Dual O2-Inspired, SMD Headphone Amp - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems

Headphone Systems Everything to do with Headphones

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 30th May 2013, 10:27 PM   #11
diyAudio Member
 
gastro54's Avatar
 
Join Date: Nov 2003
Location: Atlanta, GA
And we are live! It "sounds" good - sorry nwavguy But seriously, I need to get this thing measured...
Click the image to open in full size.

Quote:
Orthos can be quite demanding. Hifiman HE-6s are pretty notorious, for example. They measured 53 ohms @ 1 kHz and needed 1.0 Vrms or 20 mW for 90 dB SPL.

Those would still make it to a bit over 100 dB on 4 Vrms, though honestly I'd be more worried about distortion at this point. Poor ol' 4556. NwAvGuy didn't even spec the O2 to drive these (though people have apparently reported pretty good results), and that's with twice the output current available.

BTW, 4.0 Vrms != 5.7 Vpp (but rather 5.7 Vp or 11.4 Vpp).
Oh snap. Yes 5.7 Vp, right. Thanks for the heads up on the tough headphones. Thats good info to know sgrossklass.
__________________
Bipole Transmission Line TangBand 871s

Last edited by gastro54; 30th May 2013 at 10:46 PM.
  Reply With Quote
Old 31st May 2013, 02:03 AM   #12
agdr is offline agdr  United States
diyAudio Member
 
agdr's Avatar
 
Join Date: Sep 2010
I like those battery holders! Pretty neat.
  Reply With Quote
Old 3rd June 2013, 05:05 AM   #13
diyAudio Member
 
gastro54's Avatar
 
Join Date: Nov 2003
Location: Atlanta, GA
I hadn't considered this when I was building the circuit, but as it stands, the turn-on transient is an issue that needs to be addressed. There are differences in the rise time of the positive and negative rails that the battery protection circuit of the O2 guards against.

Quote:
Originally Posted by RocketScientist
@stockpickerhk, please read the Circuit Description section. The circuit does protect the headphones, and it also greatly reduces the turn on transient every time you turn the amp on. Because the O2 uses a true bipolar power supply, if the positive and negative rails are not perfectly symmetrical on power up and power down, you get a transient at the output. The power circuit reduces that to safe levels.
My mistake. It will be fixed.
__________________
Bipole Transmission Line TangBand 871s

Last edited by gastro54; 3rd June 2013 at 05:08 AM.
  Reply With Quote
Old 20th June 2013, 07:21 AM   #14
diyAudio Member
 
availlyrics's Avatar
 
Join Date: May 2011
Quote:
Originally Posted by gastro54 View Post
I hadn't considered this when I was building the circuit, but as it stands, the turn-on transient is an issue that needs to be addressed....
Hey congratulations, pretty good job! Looks very professional.
According to agdr's idea try pair of 4.7K or 10K(as a bleeder resistor) in parallel with electrolyte cap. to reduce the turn-off transient (if its there). As for turn ON transient I had used 47uF with 0.1uF & toggle switch instead of push-switch for my JRC4556 CMOY with no audible thump.
BTW does those smd JRC4556 gets little warm (no load). I faced thermal issues with smd JRC4556 at +/-7.5V. With +/-5V everything was fine.
Have you(or planning to) published BOM, build-guide, e.t.c. like NwAvGuy?
__________________
Thanks,
availlyrics

Last edited by availlyrics; 20th June 2013 at 07:30 AM.
  Reply With Quote
Old 2nd July 2013, 01:24 PM   #15
diyAudio Member
 
gastro54's Avatar
 
Join Date: Nov 2003
Location: Atlanta, GA
Quote:
Originally Posted by availlyrics View Post
Hey congratulations, pretty good job! Looks very professional.
According to agdr's idea try pair of 4.7K or 10K(as a bleeder resistor) in parallel with electrolyte cap. to reduce the turn-off transient (if its there). As for turn ON transient I had used 47uF with 0.1uF & toggle switch instead of push-switch for my JRC4556 CMOY with no audible thump.
BTW does those smd JRC4556 gets little warm (no load). I faced thermal issues with smd JRC4556 at +/-7.5V. With +/-5V everything was fine.
Have you(or planning to) published BOM, build-guide, e.t.c. like NwAvGuy?
Thanks!
I could try wiring in the 10Ks for the turn-off transient - that would be an easy experiment. Interesting note about the toggle switch. The BOM is in the original post. I wont be doing a build guide for this revision since there are practical issues that make it inconvenient to use. Once I've finished the second revision, I will publish more complete documentation.

The NJM4556AM feel slightly warm, but I don't think its an issue. I used an IR thermometer and the IC temperature never got above 30 C during operation.
__________________
Bipole Transmission Line TangBand 871s

Last edited by gastro54; 2nd July 2013 at 01:27 PM.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
An "O3" - 35% smaller SMD RS O2 headphone amp version agdr Headphone Systems 16 2nd September 2013 10:03 PM
Dual O2-Inspired, SMT Headphone Amp gastro54 Solid State 0 16th May 2013 11:35 PM
Nelson Pass inspired headphone amp Fenris Headphone Systems 39 21st April 2012 10:36 AM
FS: O2 Headphone Amp its_bacon12 Swap Meet 1 10th March 2012 04:21 PM
O2 Headphone amp for sale! agdr Vendor's Bazaar 10 9th December 2011 03:05 AM


New To Site? Need Help?

All times are GMT. The time now is 05:33 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2