FAQ: Denon 2500, Panasonic DMP-BD10, Panasonic DMP-BD30 "LFE Bug"
Update:
Issue is resolved on DMP-BD30 ONLY with firmware v1.6.
There is currently no resolution for Denon 2500 or DMP-BD10.
What is the issue?
The LFE channel (the .1 in 5.1 or 7.1) for PCM output over HDMI is 5db lower than it should. This applies to any tracks internally decoded to PCM or native PCM track on the disc.
What is a LFE?
The LFE or Low Frequency Effect is channel that contains frequencies below 120Hz. It is the ".1" in 5.1 or 7.1 tracks. It contains sounds designed to go exclusively to the sub woofer.
Is analog affected?
No. Analog does not appear to be affected. The output leaving the mixer is -5db but the LFE channel is amplified 5db after DAC (digital to analog conversion) so it is at the proper level.
Is SPDIF (digital out, optical out) affected?
No. This only affect PCM output on the LFE channel. PCM is limited to 2 channels (Left & right) over SPDIF. There is no LFE output to be affected.
Is bitstream output affected?
No. Bitstream output which is sending the raw compressed track is not affected. DD, DTS, DD+, TrueHD, DTS-HD, DTS-HD MA tracks are NOT affected if the player output is bitstream. Regardless of the player settings LPCM tracks are always sent as PCM so LPCM tracks on a BD disc output over HDMI will always be affected.
So if I have player set to bitstream to a compatible receiver (Onkyo-705) I am not affected?
No. LPCM tracks on the disc are output as PCM regardless of player settings. Since they are output as PCM they will be affected. There is currently no player setting to bypass the issue when playing a PCM track.
Can't I just boost the LFE channel +5db on my AVR (receiver)?
Virtually all AVR only allow lowering the LFE channel not raising it. If you AVR has a +5db setting it could compensate but I am not aware of any AVR that has such a setting. This is not the same thing as boosting the sub (see next questions).
Can't I just boost the subwoofer output +5db on my AVR (receiver)?
Not if you are using any bass management. Most HT setups redirect bass below a certain cutoff (40Hz, 60Hz, 80Hz) from main speakers to the subwoofer. Boosting the sub +5db will make the LFE channel have proper level but now the redirected bass from other 5 or 7 channels is now running "+5db too hot".
I am not using any bass management (speakers set to "large"). Can I boost subwoofer output +5db?
Yes. If the AVR is not applying ANY bass management then all bass from main channels goes to main speakers. There is no redirected bass, only the LFE channel goes to the subwoofer. The sub should be raised +5db for LPCM tracks and set to normal on all other tracks. For bass management to be turned off all speakers must be able to handle full range as main channels routinely have bass <40Hz. With bass management that bass is redirected to the subwoofer. If bass management is turned off and speakers can't handle the low frequency then sound quality will be negatively affected.
I want accurate channel balance. What can I do?
For the Panasonic DMP-BD30 download and install firmware version 1.6 or later. The issue has been confirmed resolved with firmware 1.6.
There are "workarounds" for the other two players until a fix is made available. Each has a drawback. Also if you have speakers set to "large" (full range) then you can also raise/lower SW output (see above).
On Denon 2500 ONLY lower other channels in player menu:
In player setup change all the channels except the LFE to -5b. The LFE should be left at +0db. Since the LFE is already incorrectly lowered 5db now all the channels will have the same level. The settings only affect PCM output so bitstream is not negatively affected. The overall film volume level for PCM output will now be 5db lower and can be compensated by turning up volume 5b on AVR. You can not used this workaround on the Panasonic players. While they have the level options in player setup menu they only affect the analog output not PCM over HDMI.
On DMP-BD10 ONLY use analog output for PCM tracks:
Connect the player via 6 channel analog out to AVR. All tracks except PCM should be bitstream by HDMI normally. For PCM tracks switch to analog input. The speaker distances, levels, and crossovers will need to be set in player as most AVR do not apply any DSP logic to analog in.
Is there a simple workaround to get bass response that is "close"?
While not a true fix or workaround some members have been raising SW output 2-3db. You will not want to raise SW level +5db if using bass management as this will cause SW to run "too hot". The LFE level will be correct but all redirected bass will be +5db. Setting SW level +2db or +3db is a compromise. The LFE output will be 2-3db too low and redirected bass will be 2-3 too high. Understand this is not a 100% accurate fix but rather a method to boost SW response to compensate for LFE drop without over compensating.
I don't notice this issue with my player. Are you sure it is affected?
If your player is one of the affected players then you have the bug. It isn't a player build issue but rather a design issue that affects all players of that model. Stating 100% that a player is not affected without doing a comparison to another player is not possible. If during a point in the movie the LFE channel hits 85db, then 80db will be output. A viewer has no way to know the track is 85db. Without a frame of reference how can it be determined that 80db is right or too low? It may be possible to say "it doesn't bother me", "even with the bug output is good" but saying the bug doesn't exist is simply wrong.
What about using Analog output (thanks Krisjan)?
The 6 channel analog output is NOT affected by the LFE issue. PCM tracks can be output properly over analog out. However player can not decode DD+,TrueHD, DTS-HD, DTS-HD MA tracks for output over analog out.
The analog output can be used for PCM tracks only and the HDMI output used for all other tracks via bitstream. Since the issue only affects PCM over HDMI (which isn't being used) all outputs will be accurate.
While the LFE bug is "fixed" by using Analog outputs, analog has it's own set of limitations. The largest is that analog out is only 6 channel which can not output 7 & 8 channel tracks. Most AVR can not matrix 5.1->7.1 speakers via analog input. Bass management needs to be done in the player as most AVR will not apply any logic to analog inputs. Bass management in player may not be as capable as AVR. Some AVR apply room balancing, speaker distance calculations that exceed those offered in player (Audessey processing on Onkyo). You will need to switch input on AVR for each movie (analog in for PCM tracks, HDMI in for all others).
More information on analog workaround can be found here:
http://www.avsforum.com/avs-vb/showthread.php?t=993305
Update:
Issue is resolved on DMP-BD30 ONLY with firmware v1.6.
There is currently no resolution for Denon 2500 or DMP-BD10.
What is the issue?
The LFE channel (the .1 in 5.1 or 7.1) for PCM output over HDMI is 5db lower than it should. This applies to any tracks internally decoded to PCM or native PCM track on the disc.
What is a LFE?
The LFE or Low Frequency Effect is channel that contains frequencies below 120Hz. It is the ".1" in 5.1 or 7.1 tracks. It contains sounds designed to go exclusively to the sub woofer.
Is analog affected?
No. Analog does not appear to be affected. The output leaving the mixer is -5db but the LFE channel is amplified 5db after DAC (digital to analog conversion) so it is at the proper level.
Is SPDIF (digital out, optical out) affected?
No. This only affect PCM output on the LFE channel. PCM is limited to 2 channels (Left & right) over SPDIF. There is no LFE output to be affected.
Is bitstream output affected?
No. Bitstream output which is sending the raw compressed track is not affected. DD, DTS, DD+, TrueHD, DTS-HD, DTS-HD MA tracks are NOT affected if the player output is bitstream. Regardless of the player settings LPCM tracks are always sent as PCM so LPCM tracks on a BD disc output over HDMI will always be affected.
So if I have player set to bitstream to a compatible receiver (Onkyo-705) I am not affected?
No. LPCM tracks on the disc are output as PCM regardless of player settings. Since they are output as PCM they will be affected. There is currently no player setting to bypass the issue when playing a PCM track.
Can't I just boost the LFE channel +5db on my AVR (receiver)?
Virtually all AVR only allow lowering the LFE channel not raising it. If you AVR has a +5db setting it could compensate but I am not aware of any AVR that has such a setting. This is not the same thing as boosting the sub (see next questions).
Can't I just boost the subwoofer output +5db on my AVR (receiver)?
Not if you are using any bass management. Most HT setups redirect bass below a certain cutoff (40Hz, 60Hz, 80Hz) from main speakers to the subwoofer. Boosting the sub +5db will make the LFE channel have proper level but now the redirected bass from other 5 or 7 channels is now running "+5db too hot".
I am not using any bass management (speakers set to "large"). Can I boost subwoofer output +5db?
Yes. If the AVR is not applying ANY bass management then all bass from main channels goes to main speakers. There is no redirected bass, only the LFE channel goes to the subwoofer. The sub should be raised +5db for LPCM tracks and set to normal on all other tracks. For bass management to be turned off all speakers must be able to handle full range as main channels routinely have bass <40Hz. With bass management that bass is redirected to the subwoofer. If bass management is turned off and speakers can't handle the low frequency then sound quality will be negatively affected.
I want accurate channel balance. What can I do?
For the Panasonic DMP-BD30 download and install firmware version 1.6 or later. The issue has been confirmed resolved with firmware 1.6.
There are "workarounds" for the other two players until a fix is made available. Each has a drawback. Also if you have speakers set to "large" (full range) then you can also raise/lower SW output (see above).
On Denon 2500 ONLY lower other channels in player menu:
In player setup change all the channels except the LFE to -5b. The LFE should be left at +0db. Since the LFE is already incorrectly lowered 5db now all the channels will have the same level. The settings only affect PCM output so bitstream is not negatively affected. The overall film volume level for PCM output will now be 5db lower and can be compensated by turning up volume 5b on AVR. You can not used this workaround on the Panasonic players. While they have the level options in player setup menu they only affect the analog output not PCM over HDMI.
On DMP-BD10 ONLY use analog output for PCM tracks:
Connect the player via 6 channel analog out to AVR. All tracks except PCM should be bitstream by HDMI normally. For PCM tracks switch to analog input. The speaker distances, levels, and crossovers will need to be set in player as most AVR do not apply any DSP logic to analog in.
Is there a simple workaround to get bass response that is "close"?
While not a true fix or workaround some members have been raising SW output 2-3db. You will not want to raise SW level +5db if using bass management as this will cause SW to run "too hot". The LFE level will be correct but all redirected bass will be +5db. Setting SW level +2db or +3db is a compromise. The LFE output will be 2-3db too low and redirected bass will be 2-3 too high. Understand this is not a 100% accurate fix but rather a method to boost SW response to compensate for LFE drop without over compensating.
I don't notice this issue with my player. Are you sure it is affected?
If your player is one of the affected players then you have the bug. It isn't a player build issue but rather a design issue that affects all players of that model. Stating 100% that a player is not affected without doing a comparison to another player is not possible. If during a point in the movie the LFE channel hits 85db, then 80db will be output. A viewer has no way to know the track is 85db. Without a frame of reference how can it be determined that 80db is right or too low? It may be possible to say "it doesn't bother me", "even with the bug output is good" but saying the bug doesn't exist is simply wrong.
What about using Analog output (thanks Krisjan)?
The 6 channel analog output is NOT affected by the LFE issue. PCM tracks can be output properly over analog out. However player can not decode DD+,TrueHD, DTS-HD, DTS-HD MA tracks for output over analog out.
The analog output can be used for PCM tracks only and the HDMI output used for all other tracks via bitstream. Since the issue only affects PCM over HDMI (which isn't being used) all outputs will be accurate.
While the LFE bug is "fixed" by using Analog outputs, analog has it's own set of limitations. The largest is that analog out is only 6 channel which can not output 7 & 8 channel tracks. Most AVR can not matrix 5.1->7.1 speakers via analog input. Bass management needs to be done in the player as most AVR will not apply any logic to analog inputs. Bass management in player may not be as capable as AVR. Some AVR apply room balancing, speaker distance calculations that exceed those offered in player (Audessey processing on Onkyo). You will need to switch input on AVR for each movie (analog in for PCM tracks, HDMI in for all others).
More information on analog workaround can be found here:
http://www.avsforum.com/avs-vb/showthread.php?t=993305
