Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Headphone Systems Everything to do with Headphones

The Objective2 (O2) Headphone Amp DIY Project
The Objective2 (O2) Headphone Amp DIY Project
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th August 2011, 01:53 AM   #191
RocketScientist is offline RocketScientist  United States
diyAudio Member
 
RocketScientist's Avatar
 
Join Date: Mar 2008
Location: Northwest
Thanks for the comments Steve. I own HD650s and they are a bit more power hungry than a lot of headphones. Specifically they need more voltage than a lot of portable and USB powered gear can manage. The E11 is probably going to be marginal with highly dynamic music (low average levels but large peak levels). The E11 is essentially a Chinese AMB Mini3 with a different power supply scheme. But it depends on your volume tastes.

The voltage problem was one of the inspirations for the O2. The only 5+ V RMS portable amps I could find that didn't have huge price tags were Cmoy-like designs with dual batteries that put your headphones at risk if one battery dies first or becomes disconnected. They also tend to be single stage designs with much higher distortion, offset problems, much higher noise, etc. when run at the higher gains necessary for using high impedance headphones with an iPod LOD.
__________________
http://nwavguy.com - Personal non-commercial audio blog
  Reply With Quote
Old 24th August 2011, 05:21 AM   #192
MoonL is offline MoonL  Hong Kong
diyAudio Member
 
Join Date: Aug 2011
In my setting, I have changed
2903 to OPA2604AP,
2068 to OPA2111KP,
4556 to AD8620BR,

I don't have any equipment to test the performance of IC, I only use my Etymotic ER4S to listern to the change before and after change IC. Personnally, the sound become more clear and more detail on the song can be listerned.

It may not be fair to compare the IC I used with the orginal setting. Just want to share what I have changed in O2.
  Reply With Quote
Old 24th August 2011, 06:35 AM   #193
MoonL is offline MoonL  Hong Kong
diyAudio Member
 
Join Date: Aug 2011
For Q1 and Q2, as I don't have them when I taking the photo, I bypass them.
It may have effect on sound quality, but no effect on complete the AMP. O2 can work normally when bypass Q1, Q2.
Now I have installed Q1 and Q2 back to O2 to complete the original design, and start to make a case for it (the wood case I post before is made by my friend).
  Reply With Quote
Old 24th August 2011, 05:42 PM   #194
RocketScientist is offline RocketScientist  United States
diyAudio Member
 
RocketScientist's Avatar
 
Join Date: Mar 2008
Location: Northwest
I finally got the O2 Summary article done and everything fully cross-linked. I've also provided the latest info on several topics like the future desktop version. Consider it a "Best Of" version of the three much longer O2 articles.

I've conducted additional testing (and published the scope shots) on the input stage overload level. Even with the batteries past the 8 hour mark (nearly dead) the input stage can still put out 4.5V cleanly. So the new math for maximum gain on battery is Gain = 4.5/Vin (improved from the previous 3.8/Vin). All the info, and links to more, are in the new article:

O2 Summary Page

@MoonL your case is just amazing. Thanks for sharing the pictures of it being made. Very nice! Thanks for answering the Q1 and Q2 question as well. They are important to reduce turn on transients and protect the headphones during battery operation.

Click the image to open in full size.
__________________
http://nwavguy.com - Personal non-commercial audio blog

Last edited by RocketScientist; 24th August 2011 at 05:44 PM.
  Reply With Quote
Old 24th August 2011, 05:47 PM   #195
MoonL is offline MoonL  Hong Kong
diyAudio Member
 
Join Date: Aug 2011
2nd day work of my friend
Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

To be continous...
  Reply With Quote
Old 24th August 2011, 05:51 PM   #196
sebash is offline sebash  United States
diyAudio Member
 
Join Date: Aug 2011
Location: Hawaii
That case is going to look good MoonL. It doesn't seem to be too hard to make either if you have the right tools. I'm going to have to see If there's a a way I can make something similar with the tools I do have.
  Reply With Quote
Old 24th August 2011, 06:56 PM   #197
Earfanatic is offline Earfanatic  Hungary
diyAudio Member
 
Join Date: Apr 2010
Location: Hungary
Wow MoonL! I simply have no words... Until the last two pictures I thought it will be some king of front plate, then I realized the design, which is fantastic! I like Your idea and the final look will be awesome!
What kind of wood is that? Is it plain or does it have some kind of finishing?
  Reply With Quote
Old 24th August 2011, 07:50 PM   #198
olli1324 is offline olli1324  United Kingdom
diyAudio Member
 
olli1324's Avatar
 
Join Date: Dec 2008
Location: Exeter/London
Hello!!

Please follow the link at the end of this post to check your order and mke your payment. The details of how the cost is calculated is all done in my big spreadsheet (one column has about 9 nested IF statements!) but it breaks down as follows:
-1.29 cost of board (seeedstudio)
- 15p packaging
- Postage via Royal Mail (dependent on weight, starts at just 77 odd pence for 1 or 2 boards to the UK and 2.11 for 6 boards shipped to the EU)
- nominal 5% buffer

I am currently taking payment ONLY FOR NON-US ORDERS! This is because I am hoping to find a US distributer (who would handle US and CAN orders) so that we can take advantage of cheaper postage. It will cost less than 30p per board for me to send a big batch to the US, making potential savings quite considerable.

Please read all of the interested instructions and bits of info which are repeated numerous times down the side of the list.

https://spreadsheets.google.com/spre...JfcHc&hl=en_US

Please share this link around to make sure that everyone sees it as soon as possible.
  Reply With Quote
Old 24th August 2011, 09:46 PM   #199
agdr is offline agdr  United States
diyAudio Member
 
agdr's Avatar
 
Join Date: Sep 2010
The Objective2 (O2) Headphone Amp DIY Project
Quote:
Originally Posted by MoonL View Post
In my setting, I have changed
2903 to OPA2604AP,
2068 to OPA2111KP,
4556 to AD8620BR,
Hello MoonL,

Thank you for sharing your build! The case is just fantastic as so is your PC board. I wish that I had woodworking skills like that.

I have a suggestion. For an upgrade chip on the gain stage you might actually get more milage out of the $3 LM4562 (same chip as the LME49720). I see RocketScientist has done a review on the LM4562 in his latest op amp review:

NwAvGuy: Op Amp Measurements

The OPA2111 is certainly a high end chip - I see it goes for about $17 USD - but it may be more tailored to life as an instrumentation amplifier. The LM4562 is probably more optimized for audio. Here are a couple of comparison graphs I pulled off the data sheets. It is hard to get an apples-to-apples set of test conditions with data sheets, but these are fairly close.

The first (leftmost) graph is OPA2111 THD+noise distortion vs. frequency and the second graph is the same for the LM4562. Both are feeding a 2k ohm load with +/-15V rails. The LM4562 is only swinging 3Vrms though while the OPA2111 is doing 7Vrms. On the 20kHz end of the graph the OPA2111 is clocking in at 0.1% THD+N while the LM4562 is at about 0.00007% THD+N. On the 20Hz end of the graph the OPA2111 is at about 0.002% THD+N while the LM4562 is at about 0.00003% THD+N. Lower is better, of course, in these.

The third graph is the OPA2111 input voltage noise vs. frequency while the forth graph is the same for the LM4562. Both are done with +/-15V rails again. On the 1Hz end the OPA2111 clocks in at around 100nV/sqrt(Hz) while the LM4562 gives about 28nV/sqrt(Hz). On the 20kHz end the OPA2111 runs at about 5.5nV/sqrt(Hz) while the LM4562 is down to 2.7nV/sqrt(Hz). Lower is better again.

If you happened to socket that gain IC and have an opportunity to try the LM4562 in place of the OPA2111, I would really be interested in your thoughts on the listening results! The numbers on both chips are so good that any difference may turn out to be totally inaudible anyway. But at least the LM4562 may save you some money if you build any more O2s.

Thanks again for sharing your build pictures and info!
Attached Images
File Type: png OPA2111 distortion.png (36.0 KB, 97 views)
File Type: png LM4562 distortion.png (45.6 KB, 76 views)
File Type: png OPA2111 noise vs freq.png (26.2 KB, 66 views)
File Type: png LM4562 noise vs freq.png (25.0 KB, 61 views)

Last edited by agdr; 24th August 2011 at 09:58 PM.
  Reply With Quote
Old 25th August 2011, 05:20 AM   #200
MoonL is offline MoonL  Hong Kong
diyAudio Member
 
Join Date: Aug 2011
The wood my friend used is Black ironwood (Olea laurifolia), and in the picture, it is the natural colour of the wood.
  Reply With Quote

Reply


The Objective2 (O2) Headphone Amp DIY ProjectHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Headphone amp project grahamfocal Headphone Systems 7 21st June 2011 05:28 PM
My latest project - DAC + headphone amp gmarsh Digital Line Level 105 13th December 2010 02:31 PM
My headphone amp project trifidmaster Headphone Systems 2 22nd December 2008 03:52 PM
Mini Ipod headphone amp DIY project Nordic Headphone Systems 14 11th March 2007 02:35 PM
Need help for a battery headphone amp project dismalonyx Headphone Systems 1 15th April 2004 11:22 PM


New To Site? Need Help?

All times are GMT. The time now is 04:08 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki