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Handling Various Bass Management Dilemmas

by August 30, 2004
Q: I read your article regarding LFE output. I am getting conflicting information from the people who make my receiver (Yamaha RXV520) and the people who make my surround sound speakers (Polk Audio RM6000). Polk says the sub-woofer should be connected to the system via the main speakers using speaker wire (not a RCA cable) or else I lose a bunch of mid-range bass. Yamaha says that is a fine way to hook it up but I lose the .1 of 5.1 surround sound. Polk Audio says that is not true and that even though the .1 is directed to the LFE output it will be redirected to main (set to large) since the LFE output is disabled (no wire). Can you help solve this mystery for me. Who is right?

Audioholics: Terry, I think I understand why there is a conflict between Polk and Yamaha.

Polk's Issue: If you hook up the subwoofer line level out of the Receivers subwoofer output, you will lose midbass information.

Polk may be worried that if you use the sub output on the Yamaha receiver, it may roll off the sub too low in frequency since the Yamaha has a built in Low Pass Filter (LPF) which would make for a poor blend in the mid bass region between your subwoofer and your main speakers.

I don't believe this is the case however for two reasons:

  1. The LPF on the sub output from your Yamaha receiver is set at about 90Hz.
  2. Your main speakers should play with enough Sound Pressure Levels (SPL) at 90Hz and probably down to about 80Hz I suspect. Therefore you should not have a frequency gap between the subwoofer and main speakers.

Yamaha's Issue: Hooking the subwoofer to the Receivers main speaker level outputs will result in a loss of the 0.1 LFE channel.

Yamaha may have misinterpreted how you planned to configure your speaker system. It is true that you will lose the .1 LFE channel if you set up the bass management in the Yamaha as having a subwoofer when you actually don't connect your subwoofer to the subwoofer output of the Receiver. However, if you configure the bass management as illustrated below, you will not have this problem. In addition, the subwoofer will always operate in two and five channel modes.

Bass Management Configuration

  • Main Speakers: Small
  • Center Speaker: Small
  • Rear Speakers: Small
  • Bass Output: Subwoofer

Note: Do not set the Bass Output to "Both" as the result would be to direct bass below 90Hz to your main speakers. Your main speakers are not capable of producing bass frequencies with authority and the result may cause damage to your speakers if they become overdriven.

Recommendations
I recommend hooking your subwoofer to the line level subwoofer output of your Yamaha Receiver and configure your bass management as I illustrated above. This is the best method to ensure optimal performance of your system while at the same time offering you the most convenience, as you will now have the ability to make on the fly adjustments to subwoofer and LFE levels via the Receivers remote control and/or user interface.

I recommend setting the LPF of your subwoofer to the "off" position if possible. If not, then set it to the maximum frequency (rotate clockwise) to minimize interaction between the Subwoofer and Receiver LPF's. For more information about configuring your speaker system, please see our many articles on Bass Management in the Tips & Tricks section of the site.

 

About the author:

Gene manages this organization, establishes relations with manufacturers and keeps Audioholics a well oiled machine. His goal is to educate about home theater and develop more standards in the industry to eliminate consumer confusion clouded by industry snake oil.

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