ASR Headphone Testing and BK 5128 Hats Measurement System

[amirm]

In that case Amir the Struck Approach described by Mad_Economist here could be a way to simulate the Harman Curve for the B&K 5128.....and with greater resolution too, in terms of less smoothing. What do you reckon?

I reckon it is too much work for me. I will post the raw results and you all can do the correction.

 

[amirm]

But this was 30 years ago and I don’t know what improvements were made to the soft pinna. Food for thought! Measuring headsets in a meaningful way is a royal pita!

It is a problem that remains still. The softer pinna on the 5128 and GRAS high-res ones are supposed to help with this. What other places do is try multiple times and average.

 

[DDF]

It is a problem that remains still. The softer pinna on the 5128 and GRAS high-res ones are supposed to help with this. What other places do is try multiple times and average.

I would recommend using the force gauge then. I can’t recall where we sourced it but it was for headphone measurements. So probably B&K and the cost of an entry Tesla

 

[zelig]

What if instead of the rig being made by "Brüel & Kjær" it was made by "Boggs and Schitts"? My guess is that it would work the same but cost 1/10th the price. Does hi-fi consumer snobbery extend to into hi-fi testing?

 

[DDF]

Oh, and iirc, I played a ~250 Hz tone while setting up the headset in the jig, fiddling position until maximizing SPL on a meter, before finalizing force gauge and taking the sweep

 

[solderdude]

I reckon it is too much work for me. I will post the raw results and you all can do the correction.

For 1 or 2 headphones can you also post overlays of raw with DF and FF, and when present other corrections and or available 'room targets' ?
The HD650 should be quite well suited for this given it has a quite predictable response, consistency and linearity without much peaks and dips.

As most folks kind of 'know' the HD650 sound perhaps overlays of 2 headphones with HD650 as the common factor. This way it is easy to see where they differ and can make a mental map of differences between these.

Raw plots say nothing to me as there is no relation as to how these sound unless the correction is plotted along with it.

I use this method when trying to use unknown measurements on the same rig so I can sort of 'guess' how it measures (and sounds) different from the HD650 and then, in my head, superimpose those differences over my (or others) HD650 and then apply my EQ to that to determine its 'character' or to find out what is bare minimum to EQ, how much and what Q.

 

[Mad_Economist]

I reckon it is too much work for me. I will post the raw results and you all can do the correction.

In that case, can you also post the HRTF data for your HATS when you have it?

 

[thewas]

Eyup - I mean, at the end of the day, these are all just ways you can look at the behavior of a system by comparing two inputs. ARTA's been able to do this for years, and it looks like Audio-Precision added it a year or two back, and of course Temme referenced it in a paper for B&K back in the 90s to my memory. Not a terribly high-tech trick, but it gets applause at parties, and there's some evidence to support it being a preferable test methodology for transducers.

It should be noted though that the measurement/identification of a classical transfer function only describes/approximates the linear part of a system and not its non-linearities.

 

[Mad_Economist]

It should be noted though that the measurement/identification of a classical transfer function only describes/approximates the linear part of a system and not its non-linearities.

Thus the significance of coherence! While it's not the sole potential cause, nonlinear behavior is one cause of a non-1 coherence (e.g. noncoherence). Bruel & Kjaer has an old paper on dual channel FFT analysis that's good reading IMO, although the aforementioned Temme paper also addresses this.

 

[Robbo99999]

In that case, can you also post the HRTF data for your HATS when you have it?

I think Amir already posted that at the following link, although you could probably do with having the raw data for the curve I guess rather than interpreting it from the curve? And wouldn't you need the Harman Listening Room characteristics too, I think you said Amir would have that?
https://www.audiosciencereview.com/...128-hats-measurement-system.15147/post-479999

Does that mean you might have a go at calculating a Struck Approach Harman Curve? If you do, it would be cool to see some screenshots of or something showing how you combined everything together, that way me & others would be able to learn and do this process in the future? I personally would find it very cool if Amir tests one of the headphones I have so I could see what I think to the Struck Harman Approach B&K 5128 vs GRAS Harman (ie Oratory1990)....but I'll have to see which headphones he tests (I don't think he'll be testing NAD HP50 or HD600 from what I've seen so far).

EDIT: and the beauty of learning how to do the Struck Approach is that you can simulate any model of speaker of your choice in any 'measured' room and hear that in your headphones....so it gives you the freedom to experiment with simulating different speakers & rooms. I mean that would be the ideal aim, but obviously the success of the results for any individual is gonna come down to how much their HRTF differs from the dummy head (B&K 5128 in this instance) and also come down to how valid the Struck Approach is too (which I don't know how valid it is on this latter point).

 

[amirm]

So for the second day in a row FedEx dropped the ball and refused to deliver the 5128. Each day it says it is on the truck for delivery but at 8:00pm status changes to unknown. Unlike UPS which uses same drivers for the region, FedEx uses a different driver so they are not familiar with the area. This being nearly 60 pound package, I would not be surprised if they just decide it is too heavy to deliver and just drive it back to the shop....

 

[Blumlein 88]

So for the second day in a row FedEx dropped the ball and refused to deliver the 5128. Each day it says it is on the truck for delivery but at 8:00pm status changes to unknown. Unlike UPS which uses same drivers for the region, FedEx uses a different driver so they are not familiar with the area. This being nearly 60 pound package, I would not be surprised if they just decide it is too heavy to deliver and just drive it back to the shop....

Do you have the option to pick it up at a nearby Fedex location? I've done that a few times when they needed a signature and I knew I wouldn't be at home. They'll let you do that even after it has shipped or at least they did recently.

 

[amirm]

That's a good suggestion. Alas, I see no option to do anything like that with tracking page. I have asked my contact to call them and find out what is going on tomorrow.

 

[Blumlein 88]

That's a good suggestion. Alas, I see no option to do anything like that with tracking page. I have asked my contact to call them and find out what is going on tomorrow.

Looks like one way is thru a new free service Fedex Delivery Manager.

https://www.fedex.com/en-us/search....om residence to local fedex location&cc=en_us

If this just tries to get you on the Fedex phone app, don't bother. That thing almost never works.

 

[zelig]

Do you have the option to pick it up at a nearby Fedex location? I've done that a few times when they needed a signature and I knew I wouldn't be at home. They'll let you do that even after it has shipped or at least they did recently.

You can do that on Fedex.com i believe. But why do their work for them?

 

[Robbo99999]

So for the second day in a row FedEx dropped the ball and refused to deliver the 5128. Each day it says it is on the truck for delivery but at 8:00pm status changes to unknown. Unlike UPS which uses same drivers for the region, FedEx uses a different driver so they are not familiar with the area. This being nearly 60 pound package, I would not be surprised if they just decide it is too heavy to deliver and just drive it back to the shop....

Does that mean that the length of time that you can keep the 5128 has decreased, if you have to get it back for the same date?

 

[Mad_Economist]

I think Amir already posted that at the following link, although you could probably do with having the raw data for the curve I guess rather than interpreting it from the curve? And wouldn't you need the Harman Listening Room characteristics too, I think you said Amir would have that?
https://www.audiosciencereview.com/...128-hats-measurement-system.15147/post-479999

Does that mean you might have a go at calculating a Struck Approach Harman Curve? If you do, it would be cool to see some screenshots of or something showing how you combined everything together, that way me & others would be able to learn and do this process in the future? I personally would find it very cool if Amir tests one of the headphones I have so I could see what I think to the Struck Harman Approach B&K 5128 vs GRAS Harman (ie Oratory1990)....but I'll have to see which headphones he tests (I don't think he'll be testing NAD HP50 or HD600 from what I've seen so far).

EDIT: and the beauty of learning how to do the Struck Approach is that you can simulate any model of speaker of your choice in any 'measured' room and hear that in your headphones....so it gives you the freedom to experiment with simulating different speakers & rooms. I mean that would be the ideal aim, but obviously the success of the results for any individual is gonna come down to how much their HRTF differs from the dummy head (B&K 5128 in this instance) and also come down to how valid the Struck Approach is too (which I don't know how valid it is on this latter point).

The Harman room's acoustic characteristics are published in the AES, so that wouldn't be hard to come by. I could knock together a little spreadsheet for this purpose, I suppose - it'd be really messy though, I'm terrible at Excel.

Ideally I'd really need the B&K data rather than just scraping from the plots - we're going to need to do enough interpolation on the directivity and RT60 as is...

Regarding the bolded section, since I keep seeing this concept in this thread, I'd like to specifically disclaim the idea that headphone frequency response/headphone transfer functions measured on a HATS are necessarily "one size fits none" (e.g. that the frequency response you get with one HATS will be predictive of subjective timbre only insofar as your HRTF matches the HATS'). The ear plays a meaningful role in HpTF, so an HD600 on two different heads will have two different frequency responses.

 

[Mad_Economist]

That's a good suggestion. Alas, I see no option to do anything like that with tracking page. I have asked my contact to call them and find out what is going on tomorrow.

You might want to call Fedex - if you can demonstrate that a package is intended to be delivered to your address, you can often have it held at a nearby location to be picked up. I've had to do this with Fedex specifically a few times (what's up with WA's Fedex?), memory serving.

 

[amirm]

You can do that on Fedex.com i believe. But why do their work for them?

I logged into my FedEx account but it shows the package on the delivery truck so won't let me do anything else with it.

 

[amirm]

Does that mean that the length of time that you can keep the 5128 has decreased, if you have to get it back for the same date?

They were kind enough to say I have until Monday now to return it (originally had to send it back on Friday).