Headphone Measurements Using Brüel & Kjær 5128 HATS

[BYRTT]

@amirm for grins can we have one ear cup of HD650 Klippel analyzed to see the front and open back relations.

 

[JohnYang1997]

The compensation is work in progress. The focus should be on the measurements.

Alright.

 

[amirm]

Here is the Stax SR-007 with SRM-313 solid state amp:

(this was the last position in the previous measurement).

The hump is still there.

 

[RayDunzl]

I'm surprised by the variation in the bass response with the different positionings.

Not thought about it before, maybe.

I have to try really hard to mis-position my HD650 on my real head.

 

[Blumlein 88]

Maybe I'm too pessimistic, but these multi-measures make me think you can't get there from here. No measurement can be tellingly precise and only very broad response tendencies can be found with this device. Or any device for that matter on headphones.

Now imagine if your dummy head were shaped just a little different (like every person's is compared to this one). How much more variable are the measured results then?

If this $41k device isn't delivering repeatability and it isn't delivering precision you can depend upon, then what is it buying you?

Seems solderdude's simplified measuring rig can do as much for comparative broad response outlines between phones. Combined with a trained listener giving his evaluation vs some reference phone or phones I don't see this device giving you anything you can't get otherwise. Maybe credibility with the public who doesn't know the vagaries of headphone measuring. Is that enough?

It looks like your measurement of a phone now vs. 2 minutes from now has as much variation with some of these phones as using two completely different measuring rigs with the various compensations done.

 

[amirm]

@amirm for grins can we have one ear cup of HD650 Klippel analyzed to see the front and open back relations.

I don't have a way to mount it on the Klippel.

 

[amirm]

I'm surprised by the variation in the bass response with the different positionings.

It is the leakage effect of the cups. Every cup is different and getting a tight fit is not possible with many of them.

 

[JohnYang1997]

Maybe I'm too pessimistic, but these multi-measures make me think you can't get there from here. No measurement can be tellingly precise and only very broad response tendencies can be found with this device. Or any device for that matter on headphones.

Now imagine if your dummy head were shaped just a little different (like every person's is compared to this one). How much more variable are the measured results then?

If this $41k device isn't delivering repeatability and it isn't delivering precision you can depend upon, then what is it buying you?

Seems solderdude's simplified measuring rig can do as much for comparative broad response outlines between phones. Combined with a trained listener giving his evaluation vs some reference phone or phones I don't see this device giving you anything you can't get otherwise. Maybe credibility with the public who doesn't know the vagaries of headphone measuring. Is that enough?

It looks like your measurement of a phone now vs. 2 minutes from now has as much variation with some of these phones as using two completely different measuring rigs with the various compensations done.

Have to choose between repeatability and accuracy. You can recover from lacking repeatability by measuring multiple times. If you lack accuracy, you can only imagine what it could be like. Although I also don't think accuracy is that much greater. At least not better than the lower priced test fixtures.
This comes back to the saying: Measurement is an art.

 

[amirm]

I have to try really hard to mis-position my HD650 on my real head.

The 650 fits really well and consistently as the measurements showed. It is the other headphones that are showing larger variations. Perhaps this should be a demerit than running with some kind of average.

 

[amirm]

The head is sitting on top of the noisy APx555 but I thought I share some THD measurements.

Sony MDR-7506:

Lots of low frequency distortion together a bunch in mid-range.

Stax SR-007

Seems to have an issue around 2 to 4 kHz:

AKG N700NC

Sennheiser HD-650:

Wow, the HD-650 is quite clean! The Sony seems the worst.

 

[AudioJester]

Amir, have you tried any iem's?

 

[test1223]

Hello,

now headphone, yes

@amirm another important point which is overseen a lot is the difference due to temperature changes. Ear pad properties change if you consider room temperature or near body temperature.

Since the fit is essential a different formed head and ear will alter the results a lot.

As you already mentioned the age of the pads will also change a lot.

There are differences in the way different dummy heads transfer and measure vibration. Since the vibration transmission in the bass is essential the whole mounting trouble has another component to consider.

Best
Thomas

 

[RayDunzl]

Wow, the HD-650 is quite clean!

When I went headphone shopping I bought the HD650 because they looked like the "safe" choice (just from reading reviews and calculating a consensus).

I'm not disappointed with them.

I think they sound (frequency response) like my speakers. Interchangeable.

The Sony seems the worst.

I had a pair of Sony from 1992.

They sat on the shelf because I thought they were awful.

When I pulled them off the shelf a couple of years ago they had deteriorated to the point of uselessness just sitting there.

---

A hilarious review which matches my own impression:

Sony MDR CD-750 Digital Reference Headphones

Palmer (USA)
7 years ago
Purchase year : 1991 Price paid : 100 USD (used)
I am 44 years old, and have been a professional, working musician since I was in my mid-teens. I purchased these headphones after getting a recommendation from a fellow musician (whose taste obviously varies from my own). These are the worst sounding headphones I have ever used, for any purpose, from a "boombox" accessory to studio sessions. They are bulky, uncomfortable, and have little to no highs OR lows. They get mid-range ONLY, and even that is "tinny." I recently gave the exact headphones to another lifelong, professional musician friend of mine (he's 55) to see if he wanted them, and he was not impressed either. We then passed them around the room, and after allowing a band AND sound engineers try them out, in search of someone who might want them, these phones went into the trash, which is where they belonged from the beginning.
S. Palmer
Nashville TN

 

[amirm]

Looks like we can get some insights from IMD tests:

Seems like acquisition mic is doing a fine job of being transparent relative to IMD tests. Even noise is inconsequential.

AKG's high IMD confirms the distortion tests. And in reverse the HD650.

The surprise is the Ether CX which has the least distortion.

The combination of Audio Precision closed loop measurements and the HATS is producing unique measurements like this.

 

[RayDunzl]

Looks like we can get some insights from IMD tests:

At what level of, uh, let's call it "percieved SPL" are these tests run?

The charts show 0dB as the centerline.

If I missed it, sorry.

 

[solderdude]

Sennheiser HD-650:
View attachment 78394

Wow, the HD-650 is quite clean!

I am getting about 2% at 50Hz as well and about 0.1%
Mine is slightly higher (0.15%) as that is my limit for my $3.- mic, noisy DIY mic pre-amp. (at 90dB SPL)
The LCD measures 0.2% at 50Hz and is, I presume, determined by the rig and the LCD-2 may well be lower.
That headphone would be a good test to see how low you can go. Would need a really quite place to measure such an open headphone.

 

[ClosDeLaRoche]

Hey good to see the Ether CX scoring some points! I've heard tons of headphones, bought and sold more pairs than I care to mention, and my "end game" or "life-long keepers" are the Sennheiser HD6XX, Ether CX with ZMF Universe Lambskin pads & two-notch white filters, and the Etymotic ER4SR (also the ER3SE which I use for running).

 

[solderdude]

Here is Hifiman HE-400i. I am not annotating these graphs in the interest of time:



Compensated:

View attachment 78332

What do we think? Is that peaking between 6 and 10 kHz real?

Yes, I think it is real.

I know... $3.- mic and incorrect measurements come from flatplates but am pleased to see that cheap DIY contraption isn't far off from $ 41k official HATS.
Do note that my bass correction is not as 'extreme' as the average preference determined by Harman.

Of course, due to a lack of pinna 1kHz - 5kHz can be 'off' a little.

 

[Mad_Economist]

Here is the Stax SR-007 with SRM-313 solid state amp:

View attachment 78390

(this was the last position in the previous measurement).

The hump is still there.

The response hump is a phenomenon of planar (whether electrostatic or magnetic) drivers with open rear volumes and sealed front volumes - with an ideal coupling to the ear, the response is essentially linear, but when that coupling is lost, you see a rise around the resonance of the driver, followed by a drop below.

The distortion measurement of the SR007 is somewhat surprising - typically the Omegas have extremely low distortion.

 

[ClosDeLaRoche]

"pleased to see that cheap DIY contraption isn't far off from $ 41k official HATS."

So what's the point of the HATS? Let's see how close something like a miniDSP Ears gets to it. If it's really close maybe Amir should save a boat-load of money and get that.