A Comparison of Beyerdynamic DT 880 32 ohm, DT 880 250 ohm, and DT 880 600 ohm Headphones

Back before the Sennheiser HD 800 broke the $1000 high-end headphone barrier and started a flurry of ground-breaking new reference cans, there were three staples for enthusiast searching for great sound: the Sennheiser HD 650 ($649.95 MSRP); the AKG K701 (now reincarnated as the Quincy Jones Q701; $399 MSRP); and the Beyerdynamic DT 880 ($313.95 MSRP). All three, in my mind, remain good value when properly chosen for your listening tastes. (HD 650 – warm and smooth, though somewhat lacking in detail; AKG K701 – articulate, but slightly hard; DT 880 – detailed with depth and air, but somewhat lacking weight through the mids.)

A rather cool and unusual feature of the Beyer DT 880 is that it is available in three different impedance values in order to give you better options in suiting them to your needs. I thought it would be fun to have a look at the three different versions, and evaluate their suitability to home, portable, and general use.

Read on for the techno-geekly details, but go ahead and skip to the summary if you just want the recommendations….

The Import of Headphone Impedance and Damping
In order to understand why you would choose one of these various impedance DT 880s over the others, you’ll have to know a little about “damping,” and how it works.

Imagine a pendulum made of a steel rod pivoting freely at the top and with a canon-ball welded to the bottom. Push the rod, and it will swing back and forth for a while, slowly loosing energy to the minimal friction of the pivot and the air-resistance, resulting in ever-smaller swings until it comes to rest. The frequency of its swing is the systems resonant frequency; and the ongoing oscillations characterize this as an undamped system.

Now attach a pushrod and a small electric motor to the pendulum, and drive it at the resonant frequency. Because that’s the natural speed of the swing, it will move easily. But try to drive it faster or slower, and the pendulum will want to swing at its own rate and it will “fight back” against the motor. If the motor is weak, the resulting swings will neither be what the motor wants to do, nor the natural resonant swinging of the pendulum, but rather, will be a complex result of the interaction of the two. This system is poorly damped.

Now imagine a huge motor attached to the pendulum. In this case the motor is so big that it hardly feels the pendulum’s moment at all. The motor will be able to do what ever it wants regardless of whether it’s near the resonant frequency or not. The large available horsepower of the motor “damps” the pendulum’s natural moments.

Rather than talk about swinging the pendulum at various frequencies, let’s talk about two special case signals: impulse response and square wave response. Impulse response is like taking the pendulum at rest, and then moving it hard in one direction and back to the rest position as fast as possible. Square wave response is like holding the swing half way up one side, and then moving it as fast as possible to half way up the other side, and then stopping and holding it there, and then going back to the first side as fast as possible. The thing both signals have in common is very rapid movement to a fixed position. Good damping is that which allows those rapid transitions to happen as quickly and as accurately as possible.

The above graph shows various system responses to a step function (essentially one transition of a square wave). An under-damped system (red) will permit oscillations to continue for some time. An over-damped system (orange) will be slow to respond. A critically damped system will get where it needs to go quickly without the ringing oscillations. The problem is that a critically damped system needs to be implemented with a servo circuit with lots of special feedback (proportional/integral/derivitive controls)directly from the driven device. In a simple system where there is no direct feedback, some overshoot is required to get the system to respond quickly. Therefore, with headphones, it is normal and desirable to have a quickly damped ring (blue) at the leading edges of the signal.

A headphone driver is somewhat like this pendulum: Use an electric current to push it away from rest, it fights back. The nature of this struggle is partly evident in the impedance and phase responses of the headphone. Let’s look at a few headphones:

The graph above shows the impedance and phase response of the Beyerdynamic DT 880 and Sennheiser HD 595; both are considered relatively low impedance headphones at 32 ohms and 50 ohms respectively. Here you can see both have bumps in the impedance curves at around 100Hz, and that the DT 880 (dark green) is at about 38 ohms at it’s maximum, while the HD 595 (dark blue) has a significantly higher maxima at about 220 ohms. These bumps in impedance indicate the primary driver resonance. This is analogous to the pendulum’s natural swinging frequency, and is the point at which the headphone is hardest to control. The larger phase swings of the HD 595 (light blue) are indicative of the difficulty the amp will have driving the headphones, and shows significant amounts of opportunity for interaction between the two. The phase swings of the Beyerdynamic DT 880 (light green) are much less severe, making this an easier headphone to drive.

Going back to our original analogy, we will need a motor with more horsepower to drive the HD 595 as accurately as the DT 880. The motor, in this case, is the headphone amplifier; and its horsepower is the output characteristics needed for the amp to achieve a given listening volume without “feeling” the momentum of the headphone driver in the electro-motive forces represented by the larger phase angles of the HD 595. This is largely the headphone amplifier's output impedance (assuming it has the modest power and voltage needed to drive headphones)

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COMMENTS
LFF's picture

Nice review once again and very informative to boot!

Leaffan's picture

Brilliant article Tyll. I wonder what differences in sound quality you would find using an OTL amp? I guess the 600 ohms would be the most ideal.

sgrossklass's picture

While the effort of coming up with a layman-compatible explanation of damping and how it relates to headphones is certainly commendable, I'm afraid the result doesn't do a particularly good job.

My quibbles:

1. Why refer to the impedance's *phase* response of all things? The phase is one of the most elusive and least intuitive quantities in this context.

Why not stick to magnitude? Unless someone comes up with a very convincing argument, I'm going to assume that headphones are bog standard minimum-phase LTI systems (linear for low volumes at least), as most anything in the analog world is by default. This means that magnitude and phase response are very closely linked, in fact the Hilbert transform allows converting one to the other.

Once we have decided that impedance *magnitude* is the interesting part, the whole affair becomes a bog standard complex voltage divider. (Heck, you can treat it as a resistive voltage divider where one resistance varies with frequency as headphone |Z| likes to do.)
Jan Meier wrote about that aeons ago (really, it's been there at least as long as I've been into cans, which would be since 2004/2005 or so):
http://www.meier-audio.homepage.t-online.de/tipstricks.htm

It shouldn't be too hard to come up with some illustrations for this. I'd be thinking of some bars with two sections of lengths "|Z_f| / R_out + |Z_f|" and "R_out / R_out + |Z_f|", for two different values of |Z_f|.

Complex voltage dividers may be obscure to average Joe, but they /are/ well-known to one group of people at least, those into electrical engineering, and they are well-documented even on the web. I'd rather build upon this than come up with something that's very different from what the rest of the world does. (Same reason why Rockbox makes many MP3 players' stock firmware look like a sick joke - lots and lots more invested man-hours that can be reused.)

2. Why be hung up on electrical damping factor? It is a derived quantity that has its uses for eyeballing things, but that's about it. Otherwise it's a pretty meaningless number. (More on that later.) Even if you define it as min{|Z_f|}/R_out, it /still/ doesn't capture the magnitude of |Z_f| variation.

When the Sennheiser dev guys were posing a quiz over @ German HiFi-Forum when they wanted to "get rid of" some promo cans, one of the questions went something like, "Why should mechanical damping dominate electrical damping in headphones?"

The answer is obvious: You don't want total (system) damping factor to be severely compromised when electrical damping is lousy (high output impedance)! This could have very phunni effects on frequency response at the very least, beyond those afforded by impedance variation. Thus we *don't* have a simple resonator setup with only electrical damping, and the corresponding model doesn't apply... which in turn blows the whole explanation out of the water, sorry.

Speaking of frequency response: Never forget that step response is merely impulse response integrated, and that in turn has its frequency-domain counterpart in frequency response. In other words, if you see some effect in step response, it will always, ALWAYS have a counterpart in frequency response. It may be more obvious or less obvious, but it'll be there. Works for the headphone seal check with low-frequency square wave, works for everything else.

Therefore, if you see more pronounced ringing in the step response for the 32-ohm DT880, I'll be damned if there isn't some more pronounced high-frequency peak in frequency response to go along with it. In fact, a quick check over @ Headroom reveals like 2 dB more low mids and 3 dB more highs (esp. the 5k..10k region), with less highs beyond 10 kHz.

Yes, I'm a frequency domain guy. While time domain considerations still have their place, looking at things in frequency domain is more intuitive more often than not. Even the human ear is a frequency domain device, if with somewhat wacky frequency scaling (most closely resembling a mel scale, i.e. about linear to ~500 Hz and logarithmic beyond). (The only exception I can think of offhand would be troubleshooting reflections on RF cables. Determining trouble spots by looking at periodic ripple in frequency domain is perfectly feasible, but seeing kinks in the signal in time domain certainly is more intuitive.)

Finally, concerning the actual review,

3. What is an "iTouch" and why are you certain that it has an oddball 32 ohm output impedance?

I assume it's supposed to be an iPod Touch. Which generation (if in doubt, look up the "how do I identify my device" page of its fruity manufacturer)? I'd be surprised if any of them had an output impedance beyond 10 ohms. Only us volume-capped Eurotypes are commonly treated to larger values (e.g. 43 ohms on Sony NWZ-A82x), but never on Apple players AFAIK.

The most simple way of approximately determining some digital audio device's output impedance applies the aforementioned complex voltage divider theory by making use of
a) a RMAA (Rightmark Audio Analyzer) test file, usually for 44.1 kHz,
b) a 3.5 mm (1/8") stereo Y cable,
c) some known-critical multi-driver IEM with known min/max impedance, like triple.fi 10 Pros (ranging from about 7 to 65 ohms, ideally wants <1 ohms R_out) and
d) a reasonably high-quality soundcard line-in that accepts the sample rate in a).

Since you can tap off the signal in between output series resistor and load, you can determine frequency response at this point, one of the standard RMAA measurements. There will be some deviation from a nominally flat response in loaded state, corresponding to impedance variation. Then all you need to do is determine the peak-peak magnitude of this deviation and feed the inverse output impedance calculation table...
http://stephan.win31.de/out-imp-calc.ods
... et voilà.

A few examples:
(triple.fi)
http://www.markuskraus.com/RMAA/rmaa%20complete%20-%20html.html
(SE530)
http://rmaa.elektrokrishna.com/index.php?dir=Comparisons/&file=32%20Ohm%...
http://rmaa.elektrokrishna.com/index.php?dir=Comparisons/&file=32%20Ohm%...

With all this in mind (and considering the rather low impedance variation observed in the DT880 32 ohm), I'd claim that the reason for the "more confused" sound on the Touch has to lie elsewhere. It might be nonlinear distortion, it might be insufficient processing headroom to accomodate for lossy audio format related overshoots or intersample-overs (in which case the result with and without an external amp would be the same), it might be reduced channel separation. And of course, placebo effect never sleeps...

Jumping to premature conclusions when evaluating experiments has happened to the best, so don't let that cause you too much grief. ;) Shit happens. *shrug*

Whatever... G'night everyone...

Tyll Hertsens's picture
"1. Why refer to the impedance's *phase* response of all things? The phase is one of the most elusive and least intuitive quantities in this context."

Exactly, because it is elusive, and I thought people would like to know why the impedance curve has a bump in it. Sure you could look at it from the resistor divider point of view, but that misses the point of why the impedance changes.

"2. Why be hung up on electrical damping factor? It is a derived quantity that has its uses for eyeballing things, but that's about it."

Being able to eyeball things is about all most people need. Getting the gist of the issue across to folks is all I was looking to do.

"I'd be surprised if any of them had an output impedance beyond 10 ohms. "

Hm. I have to admit that I just rummaged around teh interweb and found the spec in a couple of places. It may certainly be wrong; I'll have to measure it myself I suppose to be sure. The principle is the same regardless.

"I'd claim that the reason for the "more confused" sound on the Touch has to lie elsewhere. It might be nonlinear distortion, it might be insufficient processing headroom to accomodate for lossy audio format related overshoots or intersample-overs (in which case the result with and without an external amp would be the same), it might be reduced channel separation. "

Could be. I wasn't using lossy files though.

"And of course, placebo effect never sleeps..."

I'd say hearing the differences between the two higher impedance cans more likely a placebo effect thing. The 32ohm can was pretty obviously worse sounding.

";) Shit happens. *shrug*"

Indeed. No worries.

dalethorn's picture

This was interesting. One technical site had the iPod Touch's output impedance as 0.9 ohms, another at 32 ohms. The Apple site seems to imply 32 ohms, but I believe it's referring to the impedance of the included earbuds. Another tech site said that the iPod Touch 3rd gen. has an output impedance of 4.1 ohms. It may be premature to say this, but I would guess the actual output impedance of the latest iPod Touch is probably a respectably small fraction of the 32 ohm earbuds, not that that would make much difference with those earphones. 32 ohm headphones are pretty common though, so my money would be on the 4 ohm or less values. This article was very informative, and while the long technical response (rebuttal?) was difficult to follow, I found it somewhat useful just for pointing up names of things that can be researched later.

I assume the 3 headsets were manufactured at more or less the same time to the same era specs. I know those things change, and QC specs can change as well, so good to know that we don't have to consider differences other than impedance. So I wonder exactly how they make the different impedances - voice coil windings or something? And could it affect other parameters like frequency response, ignoring damping factor?

Tyll Hertsens's picture
... I'm just gonna have to measure the output impedance myself and find out.

Unfortunately, I have a lot of measuring to do, and I can't put it above the priority of writing my scripts for amplifier measurements. I want to start doing amp review relatively soon and it's important to begin measuring them as well. Then I will write the scrips for measuring portable media players. When I do, the iTouch will be the first on the block.

All the principles above remain valid, however. Though the damping factor may be better than stated above, it remains less than the case with the other two headphones, and the 32 ohm DT 800 sounded clearly more confused than the other two to me.

@Dale - the peaks and valleys at the higher frequencies are the resonant modes of the ear canal and the enclosed space of the headphones. Your brain is acclimated to the peaks and valleys from ear canal resonances so you don't hear them. The resonances from the chamber size would be perceptible.

jerseyd's picture

It's like you wrote this just for me! Thanks! Just recently bought a pair of DT880 600ohm. The store I went to (DXC in Carson City, CA) only had the 250 ohm version to audition, but I preferred them the other contenders (HD600 & AKG701). Bought the 600 ohm and had them shipped home, hoping they would sound mostly the same, with some refinement in the upper end. Glad that is the conclusion you made. They are sounding great teamed with the Bellari HA540 amp.

DavidSolo's picture

Excellent review!

I've owned all three versions myself but I found that the 600 ohms, when driven well are the best choice. In many ways I think they're the best headphone for under $500 in terms of sonic performance. They sound great with all the genres I throw at it (classical, jazz, rock)

-David

HeadphonesCom's picture

Hi all,

Truly awesome review!!

We at headphones.com also really enjoy the Beyerdynamic DT880! It happens to be one of our most popular sellers. We find that it suits a variety of tastes. When paired with a good headphone amp such as the Beyerdynamic A1 Headphone Amp, it becomes apparent that the 600 ohm version of this headphone presents some obvious benefits in clarity. Some of our customers enjoy the 250 ohm version most for the fact that it is not as dependent on a headphone amplifier. It’s worth mentioning how darn comfy these headphones are!!! What we do notice specifically about the DT880 is that the soundstage on these puppies is amongst the best at its price point. I find the sound envelops the head in a way that compliments both popular music genres (such as rock, pop, electronic, reggae& rap)as well as classical and jazz. The imaging and soundstage abilities of this headphone are wide and defined without sounding exaggerated with genres that prefer intimacy. This aspect, for me is one of the most distinctive qualities of this wonderful headphone!

jjneely's picture

I too own the DT880 600-ohm phones. This was a fantastically enlightening article about all the different versions and how damping works.

I'm looking for a tube headphone amp to match them. Looks like tube amps seem to have higher output impedance. Perhaps that's why higher impedance phones seem to work best with tube amps? Does the same damping factor rule apply here as well?

Tyll Hertsens's picture
With the higher output impedance amps, you want the highest impedance headphone you can. (As long as there's enough drive voltage, which shouldn't be a problem.)
fortunesolace's picture

Hi, Tyll!

After reading the review, I was wondering if you can advise me about the headphone amplifier I'm buying that have the NJM 4580D as the amp chip.

Which Beyer DT880 on what ohm will be suitable for the amp? I cannot understand the specs of the chip to calculate the output impedance of the amp.

The specs for NJM4580D that I have managed to research:

Operating Voltage (+-2V/+-18V)
Low Input Noise Voltage (0.8u Vrms typ.)
Wide Gain Bandwidth Product (15MHz typ.)
Low Distortion (0.0005% typ.)
Slew Rate (5v/ us typ.)

Thanks!

star's picture

I thought be able to enjoy the top rated dt 880 ,but since am using them to a laptop ,which will require to use the one with 32 ohms ,and now you telling us that I wont get at all the quality of dt 880 with this impedance , in other words ,its no longer considered top ;now' which is the headphone for me ,the dt 860 or 440 ?or from a different manufacture that will do better at 32 impedance ?

star's picture

I thought be able to enjoy the top rated dt 880 ,but since am using them to a laptop ,which will require to use the one with 32 ohms ,and now you telling us that I wont get at all the quality of dt 880 with this impedance , in other words ,its no longer considered top ;now' which is the headphone for me ,the dt 860 or 440 ?or from a different manufacture that will do better at 32 impedance ?

star's picture

Beyerdynamic DT 880 32 ohm
While I found this headphone to be driven to satisfactory levels from portable devices, I felt the sound quality was degraded (likely by the poor damping factor) to the point that the price/performance ratio was poor. Essentially, you are not going to get DT 880-like performance from this pairing. I suggest that if you are looking for a portable headphone, the DT 880 32 ohm is a poor choice from a sound quality perspective. Additionally, you should be looking for a sealed design for portable use so that you will get some isolation from outside noise. I do not recommend this headphone.

Alternatives at or below this price would include: Denon AH-D2000 ($349; fast sounding); Shure SRH840 ($250; warm sounding); Audio Technica ATH-M50 ($199; slightly edgy but good otherwise); and the Skullcandy Roc Nation Aviator ($149; great sound, poor isolation).

what you saying is that the dennon have higher dampening ,and diffrent then the dt 880 ,I will get its full performance ?

how about using the dt 880 along with FiiO E17 "ALPEN?

now ; how does compare the dennon to beyerdynamic at these models ,when boosting amps ?

Matt321's picture

Would you argue for the slightly different sounding highs to be objective, and make a noticeable difference if someone doesn't like the highs of the 32 Ohm but otherwise thinks these headphones are a good deal, or could they be purely subjective or not really noticeable when you get down to it? I'm thinking of driving these on a good amplifier (the ODAC-O2).

Is this represented in the "ringing" of the square wave response? Could this result in a slightly more or less metallic or tinny sound?

 

Do you know of any alternative headphone that is as neutral and natural as these, but less problematic (AKG, Shure, Grado), or that I at least might want to look into if you don't want to make any definite statement?

The first question would suffice.

SlimeyLimey's picture

Is it just me or does Mr Smarty Pants above come across as a little intellectualy arrogant and a tad condoscending??

"Complex voltage dividers may be obscure to average Joe, but they /are/ well-known to one group of people at least, those into electrical engineering" ...." I'd rather build upon this than come up with something that's very different from what the rest of the world does."

Sorry, electrical engineers are not "the rest of the world" so headphone guys can keep measuring things how they like for a consistent and clear VISUAL comparison. 

"Why be hung up on electrical damping factor?...Why should mechanical damping dominate electrical damping in headphones?...Thus we *don't* have a simple resonator setup with only electrical damping, and the corresponding model doesn't apply... which in turn blows the whole explanation out of the water, sorry."

Alright, isn't it abundently clear that these drivers are the same with the exception of the voice coil weight being lighter on the 600ohm version with higher electrical dampening? If the cone design is the same for all three (which should be obvious from the frequency and response graphs AND Beyer themselves) you can get "hung up" on electrical damping. All things being equal except the reduced voice coil mass and higher impedence which are physically linked (can't have lower impedence (more coils) with less mass), a direct comparison between the 3 based on impedence alone is both consistent and logical. The 300hz and impulse response clearly show the damping difference between the 3 versions and the diminishing returns of the higher impedence.

"Therefore, if you see more pronounced ringing in the step response for the 32-ohm DT880, I'll be damned if there isn't some more pronounced high-frequency peak in frequency response to go along with it"..."looking at things in frequency domain is more intuitive more often than not."

How does a wavy frequency response graph with a 2db dip or peak at certain frequencies illustrate damping differences more clearly than an impulse graph? It clearly doesn't, and with the mass differences of the 32/250/320 voice coils I'd argue that would be the last place to look for an accurate representation of damping because the frequency changes are the effect of electrical damping and mass variations while the impulse graphs illustrate the quantity and quality of damping which IS the point.

Typical engineer that is very intelligent and likely techincally correct but can't see the forest for the trees.
 

pinoyb's picture

Thanks for sharing the information. Love your idea on the topic. Looking forward for more interesting posts. buy keek views

Tacoboy's picture

Have anyone ever do this type of comparison with the DT990s?

grajek's picture

Awesome review! They sound great... with all the genres I throw at it (classical, jazz, rock)

loveislikethesun's picture

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