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Unconventional Subwoofer Configuration

Scott Wilkinson  |  Jun 27, 2012

I have a Marantz SR6004 A/V receiver with a 5.1 speaker system, including Focal Chorus 826 V speakers for the front left and right, Chorus CC 800 V for the center channel, Chorus 806 V speakers for the surrounds, and Chorus SW 800 V subwoofer. In the receiver, I set the front left and right as Large and the others as Small. I set the subwoofer output to Off and use the receiver's Speaker C function to drive the sub's high-level inputs from the receiver's surround-back speaker outputs with the sub's internal crossover set to 60Hz. This configuration produces a very nice sound; I feel that the bass is more structured and integrated than when I use the crossover in the receiver. My question is, does the receiver lose power in this configuration?

Santiago Blint

The SR6004's Speaker C setting is designed to let you bi-amp the front speakers using the main and surround-back outputs. For each channel, both outputs send the same full-range audio signal, and the bi-amped speaker must have an internal crossover to direct the highs and lows to the appropriate drivers. In your case, the subwoofer's internal crossover allows only the low frequencies to reach its driver.

To answer your question, the receiver does lose a bit of power when all seven channels are driven. Our measurements reveal that the SR6004 reaches 0.1% distortion at 73.1 watts with five channels driving 8-ohm loads and 1% distortion at 86.4W; with seven channels driving 8 ohms, it reaches 0.1% distortion at 70.8W and 1% distortion at 81.9W. More importantly, in your configuration, the sub is not receiving the LFE channel (the ".1" in 5.1), so you're not hearing the low-frequency effects in movie soundtracks.

You say you prefer the sound of the sub's crossover, but your configuration is far from optimal in other ways, so I recommend that you reconsider your strategy. I would definitely set the front left and right speakers to Small in the AVR and connect its subwoofer output to the sub's LFE input. This bypasses the sub's crossover, so use the receiver's crossover to redirect frequencies below 80Hz (or 60Hz if you prefer) to the sub.

If you have an A/V question, please send it to askhometheater@gmail.com.

COMMENTS
esappy's picture
Submitted by esappy on June 27, 2012 - 8:36pm

Scott, you are saying that in Santiago's configuration that he is not receiving any LFE's. I thought if you set any of the main channels to large and turned the sub/LFE channel off that all low frequencies where redirected to the large channels? Am I out to lunch on this? Not that I would personally choose this configuration due to the amps in the receiver are now working much harder because they are supplying the lower frequencies to the front left and right speakers. I would set them to small and cross over somewhere around the 80hz standard and get that headroom back. But I guess if it sounds better to him in his current configuration and he's happy, then go with it. That's the name of the game after all.

Oh and by the way Santiago, that is a sweet setup that you have there!

Scott Wilkinson's picture
Submitted by Scott Wilkinson on June 27, 2012 - 9:54pm
I contacted Marantz to be sure, and I was told that, in fact, when you set the front left and right speakers to Large and set the subwoofer to Off in the SR6004, the LFE (".1") channel is not sent to the mains. Any low frequencies in the main channels do go to the main speakers, but not the LFE channel.
msardo's picture
Submitted by msardo on June 28, 2012 - 9:39am

I think the misunderstanding here is the difference between

Low Frequencies and LFE

What I mean is that all of the regular channels - the 5 or the 7, etc. may have a full range of frequencies. The .1, or LFE, is only low frequency effects and during movies, this particular channel is only playing when there is such information (helicopter flyovers, volcano blasts, etc.).

If I may, I believe what people forget, or do not completely understand from the outset, is that a sub is actually performing two separate roles simultaneously. First, it provides the thrilling LFE effects as I mentioned, and second, it is playing all of the lower sets of frequencies that are being redirected to it, by the AVR for all speakers set to small and for under whatever crossover(s) is/are set.

Scott - does this help?

Have I got it right?

Thanks,
Mark

Scott Wilkinson's picture
Submitted by Scott Wilkinson on June 28, 2012 - 10:04am
Yep, you've got it! Thanks for the clarification.
mailiang's picture
Submitted by mailiang on June 28, 2012 - 8:48pm

I believe what Scott was pointing to was that this particular receiver only directs the LFE channel to the sub/lfe pre-out. However, unlike the Marantz, many AVRs like my Pioneer, will automatically re-direct the LFE channel to the mains when there is no sub and the speakers are set to large.

Ian

Santeini's picture
Submitted by Santeini on June 29, 2012 - 12:13am

There are several ways to set up a sub in a home theater environment.One of it is by setting Large in the reciever and sending the speaker out of the left and right ch,to the speaker input of the sub.How ever in Oder for this to woke properly, the sub should also have out put to the speaker.With this you will able to cross over the main speaker low frequency to the sub and the rest to the left and right speaker.This type of set up ensures that there will not be any bass clash between the sub and main speaker.Unfortunatly not many manufacture allows for this type of set up.I my system i have both line level ( theater room) and speaker level(hall).The speaker level set up integrates seamlessly well with the rest of the speaker system.It is also very good set up for audio listening.I wish to set up my theater room in similar manner but my sub don't allow me to do it.Over the years I've gone through many arguments weather to set up sub to line level or speaker level, with my friends and dealer and always fine that the speaker level set up produces better over all result.

Santeini's picture
Submitted by Santeini on June 29, 2012 - 12:30am

To be very frank there is nothing unconventional about setting the sub using the speaker level.There were times where this is the only method available.Those who have listening to audio will know what I'm talking about.One more thing I'll like to share.If your sub has streo line level in and streo line level out,you could also try connecting the pre out of you left and right ch to the sub and left ,right of the sub out back to the reiciver.(your reiciver should have pre out and power in link for you to do this)
This method also produces better overall sound than a single line in sub set up.

mailiang's picture
Submitted by mailiang on June 29, 2012 - 9:01am

Using speaker level inputs for a powered sub significantly increases distortion. And although it may not be the best solution for the OP, for the cleanest sound, I would have to agree with Scott's recommendation using the line level input, whenever possible.

Ian

Matt_G's picture
Submitted by Matt_G on February 12, 2013 - 10:47am

Jonathan lines posted: "I believe the reason this sounds better for you is probably because of phase issues between sub and sat/towers when using a .LFE input."

I don't see how phase alignment could be much improved with the Op's setup. By allowing the subwoofer's bass output to overlap with the front speakers up to 60Hz (sub crossover) it seems more likely that phase distortion could occur.

Also, Av Receivers and controllers contain phase issues to a degree by allowing adjustment for speaker distance. When adding a third "front speaker" (left, right, and l/r sub)the distance setting is compromised.

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