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Confused about 'LFE Input/Crossover bypass switch' on my subwoofer. To activate or not? (1 Viewer)

erotavlas

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I have the PSP Alpha SubZero i subwoofer. (image below) I've been trying to read the manual about this switch and also search online but I'm getting really confused about
-> what I should set it to
-> and if it is related in any way to the LFE or LFE+Main setting of the receiver.

In the manual section for Set up Calibration it says "Ensure the LFE Input/Crossover bypass switch is set to off unless the subwoofer is connected to the LFE/Subwoofer output of your receiver/processor and the output is low pass filtered."

-> Also how do I know if the output is low pass filtered or not?

Sub is connected to Denon AVR-1907 and my front L and R speakers are PSB Image T45.

_20231230_002421.JPG
 

JohnRice

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The wording for the LFE input on that sub is a little counterintuitive. In any case, you want to set it to "Active", since the receiver will do the crossover. Then there should be something in the speaker setup of the receiver where you set the sub to "Yes" or "On", all the speakers to "Small" and the crossover for them in the 80-100Hz range.
 

erotavlas

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The wording for the LFE input on that sub is a little counterintuitive. In any case, you want to set it to "Active", since the receiver will do the crossover. Then there should be something in the speaker setup of the receiver where you set the sub to "Yes" or "On", all the speakers to "Small" and the crossover for them in the 80-100Hz range.
There is a dial on the front of the subwoofer to select the crossover frequency. If I set the LFE switch on the back to 'Active' and the receiver does the crossover, does this mean that the crossover setting on the subwoofer has no effect? Or do I still have to set it to the same value as what I set in the receiver?

_20231230_003224.JPG
 

Wayne A. Pflughaupt

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In the manual section for Set up Calibration it says "Ensure the LFE Input/Crossover bypass switch is set to off unless the subwoofer is connected to the LFE/Subwoofer output of your receiver/processor and the output is low pass filtered."

That passage fully contradicts what’s written in the previous Section, Connecting the Subwoofer to you Audio System:

“The subwoofer output/LFE signal is filtered by most receivers/processors. The subwoofer’s variable low pass filter is usually not required and should be bypassed by switching the LFE Input/Crossover bypass switch to active only if the receiver/processor subwoofer/LFE output is low pass filtered. The default position for this switch is off.” (Emphasis in original.)

I expect the only way you’ll be able to tell for sure which setting to use is simply to test it. In your AVR’s menu, set the subwoofer output for its highest setting. Unplug or otherwise turn off the main speakers , play some music, and adjust the PSB’s front-panel frequency knob from its highest (150) to lowest (50) setting.

Ultimately, you want the back-panel switch to be in the position that makes no audible change when you turn the front-panel knob.

Regards,
Wayne A. Pflughaupt
 

JohnRice

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That passage fully contradicts what’s written in the previous Section, Connecting the Subwoofer to you Audio System:

“The subwoofer output/LFE signal is filtered by most receivers/processors. The subwoofer’s variable low pass filter is usually not required and should be bypassed by switching the LFE Input/Crossover bypass switch to active only if the receiver/processor subwoofer/LFE output is low pass filtered. The default position for this switch is off.” (Emphasis in original.)

I expect the only way you’ll be able to tell for sure which setting to use is simply to test it. In your AVR’s menu, set the subwoofer output for its highest setting. Unplug or otherwise turn off the main speakers , play some music, and adjust the PSB’s front-panel frequency knob from its highest (150) to lowest (50) setting.

Ultimately, you want the back-panel switch to be in the position that makes no audible change when you turn the front-panel knob.

Regards,
Wayne A. Pflughaupt
You're right. That's why I said the wording is counterintuitive. To be honest, I'm still not sure what the correct setting is either.

The solution I highlighted really is the best way to find out.
 

Wes Candela

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I have the PSP Alpha SubZero i subwoofer. (image below) I've been trying to read the manual about this switch and also search online but I'm getting really confused about
-> what I should set it to
-> and if it is related in any way to the LFE or LFE+Main setting of the receiver.

In the manual section for Set up Calibration it says "Ensure the LFE Input/Crossover bypass switch is set to off unless the subwoofer is connected to the LFE/Subwoofer output of your receiver/processor and the output is low pass filtered."

-> Also how do I know if the output is low pass filtered or not?

Sub is connected to Denon AVR-1907 and my front L and R speakers are PSB Image T45.

View attachment 208003
Hey
Personally and this is just me
First of all, where is that subwoofer? Is it positioned to fire towards you?
because if it is, you’re gonna set that phase to 0
not 180.
As far as the crossover bypass goes:

looking at the photos of the crossover settings, if you set it to active, your subwoofer is going to handle the crossover.
If you turn it off, your receiver, will handle the crossover

Agreeing with the comment above, I would set it off. See what you think.

if you set it on, I would set that crossover to about 100 Hz – 120 Hz

just my opinion I hope this helps
 
Last edited:

JohnRice

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Well... as Wayne pointed out, two successive statements in the instructions contradict each other. That and the poor labeling on the sub make it almost impossible to determine the correct setting, other than trying what Wayne suggested.

What I suspect is the labeling on the sub is wrong. "Active" on the crossover option should mean the sub's internal crossover is active. That would mean you want to turn it off when the receiver is doing the crossover, which is the best way to set it up.
 

MitchFlorida

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Well... as Wayne pointed out, two successive statements in the instructions contradict each other. That and the poor labeling on the sub make it almost impossible to determine the correct setting, other than trying what Wayne suggested.

What I suspect is the labeling on the sub is wrong. "Active" on the crossover option should mean the sub's internal crossover is active. That would mean you want to turn it off when the receiver is doing the crossover, which is the best way to set it up.
If you want to use the LFE feature you must put the LFE active switch in the up position. My sub has a separate LFE-marked jack and there is no need for that switch.

The Subzero subwoofer he is using dates back to 2000, so it is a rather old design.
 

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