some Blu Ray LFE Bass bottoming out my JL Audio fathom subs... Something is wrong...

[gordonmenninger]

I own one of the older Sony Blu Ray players - the Sony BDP 500. It has worked fine over the years but I have noticed that on certain movies, (Transformers, etc...) during certain heavy bass scenes both of my JL subs bottom out. You can hear what sounds like "mechanical noise". The sub plays totally fine but on some "overcooked bass moments" i can hear what sounds somewhat like a popping sound in the speakers. Now I have the volume turned up to reference levels, but it is not turned up to 11!

The strange thing is that I cannot recreate this with any music I throw at the sub - just some DVDs and Blu rays. I am using the Krell S1200U as a processor.
I am starting to think that it may be the Sony player after all... I have done all of the firmware updates, but do you think that this could have anything to do with being an older 1st gen player? I am running the video through the HDMI and the audio through Coax into the Krell.
Maybe it's time to buy an OPPO? Any suggestions are appreciated!

 

[Gordon Gray]

Gordon,

Assuming the problem is with the Sony and given the price of two JL subs versus a new DVD player, seems like a no brainer to me.

GG

PS: The noise is most likely the drivers reaching full excursion and "bottoming out". Not a good thing. May have same problem with new player if volumes are set too high.

 

[gordonmenninger]

Gordon, it almost seems like some discs have some subharmonics that were not meant to be in there that are recorded at a much louder level than the rest of the program material... Maybe the Sony is screwing something up in the bass encoding department? Since this SOny player does not have the newest Dolby and DTS codecs, could it be that something is going haywire when playing the non high rez codecs?

In any case the JL should be handle it I would think given its specs...

 

[Gordon Gray]

Gordon,

Don't have the newest DVD technology. Hopefully, others will respond.

My DVD player went south 8 months ago and I haven't replaced it. 2 channel audio w/o TV seems to be my current mode.

GG

 

[robertawillisjr]

Some of these movies really test a subwoofer. Call JL and see if they have received any other complaints.

 

[GaryG]

I have the Oppo 93 and an Oppo 95 (different systems).They are great and I would say it wouldn't hurt if you got the Oppo even if the Sony is not the problem.

Gary

 

[jaandmel]

Have you tried going into your processor and lowering the LFE by -10? You could be experiencing a doubling of the LFE by having both the player and processor adding it back in.

 

[DanR]

Hi Gordon, I haven't posted here in years although I am still a member I no longer own Logan speakers, but I lurk around as I still find the site very interesting. As to your question, there is nothing wrong with your system, quite the contrary the high quality of your system is just trying to play what the what I call "brain surgeon" audio engineers making the bluray sound tracks put in the disc. Many many bluray discs have audio content that I have seen now down to 12Hz and it is not by mistake it is done on purpose. Go to the AVS forum and look at the subwoofer threads where they have graphs of a lot of the movies sound traks showing how low the signal goes. Most peoples systems do not have the ability to even pass that low of a signal on to their sub woofer(s), but yours does. I build all of my own subs and my lfe subs are 15" with 18" passive radiators fed 950 watts each, they are tuned to 17 Hz, so I figured I would be able to run them with no eq or filtering. Boy I found out I was wrong right away the remake of A Nightmare on Elm Street bottomed my subs out as well as quite a few other movies so I ended up having to utilize a subsonic filter set to 17Hz that I designed the subs to, once I added that unit (a Reckhorn B-1) the problem was solved. Your JL subs are very high quality, I would just get a subsonic filter and try it at 17 or 18 Hz and see if that helps if not move it up to 19 or 20Hz, it will solve your problem. The reason the music won't bottom the subs out is that there is almost no music out there going down to even 20Hz, the vast vast majority of music goes down to about 24-26 Hz and your JLs can handle that no problem. Nice system Gordon!!

Dan

 

[gordonmenninger]

Yes I will probably end up getting the latest Oppo player very soon...

I do not think the processor settings are incorrect as far as sub level is concerned because the bass normally isn't overpowering the rest of the audio and sounds pretty balanced...
I agree wtih Dan - I think that on certain scenes there are just too much ultra low sub harmonic frequencies mixed in and they are recorded too hot! What is the purpose? 90% of the population does not own multiple $4,000 subwoofers capable of reproducing those low thumps ! My JL's play very low and very clean at high volumes and it does not happen very often. How would you put a subsonic filter in line with the subs?

 

[DanR]

The Reckhorn unit is quite simple actually, I can only find a B-2 unit now not the B-1 they are both under $100. The B-2 is available from I believe a supplier in the UK, do a search on Reckhorn. As for how to put it in line, real simple on the back of the unit there are rca connections a L & R in and a L & R out. Simply use IC cables from your processor to the Reckhorn or other sub sonic filter then IC cables to the sub(s) from the unit.

Dan

 

[robertawillisjr]

Gordon,

Did you call JL?

 

[audvidmaster]

Dan and GordonM are both right, there is way more deep audio in a movie mix than is either necessary or desireable in a home theater. I am not a sound engineer but I have two friends who are, and have had the pleasure of being present during the mix sessions for several movies as well as various albums. The speakers and subs used in motion picture theaters are huge compared to home audio, and are designed to energize very large spaces. In theory, when a movie soundtrack is engineered for a Bluray or DVD it should be completely remixed. But that is expensive, and knowing that maybe .001% at most of potential customers have the high-end equipment which could detect that signal range, let alone try to reproduce it, there is the cynical and practical decision to just roll with it. With the vast increase in downloading and streaming rather than buying of discs, the audio will only get worse.

 

[DanR]

Hi Audvidmaster, wow your last sentence sure said a mouthful, unfortunately I totally agree with you. Also that was a very good explanation as to why the bluray discs contain the audio info that they do.

Dan

 

[rasmaudio]

Very Low frequencies

The answer is a subsonic filter with most subwoofers to
prevent overdriving at subsonic frequencies. That is what
I did with my 24" Hartley subwoofers which were capable
of response down to 16 hz, but any lower than that they would be overdriven. I utilized a Velodyne SMS-1 subsonic
filter and that took care of the problem.
But now I use a TRW-17 Rotary subwoofer and a subsonic
filter is no longer needed. This sub handles anything with
no worries of overdriving and the result is awesome.
Many blueray movies have content below 10 hz and lower.
Until one hears and feels what this sub can do, one will never
experience what it is like.

 

[Hocky]

I have never been able to make my decent run out of travel on any of those movies. That concerns me - I was considering swapping to a jl sub or two.

 

[robertawillisjr]

A subsonic filter seems to be needed. BUT, I would also contact JL and then try a different amp as there may be a problem that a subsonic filter would mask.

 

[Hocky]

Did you ever find a resolution to the issue? I should've listened to your problem and not bought JL. I grabbed a JL F212 and it bottoms out HARD on the very low frequency stuff in the opening credits of transformers 2. The sub is barely at 25% on the gain dail. This is pretty damn disappoting for a sub that is MSRP $6000. My Descent NEVER would bottom out in that same scene and would move plenty of air at that frequency to shake everything. Blah.

 

[gordonmenninger]

Hockey, I am not sure if there is something wrong with one of my subs or if I may be just overdriving them with subharmonic material. I have contacted JL who have been great to work with and they have suggested shipping the sub back to them which I may or may not do...

 

[Jungle Jack]

It pains me to think of the Shipping Costs and risk of Damage. Provided it is working fine, perhaps selling it and going with dual Descent i's might work? I am actually using a Descent i and a Depth in my HT and it sounds far better than I thought it would as I am using different Subwoofers. I really think Audyssey XT32/SubEQ HT greatly assisted the integration.
Cheers,
JJ

 

[Hocky]

Hockey, I am not sure if there is something wrong with one of my subs or if I may be just overdriving them with subharmonic material. I have contacted JL who have been great to work with and they have suggested shipping the sub back to them which I may or may not do...

I called them, too, and they were very fast to respond. They assured me that the F212 should NEVER bottom out and that I may have an electronics problem. He is going to call me today and follow up, but I am sure it will end up with me sending it back for probably the low cost of $300 in freight.