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DT880 600ohm BS  

post #1 of 352
Thread Starter 

Hi everybody,

 

I see that everyone is on a DT880 (600ohm) kick these days, and head-fier's feel that it's important to put the emphasis on the "600ohm" just so everybody knows that you clearly have the best DT880.

 

My question is: does anybody have any objective (that's right I said objective) proof that the DT880 600ohm is any different than the other impedance options in terms of sound quality.  I have redone this first post, with a summary of the first 7 pages of responses that have been submitted by faithful members of the head-fi sound science forum.  You will find evidence in both support and rejection of my hypothesis, using evidence obtained from various sources (what constitutes "evidence" is in the eye of the beholder).

 

Hypothesis #1 – Beyerdynamic DT880 250ohm and 600ohm are audibly identical when connected to a source/amp with a Zout of zero.

 

Evidence

 

The Beyerdynamic DT880 600ohm has identical housing, identical drivers / diaphragm (voice coil has thinner wire / more windings), and identical model # to the DT880 250ohm / 32ohm. It would be unreasonable to expect massive differences (as many head-fiers suggest) when comparing different impedance options of a single model #.  Furthremore there is no evidence to suggest that the drivers (including voicecoil) in the various Beyerdynamic headphones of different impedances are of different mass.  This isn’t a K701 / DT880 / HD650 comparison where you would expect to hear or measure real differences.

 

There is no evidence to show higher impedance loads are consistent with better / specific sound qualities.  Headphones ranging from 25ohm (Denons), to 32ohm (Grado), to 70ohm (Sony) to 300ohm (Sennheiser) exhibit excellent transient response, decay, impulse response etc and there is no positive or negative correlation between impedance, mass (perhaps largely because mass is always undetermined) and impulse response.  There is evidence however, that lower impedance headphones draw more current which has a very negligible negative impact on measures such as THD, SNR, and crosstalk.

 

http://rmaa.elektrokrishna.com/Comparisons/Comparison%20-%20Cowon%20D2%20-%2012%20-%2048%20Ohm.htm

 

 

The following measurements demonstrate that lighter diaphragms are not necessarily “faster” (as measured by impulse response graphs / spectral decay graphs).  I’ve contrasted the Stax 4040 (considered a “light” electrostatic diaphragm), and the Denon AH-D5000 (considered a “heavy” dynamic diaphragm).  These graphs illustrate that such oversimplifications are faulty.  Shike has posted further comparisons between electrostatic "light" transducers, and dynamic "heavy" transducers on page 6 to further challenge this simple generalization.

 

First, the Stax 4040: 

SRS-4040-imp.gif

SRS-4040-Accumulate.gif

 

Denon AH-D5000

 

AH-D5000-imp.gif

AH-D5000-Accumulate.gif

 

 

Headroom graphs show that DT990 and DT880 show no noticeable difference in any objective measurement (other than impedance curves).  Though some posters insisted that the higher inductance of the high impedance voice coils attenuate high frequency SPL, headroom graphs suggest otherwise. 

 

 

First, to illustrate that there are slight variations when measuring identical headphones (experimental variance), I’ve used the MDR-V6 / MDR-7506 and the K701/K702 charts to act as controls.

 

75061.png

7011.png

 

 

UPDATE EDIT:

 

Here are the most recent measurements performed by Headroom and Donald North comparing various DT880 impedance options (yellow dotted line is 250ohm, solid green is 600ohm:

 

DT880FQ.png1000x500px-LL-4bb9c542_1000x800px-65da329f_DT880comparison0ohmsource.tif.jpg

 

And finally, here are some other measurements illustrating similar (non-differences) between different impedance options for the DT880

 

DT88050hz.pngDT880500hz.png

 

0728.png2756.png

 

 

As illustrated on page 7, THD measurements between different impedance options yield minimal results, well below the threshold of audibility.  THD differences cannot account for perceived differences in sound quality.

 

No proper blind ABX tests have been performed with more than 1 subject comparing the DT880 250ohm and the DT880 600ohm.  ABX tests that have been performed without proper methodologies have led to conflicting results. Some people have found little to no difference, others have found huge differences resulting in inconclusiveness.   A recent "level matched and sighted" ABX among head-fiers who didn't seem to care which impedence version sounded best found that there was no audible difference between the 250ohm and 600ohm.  Refer to posts by wavoman on page 16 of this thread.

 

Hypothesis #2 – Beyerdynamic DT880 250ohm and 600ohm are audibly different when connected to a source/amp with Zout of zero.

 

Evidence

 

Higher gain settings might introduce more distortion when driving 600ohm version though this is a reflection of the amp and not the headphone and is likely achieved with amplifiers with Zout >0ohm.

 

600ohm DT880 likely has flatter response when plugged into a high impedance output (>250ohms for example).  The difference is likely to be subtle (+/- 1dB)

 

600ohm Drivers are smaller (nikongod) – any evidence to confirm this? EDIT (This has been confired NOT to be true, by concurent observations - see page 16)

 

600ohm Drivers are lighter when held in hands (leeperry) – any evidence to confirm this?


Edited by Catharsis - 11/1/10 at 4:42am
post #2 of 352
Thread Starter 

Sorry if I sounded firm on that last post - I'm just a science nazi and that's the way it is.

post #3 of 352

Last year I received on loan from beyerdynamic both the 250 ohm and 600 ohm versions of the DT880. I listened to both and measured them. They do sound different and measure differently (I'm trying to find the curves). I personally preferred the sound of the 250 ohm version (more midrange presence and treble sparkle) and bought the demo set.

post #4 of 352

Yes, here it is, though it is so little I don't believe anyone could hear it! Here is my objective data:

Beyerdynamic Impedance Comparison

 

I you look at the 32 and 600 ohm DT770 though, you will see that there is a huge difference!

post #5 of 352
Thread Starter 

True enough - I've done lots of comparisons at head-fi, though I wouldn't discount testing variations.  It's been proven that if you test the exact same headphone over and over, you'll still come across some frequency variation. 

 

Take a look at the MDR-V6, MDR-7506, and the K701 / K702 for examples of what I'm suggesting.  The 32ohm DT770 could just be way off (fluke measurement), it's hard to say.

 

If you produce a headroom FQ response graph with the 32ohm DT880 and the 250ohm DT880 you'll notice very little difference.  I would suspect the same would happen if you increase the impedance to 600ohm.  If a 7.8x variation in impedance (250ohm divided by 32ohm) causes such little diff, it's likely that a 2.4x variation (600ohm divided by 250ohm) would cause any difference either.

post #6 of 352

I'd like to know what accounts for the difference between the two DT770 'phones I also graphed... They seem hugely different in the lower bass range.

post #7 of 352
Thread Starter 

I should also mention that the distortion and square wave graphs also come up (near) identical too between the 32ohm and 250ohm DT880.  However headphones have THD below audible threshold generally anway from my understanding.

post #8 of 352
Thread Starter 
Quote:
Originally Posted by stevenswall View Post

I'd like to know what accounts for the difference between the two DT770 'phones I also graphed... They seem hugely different in the lower bass range.


Agreed.  Hey headroom - can we have a redo!

 

post #9 of 352

It would not be too difficult for someone to set up a test of these headphones. 

 

Buy one of each DT880 (32, 250, 600ohm) and cover identifying marks. Hook them up to 3 identical amps and volume match with an SPL meter. Control volume with a single pot set up as a passive preamp. Taah-Daah! you can quickly determine if they sound different this way.

 

You could ABx by handing the tester an unknown to him headphone (keeping all 3 hidden behind a curtain) after telling him which he was listening to...

 

Alternately you could get a binaural head, and record a few tracks coming out of each headphone. Pass it along to a few people and see what they think without any knowledge of which sample is which headphone.

 

edited/added:

From the 1 600ohm beyer I have taken apart, the drivers are smaller than the 250 ohm drivers. just got to throw that in there.


Edited by nikongod - 8/12/10 at 3:25pm
post #10 of 352

I'm not sure why this is a big mystery.  Listen to the Ety ER4-S and P.  Both exactly the same except for the resistor.  Clearly audible and measured difference.

post #11 of 352
Thread Starter 

True, but we're dealing with different driver technologies (balanced armature) and I don't know if anyone can confirm if there's a difference using a ER-4S - ER-4P resistance cable with other dynamic headphones.  Does adding a 75ohm cable drastically alter the FQ response of other headphones?  My understanding is that it doesn't. Take a look at the impedance graphs for the ER-4P and the ER-4S on headroom, and you'll clearly see that one attenuates the high frequencies, and the other boosts the high frequencies.  This is atypical for most dynamic headphones I've seen.

 

If I'm not mistaken, a 75ohm cable would effectivlely increase the output impedance of the source / amplifer, which may or may not make much of a difference to headphones that are already of high impedance.  (This can be calculated)


Edited by Catharsis - 8/12/10 at 4:30pm
post #12 of 352
Quote:

Originally Posted by Catharsis View Post


 And don't give me the "it's lighter so it is faster" crap - what rubbish.


F=M*A, so unless they give higher impedance drivers smaller magnets or something to compensate they have to be faster.

 

What's rubbish about that?


Edited by maverickronin - 8/12/10 at 4:50pm
post #13 of 352

F=M/A or F=M*A?  We talking about Newtonian mechanics or something else?

post #14 of 352
Quote:
Originally Posted by Catharsis View Post

True, but we're dealing with different driver technologies (balanced armature) and I don't know if anyone can confirm if there's a difference using a ER-4S - ER-4P resistance cable with other dynamic headphones.  Does adding a 75ohm cable drastically alter the FQ response of other headphones?  My understanding is that it doesn't. Take a look at the impedance graphs for the ER-4P and the ER-4S on headroom, and you'll clearly see that one attenuates the high frequencies, and the other boosts the high frequencies.  This is atypical for most dynamic headphones I've seen.

 

If I'm not mistaken, a 75ohm cable would effectivlely increase the output impedance of the source / amplifer, which may or may not make much of a difference to headphones that are already of high impedance.  (This can be calculated)


If this is so how do we explain the variances between the DT770s?

post #15 of 352
Quote:
Originally Posted by Anaxilus View Post

F=M/A or F=M*A?  We talking about Newtonian mechanics or something else?


Whoops!  Fixed it...

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