Reciever Bass Management

[Nuglets]

I think I am beginning to understand something about subwoofer level control. I would like a confirmation. I have my powered towers set up with my sub out going to the line in on them with no sub anymore. I know that when my reciever is in direct stereo, it send my fronts a full range signal regardless of whether they are set to large or small(I currently have them set to small). I have my sub level calibrated with the recievers test tones for movies. When I listen to music in 2-channel stereo(very rarely) my sub channel is put to use in music, but if it is calibrated for movies I can hardly even hear it. When I increase the level to +10dB, it sounds almost exactly as it does when the fronts are getting a full range signal without the reciever's bass management(as far as 'loudness' is concerned, the sound is slightly different, which I would expect, but the 'loudness' is nearly identical). I know that Dolby's LFE channel is recorded +10dB greater than the rest of the channels to reach a maximum of 115dB in a movie. My question is, when the subwoofer channel is calibrated for movies it seams I have to add 10dB when listening to music, but I would like confirmation. I have my reciever set up that the LFE level is it at -10dB so I don't have to change anything when going from music to movies but it seams like it could cause confusion for someone, including myself, when calibrating the level of a system that doesn't have a separate LFE level control. If you rely on a separate subwoofer for all of your bass, and don't have a LFE level control you would have to mess with the sub level every time you want to switch from movies to music, which seems like a hassle to me. Does anybody know why reciever's are designed in this way instead of just automatically adjusting Dolby Digital LFE to -10dB?

I posted this in the Speaker section on accident, so feel free to delete it out of there.

 

[tbewick]

I think I am beginning to understand something about subwoofer level control. I would like a confirmation. I have my powered towers set up with my sub out going to the line in on them with no sub anymore. I know that when my reciever is in direct stereo, it send my fronts a full range signal regardless of whether they are set to large or small(I currently have them set to small). I have my sub level calibrated with the recievers test tones for movies. When I listen to music in 2-channel stereo(very rarely) my sub channel is put to use in music, but if it is calibrated for movies I can hardly even hear it. When I increase the level to +10dB, it sounds almost exactly as it does when the fronts are getting a full range signal without the reciever's bass management(as far as 'loudness' is concerned, the sound is slightly different, which I would expect, but the 'loudness' is nearly identical). I know that Dolby's LFE channel is recorded +10dB greater than the rest of the channels to reach a maximum of 115dB in a movie. My question is, when the subwoofer channel is calibrated for movies it seams I have to add 10dB when listening to music, but I would like confirmation. I have my reciever set up that the LFE level is it at -10dB so I don't have to change anything when going from music to movies but it seams like it could cause confusion for someone, including myself, when calibrating the level of a system that doesn't have a separate LFE level control. If you rely on a separate subwoofer for all of your bass, and don't have a LFE level control you would have to mess with the sub level every time you want to switch from movies to music, which seems like a hassle to me. Does anybody know why reciever's are designed in this way instead of just automatically adjusting Dolby Digital LFE to -10dB?

I posted this in the Speaker section on accident, so feel free to delete it out of there.

You should not need to make any adjustment to the LFE when switching from movies to music, this is unless you are listening to DTS sources. On my receiver, once you have set up the channel volume levels using a test disc, then no further adjustment is necessary, apart from with the DTS sources. According to my receiver manual, DTS music discs should be listened to at -10 dB LFE, whereas DTS movies should be listened to at 0 dB LFE.

Just to reiterate, apart from with DTS discs, after getting your subwoofer volume set up correctly using a test disc, then no further adjustment is required. One of the signs that you have got your subwoofer set up correctly is that the sound it produces is not noticeable. You could try looking for a CD mixed to show off low frequencies, e.g. Telarc's 1812 overture or maybe the Stereophile sampler disc. The subwoofer should add lots of kick to recent sci-fi movie soundtracks, the amount of kick just depends on its capability and sub/listener room placement.

 

[Nuglets]

So then I ask...Is it just a coincidence that when I send my fronts a full range signal without any equalization in direct stereo, then go to 2ch-stereo, which crosses-over the low frequencies and sends them to the sub-out(the same bass drivers with a different signal), they sound identical only when the subwoofer level is calibrated exactly 10dB greater than it is with movies?

I don't use a test dics to calibrate because I do not own one. I just use the reciever's test tones to level match. If I play music that has a lot of bass(ie: rap) with the speakers all matched to the same level and do an A/B comparison of direct stereo(full range signal to speaker level input on fronts) and 2-channel stereo(crossover set so low frequencies are directed to the subwoofer pre-out with my fronts connected to), the subwoofer's bass is barely audible in 2-channel stereo. If as I'm listening to the music, I boost the sub up 10dB, then do the comparison they sound very similar(almost exact).

I know what you are trying to say...and that is what I have always thought, but my experiments show otherwise. When I watch movies with the level's matched it sounds perfect, I couldn't ask for any more bass, but with music, there is none until I boost the subwoofer signal. And no, I am not the type of person who cranks up the bass just to shake my house and try to impress my friends(I listen to all of my music in Direct Stereo), I listen to many different types of music, and enjoy great speakers.

If I used test tones from a test cd, and matched the levels while using an analog input from my cd player, I would be willing to bet that music would sound great, but the movies would have far too much bass(ie: +10dB).

When I set my levels, the LFE is set at +/-0, and I match the levels(which requires me to turn the subwoofer level on the reciever to -10 while the sub level on my towers is 2 lines past minimum). I then boost the subwoofer level on the reciever to 0dB, and reduce the LFE to -10dB to compensate. Only when I do this does it sound correct with both movies and music.

This is completetly based on experimentation since I sold my separate subwoofer. I know I am being very redundant, but I am trying to stress what I have observed and give a full understanding of my setup.

 

[tbewick]

So then I ask...Is it just a coincidence that when I send my fronts a full range signal without any equalization in direct stereo, then go to 2ch-stereo, which crosses-over the low frequencies and sends them to the sub-out(the same bass drivers with a different signal), they sound identical only when the subwoofer level is calibrated exactly 10dB greater than it is with movies?

I'd guess that your main speakers and you the listener are positioned so that the mains are receiving a bass boost.

I don't use a test dics to calibrate because I do not own one. I just use the reciever's test tones to level match.

I would recommend you use a test disc as, for some reason, test tones produced by the receiver sometimes give different results. This is what I've experienced.

If I play music that has a lot of bass(ie: rap) with the speakers all matched to the same level and do an A/B comparison of direct stereo(full range signal to speaker level input on fronts) and 2-channel stereo(crossover set so low frequencies are directed to the subwoofer pre-out with my fronts connected to), the subwoofer's bass is barely audible in 2-channel stereo. If as I'm listening to the music, I boost the sub up 10dB, then do the comparison they sound very similar(almost exact).

I think that this is the same as I said above, that the main speakers are positioned so that they are receiving a bass boost. This bass boost is removed when the sub is used because it has been level matched.

I know what you are trying to say...and that is what I have always thought, but my experiments show otherwise. When I watch movies with the level's matched it sounds perfect, I couldn't ask for any more bass, but with music, there is none until I boost the subwoofer signal. And no, I am not the type of person who cranks up the bass just to shake my house and try to impress my friends(I listen to all of my music in Direct Stereo), I listen to many different types of music, and enjoy great speakers.

When I listen to music, for the most part, my sub doesn't do very much either. This is mostly because I listen at quite a low volume. On some music which is listenable at higher volumes, the sub does kick in. This is in the sense that there is appreciable low bass. My guess is that you are used to listening with a bass boost provided through your main speakers. If you're not satisfied with the sound of music, you could try further experimentation with sub placement. If you find a better position for the sub, you'll get better results in movies and music. You know, there isn't anything wrong in cranking up the sub volume sometimes. It is just a case of personal preference.

You should note that only the largest subwoofers will be able to produce good output in the extreme bass, e.g. VELODYNE Signature Digital Drive 1812 review -

"Having decided on a setting, I proceeded to throw every test track in my armoury at it. It loved everything I tried. So to push it to its limits, I pulled out a politically-incorrect CD with an illustration of some bloke holding his ears with blood spurting out of them, called Bass Boom Bottom from the extreme car scene. It reaches down to single figures in Hertz. This got chewed up and spat out whole. This Velodyne effortlessly delivers over 100dB at 16Hz.

...My only disappointment came when I had to stop playing – it transpires that the beast was preventing the entire office from doing their job. The whole building shook, coffee quivered and a stream of incredulous colleagues came in and out to experience the sheer absurd might of this signature product."

- http://www.homecinemachoice.com/cgi-bin/displayreview.php?reviewid=5448

If I used test tones from a test cd, and matched the levels while using an analog input from my cd player, I would be willing to bet that music would sound great, but the movies would have far too much bass(ie: +10dB).

You should get the same results, assuming the test tones are 'well-designed'. I use the DVD Video Essentials for setting the sub volume.

When I set my levels, the LFE is set at +/-0, and I match the levels(which requires me to turn the subwoofer level on the reciever to -10 while the sub level on my towers is 2 lines past minimum). I then boost the subwoofer level on the reciever to 0dB, and reduce the LFE to -10dB to compensate. Only when I do this does it sound correct with both movies and music.

I'm a bit confused here. What I do is to leave the receiver volume for the sub on 0 dB all the time. I'd just adjust the sub's volume control for level matching. I could be being pedantic here, but the LFE volume will only be an option on DTS/Dolby Digital. Otherwise it will be called the subwoofer volume.

 

[Nuglets]

I am pretty sure that there isn't any bass frequencies being boosted up to 10 dB, because of the size of my room. It is at least 25 x 25 x 18 and open to the kitchen and entryway. If is also carpeted, has a lot of furniture and some fabric on the walls. Also, why it sounds correct with movies, but not music until I tweak LFE and sub level isn't explained by a room acoustics problem. I feel that I have my setup as good as it can be as far as level matching and would encourage someone to try to simulate what I have explained.

With my old setup...in a very small room I had the same issue. I had my levels matched and wouldn't get much output from my sub, so I just adjusted it with my ears during music, and figured it was an room acoustics issue. This was with a Denon reciever, and a separate subwoofer that I used to own. Now in a completely huge room I am experiencing the exact problem I had in my tiny room, so I am pretty much ruling out any resonance issues causing a bass boost. Another reason I rule out a bass boost, is that my speakers are 2.5ft. from the back wall, 2ft. to the left of my left speaker and ~10ft. to the right of my right speaker. Thank you for the help in trying to explain...but everything you are telling me is what I once believed, and I know exactly what you mean...but like I said, experimentation is how I came to this conclusion. If anyone wants to try this...I think I explained it pretty well in my second post, exactly what I experienced, so try what I tried and tell me what you think. If you have any questions feel free to ask and I will clarify. Again thank you for the replies, I won't stop at that though...I am convinced otherwise.

I would recommend you use a test disc as, for some reason, test tones produced by the receiver sometimes give different results. This is what I've experienced.

Maybe this is exactly what I am experiencing.

I'm a bit confused here. What I do is to leave the receiver volume for the sub on 0 dB all the time. I'd just adjust the sub's volume control for level matching. I could be being pedantic here, but the LFE volume will only be an option on DTS/Dolby Digital. Otherwise it will be called the subwoofer volume.

That is what I mean...The LFE adjustment on the reciever is separate from the Subwoofer level adjustment on the reciever...When I initially adjust the Subwoofer level on the reciever I have the LFE level on the reciever set to 0. When using the reciever's test tones to match the levels, I must adjust the Subwoofer level on the reciever to -10dB to get about 75dB on my sound level meter. If I were to watch a movie at this point, it is perfect. The problem is, if I listen to music (in a mode that the sub is utilized, which I hardly ever do) when it is setup like this, there is no audible bass (and I don't mean not much bass, I mean I can't hear any from the listening position), just midrange and treble. So what I do is boost the Subwoofer level on the reciever up to 0(10dB greater than when calibrated), and it matches the sound that my speakers make when given a direct "full range" signal without the use of the Subwoofer pre-out. If I leave it like this, then my movies are obviously going to have far too much bass, so I go into the reciever setup and decrease the LFE(used for Dolby Digital) by 10dB to compensate for the boost on the Subwoofer level. By the way, I don't use the level controls on the Subwoofer's themselves because they are separate, and it is much easier to just set them at an equal level, then use the reciever's level control to adjust it. Also, like I said in before, the Subwoofer in on my subs are set a the 2nd line past minimum, so I am assuming that if I set the reciever's level to 0dB, it would be much louder than 75dB, even with the levels on the subs themselves all the way down. I hope this is stated clearly, all the different levels and such could get confusing without reading carefully.

I don't like boomy bass, so I can tell you with confidence that there isn't way too much bass like you are thinking. I just took a Jazz class at my University and they have a treated room with Paradigm towers and I have compared the amount of bass in a Jazz recording there vs. my house, and I know that I don't have a huge peak at any of the lower frequencies. I can tell you, however, that when I listen to it with the lack of bass when the levels are matched for movies(without messing with the LFE like I did), that there is far less bass(like I said...not audible from the listening position) at my house than at the University.

I really appreciate your help...I don't underestimate your knowledge, but I would encourage you to experiment with this. Trust me when I say that everything that you have said has been my theory until now. I was convinced it was a room acoustics issue, but in my position, where I have fronts with an optional Sub in, I was able to do more accurate experimenting than with my previous setup.

 

[MDS]

What brand and model of receiver? Not many receivers nowadays have a separate 'LFE level' adjustment as that was included when receivers did not automatically attenuate DTS soundtracks by 10 dB.

If you had to set the subwoofer level to -10 dB to get your target SPL of 75 dB then either the subwooofer is too small for that room or you have the volume setting on the sub too low. Ideally you should try to keep the receiver's subwoofer level right around zero - otherwise the 'auto-on' and 'auto-standby' features don't work too well because the signal level is so low. Try to recalibrate with the receiver's subwoofer level at zero and turn up the volume on the sub itself. If you end up turning the sub volume past 3/4 to accomplish the 75 dB SPL reading, then the sub just may be too small for the room.

With the receiver's sub level at zero you shouldn't notice such a drastic difference between movies and music as you do now, but do keep in mind that movie soundtracks often have much lower bass at much higher amplitudes than typical music so the bass will almost always seem lower with music than movies.

 

[Nuglets]

Thanks MDS, but I think you are mistaken. If I set the Sub level on the reciever to 0dB and play the test tones, it will be past 75dB, even with the levels on the subwoofer's amplifier's at minimum. It is a Yamaha RX-V1400.

Another thing...The amplifiers connected to my subs turn on whenever there is any signal to the speaker level inputs. I have Paradigm 90P's with powered subwoofers.

With the receiver's sub level at zero you shouldn't notice such a drastic difference between movies and music as you do now, but do keep in mind that movie soundtracks often have much lower bass at much higher amplitudes than typical music so the bass will almost always seem lower with music than movies.

I know some of the rap I listen to extends to very low frequencies.

 

[Nuglets]

Okay. I just remembered that I had a program on my PC called TrueRTA. It's a real time analyzer with test tones and an SPL meter. I connected my YPAO mic to my Audigy 2 sound card and used the Rives Frequency chart to chart my response. Does anyone have any idea how accurate this mic is? I set the frequency in the program to 1000Hz and set my volume so the reading in the program said 40 dB. Then I started testing at 100 Hz and went from there down using 40dB as the reference level. I came up with a graph using a spreadsheet. I guess if this is accurate...I can't rule out peaks . I do have an eq that I never really felt like hooking up...maybe I'll mess with that in the next couple weeks. School starts tomorrow and my schedule is tedious so I don't know how much messing around I can do for a while.

The program is the demo version. It has most of the useful features but the "resolution" as they call it is not as accurate. If you go to www.trueaudio.com you will see what I mean. I'm not sure how important that is.

 

[tbewick]

Okay. I just remembered that I had a program on my PC called TrueRTA. It's a real time analyzer with test tones and an SPL meter. I connected my YPAO mic to my Audigy 2 sound card and used the Rives Frequency chart to chart my response. Does anyone have any idea how accurate this mic is? I set the frequency in the program to 1000Hz and set my volume so the reading in the program said 40 dB. Then I started testing at 100 Hz and went from there down using 40dB as the reference level. I came up with a graph using a spreadsheet. I guess if this is accurate...I can't rule out peaks . I do have an eq that I never really felt like hooking up...maybe I'll mess with that in the next couple weeks. School starts tomorrow and my schedule is tedious so I don't know how much messing around I can do for a while.

The program is the demo version. It has most of the useful features but the "resolution" as they call it is not as accurate. If you go to www.trueaudio.com you will see what I mean. I'm not sure how important that is.

I think my system/acoustics are quite like yours. My sub's set at around -9 dB, and, for the most part, I don't get very much bass with music. Looking at your amplitude response chart, it could explain the problems you're having. As MDS said, modern movies can contain a lot of low bass, so setting your sub too high (above the 75 dB SPL reference vol) will make it sound dodgy. With most types of music, the low bass area isn't often used, and turning up the sub volume may make things sound better. If however, you listen to something with a varying bass line, like with a bass guitar, you'll probably notice those large room amplitude variations as changes in the volume of the notes being played.

I found this link quite helpful when I set up my subwoofer:

http://www.soundonsound.com/sos/jul02/articles/subwoofers.asp

and the link below might also be helpful:

http://www.soundonsound.com/sos/jul05/articles/qa0705_4.htm

I think it's also worth saying that a lot of modern music has a limited dynamic range, which restricts the amount of possible bass. The dominance of the mid- and treble ranges helps to increase the sound quality on low-quality equipment, like small FM radios. In fact, distortion due to compression of dynamic range is used here to increase the loudness of the music (mainly modern pop). Due the high-frequency limitations of the old academy mono format, this was also once done with movie soundtracks.

 

[Nuglets]

Good articles...I am having trouble deciding whether or not I wish to use my equalizer. I am afraid that it will degrade the quality of the sound. I don't really know how good of an equalizer it is if that really makes a difference. It is a Stageworks E231X, with 31 bands for each channel. I am also wondering how to go about fixing my peaks. Will I want to play a sine wave and adjust both channels equally while the sound is playing from both channels, or would I want to do each channel separately? If I use my equalizer I will be forced to set my fronts to large, tell my reciever I have no sub, and not use the pre-out at all. All of the low frequencies that would normally go to the sub would then be directed to Front speakers so this shouldn't cause any issues of lost material. I honestly think that this audio stuff should be classified as "rocket science" because it is ridiculous trying to get it all set up right.

 

[Nuglets]

I hooked up my EQ, got to within about +5dB on all of my peaks, and level matched everything again. I still think the bass is lacking a little bit in music, but that could be just what I'm used to. Hopefully I'll get used to it. However for the movies, excellent is an understatement. I haven't been able go crank it past -15dB because it is too late tonight. Before I did this I was cautious even going this high with War of The Worlds, probably because of the enourmous peak at 31.5Hz that is now tamed to +5dB. I am now under the impression that you are correct but will still experiment more when I have time. Thank you for the help, you got me motivated to try something new and it turned out for the better so far. I think I am going to check my frequency response at a louder volume tomorrow to see if that changes anything because I have been doing it late at night at a lower volume.

EDIT: I probably pissed off my neighbor's but I cranked up some Red Hot Chili Peppers and at louder volumes it is quite satisfying. I think I could get used to it

 

[Nick250]

I hooked up my EQ, got to within about +5dB on all of my peaks, and level matched everything again. I still think the bass is lacking a little bit in music, but that could be just what I'm used to.

Nothing wrong with tweaking the bass to your liking. Heck, your hearing may a bit different than the average person and a bump in bass is just what you need to get to baseline. Who knows. In any case, I say, set it to the level that sounds best to you and gives you the best listening pleasure.

Nick

 

[Nuglets]

Nothing wrong with tweaking the bass to your liking. Heck, your hearing may a bit different than the average person and a bump in bass is just what you need to get to baseline. Who knows. In any case, I say, set it to the level that sounds best to you and gives you the best listening pleasure.

Nick

I agree, but I really did want to hear it with a flatter frequency response. I am still waiting to really crank it up because my roommate is still sleeping. I was beginning to get used to it last night with Red Hot Chili Peppers. Obviously when you have peaks >10dB it will take some getting used to after the adjustment. I did notice a problem when I was messing around with it last night. I can't seem to use 1000Hz as a reference point because for some reason anything I do, including moving my arm, causes it to jump around, even though I'm not even close to the mic. It doesn't do this at lower frequencies so I used 500Hz as a reference point. I am also considering upgrading from the 1 octave resolution version of TrueRTA to 1/3 octave. I have a feeling it isn't entirely accurate, but probably more accurate than a Radio Shack SPL meter with Rives. I really don't know about the accuracy of the microphone either, but again I am assuming it's better than the Radio Shack version. Like I said, I really don't know but it is definitely easy to use, so if I need to upgrade the program and mic in the future, I will.

The reason I want to hear it "flat" is that I think "sensory adaptation" changes the way I hear it. If I listen to something that is wrong, long enough to get used to it, it begins to sound good. I know it's all about preference, but I'd like to hear it the way it was recorded just to know.

[EDIT] Cranked it...I am quite pleased with the results. Thanks again

 

[The Hun]

Well I'm experiencing a somewhat similar issue, however my set up is a bit different[bookshelf speakers all around], and I 've been EQ ing my subs for over 5 years, so response isn't an issue.
I need about 5db boost on the sub out on my pre/pro to achieve satisfactory bass with music sources. I used Avia, and Telarc's DVD-A for test tones. I also used RS meter, which reads incorrectly the bass frequencies below 100 hz.Technically it should read 3db less then the rest of the speakers, when calibrating with "pink" noise.
The 10db boost on DD and DTS has nothing to with any of it, as 2 ch recordings don't have dedicated LFE, which is where that boost resides. The redirected bass is independent from that, so it could be there where some problems may exists, but it would be very hard to trace it without the know how, and test equipment.