KEF THX Sub Problem

Kebbidge

Standard Member
Joined
Apr 20, 2007
Messages
71
Reaction score
2
Points
69
Location
Borough Green, Kent
Hi Guys,

PLEASE HELP!
I've got a new set-up:
Pioneer SC LX-83 receiver
Pioneer BDP-LX54
with my existing KEF THX 5.1 speakers inc. SW TDM 45B

My problem is when i'm playing a Blu-Ray copy of INCEPTION, DTS-Mstr Audio soundtrack and with THX mode on or off, the base is so loud it distorts. I've tinkered with the LFE level but it still sounds awful.
Other movies have been ok, any suggestions?

Compatibility issue??
Disc problem??
Sub knackered??

Sounded so cr8p i stopped the movie. . . . .

All comments welcome. . . .
 
Have you played any other movies since? Just in case the sub's volume control has gone up. Keep the sub's LPF setting to max on the physical sub itself, no need to change this. On my Onkyo, there is a setting which allows you to have predefined sub woofer settings per sound encoding. If yours has the same options, make sure the setting for DTS hasn't been accidently altered.

Also, do you have any other blu-rays with DTS Master Audio encoded?
 
Hi Toadus,

Thanks for your comments!:thumbsup:

I've tried playing clips from other discs, Soloman Kane for example, but not sat through a full DTS master audio soundtrack movie yet. The sub did struggle a bit on Kane but nothing like the Inception soundtrack (example clip; as Leo Di Caprio falls into bath about 5 mins in, sub sounded like it was going to blow.. :(

In THX mode the level & crossover controls on the sub are by-passed.

The amp has an acoustic set-up (MCACC - tests are analysed via a mic) that are saved to one of 6 user presets that you can adjust. This automatically set the sub at the lowest level -12db with the other speakers between +1db and -1.5db.
In the meantime i've adjusted one of these set up's by raising all of the other speakers by 3db whilst leaving the sub at -12db. Not convinced about the results yet, more testing to come. . . .
But how can i prove where the failing is??
I don't want to condemn the sub but what else can i do??

Having spent a large wad on highly recommended THX rated, DD & DTS HD sound systems to feed my KEF THX speakers, only to abort a long awaited viewing of the latest Chrisopher Nolan movie because it sounded awful. . . . .

IT'S SOOOOOOOOOOO FRUSTRATING !!

Any other ideas. . . . .:lease:
 
Hmmm... I'm only familiar with the Audyssey setup I'm afraid. What I can say is, however, if the calibration sets your sub to a maximum alteration, (in your case either -12db or +12db) that is actually a bad thing! Ideally, you want the sub level somewhat close to the ballmark figure BEFORE calibration, so that the calibration only adjusts is by a margin within the +/- 12db range. Does that make sense?

Can you try to rule out whether it's the THX mode on your amp? Try just playing back in DTS Master Audio without choosing to add THX processing. Surely this is just the flick of a listening mode button on your remote control?

The fact that the calibration has tried to set your sub's volume to as low as it can, pretty much tells me that something ain't right I'm afraid. Are you sure your sub doesn't have a physical volume dial on the back? If it does, set it to about half way, and then re-run the calibration.
 
Hi Toadus,

Thanks again :smashin:
There's a thread re: Pioneers MCACC and it has been interesting reading but no solutions:(
The distorted bass problem is also apparent without THX mode selected however i haven't tried running the calibration with the THX speakers selection as 'NO'.

There is a vol/level control on the sub but this is disabled when the subs THX mode button in pressed.

Seems like I should do a complete non THX set-up and adjust the sub's vol/level control and see what I get. . . if it works ok then i'll need to investigate the thx set-up.....:suicide:

I'll try to post a query in the Pioneer forum too. . . .

Thanks
 
Hey.

Yes, you would be more likely to get the right answer from someone who's already 'been there and done that'. Going back to what I said earlier though, if the calibration is setting the sub to the end of either scale, it means it's reached its limit, and more than likely would need to adjust it further to get it where it should be. It makes sense that you are getting too much bass, as the calibration tool has detected that the sub's level is way too high, but the calibration is bound to a specific rule which doesn't allow it to modify the level by any more than 24db. (-12db to +12db)
 
Hi Mate,

Yeah, understood. I've made my own adjustments to compensate, raised the level of all other speakers by 3db, however, i'm not convinced this is the right solution. . . . need more time testing me thinks!

Thanks again!
 
Definitely not the right solution.

Going back to a quesiton I asked earlier, is there a physical volume knob on the sub? If so, lower it and re-run the auto calibration.
 
Definitely not the right solution.

Going back to a quesiton I asked earlier, is there a physical volume knob on the sub? If so, lower it and re-run the auto calibration.

There is a vol/level control on the sub but this is disabled when the subs THX mode button in pressed so can only use in non-THX mode.
 
I wonder if its setting is used as some sort of reference point before THX is enabled. If not, then the amp would control it entirely. Can you run the calibration again, but with a lower sub volume, so when you get your calibrated results the amp isn't trying to turn the sub's volume down my the maximum it's allowed.
 
It's just that movie:

When I went to see it at Imax I could hear it outside in the street, which considering the sound proofing in an Imax centre says it all. I also went to see the film at an Odeon cinema and it physically distorted their sub's to the point of damage (They stopped showing the film at this one all together).

I have the film on BR too and like the Dark Knight film I have to run my entire setup at a reduced volume to avoid distortions.
 
It's just that movie:

When I went to see it at Imax I could hear it outside in the street, which considering the sound proofing in an Imax centre says it all. I also went to see the film at an Odeon cinema and it physically distorted their sub's to the point of damage (They stopped showing the film at this one all together).

I have the film on BR too and like the Dark Knight film I have to run my entire setup at a reduced volume to avoid distortions.

Hi Snedie,

This is what I was hoping. . . . however having tested numerous movies i have found a few clips that the sub struggles with, for example, start of Star Wars 5 on DVD as large cruiser passes by, a michael jackson trailer on a couple of Blu-Rays.
That said, I think you're probably on to something in that the use of, what I consider, excessive/OTT bass, is becoming more apparent as technology allows for it.
I haven’t given up yet, more tests to do, but it is looking like my sub is at fault in that it cannot cope with very low, high volume bass.

Thanks for your input mate!
:smashin:
 
Hi Snedie,

This is what I was hoping. . . . however having tested numerous movies i have found a few clips that the sub struggles with, for example, start of Star Wars 5 on DVD as large cruiser passes by, a michael jackson trailer on a couple of Blu-Rays.
That said, I think you're probably on to something in that the use of, what I consider, excessive/OTT bass, is becoming more apparent as technology allows for it.
I haven’t given up yet, more tests to do, but it is looking like my sub is at fault in that it cannot cope with very low, high volume bass.

Thanks for your input mate!
:smashin:

Dark Knight has to be the worst film for OTT bass I have watched in my cinema so far, it physically distorts my surrounds which is quite ridiculous on the part of the audio engineer who thought that was clever. :suicide:

My subwoofer actually packed in a couple days ago (random fault, I don't push my system) so I'm thinking to upgrade it to the BK Monolith: Might start a thread asking if someone has one for sale...

Happy to chip in :thumbsup:
 
I wonder if its setting is used as some sort of reference point before THX is enabled. If not, then the amp would control it entirely. Can you run the calibration again, but with a lower sub volume, so when you get your calibrated results the amp isn't trying to turn the sub's volume down my the maximum it's allowed.


Hi Toadus,

Thanks again.
I have re-run (and re-run :)) with the subs THX button OFF and the subs level set to be within the amps control. The results are much improved but the distortion does still show up on the Inception clips (and a few others too :(). The sub may be at fault, more testing needed. . . .
I've tried presenting the problem in a different thread in the av-amp forum (see link below) so I probably should close this thread now. If you have time please take a look here:
http://www.avforums.com/forums/av-a...x83-thx-mcacc-kef-sub-too-loud-distorted.html
 

The latest video from AVForums

TV Buying Guide - Which TV Is Best For You?
Subscribe to our YouTube channel
Back
Top Bottom