How much output impedance affect frequency response

[Keltere]

Hi like the title i want to ask how much a hight output impedance can affect frequency response.

I've read online that for an optimal solution the impedance output must be less than 1/8 of the headphones impedance. Is that true?
What about measurements? There are any, expecially for a 10ohm output with 32ohm headphones?

Thanks.


PS: i've searched the forum but i couldn't find anything about it. If there is already a thread about it i'm sorry.

 

[andreasmaaan]

Hi like the title i want to ask how much a hight output impedance can affect frequency response.

I've read online that for an optimal solution the impedance output must be less than 1/8 of the headphones impedance. Is that true?
What about measurements? There are any, expecially for a 10ohm output with 32ohm headphones?

Thanks.


PS: i've searched the forum but i couldn't find anything about it. If there is already a thread about it i'm sorry.

It depends on how the impedance of the headphones changes with frequency. If the impedance remains more or less flat from 20Hz to 20Khz, a higher than 1/8 output impedance will have little effect and shouldn't be any problem.

Which headphones are they?

 

[Keltere]

It depends on how the impedance of the headphones changes with frequency. If the impedance remains more or less flat from 20Hz to 20Khz, a higher than 1/8 output impedance will have little effect and shouldn't be any problem.

Which headphones are they?

An example would be philips SHP9500 with topping a30

 

[andreasmaaan]

According to Golden Ears, this is the impedance response of the SHP9500 (black trace):

It does vary quite a bit in the bass (peak of 50 Ohm at around 80Hz). There would probably be an audible effect on the frequency response if driven by an amp with 10 Ohm output impedance vs an amp with 4 Ohm or less.

 

[Keltere]

According to Golden Ears, this is the impedance response of the SHP9500 (black trace):

View attachment 15744

It does vary quite a bit in the bass (peak of 50 Ohm at around 80Hz). There would probably be an audible effect on the frequency response if driven by an amp with 10 Ohm output impedance.

Thanks
For example The HD598 with a 320ohm peak (from 80ohm) the difference will not be audible because is around 1/8 right?

For the shp9500 do you know how many db will be for 20ohm difference?

 

[solderdude]

Hi like the title i want to ask how much a hight output impedance can affect frequency response.

I've read online that for an optimal solution the impedance output must be less than 1/8 of the headphones impedance. Is that true?
What about measurements? There are any, expecially for a 10ohm output with 32ohm headphones?

http://www.mediafire.com/view/82kf0r5kdckdcer/resistance,_impedance_and_other_issues.pdf

How much depends on the impedance of the headphone and output resistance of the amplifier.

The 1/8th or 1/10th rule is nonsense for most headphones but certainly NOT for all. It thus depends on the headphone itself.
I have measurements of some headphones with 0.1 Ohm and 120 Ohm but a Russian website has calculations for a number of output resistances per headphone (RAA)

For the SHP9500 you get 0.35dB more 'bass' around 100Hz.

 

[Keltere]

http://www.mediafire.com/view/82kf0r5kdckdcer/resistance,_impedance_and_other_issues.pdf

How much depends on the impedance of the headphone and output resistance of the amplifier.

The 1/8th or 1/10th rule is nonsense for most headphones but certainly NOT for all. It thus depends on the headphone itself.
I have measurements of some headphones with 0.1 Ohm and 120 Ohm but a Russian website has calculations for a number of output resistances per headphone (RAA)

For the SHP9500 you get 0.35dB more 'bass' around 100Hz.

Thanks this is really helpful.

So for the SHP9500 is a good thing then.

 

[solderdude]

Not so bad for the SHP9500 as they are on the lean side anyway.
For some IEM's (the multi-armature ones) the 10 Ohm could be bad news, for other headphones the 10 Ohm could be good news or irrelevant.