Maths help -Output cap selection
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Construction Tips Construction techniques and tips

 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
zebra100
diyAudio Member

Join Date: May 2008
Maths help -Output cap selection

Can someone please help with the equation at the bottom of the diagram?

I have some headphones with a frequency response of 16Hz to 22kHz and and impedance of 24 ohm's, but no matter how I manipulate the equation, I can't seem to work out the output cap value (C2).

Thankyou.

Chris.
Attached Images
 szekeres%20ccs.gif (4.4 KB, 62 views)

 16th July 2010, 02:03 PM #2 abraxalito   diyAudio Member     Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... You don't need to manipulate the equation, just stick in your values. They're assuming an LF cut-off frequency of 10Hz, I'd go a bit lower myself as a 10Hz -3dB point introduces phase distortion below 100Hz. But assuming you want to follow their equation then C2 (in microfarads) is 1E6/(2*pi*10*24) which my calculator says is 663uF. I'd be inclined to use 2,200uF myself. don't forget to heatsink the LM317 __________________ 'The total potential here must be nothing less than astronomical.' 'Nothing less. The number 10 raised almost literally to the power of infinity.' Last edited by abraxalito; 16th July 2010 at 02:08 PM.
 16th July 2010, 02:22 PM #3 sreten   R.I.P.   Join Date: Nov 2003 Location: Brighton UK Hi, Its just a re-arrangement of R=1/(2piFC) for a 1st order filter. I do not see why "must" comes into it, 2,200uF will be fine for any headphones (the min is 8 ohms & any higher value). /Sreten.
 16th July 2010, 02:40 PM #4 sreten   R.I.P.   Join Date: Nov 2003 Location: Brighton UK d.p. delete does not work
 16th July 2010, 02:47 PM #5 zebra100   diyAudio Member   Join Date: May 2008 Doh!!!! Thank's, it was giving me a headache. I (stupidly???) assumed that the calculation gave the answer as farad's as opposed to uF's. That's why I couldn't see it. I'm using 470uF at the moment. Will this be too low, and if so, how will it affect the circuit/sound? Chris.
 16th July 2010, 02:52 PM #6 abraxalito   diyAudio Member     Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... 470uF just means that you'll get more bass roll-off, and I guess that subjectively the bass will sound 'slower' than with 2,200uF. The bigger value I imagine will 'tighten' the bass. __________________ 'The total potential here must be nothing less than astronomical.' 'Nothing less. The number 10 raised almost literally to the power of infinity.'
 16th July 2010, 03:06 PM #7 zebra100   diyAudio Member   Join Date: May 2008 Will this value adversly affect the circuit i.e. extra heat? Chris.
 16th July 2010, 03:08 PM #8 abraxalito   diyAudio Member     Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... No, can't think of a single adverse effect on the circuit operation. __________________ 'The total potential here must be nothing less than astronomical.' 'Nothing less. The number 10 raised almost literally to the power of infinity.'
sreten
R.I.P.

Join Date: Nov 2003
Location: Brighton UK
Quote:
 Originally Posted by abraxalito 470uF just means that you'll get more bass roll-off, and I guess that subjectively the bass will sound 'slower' than with 2,200uF. The bigger value I imagine will 'tighten' the bass.
Hi,

Its actually quite the opposite with manipulating bass roll offs.

FWIW 470uF is a fine value for typical walkman type headphones.
They are around 32 ohm, yours are lower than typical but will
still be fine with 470uF. Only if you want 8ohm compatibility
do you need to increase it, to between 1,100uF and 2,200uF.

And FWIW the equation is wrong, it should read C(uF) = ....

/Sreten.

Last edited by sreten; 16th July 2010 at 03:27 PM.

abraxalito
diyAudio Member

Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Quote:
 Originally Posted by sreten Its actually quite the opposite with manipulating bass roll offs.
So you've listened and found that a smaller cap tightens the bass and a bigger one slows it down? Which 'phones did you hear that with?
__________________
'The total potential here must be nothing less than astronomical.'
'Nothing less. The number 10 raised almost literally to the power of infinity.'

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post arthur Solid State 10 25th September 2009 11:40 AM layt Tubes / Valves 0 2nd July 2006 01:55 AM Deltat Parts 10 12th May 2006 04:54 PM SY Everything Else 120 17th June 2003 03:33 PM

 New To Site? Need Help?

All times are GMT. The time now is 02:50 AM.

 Home - Contact Us - Advertise - Rules - diyAudio Store - Sponsors - Privacy Statement - Terms of Service - Top - Opt-out policy

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.