Overwhelming inexplicable bass

Discussion in 'AV Receivers & Amplifiers' started by LazyGit, Jan 10, 2012.

  1. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Firstly, I'm assuming this is an amp problem rather than a speaker problem so I've posted it here. Secondly, I hope you guys understand what I'm referring to and can offer some solution.

    A year or so ago I bought a Denon 1911 which replaced the slimline amp from a cheap and cheerful Sony HT kit (from which I still used the speakers) which is nearly 10 years old. Everything was fine until my sub started to give up the ghost. I recently purchased some B&W 602.5 S3 speakers (second hand from here) to use as fronts. I'm attempting to run a 5.0 configuration in the absence of a sub.

    What I have been experiencing is, as the title describes, ugly, overwhelming bass. Now this isn't just, 'too much bass' like the house shaking down when there's an explosion. It's inexplicable, or inexpicably loud, low frequency bass.

    For instance, during a film, a couple of people were simply talking with no other background noise. The whole time there was a thumping noise, like the sound of someone heavy walking around upstairs.

    I tried some music, namely a lossless copy of Out of Space. Everything is fine until the deep bass section kicks in whereupon it overwhelms the whole song.It's the kind of bass that reverberates in your chest. It is also out of time with the rest of the audio, slightly delayed. It occurs at quiet and loud volumes.

    I used Audyssey with 3 reference points (small room). I altered the source input levels which alleviated the problem somewhat but made the audio tinny. I went into the options and adjusted speaker settings to small all round and also tried setting the sub to LFE+Main, neither made much difference: overall bass was reduced but the ugly bass was still there.

    Obviously it's something I want to fix, I'm also worried that it could be damaging my speakers as I don't think they're supposed to produce that level of bass.

    Do any of you even understand what I'm talking about and have any ideas on how to fix it? Could it be damaging my speakers?Thanks for reading.
     
    Last edited: Jan 10, 2012
  2. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Sorry for the wall of text. I typed it in paragraphs; I have no idea why it's come out like that.
     
  3. MaturityDodger

    MaturityDodger
    Well-known Member

    Joined:
    Feb 21, 2011
    Messages:
    3,805
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    133
    Location:
    Near Slough
    Ratings:
    +604
    Is it always the same frequency? Could be that your room has a resonance there. Try moving your speakers around a bit. Particularly, move them away from the wall if they're very close (you'd want at least a foot)

    Otherwise, what's the impedance on the speakers? I've found in the past that less capable amps can cause the bass to 'boom' a lot. I think this is when they can't keep up with the current requirements of larger speakers. I wouldn't expect an AVR's amp circuitry to be up to much if the B&Ws are particularly hungry.
     
  4. PSM1

    PSM1
    Distinguished Member

    Joined:
    Dec 20, 2008
    Messages:
    26,230
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +5,404
    How are the speakers positioned? Are they right next to a wall or corner? What have you got the speakers sat on? Proper stands or on a cabinet? Do you have a full 5 speaker set of B&W or just the fronts (if just the fronts what are the other speakers?). Is the bass level the same all around the room or does it change as you move around the room? What are the room dimensions and can you describe your layout as well as furnishings etc a little more.
     
  5. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Thanks for the interest, guys.

    The low thumping noises during speech are just that and the loud bass in music and bass heavy sections of films seems to be a very narrow band right at the bottom of the register. Imagine a tone sweeping from high to low, everything is level until it gets to the lowest register when it suddenly becomes very loud and produces harmonics at higher frequencies.

    I was using a 5.1 system in that room with the same amp for close to a year without experiencing this problem. It comprised 5 small, 8 ohm satellite speakers and a subwoofer which could easily reach this low a bass tone. The centre and surround speakers are still in use, the sub is not being used and the B&Ws are front lefts and rights. B&Ws are floorstanding and are on spikes, I believe they are 8 ohm. Satellites are on various shelves. The amp is a Denon 1911. Audyssey accurately auto-detected large fronts, small centre and surrounds and no sub. Calculations were performed based on that.

    The room is small, roughly 8m x 4m but the system is arranged across the room. From memory, the distances from main position are 2.6m to FL, C and FR, 1.3m to SR and 0.5m to SL. All speakers are close to walls by necessity.Layout is difficult to describe. Imagine the room as a sheet of paper in landscape layout. There is a bay window on the right hand 4m wall. There is a chimney breast in the middle of the 8m wall closest to you resulting in two alcoves either side. The sofa is in the alcove next to the bay window. The top left corner of the room is taken up by a porch, roughly 1m x 1m. The TV is next to this porch, at an angle, facing the sofa across the room. Between the TV and the right-hand wall is a desk, in the recess for the bay window is a single seater. The centre is on a shelf under the TV, the front left is to the left of the TV, facing the sofa, at an angle, with one corner close to the wall. The right speaker is in the space between the TV and desk, 10cm from the wall, at an angle. The left surround is on a shelf in the left hand corner of the alcove, the right surround is on a table to the right of the sofa.

    Bass in general is not too loud. After calibration sound quality was excellent except for this problem. The problematic bass tones are emanating from the B&Ws so can be heard around the room but are accentuated at the main listening position.

    My thinking is that it's a result of Audyssey over-accentuating the very lowest reaches of the bass frequencies. Can you think of an easy way for me to test this? If this is the problem can you think of a way to prevent Audyssey from doing this? I may be without a sub for some time.

    Thanks
     
    Last edited: Jan 10, 2012
  6. PSM1

    PSM1
    Distinguished Member

    Joined:
    Dec 20, 2008
    Messages:
    26,230
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +5,404
    Just as a test try moving the front speakers away from the wall and into the room. I know this may not be a practical solution but would rule out the boundary effect and speaker placement. If it solves the problem you could try putting a bung in the bass ports on the speakers (could try this anyway).
     
  7. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    I could only move one speaker away from the wall and it didn't make any noticeable difference.

    I tried recalibrating with just one point but further away from the wall and out of the alcove but it hasn't made any difference to the overwhelming bass.

    It looks like the only way I can alleviate it is to put the amp in 'direct' mode. It seems like the amp is sending the subwoofer signal to the front speakers even though the crossover is set at 80 Hz and sub is set to 'no'. My speakers just can't handle that level of bass so it comes out as a mess.

    If anyone has any better ideas they are welcome to inform me.
     
  8. MaturityDodger

    MaturityDodger
    Well-known Member

    Joined:
    Feb 21, 2011
    Messages:
    3,805
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    133
    Location:
    Near Slough
    Ratings:
    +604
    I think this could be your problem.
    It wouldn't surprise me to hear that if the AVR thinks there's no sub, then it redistributes the signal that would usually go to the sub to the fronts (or maybe all 5, but your other 3 just can't reproduce it at all).

    So try lying to your AVR. Go on, it's ok to lie to machines, they're going to take over the world in the end anyway.
    Tell it you do have a sub.
    You might then want to try the fronts as 'large' to get a little more low-end, but not as much as now.
    Play with those settings and see what happens.
     
  9. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Thanks, I have tried this and I don't think it made a difference but I'll give it another go and keep on fiddling. I'll have to do it tomorrow evening.
     
  10. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Okay, setting the sub to 'on' along with some other settings changes seems to have fixed it. I guess I glossed over this when I first tried it.

    With sub 'on', fronts set to large, cross over on the fronts at 60Hz, sub set to 'LFE + Main' and LPF on LFE set to 80Hz (not sure what difference this makes) I don't have the problem any more. Although I think I am trading some of the range of my fronts as a consequence.

    Thanks for the help. Now to find a good sub.
     
  11. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    You cannot both set speakers as being LARGE and use a crossover setting with them. The crossover setting is only applicable to speakers designated as being SMALL. You are sending full range audio to your fronts if they are set as being LARGE and this is beyond their frequency handling abilities.
     
  12. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Well it is working fine on this setting. The booming bass has been eliminated.

    My understanding is that setting the speakers to large means that the frequencies for other speakers that are below cut-off of those speakers is directed to the large speakers. The large speakers would then play all frequencies down to their cut-off.

    Or perhaps it's this LPF for LFE that I've changed from 120Hz to 80Hz. Does anyone know what that setting actually does?
     
  13. PSM1

    PSM1
    Distinguished Member

    Joined:
    Dec 20, 2008
    Messages:
    26,230
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +5,404
    LDf for LFE is an upper cutoff for the sub. So anything in the .1 signal above this value will be cutoff and not sent to the sub.
     
  14. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    So your front speakers can handle full rang (20 - 20,000Hz)? Movie theatres don't even use their main speakers for full range audio so doubt your front speakers can handle it???? You can spend tens of thousands on speakers and still not have anything that can output full range audio.

    The LPF helps eliminate directional frequencies that may manifest themselves in the 20 - 120Hz range of the LFE channel. The higher a frequency is, the more directional it becomes but this is undesirable when dealing with LFE and a subwoofer. The subwoofers output should be non directional. The LPF cuts off all frequencies above it and discards them.
     
    Last edited: Jan 11, 2012
  15. clockworks

    clockworks
    Well-known Member

    Joined:
    Dec 7, 2005
    Messages:
    3,573
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    West Country
    Ratings:
    +297
    I always thought that a speaker's quoted frequency range was the frequencies that it could successfully output at a certain relative level when fed with a "flat" signal, rather than the frequencies it could handle without damage ? Signals at a lower frequency would just be rolled off, as the drivers are too small to reproduce them (at the bottom end).

    My feeling is that Audessy was boosting the low frequencies because the speakers were set to "large", but the mic wasn't picking up the low frequencies, because the speakers were incapable of reproducing them. The result was excessive bass in the lowest register/band that the speakers COULD reproduce.
     
  16. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    Correct, but why do this when you've a sub that can handle the lower frequencies much better and without it causing distortion in the mid range?

    No, LARGE just determines that your speakers are full range and are therefore sent full range audio without being filtered by the crossover. Designate them SMALL and the frequencies are diverted to the subwoofer by the crossover.
     
    Last edited: Jan 12, 2012
  17. clockworks

    clockworks
    Well-known Member

    Joined:
    Dec 7, 2005
    Messages:
    3,573
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    West Country
    Ratings:
    +297
    The OP said he was running 5.0 - no sub. With the speakers set to "large", and no sub configured, the speakers would receive the full range, like you say. Not a problem if the amp is set "flat".

    Now, you run Audessy. It's expecting to hear signals down to 80Hz or less, but nothing reaches the mic - the speakers are too small to reproduce those low frequencies. Audessy assumes that there's a room response problem, and ramps up the bass. Sounds OK with test signals, so the settings are saved.
    Play some real signals, and the bass has been boosted too much.
     
  18. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    He has no option other than to run his fronts as large if a sub is not present. The amp automatically redirects the LFE channel to your front speakers if no sub is present. Speakers designated SMALL also direct any frequencies below the crossover to the fronts in this scenario.

    Flat has nothing to do with bass management. It is a curve enacted to flatten the frequency response from all speakers in an attempt to equalise them tonally.

    Solution. Reintroduce the sub rather than have the amp redirect the LFE channel to the fronts. Set a crossover of 80Hz and designate all speakers as being SMALL.
     
    Last edited: Jan 12, 2012
  19. clockworks

    clockworks
    Well-known Member

    Joined:
    Dec 7, 2005
    Messages:
    3,573
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    West Country
    Ratings:
    +297
    So it's a shortcoming with Audessy, and the only way around it is to pretend you've got a sub?
     
  20. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    No, it is the same situation with all AV amps, even those that do not utilise Audessey. The amp has to send the LFE channel somewhere and if there's no sub then the amp sends it to your front speakers.

    The OP has a sub, but isn't using it for some reason? I suggest he uses it rather than let the amp send the LFE channel to his front speakers. He can then use the crossover to direct the problematic frequencies away from his front speakers and to the sub.
     
  21. clockworks

    clockworks
    Well-known Member

    Joined:
    Dec 7, 2005
    Messages:
    3,573
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    West Country
    Ratings:
    +297
    I understand what you are saying, and using a sub will undoubtedly solve the problem.

    I still feel that if the response was left flat (or tweaked manually), rather than letting Audessy do it's thing, then the problem of excessive bass wouldn't have arisen.

    I've used small speakers with limited bottom end response on stereo systems with with top-notch turntables or CD players, and quality pre/power amps, and never suffered from excessive bass. The natural low-end roll-off of the speakers prevented booming.
     
  22. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    As far as I'm aware, the OP is using B&W floorstanders, not "small speakers with limited bottom end"? Note thay conventional audio doesn't have to deal with the LFE channel so direct comparisons cannot be made. The only issue is that of where the LFE is being sent and the front speaker's ability to deal with it. Combine this with the floorstanders and a confined space and you are bound to have issues with bass. The lower end bass needs to be redirected away from the floorstanders and to a subwoofer. It may even be a case of more appropriately sized speakers being utilised rather than the floorstanders, but the LFE bass still needs somewhere to go.
     
    Last edited: Jan 12, 2012
  23. clockworks

    clockworks
    Well-known Member

    Joined:
    Dec 7, 2005
    Messages:
    3,573
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    West Country
    Ratings:
    +297
    I didn't realise that the speakers were floorstanders.

    So, the problem is that the amp re-directs the LFE channel to the fronts when you tell the truth about there being no sub (which is fair enough), but Audessy can't compensate for this during setup by limiting the LFE level to what the speakers can handle?

    Seems a bit daft that the only option (in the absence of a sub) is to do without the LFE channel completely by sending it to a sub that isn't there, especially if the front speakers are capable of handling some of the LFE, albeit at a lower level?

    When I set up my 3312, I did wonder how effective Audessy would be. The test tones coming from the speakers seemed to be quite limited in range, seemingly just concentrating on the mid-range frequencies for the 5.0 channels. I assumed that this was because I actually had a sub. I wonder if the test tones are different if no sub is declared?
     
  24. MaturityDodger

    MaturityDodger
    Well-known Member

    Joined:
    Feb 21, 2011
    Messages:
    3,805
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    133
    Location:
    Near Slough
    Ratings:
    +604
    For the record, here's my understanding of the various settings under discussion, as there seems to be some confusion.

    For my terminology, I'll use "audio channel" to talk about audio as it comes off the blu-ray, and "speaker channel" to talk about audio as it comes out of the power amplifier to the speaker.

    LFE: This is the dedicated '.1' audio channel for the subwoofer effects. It's not generic low-frequency audio. I don't think anybody got that wrong, but just spelling it out.

    Subwoofer on/off: When on, LFE audio channel goes to the sub speaker channel. When off, LFE is re-routed and mixed into other speaker channels.

    Large/small speakers, and crossover: For any speaker set to small, all audio below the crossover point is removed from that speaker's channel. It is mixed with the LFE audio channel and sent to the subwoofer speaker channel.

    Double bass (where available): This duplicates audio in the LFE audio channel, and as well as sending it to the subwoofer channel as usual, it mixes it into the front speaker channels (if set to large)



    So as the OP has set sub to 'on' (without having an actual sub) and fronts to 'large', he's not hearing any of the LFE audio channel. But full-range audio from the front audio channels is being sent to the front speakers. I can see why this is an improvement in bass control over what he had before, and a compromise between being too boomy (sub to 'no') and no low-end at all (fronts to 'small').
     
    Last edited: Jan 12, 2012
  25. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Thanks for the interest, guys.

    audioenthusiast, thanks for the clarifications, what you have described concurs with my current understanding and experience post-fiddling. What I didn't understand before was that the sub channel is actually just the LFE channel.

    dante01/clockworks, I'm guessing you both understand my problem and how it was resolved now. Just to clarify something based on this experience, I don't think it's the amp's fault specifically, I think it is an issue with Audyssey and its calibration routine. As I pointed out previously, when I set the amp to 'direct' the issue was no longer apparent. This says to me that without intervention, the amp will send the LFE to the absent subwoofer and the fronts (and other speakers) are free to deal with the standard range of audio.

    clockworks, I think what you have surmised is correct. That the calibration routine has decided, even though it's worked out that there's no sub, that it needs to boost the lowest frequencies that would normally come from the sub. As you say, you then need to trick it into sending the messed-up bass frequencies to the phantom sub.

    What you should bear in mind is that this problem was apparent not just with 5.1 audio but with stereo audio too.

    If you're interested, I used this guide to help me understand the settings for my Denon amp as well as the advice provided on this forum:
    BATPIG'S DENON-TO-ENGLISH DICTIONARY

    I really didn't expect to have these kind of problems. I actually thought that a lot of people might be running 5.0 set-ups because they have 5 'large' speakers and so didn't feel the need for a sub.
     
  26. dante01

    dante01
    Distinguished Member

    Joined:
    Mar 5, 2009
    Messages:
    43,770
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +10,135
    As I said earlier, even movie theatres don't send full range audio to their speakers and low end bass is always directed to subwoofers. I've listened to home theatre setups costing tens of thousands and even they designate all speakers as being small. The Sub can be done away with, but this is a compromise and you should never expect floorstanders to fully usurp the sub in a home theatre.
     
  27. sanejo

    sanejo
    Active Member

    Joined:
    Sep 17, 2002
    Messages:
    220
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    28
    Location:
    way down west
    Ratings:
    +35
    Dante is right,(as usual):smashin:. The idea of running even large floor standers"full range" is pretty much not a good idea, especially 5 of the buggers. The receiver / amplifier is going to be working awfully hard to drive such a load.
    Even a quite basic powered sub will ease the strain on your receiver / amp and generally plumb depths unknown to most floor standers.
     
  28. LazyGit

    LazyGit
    Member

    Joined:
    Jun 28, 2008
    Messages:
    26
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    "as usual"? Well he wasn't right earlier.

    I'm of course very impressed that you've listened to tens of thousands of pounds of HT equipment, dante. The fact is that you can send the full range of audio frequencies to any speaker, it will simply play the audio according to its frequency response curve. The problem I experienced was due to the amp delivering low frequencies that my speakers could just deliver but at far too high a level.

    In theory (and in practice if you see my mention of 'direct' mode above) there's no reason why you couldn't have an HT setup of 5 physically large speakers and have a perfectly adequate experience without a subwoofer. You just have to hope that your amp doesn't try to deliver over-amplified LFE and bass to them like ot did mine.

    On the matter of over-working your amp if all, or even some, speakers are set to 'large': is this really the case? If your cross-overs are set to 40 or 60 Hz then the only difference is that you're sending an additional frequency range of 20 to 40/60 Hz.

    Anyway, I agree that using a subwoofer is ideal and for me it would be preferable but, at the moment, not possible.
     
  29. clockworks

    clockworks
    Well-known Member

    Joined:
    Dec 7, 2005
    Messages:
    3,573
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    West Country
    Ratings:
    +297

    The lower the frequency, the more power it takes to generate the same sound level (SPL). If you get the chance, look at, or feel, how far the cone of a sub has to move to generate even modest volume levels. You'll probably notice the difference on the bass driver cones of your own speakers if you switch between sub on and off on your receiver.

    Sending those very low frequencies to a sub (with it's own amplifier) will remove a disproportionally large part of the load from the receiver's amps and power supply.

    That's the way I've always understood it works.
     
  30. stevelup

    stevelup
    Well-known Member

    Joined:
    Aug 13, 2002
    Messages:
    6,606
    Products Owned:
    1
    Products Wanted:
    1
    Trophy Points:
    136
    Location:
    Swindon
    Ratings:
    +1,144
    The problem with setting the sub to on when you don't have one is that you are just throwing away the LFE channel.

    Can I suggest something? Why don't you try just not using Audyssey as an experiment.

    If you go into EQ Customize and choose Manual, then select Base Curve Copy, it will set the EQ roughly using the Audyssey values as starting point. You can then back off the bass settings until it sounds right.
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice