Headphone maximum power - 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 12th January 2013, 11:47 AM   #11
diyAudio Member
 
Join Date: Oct 2004
Location: Denmark
Having a high supply voltage of more than the usual +/- 12-15VDC has a few advantages, especially when working with discrete amplifier circuits.

Higher headroom - amp can be designed to never clip.

Lower distortion - due to the higher headroom the output signal will never be getting even near the supply rails which should help keep the distortion lower.

Better linearity - a discrete headphone amplifier, especially ClassA, usually have some kind of largish BJT(s) or FET(s) in the output stage and most of those like a certain amount of C-E or D-S voltage across them to perform at their best.

Now, what I usually do with my +/-12-15VDC discrete ClassA designs is that I adjust the gain to suit my own personal goal of about 115dB maximum output power into my headphone of choice(Beyerdynamic DT 880 PRO, 250 Ohm, 96dBmW).

I'm using a self designed ES9023 DAC with a line level output of 1.9VRMS, my discrete ClassA headphome amplifier is configured to a gain of x 2.5 which in combination gives me an output level of 4.75VRMS.

4.75VRMS into 250 Ohm equals 90.25mW of output power which in turn equals a maximum headphone SPL of 115.55dB.

The result is no possibility of clipping, ever, and very low distortion all the way up to 115dB SPL.

To make it short, having very high supply rails is not much of a problem if you know exactly what headphone impedance and sensitivity you are designing for as well as how much power you need to get the SPL you want. You can always change the gain of your headphone amplifier to suit your needs.

Last edited by Neutrality; 12th January 2013 at 12:13 PM.
  Reply With Quote
Old 12th January 2013, 02:10 PM   #12
diyAudio Member
 
Join Date: Jan 2013
Quote:
Originally Posted by Blues View Post
These are 102dB/1mW at 600ohms beyerdynamic T 1

sqrt(1mW*600) =0.775V; So we need 0.775V to get us to 102dB -very, very loud directly into our ears;
So 2.2Vpp

Quote:
Originally Posted by Blues View Post
Extended levels of 87dB is deemed to cause hearing loss by OSHA. 120dB is at the threshold of pain for humans.
Thanks for this info.


Quote:
Originally Posted by DigitalJunkie View Post
Whatever you do,be extra careful with headphones/headphone amps. Test the amp with a small speaker or something first. NOT with headphones on your head! If something were to go wrong,a loose connection,oscillation,etc. it could easily damage your hearing.
Don't worry, i'll remember your advice !


Quote:
Originally Posted by Neutrality View Post
Now, what I usually do with my +/-12-15VDC discrete ClassA designs is that I adjust the gain to suit my own personal goal of about 115dB maximum output power into my headphone of choice(Beyerdynamic DT 880 PRO, 250 Ohm, 96dBmW).

I'm using a self designed ES9023 DAC with a line level output of 1.9VRMS, my discrete ClassA headphome amplifier is configured to a gain of x 2.5 which in combination gives me an output level of 4.75VRMS.

4.75VRMS into 250 Ohm equals 90.25mW of output power which in turn equals a maximum headphone SPL of 115.55dB.

The result is no possibility of clipping, ever, and very low distortion all the way up to 115dB SPL.

To make it short, having very high supply rails is not much of a problem if you know exactly what headphone impedance and sensitivity you are designing for as well as how much power you need to get the SPL you want. You can always change the gain of your headphone amplifier to suit your needs.
Thanks for your explaination.


On this website, they give us results of headphone tests : Headphone Data Sheet Downloads | InnerFidelity

So now I can calculate the voltage of some headphones for a specific audio pressure.
(With measurements I've done with my headphone, I can determinate that I usually listen music between 86 and 90dB. According with Blues, it's a little too much...)


Thank you for having answer my question
BT
Attached Images
File Type: png voltage_110db.png (32.2 KB, 122 views)
  Reply With Quote
Old 12th January 2013, 07:05 PM   #13
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
I keep showing estimates of dynamic headroom - can be way more than long term average listening level

a few past posts - for differing headphone's specs

Quote:
Originally Posted by jcx View Post
for the 250 Ohm Beyers I find 96 dB re 1 mW

5 Vrms will give ~+20 dB for 116 dB max SPL

if you occasionally listen at near live levels this probably isn't enough for the +120 dB peak SPL of some genre of music:

http://headwize.com/articles/hearing_art.htm

20 dB peak-to-average is very rare in popular music recordings given the "Loudness War" so many may never need even 100 dB capability if they listen at safe levels for hrs/day the ave should be kept well below 90 dB SPL

for myself, I like to know the amp can cleanly drive the headphones to a little over 120 dB SPL



it is extremely unlikely that music dynamic peaks (snare, crash cymbal) will overheat a headphone - max ratings are for continuous levels

over excursion/voice coil bottoming on bass notes is a possibility with some cans though


Quote:
Originally Posted by jcx View Post
the other number you need is 100 dB/mW sensitivity

120 dB SPL is a pretty high dynamic peak music level - requires 100 mWrms into the 16 Ohms - some may accept 110 dB peak as adequte for most listening

so a high estimate of amp capability to avoid clipping would be 1.8 V, 112 mA peak for these headphones

the current requirement can be met with some high output current op amps - but many give up at few 10s of mA so you need to look for those speced for this

paralleling a few op amp outputs could also get you more current but the current sharing R increase amp output Z - not always good with such low Z load

a higher current buffer in a "audio" op amp loop is one of the more common ways to diy a amp for such loads

HeadWize Library - Projects is inactive but archived - THE source for diy headphone amp info
check out the articles, technical papers too
HeadWize - Article: Preventing Hearing Damage When Listening With Headphones (A HeadWize Headphone Guide) is good for safe listening advice - and an appreciation of music dynamic range, required headroom
Quote:
Originally Posted by jcx View Post
the link has some unit inconsistencies and seems to be aiming for 110 dB SPL clipping level - in fact unamplified Classical concert hall levels can reach >120 dB peaks - so if "real life" sound reproduction is a goal then I would recommend higher peak power - at least enough to reach the 120 dB SPL without clipping

many listening scenarios, musical genre could be enjoyed with less - all day listening should be done at less than ~80 dB SPL average level and "good" dynamic range today is +14 dB peak levels, with rare Classical, Jazz recordings sometimes hitting +20-24 dB

reaching the 120 dB SPL level should only be for seconds of the musical performance and requires listening at elevated average levels only allowed for a hr or so a day by OSHA standards
but at headphone drive levels even Class A power is relatively cheap so I like the higher 120 dB SPL clipping free design goal

HeadWize - Article: Preventing Hearing Damage When Listening With Headphones (A HeadWize Headphone Guide)

from the schematic of the QRV09 it looks like connecting a single board for bridged output would be easy so two boards would make a "dual mono" bridged/"balanced output" headphone amp with the headroom to drive a few of the more difficult headphones that would like higher Vdrive
  Reply With Quote
Old 12th January 2013, 07:12 PM   #14
balerit is offline balerit  South Africa
diyAudio Member
 
balerit's Avatar
 
Join Date: Apr 2011
Location: South Africa
Ask Pete Townsend about headphones, they blew his eardrums and he now warns of the dangers associated with them.
  Reply With Quote
Old 12th January 2013, 07:16 PM   #15
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
I do sugget reading the headwize hearing article - several times
  Reply With Quote
Old 12th January 2013, 09:24 PM   #16
diyAudio Member
 
Join Date: Jan 2013
So, if i've understood, you adviced me to design my amp to drive headphones at 120dB ?
Even if i'll never reach this level (for continuous audio level), there can be some audio pic which need more power to be well listened ?

For exemple, with my HD448 (35ohm), 0.1mW for 90dB, it will be 100mW for 120dB, so 1.9vrms. My amp should deliver 5.3Vpp

Quote:
Originally Posted by jcx View Post
the current requirement can be met with some high output current op amps - but many give up at few 10s of mA so you need to look for those speced for this
I've no problem with electronic. I'll only use op amp for reducing distortion. Output stage will be designed with JFET (self-design AB class), so i'll not have output curent problems


Quote:
Originally Posted by jcx
I do sugget reading the headwize hearing article - several times
I'm very interesting in reading your articles, but all the links are dead :/
http://headwize.com/articles/hearing_art.htm => 404
http://gilmore2.chem.northwestern.edu => server cannot be found
  Reply With Quote
Old 13th January 2013, 02:02 AM   #17
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
the solution to offline/outdated links is often to try the WayBack Machine archive.org

HeadWize - Article: Preventing Hearing Damage When Listening With Headphones (A HeadWize Headphone Guide)
  Reply With Quote
Old 13th January 2013, 02:12 AM   #18
cotdt is offline cotdt  United States
diyAudio Member
 
Join Date: Oct 2005
Send a message via AIM to cotdt
I've plugged my headphones into speaker amps that can output 400W. It's fine. You probably are only using 0.01W with most headphones.

I like a gain of 4x with low impedance headphones and 20x with high impedance headphones. It seems high but there's always those recordings recorded at low level and it's nice to have extra gain on hand.
  Reply With Quote
Old 13th January 2013, 08:02 PM   #19
Blues is offline Blues  United States
Lightning In A Bottle
diyAudio Member
 
Blues's Avatar
 
Join Date: Sep 2003
Location: The Milky Way
Quote:
Originally Posted by Black Templar View Post
...(With measurements I've done with my headphone, I can determinate that I usually listen music between 86 and 90dB...)
Yes, that is more like it for me too...78-84dB average and peaks to about 90-96dB. Remember these are right-on-the-ear levels...great quality sound need not be ear-drum splitting be it rock or symphonic.

Quote:
Originally Posted by cotdt View Post
...You probably are only using 0.01W with most headphones.
QED!

These paragraphs for me stand out most from the HeadWize link...

"In loudspeaker reproduction, sounds must travel several feet before reaching the listener's ears. By the time they arrive, a portion of the high frequencies have been absorbed by the air. Low frequencies are not absorbed as much, but they are more felt through bone conduction than actually heard. With headphones, the ears hear all frequencies without any attenuation, because the transducers are literally pressed against them. Thus, when listening to headphones at the same effective volume level as loudspeakers, headphones may still transmit louder high frequencies that are more likely to cause hearing damage.

Another hearing phenomenon that seems to be more noticeable with headphones is a decreasing sensitivity to sound levels over time, as the ears adapt to loud sounds. The listener perceives a gradual drop in loudness even though the volume control setting hasn't changed. The acoustic isolation of headphones tends to highlight this dulling effect. It is all too easy for headphone listeners to turn up the volume to the point where hearing is at risk. Interestingly, most people find it difficult to distinguish between 85dB and 100dB SPLs, despite that the latter is more injurious to hearing. Therefore, it is important to avoid listening fatigue by resting the ears in silence after long sessions with headphones and to fight the temptation to turn up the volume."


The 2nd paragraph might explain for some heavy headphones users' preference 100dB or more levels.

Aside from low sensitivity planar mags and high voltage requirements of electrostatics, I don't see why we would need to introduce a gain stage into the equation.



ps: GO 'Hawks!

Congratulations to the Falcons...

Last edited by Blues; 13th January 2013 at 08:16 PM.
  Reply With Quote
Old 13th January 2013, 08:16 PM   #20
cotdt is offline cotdt  United States
diyAudio Member
 
Join Date: Oct 2005
Send a message via AIM to cotdt
Yes, though in your calculations, you have to take into account that average levels are at -12dB. So instead of working with a 2V source, you're looking at -12dB of 2V. And then there's those recordings that simply did not have enough microphone gain. So, it is better to have some gain on the headphone amp.
  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
AvsB Maximum Acoustic Power ro9397 Multi-Way 6 26th December 2011 11:34 PM
Power tube maximum current draw from a power supply razorrick1293 Tubes / Valves 4 4th November 2011 10:48 PM
Maximum allowable headphone amp output impedance. ashok Headphone Systems 67 6th May 2011 04:18 AM
Heatsink for two STK4050V in maximum power ElectroPower Chip Amps 2 24th July 2007 02:27 PM
Waveforms for maximum power dissipation rtarbell Everything Else 5 19th November 2005 07:54 AM


New To Site? Need Help?

All times are GMT. The time now is 05:07 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