Neumann KH 120A - spinorama and misc measurements

[nc535]

beautiful! I will work it into my Vituix model and post

 

[nc535]

Here is a sketch of my concept. Originally, I planned just 2 of the Dayton DMA80 drivers (80 mm) on each side but I got better simulation results with 3. The side chamber is 60 mm deep with 60mm radius roundover. I synthesized directivity for it in Vituix diffraction tool so I am modelling pistons with diameter equal to the Sd of the DMA80

 

[nc535]

Here is a screenshot of the simulation, top one has the side arrays disabled so you can see the delta. There is an impressive extension of horizontal pattern control to just below 100 Hz where I high pass the 3" drivers to limit their excursion.

 

[nc535]

Here is a cardioid-like directivity chart of the response at 364 Hz, where rejection to the rear is quite good. The line chart is better for visualizing where the side arrays help/hurt. It shows good rejection to the rear in the 300 Hz to 1 khz range. Just past 1 khz there is some widening in the pattern which seems to be in the original data as well. Bottom line, I doubt these simple side array adapters come close to the kii3's directivity performance. I was really looking for more help in the 100 Hz to 300 Hz region, which I can get simulating other (larger) driver configurations. Its nice to have real directivity data to use in these experiments

 

[nc535]

Just happened to look at the vertical line chart. Exported image of the raw data, no cardioid, this is how it comes from the factory. That is one heck of a crossover dip off vertical axis. You really want to have these things aimed at your ears vertically. edit - that is a bit too critical. Its down just less than 2 db at 10 degrees off vertical axis which really isn't bad.

 

[Pritaudio]

Are the kh120 too small for hifi use in a 4 by 5m living room with 2.5m height.
I will be listening from 3m away.
I’m worried the watts and 5.25 inch driver will be not enough. Will it be near clipping for decent volume.
how about with the kh750 sub too. Does it take the strain off the kh120 5.25 inch woofer when enabling dsp feature.
kinda hard to get demo right now.
much appreciated.

 

[dominikz]

Are the kh120 too small for hifi use in a 4 by 5m living room with 2.5m height.
I will be listening from 3m away.
I’m worried the watts and 5.25 inch driver will be not enough. Will it be near clipping for decent volume.
how about with the kh750 sub too. Does it take the strain off the kh120 5.25 inch woofer when enabling dsp feature.
kinda hard to get demo right now.
much appreciated.

This is the maximum C-weighted SPL for a pair of KH120As (loudspeakers alone and loudspeakers+sub) that Neumann specifies at 2,3m:

Based on the above, at 3m distance (see this calculator) a pair of KH120A should be able to reach a maximum of ~94 dB(C) SPL peaks if used fullrange, or ~101 dB(C) SPL peaks when crossed over to a subwoofer.

So assuming a generous 20dB headroom (for high dynamic range content and possibly some room EQ), you should be OK as long as ~74 dB(C) SPL (KH120 fullrange) / ~81 dB(C) SPL (KH120A with sub) average level is acceptable to you.
It would be best if you have access to a C-weigthed SPL meter to measure your current average SPL, and then see if the above would be enough for you.

Please also note that this is a bit simplified calculation, you can also see this diagram from Neumann if you want to do a more detailed analysis and calculations for specific frequency regions.

Hope this helps!