# Sony craptastic documentation: Rear Bass Enhance/Sub Direct mode 1 vs 2 vs 3?



## sumitagarwal (May 17, 2017)

I'm running a Sony MEX-XB100BT, which seems to be surprisingly solid head unit (4x 40W/channel continuous) and features either a "Rear Bass Enhancer" mode for a LPF on the rear channel, or a "Subwoofer Direct" mode to drive a mono subwoofer off the rear channel. Combined with the HPF on the front channel, can make for a tiny and reasonable sounding setup up to volumes higher than I'd like to listen.

However, the documentation is absolute garbage!!!

For both RBE and Subwoofer Direct there are the following modes: OFF, 1, 2, or 3.

With zero explanation whatsoever between 1, 2, and 3. I can easily guess what "OFF" means =P

I can clearly hear differences between 1, 2, and 3, but really wish I could know what exactly they mean. Does anyone here have any idea or documentation? I've scoured the net.

For reference, here's Sony's pitiful documentation:

REARBAS ENH (rear bass enhancer)
Rear Bass Enhancer enhances the bass sound by applying a low pass filter setting to the rear speakers. This function allows the rear speakers to work as a subwoofer if one is not connected. (Available only when [SUBW DIRECT] is set to [OFF].)
RBE MODE (rear bass enhancer mode)
Selects the rear bass enhancer mode: [1], [2], [3], [OFF].
LPF FREQ (low pass filter frequency)
Selects the subwoofer cut-off frequency: [50Hz], [60Hz], [80Hz], [100Hz], [120Hz].
LPF SLOPE (low pass filter slope)
Selects the LPF slope: [1], [2], [3].

SUBW DIRECT (subwoofer direct connection)
You can use the subwoofer without a power amplifier when it is connected to the rear speaker lead. (Available only when [RBE MODE] is set to [OFF].)
Be sure to connect a 4 – 8 ohm subwoofer to either of the rear speaker leads. Do not connect a speaker to the other rear speaker lead.
SUBW MODE (subwoofer mode)
Selects the subwoofer mode: [1], [2], [3], [OFF].
SUBW PHASE (subwoofer phase)
Selects the subwoofer phase: [NORM], [REV].
SW POSITION* (subwoofer position)
Selects the subwoofer position: [NEAR], [NORMAL], [FAR].
LPF FREQ (low pass filter frequency)
Selects the subwoofer cut-off frequency: [50Hz], [60Hz], [80Hz], [100Hz], [120Hz].
LPF SLOPE (low pass filter slope)
Selects the LPF slope: [1], [2], [3].


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## vet883 (Feb 12, 2017)

I have a Sony mex 5000bt and I agree the manual is poorly written. As far as the slope is concerned I believe 1 is 6db 2 is twelve db 3 is 18 db. As far as the the rbe I don't use it I use subs.would like to know they mean also


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## HardCoreDore (Apr 30, 2014)

Dude, you were asking about this the other day & I didn't respond b/c I figured it was some really complicated simulated Surround Sound or something similar... These are just basic functions. 

Essentially, the Rear Bass Enhancer turns the rear speakers into subwoofers in lieu of an actual subwoofer. It does this by using a low pass filter to cut out the high frequencies on the rear speakers. You will choose the frequency of the cutoff 50,
60, 80, 100, 120 and then 1,2, or 3 cooresponds to the slope of the low pass filter. (Most likely (6db per Octave/ 12 db... / 18db... ) The higher the slope, the tighter the filter. 

The subwoofer direct mode works exactly the same way except you don't have rear speakers, instead you only use one pair of the rear speaker leads to power one subwoofer. All the info above is the same. 


Sent from my Nexus 5X using Tapatalk


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## HardCoreDore (Apr 30, 2014)

I don't remember, what did you end up doing? Did you use the amp, or did you pull the amp and end up just using the head unit? 

Sent from my Nexus 5X using Tapatalk


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## dowheelies (Jan 7, 2012)

Any updates on this? Hooked one up in my golf cart yesterday with just some Alpine marine 6.5’s on the front channels. Sounds pretty good but want to add a small sub to help fill in the low end. Maybe a 6.5” Bazooka since it’s simple, cheap and will fit where I have room.

Do both rear channels actually have output in sub direct mode? I know the manual only calls to use one channel but seems odd to only have 40w when that amount is available in each channel in normal mode.

If they do a DVC sub with 40wx2 would be just fine for my setup.

Thanks Eric


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## sumitagarwal (May 17, 2017)

dowheelies said:


> Any updates on this? Hooked one up in my golf cart yesterday with just some Alpine marine 6.5’s on the front channels. Sounds pretty good but want to add a small sub to help fill in the low end. Maybe a 6.5” Bazooka since it’s simple, cheap and will fit where I have room.
> 
> Do both rear channels actually have output in sub direct mode? I know the manual only calls to use one channel but seems odd to only have 40w when that amount is available in each channel in normal mode.
> 
> ...


I've actually been using the Rear Bass Enhance feature instead, which as far as I can tell is basically the same as sub direct in terms of functionality. Its been working well, but I drive an Italian car and occasionally I'll need to jump start the car and its a pain going through all the Sony settings each time...

I still want to know what the different "1, 2, 3" modes are.


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