Beyer T1

[NightWoundsTime]

I agree Tyll, on the stupid part. I did quite a lot of back and forth with the T1, and then with a pile of 600 Ohm custom Beyers that one of the members brought to the NorCal meet. My impedance cable seemed to help all of them in one way or the other, most stunningly on the pile of crap that is the DT990. On the T1 the bass certainly didn't get flabby, it got a nice solid thump that the cans were missing straight out of the Luxman P1.

Oh and it should be mentioned, as Al first pointed out, that using the patch cable helped frequency response but seemed to hurt the soundstage a bit. There's that certain feel of "air" in the sound that goes away, but the impact makes it up for me.

Edited March 5, 2010 by NightWoundsTime

[tkam]

Tyll, it would be interesting if you could re-run the T1 measurements with a 120-ohm adapter between them and the amp.

[Tyll Hertsens]

That's exactly the kind of thing I'd like to fill my life with for the next 20 years.

Deadly serious.

[nickchen]

Personally I think it's stupid for high-end cans to be designed with a 120 Ohm output in mind.

In the eyes of audiophile geeks like us with our big balls gear it's certainly nonsense. But I think the main part of nowaday's consumers still plugs things into cheap high ohm integrated amps - and there, a higher ohm design makes indeed sense.

[nikongod]

The legend I have heard for the popularization of the 600ohm drivers by AKG & others was that they could be plugged into a 600-ohm output on a studio console. Looking at the output impedance of older consoles with transformers, and newer stuff with protection resistors on the outputs, 120 ohms is a pretty good average guess for output impedance.

I think its well within the MFR's right to still follow this, and it makes perfect sense that they do in light of that. The question is do any reviews of the gear apply when they are not made using the product according to the MFR's best usage guidelines? The MFR has given you the benefit of telling you how they think they run best why not follow that? Would you expect truly agressive summer tires to work in the snow?

The argument that the headphones should work from anything comes up. That clearly ignores professionals who only have 120ish ohm output impedance sources or the average home user with an integrated amp with a high impedance out for the headphones. You wonder how headphones designed for 0 ohm output impedances sound on 120ohm sources. I'l tell you, its crap.

[nickchen]

You wonder how headphones designed for 0 ohm output impedances sound on 120ohm sources. I'l tell you, its crap.

I'm really not the amps- and cable geek, but a typical low ohm AT or Gradessandro in a high ohm plug comes close to unlistenable for me personally. But my DT880'250 sounds lovely there, whereas the DT880'600 just doesn't care much about resistances...

[The Monkey]

So what does this mean for someone listening to the T1 out of, say, a single-ended B22?

[NightWoundsTime]

That person should probably give a 120 ohm cable a brief shot, and see what he/she thinks.

Wayne's T1 just landed on my doorstep, so better impressions coming soon, including T1 VS. DT880.

[nickchen]

So what does this mean for someone listening to the T1 out of, say, a single-ended B22?

I presume the B22 belongs to the zero ohm fraction. If they behave similar to the DT880'600, things will remain unobtrusive. If they have a more significant reaction on resistances, they'll propably sound a bit thinner & colder than intended by Beyer. All a question of taste and listening habits finally.

[NightWoundsTime]

Nick, since some of us have heard the difference on an actual T1 howsabout you stop guesstimating based off another headphone.

[nickchen]

Ok...

[Wmcmanus]

That's exactly the kind of thing I'd like to fill my life with for the next 20 years.

Deadly serious.

Living inside that box in your avatar as you do...

[Wmcmanus]

That person should probably give a 120 ohm cable a brief shot, and see what he/she thinks.

Wayne's T1 just landed on my doorstep, so better impressions coming soon, including T1 VS. DT880.

Hey, that's good news! Just don't blow them up with your mad science experiments!

[skullguise]

Interesting read on all this....wish I had read earlier, as the T1 was at a Boston area meet yesterday. And while I liked it better than the other Beyer's I've heard in the past, it still didn't wow me. I would have liked to try it on the TTVJ Millet 307 there, using the different output options....

[Voltron]

Interesting read on all this....wish I had read earlier, as the T1 was at a Boston area meet yesterday. And while I liked it better than the other Beyer's I've heard in the past, it still didn't wow me. I would have liked to try it on the TTVJ Millet 307 there, using the different output options....

I should have tried that too but the T1 sounded great on the EAR with its high Z output.

[Tyll Hertsens]

Looking at the output impedance of older consoles with transformers, and newer stuff with protection resistors on the outputs, 120 ohms is a pretty good average guess for output impedance.

I think its well within the MFR's right to still follow this, and it makes perfect sense that they do in light of that. The question is do any reviews of the gear apply when they are not made using the product according to the MFR's best usage guidelines? The MFR has given you the benefit of telling you how they think they run best why not follow that? Would you expect truly agressive summer tires to work in the snow?

The problem is we're talking about a headphone that aspires to be in the "World's Best" category. One would think that the typical amp in that intended usage is a very high quality one --- which means it should have a low output impedance.

The argument that the headphones should work from anything comes up. That clearly ignores professionals who only have 120ish ohm output impedance sources or the average home user with an integrated amp with a high impedance out for the headphones. You wonder how headphones designed for 0 ohm output impedances sound on 120ohm sources. I'l tell you, its crap.

That's true. A headphone designed for use on a low output impedance/high damping factor amp could rely on the amp to do the damping. Headphones that are designed for 120 Ohms have to provide their own essentially passive acoustical damping. That means you are going to get various phase artifacts as the acoustic damping poles and zeros fight with the various resonances in order to get best performance without the help of a low output impedance amp.

If the cans were designed with the idea of a low output impedance amp which will provide the damping, headphone designers wouldn't have to play a bunch of acoustic games to damp the driver which essentially introduces reactive impedance schmutz.

But! Here's the worst part, IMHO, no manufacturer I've found EVER represents the specified output impedance in thier specs, so you really don't have any idea what amp impedance the cans are designed for. For example here's the beyer T1 specs:

Technical Specifications

Transducer typeDynamic Operating principlesemi-open ConnectorGold vaporized stereo jack plug 6.35 mm Weight without cable350 g Frequency response5 - 50,000 Hz Nominal impedance acc. to IEC 60268-7600Ω Nominal SPL acc. to IEC 60268-7102 dB Nominal THD acc. to IEC 60268-7< 0.05% Power handling capacity acc. to IEC 60268-7300 mW Sound coupling to the earCircumaural Average pressure on ear acc. to IEC 60268-72.8 N Cable length3 m / double-sided balanced cable (6-core)

They go to great lengths to tell us that they are using the IEC spec, but they don't tell us what impedance is being used.

So, if you want better headphones in the future, we ought to be complaining about manufacturers limiting the performance of their product by designing around 120 Ohms, and encouraging them to go ahead and build 0 Ohm headphones.

[mypasswordis]

Great write-up Tyll. Indeed if the damping factor is less than 1, the drivers are damping the amplifiers.

If the cans were designed with the idea of a low output impedance amp which will provide the damping, headphone designers wouldn't have to play a bunch of acoustic games to damp the driver which essentially introduces reactive impedance schmutz.

Yup, and what you want is the easiest possible to drive load when it comes to headphones. It's part of why orthodynamics are so fantastic. Almost completely linear impedance across the frequency range and is very near a pure resistive load, which means the amplifier should have an easy time with them given enough power. The T1 already has more distortion than normal headphones due to its extremely strong magnets.

Edit:

WAT.

[The Monkey]

Can someone explain this impedance issue to me? I'm not tech savvy enough to glean the nature of the problem from the above discussion.

[nikongod]

The problem is we're talking about a headphone that aspires to be in the "World's Best" category. One would think that the typical amp in that intended usage is a very high quality one --- which means it should have a low output impedance.

The no global feedback OTL tube camp would strongly disagree. Perhaps its the problem of looking at only the people on the headphone boards, but they were considered reference grade for a LONG time. None of these do better than an output impedance of about 60ohms, solder another 60-100 ohms into the cable and you are doing exactly what the MFR expects.

If the cans were designed with the idea of a low output impedance amp which will provide the damping, headphone designers wouldn't have to play a bunch of acoustic games to damp the driver which essentially introduces reactive impedance schmutz.

But electrical damping can not control all driver resonances. The designers are still stuck messing around with acoustical damping and other fun stuff.

At the end of the day, I think its within the rights of the MFR to say that they want their headphone driven by a 120 ohm output impedance. If they can only make something great that way, thats fine. Nobody complains that high performance engines need 94 or better fuel, why should anyone complain that they need specially made amps to drive high performance headphones? The amp does not even need to be specially made, if you have an amp with a low output impedance get an impedance dongle like the Etymotic "P to S" cable but with 120 ohms.

I could not tell if it was sarcasm (I hope not, it sounds fun to me!) but you mentioned wanting to measure stuff like this for the next 20 years. If it wasnt sarcasm, I would be VERY interested to see how beyers measure driven from various source impedances.

Can someone explain this impedance issue to me? I'm not tech savvy enough to glean the nature of the problem from the above discussion.

Some (most) headphones work better 1 way, others another. Nobody can agree on which is right. The majority camp says thats how modern amps are built, the minority camp says thats what the standards dictate.

The problem is that when there are 2 standards the wrong one will inevitably be used. When only a few people really use the one standard the odds of the wrong standard being misused increase greatly. Perhaps by a reviewer. At that point the gear that works great the way it was designed to work dosnt even sound decent.

Although I think they sound GREAT driven from high output impedance amps, beyer inevitably pokes themselves in the butt for clinging to that standard. If you run them wrong they dont sound right at all.

[Dreadhead]

Yeah I have no problem with Beyer deciding to stick to the 120Ohm standard but I think that they need to include an "adapter" for phones that cost as much as T1's do.

Also I think that Beyer is pretty shaped by their home market and as I understand it, in Germany they have lots of 120Ohm amps.

[mypasswordis]

But electrical damping can not control all driver resonances. The designers are still stuck messing around with acoustical damping and other fun stuff

Or the DIYers, as it may be. I redamp pretty much every headphone that comes my way. The point was that you don't want everything to be done on the mechanical side since it has plenty of its own issues to deal with (driver and enclosure resonance, diaphragm thickness, comb filter effects, ringing, etc).

I am doubtful higher output impedance amplifiers will help the sound but I definitely want to hear Beyers with amplifiers with proper IEC output impedance, since you hold them in such high esteem. I am not in the no global feedback OTL camp.

[Tyll Hertsens]

Can someone explain this impedance issue to me? I'm not tech savvy enough to glean the nature of the problem from the above discussion.

Think of the headphone like a spring. Push it and let go and ... BOING ... it resonates.

Not good for sound quality.

There are two ways to approach driving the spring:

1. Put a shock absorber or some other resistive element in the spring to stop it from vibrating when you drive it. This would be like manufacturers building in acoustic damping features.
   
2. Or drive it with an amp so strong that it doen't even feel the 'boing' of the spring; it just drive the spring with authority. This is like the amp with a low output impedance.
   

Now, if MFRs make headphone like in case 1., and you hook up a very low impedance amp, the amp just drives through the acoustic damping and remains authoritative. But it would have done a marginally better job of making good sound if all the acoustic damping got out of the way.

But if MFRs build headphones for low impedance amps that don't have any damping, and then you hooked it up to a 120 Ohm output impedance amp, the spring would be spronging away to beat the band ... literally.

Despite what the hobbysts may think, most people still have never even heard of a headphone amp, and will be plugging into the nearest headphone jack in blissful ignorance of the fact that it's likely an op-amp with a little series resistance for protection. So, for the most part, they just have to build headphones with internal damping.

NOTE: the 120 Ohm spec comes from a simple guess at what a typical headphone jack might be. There's not other technical reason that 120 Ohms is some good or special number useful to headphone performance.

The no global feedback OTL tube camp would strongly disagree. Perhaps its the problem of looking at only the people on the headphone boards, but they were considered reference grade for a LONG time.

The answer here is complex; suffice it to say OTL amps are valued by the particular character (coloration) they create, and there is a lot of interaction between amp and speaker in this case. Not knocking it at all, but they are not technically designed to be neutral power amps. A power amp --- literally by definition --- changes a high impedance line voltage signal into a low impedance power signal. It certainly provides voltage gain (although not much in the case of headphones), but mostly a power amp provides power gain, and that, in large measure, is indicated by a dramatic lowering of line impedance.

Bottom line, all else being equal, you can almost always improve headphone performance by lowering output impedance (increasing damping factor).

[Tyll Hertsens]

but I think that they need to include an "adapter" for phones that cost as much as T1's do.

Since the damping is significantly acoustic or voice coil resistance related, you can't very easily make an undamped headphone with a damping adaptor.

In other words you can put 120 Ohms in series with the amp output if you want, but the only thing it's really doing is making the amp worse.

Also I think that Beyer is pretty shaped by their home market and as I understand it, in Germany they have lots of 120Ohm amps.

I tend to doubt the 'amp market' is big enough to have much effect. It's more about making the headphones sound good on crappy headphone jacks that still make up the majority of applications. Though, I will admit, it's getting bigger and better all the time.

[mypasswordis]

Hey Tyll, could you redo the T1 impedance plot with a bigger scale? That slight dip to under 600 ohms at 3-4kHz is the only thing there currently.

[nikongod]

Since the damping is significantly acoustic or voice coil resistance related, you can't very easily make an undamped headphone with a damping adaptor.

Series resistance is totally fine for lowering damping factors if that is the goal. I dont see the difference between an amp with a 120ohm output impedance by its nature (an OTL amp, or a high impedance transformer) and an amp with a very low output impedance by nature with a big output resistor as far as the headphones are concerned.

In other words you can put 120 Ohms in series with the amp output if you want, but the only thing it's really doing is making the amp worse.

I think that is entirely a matter of perspective and focuses too heavily on the amp without regard to the headphone.

Looking only at the amp and the theoretical goal of very low output impedance & improving electrical damping factor adding an output resistor like this is madness, but by the perspective of what the headphones seem to want it makes the amp better.

I think that gear should be compared at its best, and with such an easy guess at how to get there why shouldnt it?