Using sub when in stereo mode

Sparky · December 2003

Hello All,
I'm new to the forum as a result of my recent Christmas present from me to me. See below for equipment list.

As you all know the 150's are power hungry. My 140 wpc Denon seems to do an adequate job while in surround mode since the sub takes a big load of the fronts. My issue arises in stereo mode (170 wpc) which is about 80% of the time.

I am using the lfe input for the sub and all is fine in surround mode but the sub does not come on in 2 channel stereo. Do I need to rewire my sub or is there a setting in my receiver to change this?

I will be buying an amp to bi-amp the 150's soon but in the meantime I want to take a load off the receiver in stereo mode by using the sub.

Any help/advice is appreciated,
Sparky

shack · December 2003

There should be a setting in your receiver that sends a signal to the sub in 2 channel through the LFE output while in stereo mode. There is in my Denon AVR.

Sparky · December 2003

Thanks for the prompt reply. I'll check it tonight. Does this mean that the crossover will be controlled by the receiver and NOT at the subwoofer?

shack · December 2003

Does this mean that the crossover will be controlled by the receiver and NOT at the subwoofer?

No. Full range signal sent to the mains and to the SW also as far as I can tell. It appears that the LFE output becomes a pre-out in stereo mode.

Sparky · December 2003

Thanks Shack. I'll check it out tonight and let you know how it worked.

To All, this forum is AWESOME! I can't believe the quantity and quality of information available here. Thank you all for making this such a great resource.

Sparky

Sparky · December 2003

The sub is working while in stereo mode but it is barely audible. I had to crank it WAY up before it did much and then there was some hum. Any ideas?

Sparky

shack · December 2003

Even in stereo mode you need to set the sound level of your fronts and sub. While in stereo mode you should be able to go to setup and adjust the level for each speaker. Your sub level may be turned all the way down therfore you are getting little or no info to the sub. Cranking up nothing gets you a lot of nothing.

Sparky · December 2003

Thanks Shack, I'll check the level of the sub to see where it is set.

So I guess what you are saying is (300 watt sub) X (No Input) = No Output. :-)

Sparky

Loud & Clear · December 2003

There should be no difference, in terms of bass response from your sub, between stereo and "surround" modes; they're both crossed over by your Denon's preamp (I'm assuming at 80Hz). When your're in stereo mode, make sure the Denon's sub channel level isn't turned off or is set too low. If you're in "direct" mode, then you would be sending a full range signal to your mains.

Sparky · December 2003

I played around with sound level on my receiver for the subwoofer. I bumped it up 3db and noticed only a slight increase in subwoofer volume. It wasn't until I turned the volume up on the subwoofer to about 2/3 volume before it really kicked in. I normally never turn it up beyond 1/2. It certainly does respond now.

I'm curious if it is normal to have to turn up the speaker level on the receiver and sub volume that much before noticing a difference.

What's the difference between Direct and Stereo mode? Here is how I understand it. If I'm in Direct mode I will be sending a full range signal to the mains and a signal to the sub. In Stereo mode I will send only >80Hz to the mains and <80Hz to the sub.

Thanks,
Sparky

Loud & Clear · December 2003

Yeah, that's how it works with my Denon (2802). There's something wrong if you have to turn up your preamp gain & subwoofer gain so much so get a decent response. I don't know what the problem is. Like I said, stereo and whatever surround mode you are employing should net the same bass response assuming preamp gain is set to the same level. I don't understand, but maybe Doc or someone else can figure out what's happening.

Oh, the only other thing I can think of is if you have your bass turned really low on the tone control on the receiver in "stereo mode." You can change the values in each mode.

Sparky · December 2003

Loud and Clear,
I agree, I didn't think I would have to turn both up that much to notice a significant difference.

To much knowledge there is only one way to adjust the bass on my receiver and that is with the tone control knob. That setting would be the same regardless of which mode I was in. Perhaps I am missing a way to set the bass/treble for each mode?

Thanks,
Sparky

Loud & Clear · December 2003

My receiver has both "channel volume" and "tone control." Each value is remembered for each mode.

Sparky · December 2003

Loud & Clear,
My receiver is a bit older and don't think I have that feature. I'll check it when I get home tonight to verify.

Happy New Year,
Sparky

walk · December 2003

I don't know about Denon but on the Onkyos, "Direct" mode sends the unfiltered stereo signal to the front left & right channels and nothing else - nothing goes to the subwoofer at all. This is how I listen to music with my 150's and it sounds great.

In "Stereo" mode it sends a filtered (high-passed) signal to the fronts and the bass (low-passed at the xover point ie. 80hz) to the subwoofer. Just like in Surround mode, but with only 2 channels ("2.1" basically). It does the same thing in "All-channel Stereo" mode.

Sparky · December 2003

Hey Walk,
I believe that is how mine is too. I'm going to check tonight to verify. The manual that came when the unit is not good about explaining what all the settings mean. It just tells you how to change them.

Thanks,
Sparky

Loud & Clear · December 2003

Walk, I think we've established that, the problem is why isn't he getting any legit volume from his sub in stereo mode? He gets satisfactory results when in the surround modes, it's only stereo mode that's causing problems. What could it be, other than tone and channel volume controls? I'm confused by this one.

Doc ... anyone?

Sparky · December 2003

So am I.

Sparky

walk · January 2004

I'm guessing Denon's "stereo" mode is like Onkyo's "direct" mode that I described above. It just sends the un-modified stereo signal to the front left & right speakers. No bass management, and hence no LFE/subwoofer output is generated. There's no sound from the sub because there's no signal being sent to it, in that mode. You'll have to choose a different mode if you want the subwoofer output.

Alternately you can hook up the subwoofer using the high level (speaker wire) inputs, but that has a lot of (potentially negative) side effects doing it that way.

Before you do that, I would try using either a surround mode, or a DSP mode like "all channel" which should use BM and send a signal to the sub, and see how you like the sound of that.

Using sub when in stereo mode

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