Neumann KH80 DSP Monitor Measurements #3

[amirm]

For grins before turning up the heat I tested Frequency Response Impedance, phase and Theile Small Parameters of a JBL 2235H, JBL 2226H, JBL 2204H and several JBL compression drivers prior to turning up the heat. Everything was tested again in the morning after the heat was turned up overnight.

And what a driver does and what a driver+speaker do are two different things.

 

[LTig]

I have generated a similar signal that I use for my personal measurements, if someone wants it, just send me a PM, here an example measurement based on it:

I'd rather be interested in a list of all tones, stating frequency, amplitude and phase, so I can generate the test signal myself.

 

[Lbstyling]

makes me start to think having my 15 individual room thermostatic control system might have been worth the hassle after all! Was a absolute ball ache to set up though!

 

[DualTriode]

And what a driver does and what a driver+speaker do are two different things.

Hello,



I get it.



Start with a driver, add it to an enclosure plus add some stuffing and you have a speaker. With all of this stuff together, temperature and humidity gets even more complex. The speaker Vas Parameter for example will vary with temperature and humidity plus humidity varies with temperature. Adiabatic heating and cooling in the enclosure is sensitive to temperature and humidity changes. (One example that comes to mind)



If reliable measurement down to a gnat’s eyebrow is the goal, environmental control in the lab becomes increasingly important. IMO.



I have experience in lab design, start up and commissioning including biotech labs, operating rooms and high tech environmental chambers.



Thanks DT

 

[BYRTT]

Thousand thanks detective work in take all the tests Amir and still be here in what looks relative good mood ...... will admit from outside it looks that garage and Germany really had added some work load in 33+29+10 pages of posts and 2 times realignment of system after dismount/mount af microphone cage..

New sample 3 curves looks really nice but bit surprised it scored so high and passed Revel F208, below animation is new sample 3 analyze and the blinking overlay is a traced copy of the sample Neumann had asked Klippel Germany to measure, for info Neumann sample is offset +0,7dB but nice coherence there..

This one is bit funny or bit irritating, its sample 3 added microphone cage fix from Genelec thread plus MK-255 microphone calibration corrections in reverse or say mirror, and for folks following KH 80 it should look clear that say 500Hz and up it looks exactly as sample 1 did and okay GuyLayfield temperature analyze of KH 80 add some tiny bit of boost above 10kHz and same do calculate system on tweeter axis as was done for sample 1 verse 52mm lower as for sample 3, but still in my eyes it could rather look like MK-255 micrphone calibration in Klippel software has in past mayby been accidently set in reverse/mirror, should that happen its not a disaster if one take a lookup of that correction curve some graphs below this one..

Thanks to GuyLayfield do that temperature test and share data, have traced the 5º cold curve as seen below to get a correction curve to add to sample 1..

This beautiful curve is sample 1 added 4 times corrections, one is microphone cage fix from Genelec thread, one is MK-255 microphone calibration, one is in CAD software lower microphone height position in space relative to spindata or say tweeter axis -52mm, and fourth corrrection is above temperature fix..

Below is sample 1 animation including the 4 times correction fixes plus sample 3 on axis curve as reference, and even its modeled prediction it looks quite close, thanks to everyone share knowledge hard work and data, the four filters used below is attached to post.

 

[amirm]

Start with a driver, add it to an enclosure plus add some stuffing and you have a speaker. With all of this stuff together, temperature and humidity gets even more complex. The speaker Vas Parameter for example will vary with temperature and humidity plus humidity varies with temperature.

Then show that difference with measurements. Until then, a driver in free air doesn't work the same in a compliant box.

 

[amirm]

Below is sample 1 animation including the 4 times correction fixes plus sample 3 on axis curve as reference, and even its modeled prediction it looks close, thanks to everyone share knowledge hard work and data, the four filters used below is attached to post.

Boy, you do amazing work. But where did you get that microphone calibration?

 

[BYRTT]

Boy, you do amazing work. But where did you get that microphone calibration?

Thanks its nothing compared the other way, can't remember what thread it was but can see in my Klippel folder its some post number 108, a mini grab of that post important data below ..

 

[amirm]

That's correct but seems like you have more correction than that:

Looks like you are down 2 dB at 20 kHz.

 

[DualTriode]

And what a driver does and what a driver+speaker do are two different things.

Hello,



With the shiny objects set aside.



Environmental conditions apparently had an effect on the reliability of the measurements.



Thanks DT



If you are wearing your hoody in the garage is likely cold out there.

 

[richard12511]

Then show that difference with measurements. Until then, a driver in free air doesn't work the same in a compliant box.

Isn't that what you just showed with these measurements? or am I misunderstanding?

 

[pozz]

Thousand thanks detective work in take all the tests Amir and still be here in what looks relative good mood ...... will admit from outside it looks that garage and Germany really had added some work load in 33+29+10 pages of posts and 2 times realignment of system after dismount/mount af microphone cage..


View attachment 73346
View attachment 73364



New sample 3 curves looks really nice but bit surprised it scored so high and passed Revel F208, below animation is new sample 3 analyze and the blinking overlay is a traced copy of the sample Neumann had asked Klippel Germany to measure, for info Neumann sample is offset +0,7dB but nice coherence there..
View attachment 73354


This one is bit funny or bit irritating, its sample 3 added microphone cage fix from Genelec thread plus MK-255 microphone calibration corrections in reverse or say mirror, and for folks following KH 80 it should look clear that say 500Hz and up it looks exactly as sample 1 did and okay GuyLayfield temperature analyze of KH 80 add some tiny bit of boost above 10kHz and same do calculate system on tweeter axis as was done for sample 1 verse 52mm lower as for sample 3, but still in my eyes it could rather look like MK-255 micrphone calibration in Klippel software has in past mayby been accidently set in reverse/mirror, should that happen its not a disaster if one take a lookup of that correction curve some graphs below this one..
View attachment 73355


Thanks to GuyLayfield do that temperature test and share data, have traced the 5º cold curve as seen below to get a correction curve to add to sample 1..
View attachment 73357


This beautiful curve is sample 1 added 4 times corrections, one is microphone cage fix from Genelec thread, one is MK-255 microphone calibration, one is in CAD software lower microphone height position in space relative to spindata or say tweeter axis -52mm, and fourth corrrection is above temperature fix..
View attachment 73358


Below is sample 1 animation including the 4 times correction fixes plus sample 3 on axis curve as reference, and even its modeled prediction it looks quite close, thanks to everyone share knowledge hard work and data, the four filters used below is attached to post.
View attachment 73361

Amazing work. Especially the final set of filters.

 

[BYRTT]

That's correct but seems like you have more correction than that:

View attachment 73363

Looks like you are down 2 dB at 20 kHz.

Its was back late in Januar and admit had my speculation and trials how to read those numbers and ended up use Rephase default high shelve as below with ripple about 1,88dB..

Also added a 3,5Hz 1st order high pass because that is listed in MK-255 datasheet and one can notice the tiny roll off tendency in filter curve, i'm sorry if its wrong then let me be corrected and i can add few dollars for a cold beer in the next donation, that said it dont move so much for ASR general purpose 0,5 to 1dB or so up there.

Those standard high shelves in Rephase is a Q of 2 and thought it looked okay realistic based on its not like the mass of mics a 1/4 inch capsule but a 1/2 incher, and also thought it would be natural in a produktion unit is bit less smooth than the golden one that their datasheet brochure publish as seen in the upper black curve below, cyan is ASR as set using high shelve with Q of 2, orange is MK-255 Q of 1 and blue is MK-255 BW Q and thought those looked a bit too good enough for a 1/2 inch capsule and the golden exemplar in datasheet brochure plus a compare to the red one which is my own 1/4 incher iSEMcon mic also German but probably many $ cheaper than yours.

 

[amirm]

Its was back late in Januar and admit had my speculation and trials how to read those numbers and ended up use Rephase default high shelve as below with ripple about 1,88dB..

Yeh, the ripple or peaking with digital filters is why I have not bothered to put in the correction in Klippel (and neither does Klippel Germany). With the worst case error of just 1 dB at 20 kHz, I think we can live without the correction.

 

[DualTriode]

Conclusions
The main variable in our measurements not quite matching Neumann's was temperature. Whether this impacted just this speaker or the others, I don't know. If I get some time (yeh right), I will go back and remeasure a few of the other ones I still have and see what difference there may be. Come this winter, I will heat up the measurement room to get it closer to spring weather at least. Fortunately it never gets that cold here and hopefully we will find that other speakers are not affected as much.

Beside temperature, I have also fine tuned the system, using averaging for example to reduce noise level, deploying more optimal parameters to get the high frequencies right, etc. These have been in place for months so the bulk of what we have measured are accurate as they also enjoy warmer temperatures.
/

Hello,

I was talking about and agreeing with cold possibly affecting the measurements plus adding the thought that humidity could also be a contributing variable.

Thanks DT

 

[wwenze]

I just realized...

Does that mean that all speakers measured so far have this weird kinky bass due to temperature? (Pun not intended)
It happened to so many speakers I thought it was a quirk of spinorama.

For example LS50

Spoiler

 

[gr-e]

I just realized...

Does that mean that all speakers measured so far have this weird kinky bass due to temperature? (Pun not intended)
It happened to so many speakers I thought it was a quirk of spinorama.

For example LS50

Spoiler

In case of KEF it's just the overdamped box tuning.

 

[temps]

View attachment 73148

This section of the chart is definitely concerning. The 120 hugely outperforms the 80 through this region here. They'd be for studio use so I want to be at or under 1% THD...

As a followup - went to a store and listened to them. Sweet Lord. They sound absolutely fantastic. I don't think the output is all that limited - I couldn't hear any obvious distortion and I was pushing the level quite a bit. I just settled on a few more demo tracks that I hope will trip it up and I'll try those tomorrow.

I still might not buy it though. If the tiny little Neumann sounds this good, what does the 310 sound like?

 

[Pepperjack]

In case of KEF it's just the overdamped box tuning.

of course, if I understand this correctly the woofer plays a critical role in the tweeter function in that design, so it’s possible that coaxle designs would be even more impacted, no?

 

[DualTriode]

Hello,

Weatherunderground is my favorite weather site.

Schools, universities and high tech companies often will have a weather station on their roof.

Large HVAC systems will bring in outside air while it is cool outside for “free” AC. Sometimes I get high humidity calls. I will check the outside humidity and dial up the client’s HVAC control system to see if the humidity controls are functioning or not. Often clients will turn off the humidity control to save utility dollars.

See https://www.wunderground.com/forecast/us/wa/woodinville/47.77,-122.15


Check the humidity over the hours of the day it is interesting looking at the high Relative Humidity % compared to the afternoon low %RH.



Wounderground also a history tab to check what happened yesterday or last year in your local.

Thanks DT