News:
December 06, 2022, 10:57:50 AM

Author Topic: Low impedance headphone  (Read 230 times)

0 Members and 1 Guest are viewing this topic.

Offline Tarpon66

  • Newbie
  • *
  • Posts: 3
Low impedance headphone
« on: February 23, 2022, 11:28:08 AM »
Hello everyone.. a newbie here  with a tech question..
If an amplifiers impedance ratings are call for headphones between  60 - 600 ohms... what damage can be done  to amplifier and or headphones if using 32 ohm phones  ..being that 32 ohm is below  the 60ohm specs??
Ty

Offline Tarpon66

  • Newbie
  • *
  • Posts: 3
Re: Low impedance headphone
« Reply #1 on: February 23, 2022, 01:50:28 PM »
8 views and not one reply ??? that's a warm welcome ...Respectfully 

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 17662
Re: Low impedance headphone
« Reply #2 on: February 23, 2022, 02:03:07 PM »
I started to write an answer, then decided to mull it over a bit.

There are a few reasons why a manufacturer would set a minimum impedance cutoff, so the best I can do for you is to explain why we might run into that with our products and you can extrapolate that to your unnamed headphone amp.

For something like the Crack, there is a limited amount of output current available, and this presents a limit to the output level available into low impedance headphones.  Additionally the output impedance is a bit on the high side, so the impedance curve of a low impedance pair of headphones will drag the amplitude at the output of the amp all over the place, and you'll get fat, bloated bass and treble that's obnoxiously present.  The Crack is also cap coupled at its output and those caps are sized for headphones that don't upset the balance of the first two points.

For an amp like the SEX amp wired for 4 ohm speakers, the amp is happy with at least a 4 ohm load and that allows an appropriate load to be reflected to the output half of each 6FJ7.  As you go below that, gain will decrease a little bit and distortion will go up, though an amp like the SEX amp is pretty tolerant to this.  If you found some 2 ohm headphones, they would probably work fine like this, but it's still an illustration of other problems that can creep up.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Tarpon66

  • Newbie
  • *
  • Posts: 3
Re: Low impedance headphone
« Reply #3 on: February 23, 2022, 03:13:12 PM »
Thank you so much for the reply and information

Offline Doc B.

  • Administrator
  • Hero Member
  • *****
  • Posts: 9193
    • Bottlehead
Re: Low impedance headphone
« Reply #4 on: February 23, 2022, 03:38:18 PM »
Patience, grasshopper.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.