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Neumann KH750 DSP AES67

Teon

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Hello to the community, I have recently purchased a Neumann KH750 sub and I am struggling to figure out what each of these four settings mean. The settings are shown in the back of the device.

I have two questions:

1- what do each of these modes mean
2- why are there two columns of texts on both sides of the mode switch, the switch seems to have 4 settings, but there are 8 texts written around it

I appreciate your help if someone can be kind enough to help me out

Cheers,

Teon
 

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Welcome to ASR!

Answer your question 2 first. The aim of the right column is to provide some info on what the subwoofer outputs will be. The text mostly mostly reflects the titles of the pictograms of each mode.
kh750.png


As for the function of each mode:
StereoThe subwoofer will output the bass contents (< 80 Hz) from both left and right channels as mono bass.
The left and right outputs will be the same as the original left and right inputs but with the bass contents below 80 Hz removed (high pass filtered).
Connect the left and right main speakers to the left and right outputs.
LFE/External Bass ManagementThe channel A input will be passed to the channel A output except that the bass contents below 80 Hz will be removed (high pass filtered).
The subwoofer will output the bass contents (< 80 Hz) from the channel A input.
The LFE channel (if present) can be connected to the channel B input to be output by the subwoofer (along with the bass contents in channel A). No processing/filtering is done on the LFE channel (channel 2) signal.
LFE-Mode 1Same as the "External Bass Management" mode, but the LFE channel contents are low pass filtered to remove the LFE signals > 120 Hz.
LFE-Mode 2Similar to the "External Bass Management" mode, but the LFE channel contents are low pass filtered to remove the LFE signals > 80 Hz before being sent to the subwoofer to output. The portion of the signal in the LFE channel > 80 Hz will be sent to the channel A output to be reproduced by the channel A main speaker.
 
Welcome to ASR!

Answer your question 2 first. The aim of the right column is to provide some info on what the subwoofer outputs will be. The text mostly mostly reflects the titles of the pictograms of each mode.
View attachment 389621

As for the function of each mode:
StereoThe subwoofer will output the bass contents (< 80 Hz) from both left and right channels as mono bass.
The left and right outputs will be the same as the original left and right inputs but with the bass contents below 80 Hz removed (high pass filtered).
Connect the left and right main speakers to the left and right outputs.
LFE/External Bass ManagementThe channel A input will be passed to the channel A output except that the bass contents below 80 Hz will be removed (high pass filtered).
The subwoofer will output the bass contents (< 80 Hz) from the channel A input.
The LFE channel (if present) can be connected to the channel B input to be output by the subwoofer (along with the bass contents in channel A). No processing/filtering is done on the LFE channel (channel 2) signal.
LFE-Mode 1Same as the "External Bass Management" mode, but the LFE channel contents are low pass filtered to remove the LFE signals > 120 Hz.
LFE-Mode 2Similar to the "External Bass Management" mode, but the LFE channel contents are low pass filtered to remove the LFE signals > 80 Hz before being sent to the subwoofer to output. The portion of the signal in the LFE channel > 80 Hz will be sent to the channel A output to be reproduced by the channel A main speaker.


Thank you millions, I appreciate the time and effort you put into this detailed answer. This helped a lot. One more question if you don’t mind, what is the use of external bass management, LFE mode 1, and LFE mode 2, they only have a single channel A for non bass content, in what scenarios can they be used? I am still confused about this, I understand that the first mode is used for normal use but have a hard time wrapping my head around how the other 3 modes can be useful. I appreciate your help,
 
My guess is that the intent for the 3 LFE modes the subwoofer is to provide the sub-bass only for one single channel. (i.e. each channel/main speaker would have its own subwoofer.)

I could be totally wrong though.
 
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My guess is that the intent for the 3 LFE modes the subwoofer is to provide the sub-bass only for one single channel. (i.e. each channel/main speaker would have its own subwoofer.)

I could be totally wrong though.
Thank you for your reply, while we are on this subject, I have a question regarding mixing using a single subwoofer, I’ll try to keep my question as simple as possible, I have a pair of speakers that go down to 44 Hz, when I am mixing on this pair (without a subwoofer) I hear the full range from both speakers simultaneously, basically I am hearing the bass content in Stereo and applying mixing decisions accordingly. However, if I use the KH750 subwoofer, I will loose all signal below 80 Hz on the main stereo speakers and I can here above 80 Hz on the main stereo speakers only. The subwoofer will play below 80 Hz, basically I can no longer here until 44 Hz in “Stereo”, In other words below 80 Hz will become only Mono,

Is this scenario bad for mixing? It is a departure from conventional mixing that we hear bass from both L and R channels and in Stereo, I would appreciate your input in this. Please let me know
 
Many (semi)pro subs have a TS input for a foot switch to toggle between using the sub (with crossover enabled) and just using the monitors. This lets you see what it sounds like with and without a sub. The KH 750 has the functionality, but not the foot switch input. You need to use the 'Bass Management' switch on the back panel, or control it via the network using the app (iPad or Windows) or 3rd party khtool.
 
Many (semi)pro subs have a TS input for a foot switch to toggle between using the sub (with crossover enabled) and just using the monitors. This lets you see what it sounds like with and without a sub. The KH 750 has the functionality, but not the foot switch input. You need to use the 'Bass Management' switch on the back panel, or control it via the network using the app (iPad or Windows) or 3rd party khtool.
Thank you for your reply, this is what the manual says:
If you deactivate the bass management, the audio signal of the audio outputs OUTPUT | LEFT and RIGHT is only reproduced by the loudspeakers . Use this function to prevent the low frequency signal components of the main channels being reproduced by the subwoofer .
Set the switch BASS MANAGEMENT to “DISABLED” .

One particular sentence in this paragraph confuses me, it says if bass management is disabled the audio outputs “”OUTPUT| LEFT and RIGHT”” is only reproduced by the loudspeakers.

Shouldn’t it be INPUT instead of OUTPUT? My assumption is that if the OUTPUT of subwoofer is produced by the loudspeakers only, that means that the OUTPUT has already been passed through the high pass filter and thus the loudspeakers will not have the low end signals and as a result they are not Fullrange.

On the other hand, if putting the switch is set to disabled basically bypasses the sub and loudspeakers get full range,, then this will be great but I doubt that this is the case.

Could you please elaborate?
 
On the other hand, if putting the switch is set to disabled basically bypasses the sub and loudspeakers get full range,, then this will be great but I doubt that this is the case.
Reading the sections before and after the one you quote makes me think this is how it works - see fuller quote from the manual below. I could be wrong though - I don't have a KH 750. Maybe ask Neumann to confirm?
Using stereo bass management
* For a two-channel stereo system set the switch CHANNEL B INPUT MODE J to “STEREO/
RIGHT”
* Set the switch BASS MANAGEMENT E to “ACTIVE”
The bass management is activated This inserts a 4th order 80 Hz high pass filter into the
signal path of the audio outputs OUTPUT | LEFT and RIGHT 8 and routes all audio signals
below 80 Hz to the subwoofer The LED BASS MANAGEMENT F lights up green
If you deactivate the bass management, the audio signal of the audio outputs OUTPUT | LEFT
and RIGHT 8 is only reproduced by the loudspeakers Use this function to prevent the low
frequency signal components of the main channels being reproduced by the subwoofer
* Set the switch BASS MANAGEMENT E to “DISABLED”
Remote-controlling the bass management
It is possible to activate and deactivate the bass management filters remotely using
Neumann Control This allows one to listen to the source as if there is no subwoofer connected
in the system because the loudspeakers play full range with no filtering when the bass man-
agement is disabled
 
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