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Author Topic: (Harmonic distortion discussion) SPLIT from original Beyer DT880-2003 thread  (Read 3988 times)

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stv014

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(Harmonic distortion discussion) SPLIT from original Beyer DT880-2003 thread
« on: September 16, 2013, 02:31:02 PM »
Quote from: Solderdude on September 16, 2013, 02:07:32 PM
Tyll's plots of the newer DT880 indicate around 0.2% at 1kHz which will consist of D2 mainly and makes the measured 0.3% plausible.

If you refer to the InnerFidelity PDF files, note that they include THD+N graphs, not THD, and at 90 dB SPL the result is often dominated by noise. That is why you can so often see lower THD+N at 100 dB than at 90 dB. On the other hand, HeadRoom shows actual FFT plots generated from the same data as the InnerFidelity PDF files, and the test signal is a 500 Hz tone at (I think) 90 dB SPL. On those graphs, D2 is typically at about -70 dB, which agrees with my 0.05% figure. For comparison, here is also a graph of my DT880 Pro at 500 Hz (recorded with an ECM8000 microphone):

This shows a D2 at -68 dB at -10 dBV (about 90 dB SPL), so it is fairly similar to the HeadRoom graphs.
« Last Edit: September 18, 2013, 07:35:15 PM by purrin »
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stv014

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Re: Re: Beyer DT880-2003
« Reply #1 on: September 16, 2013, 02:37:13 PM »
Quote from: purrin on September 16, 2013, 02:25:38 PM
You sure about that? 0.05% is very very low and more typical of non-chip amps.

I do not think it is unrealistic at midrange frequencies and not too high SPL. I have just shown it above, although the accuracy of my not particularly high end test gear might be in doubt. However, the HeadRoom graph shows very similar low order harmonics.
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Marvey

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Re: Re: Beyer DT880-2003
« Reply #2 on: September 16, 2013, 02:45:27 PM »
Isn't that -58db instead of -68 for D2?
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stv014

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Re: Re: Beyer DT880-2003
« Reply #3 on: September 16, 2013, 02:52:12 PM »
Quote from: purrin on September 16, 2013, 02:45:27 PM
Isn't that -58db instead of -68 for D2?

It is -58 dB for the 0 dBV (loud) test tone, which is red and orange on the graph. For the -10 dBV signal (blue), D2 only reaches about -68 dB, and D3 is at -78 dB; this admittedly might not be easy to see, I should have created two separate graphs to avoid the confusion. These levels were chosen to roughly correspond to 90 and 100 dB SPL, based on the InnerFidelity measurement of -10.49 dBV voltage required for 90 dB SPL.
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Boda

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Re: Re: Beyer DT880-2003
« Reply #4 on: September 16, 2013, 02:54:41 PM »
The InnerFidelity graph for the 880-32 shows THD+noise at about 0.3% at 1kHz. The Headroom FFT plot at 500Hz doesn't look like the above one.
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Marvey

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Re: Re: Beyer DT880-2003
« Reply #5 on: September 16, 2013, 02:58:46 PM »
Quote from: stv014 on September 16, 2013, 02:52:12 PM
It is -58 dB for the 0 dBV (loud) test tone, which is red and orange on the graph. For the -10 dBV signal (blue), D2 only reaches about -68 dB, and D3 is at -78 dB; this admittedly might not be easy to see, I should have created two separate graphs to avoid the confusion. These levels were chosen to roughly correspond to 90 and 100 dB SPL, based on the InnerFidelity measurement of -10.49 dBV voltage required for 90 dB SPL.


Ah got it. The red sort of blended in with the purple. Eyes getting bad.
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Solderdude

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Re: Re: Beyer DT880-2003
« Reply #6 on: September 16, 2013, 02:59:09 PM »
Tyll's plots show -53dB at 500Hz
Purrin's plots show -53dB at 500Hz IF they were referenced to 0dB in the plots they too would show -68dB
STV's plots show -68dB at 500Hz

Science is fun but measuring headphones isn't as easy as measuring electronics.
It all stands or falls with references and accuracy of the gear.
10dB is a LOT though.  :D
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Use your ears to enjoy music, not as an analyser.

Marvey

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Re: Re: Beyer DT880-2003
« Reply #7 on: September 16, 2013, 03:01:46 PM »
Different headphones though. The 880-2003 may have some very different characteristics.
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stv014

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Re: Re: Beyer DT880-2003
« Reply #8 on: September 16, 2013, 03:07:23 PM »
Quote from: Boda on September 16, 2013, 02:54:41 PM
The InnerFidelity graph for the 880-32 shows THD+noise at about 0.3% at 1kHz. The Headroom FFT plot at 500Hz doesn't look like the above one.

As noted above, the InnerFidelity graphs include noise, which makes them unreliable for low distortion levels at low SPL. At HeadRoom, the 32 Ω graph shows similar D3 as mine (note that only the blue traces are relevant here, the orange/red ones are at higher SPL, and obviously show more distortion), and better D2; that can be down to sample variation, or better microphone quality. At very low distortion levels, the ECM8000 does become a bottleneck.
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stv014

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Re: Re: Beyer DT880-2003
« Reply #9 on: September 16, 2013, 03:10:01 PM »
Quote from: purrin on September 16, 2013, 03:01:46 PM
Different headphones though. The 880-2003 may have some very different characteristics.

That is true, I noted that possibility already in the first post. One might also wonder if the fact that I have the "pro" version makes a difference, although it is allegedly identical other than having a more clamping headband, which could affect bass performance.
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