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Thaddeus Smith

Question: LFE signals without a sub on mondern AVR's

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I've posed to Denon tech support, but have yet to receive a response. I'm evolving towards using a 2-in, 6-out active crossover/DSP and thinking about running my dual passive subs and 2-way mains through this device for total crossover/EQ control. I guess they'd effectively become a full range 3-way stack at that point. On modern-ish (Denon X3400h) AVR's will the LFE signal be sent to mains if no subwoofer is present and I only have 2-channel mains connected - at least as far as the AVR is concerned? Or will that content channel simply be carved off from the audio presentation unless something is connected to the sub pre-out?

 

I'm trying to determine if I can run everything through the front L/R preouts and handle via my external device for ~15Hz to 20kHz+ or if I have to keep the subs connected to my sub-preout and utilize the AVR crossover/EQ functions to playback that content. I don't yet have the device to tinker with and it impacts some of the wiring I need to purchase.

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The best shot you have is setting the sub-woofer to no and speakers to large.  You can then run some test tones through it to see what it out puts.

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i may have sufficient cables laying around to cobble together a proof of concept test. was hoping someone else with experience in this realm, cough @Chris A or @Rudy81 cough, already encountered and worked through this problem of integrating pro DSP with consumer AVR's. For reference, I'll be using the Yamaha SP2060.

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Your Denon AVR should have a configuration setting that tells it to send all the LFE sounds to the front L/R speaker pre-outs.  Basically you are telling the AVR that there is no subwoofer and your front L/R speakers are "large" to handle full-range sounds plus the LFE channel.  Then you can slice-n-dice it however you want using your digital crossover.

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35 minutes ago, pbphoto said:

Your Denon AVR should have a configuration setting that tells it to send all the LFE sounds to the front L/R speaker pre-outs.  Basically you are telling the AVR that there is no subwoofer and your front L/R speakers are "large" to handle full-range sounds plus the LFE channel.  Then you can slice-n-dice it however you want using your digital crossover.

 

I've got that super ambiguous LFE, or LFE+Main and the best I can tell is that when speakers are set to large it sends the audio content below the crossover point to both the mains and sub. I guess I'm just curious if that includes the LFE content which is it's own channel in a .1 mix. I keep thinking that they have some internal block on that content if no sub is present in order to avoid overloading main speakers.

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22 minutes ago, Thaddeus Smith said:

 

I've got that super ambiguous LFE, or LFE+Main and the best I can tell is that when speakers are set to large it sends the audio content below the crossover point to both the mains and sub. I guess I'm just curious if that includes the LFE content which is it's own channel in a .1 mix. I keep thinking that they have some internal block on that content if no sub is present in order to avoid overloading main speakers.

Yes I see what you mean.  It looks like you can set, under speaker config, the mains to large and subwoofer to none.  I'm assuming, since it forces you to have the mains set to large when subwoofer is set to none, that it will send the LFE channel to the mains but I don't know for sure.  I thought Yamaha AVR manuals were confusing.

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You will likely have to do some experimenting to find out just exactly what your AVR does.  My opinion is that if you leave out the LFE, the LFE signal will NOT be sent to the mains.  My understanding is that channel is strictly for a subwoofer, not a main. I understand the LFE+Main, or double bass which is what it is called in my unit, is a way to get the bass sent to the mains to also be sent to the LFE in order to double, or boost, your main low frequencies since subs are better at that than most mains.

 

Since you are joining the ranks of the active EQ crazies, there is a better option.  Get a second active crossover. Send the LFE signal to input one of the second crossover. Send the R and L main frequencies also to the second crossover at inputs 2 and 3.  Then, send the MIXED LF output to the subs.  With the crossover, you can limit the main signal output to just LF. You will now have the LFE and the LF of the mains going to your subs.  All, outside of the AVR.  Much easier to do that way.  Since you are dealing only with LF, you may be able to get away with just an inexpensive Behringer DCX2496. The beauty of that setup is that you will have total control of your LF main AND LFE signal going to your subs.

 

I have done the above and it works just fine.  I hope I made sense.  I may be able to help with a DCX2496 at bargain basement prices.  Unless you want to get into something more pricey like the Ashly Proea, of which I have a couple as well.

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8 minutes ago, Rudy81 said:

You will likely have to do some experimenting to find out just exactly what your AVR does.  My opinion is that if you leave out the LFE, the LFE signal will NOT be sent to the mains.  My understanding is that channel is strictly for a subwoofer, not a main. I understand the LFE+Main, or double bass which is what it is called in my unit, is a way to get the bass sent to the mains to also be sent to the LFE in order to double, or boost, your main low frequencies since subs are better at that than most mains.

 

Since you are joining the ranks of the active EQ crazies, there is a better option.  Get a second active crossover. Send the LFE signal to input one of the second crossover. Send the R and L main frequencies also to the second crossover at inputs 2 and 3.  Then, send the MIXED LF output to the subs.  With the crossover, you can limit the main signal output to just LF. You will now have the LFE and the LF of the mains going to your subs.  All, outside of the AVR.  Much easier to do that way.  Since you are dealing only with LF, you may be able to get away with just an inexpensive Behringer DCX2496. 

 

I have done the above and it works just fine.  I hope I made sense.  I may be able to help with a DCX2496 at bargain basement prices.  Unless you want to get into something more pricey like the Ashly Proea, of which I have a couple as well.

 

That does make sense, thanks. Let me finish paying for what I already have lined up and I'll go from there.. otherwise I'll just use the internal AVR functions for carving off LFE in the near term.

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Before we go too far down this trail, I looked at the AVR-X3400H. Can you tell me how you plan on hooking all this up?  Are you going to have separate amps for the mains and subs?  Are you going to just use the pre-amp section of the AVR for the mains etc?  I'm trying to get a picture of how you will be setting this up.

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L/R main preouts to the Yamaha SP2060. Then the four LF/HF outputs for those two channels to four of the five channels on my ATI 1505 for the actual drivers. Then one sub preout to my PLX1202 which allows me to bring a single signal and send to both outputs.. I currently run it that way since the subs are physically adjacent on the front stage and directly behind the mains.

 

Edit: as part of this project, I'm planning to reduce down to stereo + subs and abandon surround sound.

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1 minute ago, Thaddeus Smith said:

L/R main preouts to the Yamaha SP2060. Then the four LF/HF outputs for those to channels to four of the five channels on my ATI 1505 for the actual drivers. Then one sub preout to my PLX1202 which allows me to bring a single signal and send to both outputs.. I currently run it that way since the subs are physically adjacent on the front stage and directly behind the mains.

 

Yep, that should work just fine...in theory.  Biggest hurdle is getting good signal quality between the RCA outs from your AVR to the Yamaha inputs in XLR and then reversed again when you go from the Yamaha to the ATI amp, unless it has XLR inputs. 

 

When I started doing what you are doing, the problem that often comes up is that mixing consumer electronics with pro gear CAN, at times, cause problems due to the different voltage 'standards' of the signals in questions.  This subject gets really complex and addresses gain structure. You should read this when you have time: https://www.hometheatershack.com/threads/gain-structure-for-home-theater-getting-the-most-from-pro-audio-equipment-in-your-system.35677/#post-317665

 

IF any of the units you will be using have a high noise floor, you might be able to hear that noise in your speakers....and you are not going to like that.  I ran into that early on.  The only way to know is to plow ahead and try it out.  In no way am I trying to dampen your spirit in the project, just letting you know some hurdles may be ahead. BUT!, the effort will be worth it!

 

BTW, did you already acquire the Yamaha?

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39 minutes ago, Rudy81 said:

 

Yep, that should work just fine...in theory.  Biggest hurdle is getting good signal quality between the RCA outs from your AVR to the Yamaha inputs in XLR and then reversed again when you go from the Yamaha to the ATI amp, unless it has XLR inputs. 

 

When I started doing what you are doing, the problem that often comes up is that mixing consumer electronics with pro gear CAN, at times, cause problems due to the different voltage 'standards' of the signals in questions.  This subject gets really complex and addresses gain structure. You should read this when you have time: https://www.hometheatershack.com/threads/gain-structure-for-home-theater-getting-the-most-from-pro-audio-equipment-in-your-system.35677/#post-317665

 

IF any of the units you will be using have a high noise floor, you might be able to hear that noise in your speakers....and you are not going to like that.  I ran into that early on.  The only way to know is to plow ahead and try it out.  In no way am I trying to dampen your spirit in the project, just letting you know some hurdles may be ahead. BUT!, the effort will be worth it!

 

BTW, did you already acquire the Yamaha?

 

Thanks for the heads up. I guess I'll start with what I have planned and then adapt from there. Yes, regarding the Yamaha - Claude made me a pretty good deal on his spare that was hard to pass up.

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8 minutes ago, Thaddeus Smith said:

 

Thanks for the heads up. I guess I'll start with what I have planned and then adapt from there. Yes, regarding the Yamaha - Claude made me a pretty good deal on his spare that was hard to pass up.

 

Great!  You have a sound plan.  Forge ahead sir.  Call on me if you need anything.  I'm no expert, but I have been in your shoes. 

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Just now, Rudy81 said:

 

Great!  You have a sound plan.  Forge ahead sir.  Call on me if you need anything.  I'm no expert, but I have been in your shoes. 

 

I'm on the "just a few years behind Rudy" hand-me-down plan. :P

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Just hook everything up and play sine waves at different frequencies.  You'll see what your avr passes through.  It's not that hard.

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That would work with the normal L/R channels but I don't think that would work with the LFE channel found in movies.  

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Just now, pbphoto said:

That would work with the normal L/R channels but I don't think that would work with the LFE channel found in movies.  

If he's getting frequencies below 20Hz I would think he's getting the LFE channel.  Sine waves would let him know if the LFE is now going through the L and R ft channels.

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*** ManagementBass management allows the user to redirect low-frequency information from any ofthe five main speakers to the subwoofer; conversely, if there is no subwoofer, theLFE information can be redirected to the left and right speakers. This is important asthe vast majority of consumer home theater speaker systems require some degree ofbass management since typically none of the five main speakers is designed toreproduce frequencies below 80 Hz (i.e., satellite/sub speaker arrangements). TheDP562 provides the same bass management functions as a consumer Dolby Digitaldecoder. Even when monitoring with full-range main speakers that require no bassmanagement, this function is useful for checking how redirected low frequenciesfrom any of the main channels may interact with the LFE-channel information.Remember that the consumer will most likely use some form of bass management.Accordingly, proper bass management is necessary to emulate a consumer hometheater system. See Section 3.3 for more details

 

 

SOURCE

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I guess I thought some of you big brains would have already rabbit-holed on this topic and had a conclusive answer.

 

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