Harman Kardon HK990 subwoofer outputs?

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Hi there specialists,

I look harman/kardon HK990 amplifier and there are two subwoofer output. In the back panel there are “SUB 1” and “SUB 2”. But in the real life, both of those outputs give mono-signal.

In the schematic diagram, there is marked “Subwoofer OUT L” and “Subwoofer OUT R”. And it looks like those connectors are in stereo.

Have you any idea, why those subwoofer outputs are mono?
Is it made by software or hardware?

Thanks!
 

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  • HarmanKardon-HK990 amp subout.pdf
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Some active subwoofers have two line inputs (L and R) and filter/join those inside. This is applicable to stereo programs.
The "mono" subwoofer is actually a LFE channel applicable for 5.1/7.1 programs (Dolby Digital/ DTS... etc).
I am sure that in the manual is described a setting to use just one of thse outputs (to be joined in the receiver) for stereo programs. For 5.1 programs probably both have the same signal, so you can use only one.
 
AFAIK, they are stereo outputs if you feed the 990 with stereo sub inputs but can be stereo or mono if you have the 990 derive the sub outputs. Have you checked the user's manual about this?

Kal

Hi!

If I try with test-cd, both of those sub outputs gives the signal even if signal from disc is only one channel.
Thats really weird...
In the manual there is only "Output jacks for two subwoofers".

/vesa
 
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Hi!
If I try with test-cd, both of those sub outputs gives the signal even if signal from disc is only one channel.
Thats really weird...
That's not weird if you have programmed any EQ mode... At crossover frequency, bass will go towards on or both subs - depending of your selection in the "speaker" menu.
See page 10, 11 of the manual.
 
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Well, actually what I need is high pass filter (>100Hz) to main speaker AND two channel (stereo) full band output to active crossover/eq of subwoofers
OR
high pass filter (>100Hz) to main speaker AND two channel (stereo) low pass (<100Hz) output to eq of subwoofers.

If I use h/k high pass filter in speaker setup (40-200Hz) in manual mode, after that also preamplifier output jack gives high pass signal.
So, from where I get full pass stereo signal to sub if I use high pass filter to main speakers?
 
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