Safety when testing headphone amp for muso's - 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 19th March 2005, 07:59 AM   #1
diyAudio Member
 
Join Date: Dec 2003
Location: Sydney
Default Safety when testing headphone amp for muso's

Hi,

At work yesterday, I had to test headphones at a really loud level, to check a supposedly distorting headphone amplifier. As I half expected, the distortion was within the performance that you would expect... it only distorts at levels above what is a safe listening level. I felt really anxious afterwards, as I was testing the amplifier by listening through headphones (two different types, with different impedances, both worked fine) and almost blasted my head off.

What is a safer way to test them? Should I use a dummy load and check test tones with a CRO, and compare the results with the spec sheet? (which may not always be available)

many thanks, from Steve
  Reply With Quote
Old 19th March 2005, 09:00 AM   #2
diyAudio Member
 
Bill Fitzpatrick's Avatar
 
Join Date: Jun 2001
Location: Eugene, OR
It appears you already tested them with a dummy load.
  Reply With Quote
Old 19th March 2005, 10:33 AM   #3
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
Foam earplugs. Or mic them up and run through the main desk.
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote
Old 19th March 2005, 11:14 AM   #4
diyAudio Member
 
Join Date: Dec 2003
Location: Sydney
Quote:
It appears you already tested them with a dummy load
yes, but I was looking for some useful advice here, more like what pinkmouse had to say (I see your humor!)
  Reply With Quote
Old 19th March 2005, 11:37 AM   #5
diyAudio Member
 
Join Date: Apr 2003
Location: Portland,Oregon
Blog Entries: 4
Send a message via AIM to DigitalJunkie
Seriously,NEVER test headphone amps with headphones on your ears!
If something went wrong,and the amp went into a full-power oscillation or something wierd,that LOUD screeching sound might be the last thing you ever hear.

Use a dummyload,small speaker,or just leave the headphones sittin on the desk,you'll still hear them okay... Just NOT on your ears.

(A very useful tip I learned the hard way while working on a 1Wpc tube headphone amp.)
  Reply With Quote
Old 19th March 2005, 08:56 PM   #6
diyAudio Member
 
Join Date: Dec 2003
Location: Sydney
Thanks, I won't be that silly again! :

This is what I will do next time...

1) make a dummy (resistive) load
2) put a test tone through amp
3) measure output on CRO
4) when output distorts, measure output with AC voltmeter, calculate power output, compare with specifications. Tell those who reported it faulty that it works within the design limitations. (if that is the case)

I will also put a pair of headphones (via an attenuator) in paralell with the dummy load, for an objective sound quality test. (That is what most of us identify with!)

When I did the att'n: 'dangerous' testing I actually found that with some songs on the CD (a Daft Punk CD) the bass just deteriorated completely, even though the volume wasn't really that loud. The only way I could think of checking that this was normal performance for this amplifier was to check it against another identical unit. Both performed the same. This is where it becomes subjective, as I'm sure that the manufacturer's specs are only going to specify the power output at the frequency at which the power output is the highest. (for marketing reasons)

Has anyone got any more suggestions?

Many thanks, from Steve
  Reply With Quote
Old 19th March 2005, 09:02 PM   #7
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
Just play around with the patch panel, tell the muso you swapped the channels to a good one, but don't actually change anything. That fixes the problem 95% of the time...
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote
Old 20th March 2005, 12:22 AM   #8
diyAudio Member
 
Join Date: Dec 2003
Location: Sydney
Good idea! I like that one! But the headphone amp was sent back to me for 'repair' from a live gig.
  Reply With Quote
Old 20th March 2005, 04:07 AM   #9
sam9 is offline sam9  United States
diyAudio Member
 
sam9's Avatar
 
Join Date: Jun 2002
Location: Left Coast
Here's something I'm going to order from digikey along with regular stuff.

http://rocky.digikey.com/WebLib/Pana...A%20Series.pdf


I want to see if a headphone amp can drive them. They might be an answer to safely listening to headphones amps. I've idea what they will sound like. They are cheap and maybe I'll end up with "minim-Magnepans" beside my PC.
  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
Safety First pacificblue Chip Amps 11 31st July 2009 06:59 AM
safety fuse Tubesin Tubes / Valves 0 28th January 2006 09:55 AM
83 safety rules Tomatito Tubes / Valves 5 17th May 2003 11:17 PM


New To Site? Need Help?

All times are GMT. The time now is 12:04 AM.


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