The Objective2 (O2) Headphone Amp DIY Project - Page 99 - 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 November 2011, 02:02 PM   #981
diyAudio Member
 
Join Date: Nov 2011
Location: http://binged.it/ukmr5Y
I've got some stranded wire that's super thin which I can strip away and unravel the individual strands which I could oil or tape. I need to track down a micrometer because if these hard to see wires turn out to be something like 42 or 44 AWG then I'd need to mate a few up. That scale that @RS linked shows a steep incline to resistance as gauge shrinks.
  Reply With Quote
Old 30th November 2011, 02:24 PM   #982
diyAudio Member
 
RocketScientist's Avatar
 
Join Date: Mar 2008
Location: Northwest
@ethanolson, I have to side with qusp on staying away from 40 AWG (if you even find a source for it). I can't see any possible benefit and only downsides (most notably it would be extremely fragile and difficult to work with as qusp suggests). If you want a higher output impedance for some reason, just replace the four 1 ohm resistors with 2 ohm resistors, or add a 0.5 ohm resistor at the jack. There are "well respected gurus" also recommending Sonic Bricks on top of your amp but their recommendations often fail to make any detectable improvement whatsoever. The O2 is all about honest objective performance, not emptying your wallet with snake oil tweaks.

Uninsulated strands would be even worse as an accidental short could have disastrous results to the amp and possibly even your headphones.
__________________
http://nwavguy.com - Personal non-commercial audio blog
  Reply With Quote
Old 30th November 2011, 02:43 PM   #983
diyAudio Member
 
Join Date: Nov 2011
Location: http://binged.it/ukmr5Y
Thanks everyone. Since I can't find anything substantive for audio performance I'll assume this is speculated conjuring so I'll just use the regular stuff. It'll definately be easier to work with.
  Reply With Quote
Old 30th November 2011, 02:53 PM   #984
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Quote:
Originally Posted by RocketScientist View Post
@qusp, the 30 AWG for chassis wiring is rated at 860 mA. And those are continuous RMS currents where heating is a concern which has little to do with a musical signal. The average current delivered to even current hungry headphones playing loud is under 20 mA. See: American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies. And even the 40 AWG would result in only 0.5 ohms of resistance which still won't "limit the output power of the amp in a large way". Sorry, but I'm just trying to be factual.
all good man, i'd forgotten about that. my numbers are taken from the american wire gauge table too, but you are correct i quoted the numbers for external use. i generally er on the side of safety (or overkill,m you choose =)) and use the external ratings anyway, as i see zero point to striving for the thinnest conductor for analogue signalling frequencies or power where skin effect is meaningless and only quoted in jargon to sell cables. no money is saved at these sizes either.

I also generally buy all my wire in bulk and my favourite wire for all but the final tweaker mode builds is solid core milspec 24awg spc as i have it in 8 colours of teflon for colour coding, the rest i use solid 30awg 1.25mm pitch ribbon or belden 50r mini coax. 18 or 16awg of the same milspec for higher current, then neotech upocc in ptfe for final builds of same if i get that far. i prefer solid because it stays where its put

as for the 'guru' recommendation for 40awg, my guess is this was recommended for line level input wiring for power amps driving high impedance, not output wiring for headphone amps driving low impedance.

Last edited by qusp; 30th November 2011 at 03:04 PM.
  Reply With Quote
Old 30th November 2011, 02:56 PM   #985
diyAudio Member
 
Join Date: Nov 2011
Location: http://binged.it/ukmr5Y
Quote:
Originally Posted by qusp View Post

as for the 'guru' recommendation for 40awg, my guess is this was recommended for line level input wiring for power amps driving high impedance, not output wiring for headphone amps driving low impedance.
The lightbulb just lit, man. I think you're right about where I may have heard it... a different application altogether.
  Reply With Quote
Old 30th November 2011, 03:14 PM   #986
tschuss is offline tschuss  United States
diyAudio Member
 
Join Date: Aug 2011
Location: Boulder, CO
Quote:
Originally Posted by mikeaj View Post
Does anybody else have a build with the default small B2-080 enclosure? There are five notches for the PCB to go into. I tried putting the board into the second-lowest spot (as opposed to the lowest), and it fits in fine. Actually, the batteries press up against the top of the enclosure, so there's some friction to overcome when sliding in and out, but I reckon that's a good thing since that hopefully means the batteries are secure inside. Also (1) this prevents the PCB isn't sliding around loose, which is relevant since I'm not using any front panel that could secure it and (2) it definitely eases concerns about leads like on the gain switch, coming into contact with the enclosure.

Any drawbacks to doing so? I notice that the PCB looks very slightly bent down in the center, so it's very slightly like a U shape. The curvature is subtle at most. I imagine that the mechanical stress is not desirable, but I'd also guess that very many PCBs in any number of applications out in the wild are regularly put under greater stress with little harm. It's not like it's being regularly flexed back and forth.
Methinks you might have the case upside down. I just tried it, and there is no way you can use the second slot from the bottom with the stock parts on the BOM...all sorts of things run into the case top. Even accounting for manufacturing tolerances, I still can't imagine there would ever be enough room. However, if you flip the case over and use the second slot from the *top* (upside down), then it will _just_ fit, only touching the batteries, as you mentioned.

Not that there's that much difference in the case bottom and case top, but thought I'd throw it out there in case anyone else wanted to try this method.
  Reply With Quote
Old 30th November 2011, 03:30 PM   #987
MrSlim is online now MrSlim  Canada
diyAudio Member
 
Join Date: Jun 2009
Location: Ottawa, Ontario
Blog Entries: 2
Quote:
Originally Posted by tschuss View Post
Methinks you might have the case upside down. I just tried it, and there is no way you can use the second slot from the bottom with the stock parts on the BOM...all sorts of things run into the case top. Even accounting for manufacturing tolerances, I still can't imagine there would ever be enough room. However, if you flip the case over and use the second slot from the *top* (upside down), then it will _just_ fit, only touching the batteries, as you mentioned.

Not that there's that much difference in the case bottom and case top, but thought I'd throw it out there in case anyone else wanted to try this method.
There is a Top and a Bottom to the case, and if you use the panel design from RS, and the one from the Group Buy, you have to install the board in the first slot from the Bottom. The top of the case is the side with the extra groves in the panel. The position of the first slots (from top or bottom) is different, so you need to get it right..
  Reply With Quote
Old 30th November 2011, 03:39 PM   #988
tschuss is offline tschuss  United States
diyAudio Member
 
Join Date: Aug 2011
Location: Boulder, CO
Exactly. While the idea of the case holding the batteries in place is a pretty good one, I'm not willing to design a new custom front panel, and can easily hold the batteries with a piece of double-sided foam tape or similar.

Just be sure to double check that you've got the case oriented correctly when installing the PCB and you'll be fine.
  Reply With Quote
Old 30th November 2011, 03:46 PM   #989
agdr is offline agdr  United States
diyAudio Member
 
agdr's Avatar
 
Join Date: Sep 2010
Quote:
Originally Posted by MrSlim View Post
There is a Top and a Bottom to the case, and if you use the panel design from RS, and the one from the Group Buy, you have to install the board in the first slot from the Bottom. The top of the case is the side with the extra groves in the panel. The position of the first slots (from top or bottom) is different, so you need to get it right..
Can't imagine who would make a mistake like that, though.

O2 amp CRC, diode, cap, and heatsink mods

Quote:
Originally Posted by agdr View Post
And.. I was planning on posting measurements for the drill holes at the point, but in looking at the pictures it just occurred to me I have the box upside down!
  Reply With Quote
Old 30th November 2011, 06:52 PM   #990
diyAudio Member
 
RocketScientist's Avatar
 
Join Date: Mar 2008
Location: Northwest
The O2 PDF Documentation Package has finally been updated with the new power management resistor values, as has the BOM spreadsheet. Everything in the Mouser column is now in stock except for the volume pot but they have the first alternate (different taper) and the main part on order. I revised all the prices and incorporated many of agdr's suggestions as well. Both are dated 30 November. The links are in the usual place:

O2 Resources
__________________
http://nwavguy.com - Personal non-commercial audio blog
  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
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 03:11 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