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 7th July 2018, 04:58 PM   #5261
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
The Objective2 (O2) Headphone Amp DIY Project
Excellent well done.
  Reply With Quote
Old 9th July 2018, 07:43 AM   #5262
MaverickPT is offline MaverickPT  Portugal
diyAudio Member
 
Join Date: Jun 2018
Could someone explain me why does the O2 a voltage doubler/half wave rectifier in the power section? Why not a full bridge rectifier?

Also, why does it seem to me that the NJM4556s in the output stage seem...duplicated? Is it just so that they can supply double the amount of power?
Click the image to open in full size.

One last thing, it seems like the op amps aren't AC coupled. Why? Isn't ac coupling more advantageous?

Thanks in advance!
  Reply With Quote
Old 9th July 2018, 07:55 AM   #5263
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
The Objective2 (O2) Headphone Amp DIY Project
The power supply generates a split rail from a single AC winding and allows one side of that winding to be referred to as 'ground' or zero volts so that precludes using a bridge rectifier in the traditional way. A four terminal bridge rectifier could be fitted and would be configured with each pair of diodes in parallel by connecting together the two AC terminals.

Parallel opamps deliver twice the current.

There is AC coupling from the volume control to the final output stage. When and where and why to include it is down to design choices.
  Reply With Quote
Old 9th July 2018, 09:14 AM   #5264
MaverickPT is offline MaverickPT  Portugal
diyAudio Member
 
Join Date: Jun 2018
I find it interesting that there is no output decoupling cap. I know it was avoided to help the lower freqs, but how does it solve the DC component on the output?
  Reply With Quote
Old 9th July 2018, 09:15 AM   #5265
MaverickPT is offline MaverickPT  Portugal
diyAudio Member
 
Join Date: Jun 2018
PS: I'm been thinking for a while on making a DAC based on the PCM2912, mostly as a learning project. What do you guys think if i combined both in the same device? I know i'll have to deal with digital noise/grounding/different power supplies etc.
  Reply With Quote
Old 9th July 2018, 10:40 AM   #5266
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
The Objective2 (O2) Headphone Amp DIY Project
An output coupling cap would automatically remove any DC present and as an added bonus protect the headphones from any possible DC fault.

There is no (or very little anyway) DC present at any of the opamp outputs because the circuit uses dual supplies (a plus and minus rail). All points within the audio circuit are very close to zero volts DC unless a fault is present.
  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 08:44 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki