 deg F

Front Panel Screw Upper Right Corner: 85 deg F

Top middle case: 87 deg F

Side center/middle case: 85 deg F

Rear Panel Middle Regualtor screw : 89-90 deg F

Front panel 1/4" jack internal about 1" insertion to back of jack : 93 deg F

The entire rear panel is relatively uniform in temp distribution.

Then entire case is relatively uniform in temp distribution as well.

I have no ventilation holes in my build.

I think I will add the holes / slots in the back panel to see how well that goes.

My gut thinks not that much.

I also had a 1/4 headphone plugged into the 1/4 jack all the time except when I measured the internal temp there. So this precluded any air entering that opening.

All in all the case is slightly warm at a 88-89 temp etc.

All the best
Alex
post #33 of 40
Thread Starter 

Check this out the little ODA driving a set of full range speakers to 90+ db!!

 

https://www.youtube.com/watch?v=VTbWVEKzVpY

 

Quite amazing!!

 

Alex

post #34 of 40
Quote:
Originally Posted by adydula View Post
 

Check this out the little ODA driving a set of full range speakers to 90+ db!!

 

https://www.youtube.com/watch?v=VTbWVEKzVpY

 

Quite amazing!!

 

Alex

Looks very interesting, but I still don't understand what are the benefits of using ODA over lets say O2. Would be there any sound quality advantage, if I listen from my O2 on fairly low volume (9-10 o'clock)?


Edited by ieee754 - 8/3/14 at 12:59pm
post #35 of 40
Thread Starter 

Hello,

 

Honestly from a pure sound quality perspective there is no real sonic difference that I can detect.

 

I have done a/b testing against the O2 and could not detect which one was playing.

 

There are many benefits to the ODA which I have mentioned several times in this thread and in the other ODA thread due to its more connections, more current capacity, a pre-amp and bass option. Two dac inputs, clipping led, power led and other stuff that just make it a nicer all around amp.

 

If you ever got a set of hard to drive cans like the HE6's the ODA would drive them better than the O2.

That said I have 2 O2's that sound as good.

 

Alex

post #36 of 40
Thread Starter 

Several updates on the ODA amp from AGDR at DIYAUDIO.COM....

He has sent the ODA  to Mike G and Mike has done measurements that are posted here and at DIY Audio. Mike also hooked up the ODA and played his 15" Alec's with the ODA....amazing etc.

AGDR is working on some THD measurements and has received the ODA back from Mike G and has modified it and will be sending it back for round two... of testing.

Mike has possibly discovered a THD issue with the original O2 with the volume pot being at mid way etc..AGDR has been analyzing this and thinks he knows what the issue might be. Its still below audible hearing etch.

You can read the techie stuff again over at DIY Audio.

That said none of this affects the sonic equality at all but AGDR being a perfectionist has continued to make improvements to the ODA. None of them really would be audible but makes the ODA better, safer from line input transients and more easy to build. So the latest V2.1 boards are going to be sent out shortly after he gets parts from Mouser. The 2.1 can be seen in this thread above and photos.

Details on the 2.1 revisions are listed in great detail on agar's Google drive under the 2.1 area.

I will be updating my 2.0 ODA with a few of the component updates, one being a transorb across the AC power inputs to help with any surges, two regulator capacitors from 10uf to 22uf..based on data sheet errata, no sonic issue here, just one of a corner case oscillation possibility.... and a Pico amp fuse in series with one of the ac line inputs.

Also the big news is that agar asked me to share he will be offering ODA BOARDS with the small hard to solder SMD parts' Here is his post:

"In other news I have decided to sell ODA boards with just the SMD stuff soldered on for an additional $39 labor fee plus the $32 or so worth of SMD parts. All as time permits, lol, which will probably mean weekends, just doing them as ordered. If you run into anyone in your travels wanting a through-hole only ODA, feel free to point them to the posting:"

You can send AGDR a pm directly and/or read the post at diyaudio in the vendor area.

Alex


Edited by adydula - 8/11/14 at 8:27am
post #37 of 40
Thread Starter 
post #38 of 40

Hmm... Somebody is considering making these for sale soon. :) 

post #39 of 40

Would be nice to get a pre-built unit.

post #40 of 40

Agdr is offering to sell one at a premium of $530. He is hoping that Mayflower will soon buy items in bulk and sell them for a cheaper price (not like Agdr asked to be a businessman). Mayflower told me that they are looking into it and they have a prototype in their shop.

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