LOTR Backfiring!

Hello

I have come across a problem with my LFM-1 that I was wondering if any of you have experienced.

First of all my setup:

950/770 combo
LFM-1
Onix Rockets 850 mains, rs 300 surrounds, rsc 200 centre, MK 250 rears
Marantz DV 8400

I have my speakers all set to small with crossovers all at 40. The LFM-1 crossover is cranked all the way to 160 to bypass and the sub volume is just over half way. My 950 volume is between -15 and -20.

I have only noticed this with movies so far and not with music. As far as movies go it has happened with Das Boot and LOTR-movies with some serious bass and dynamics.

It seems on passages with heavy dynamics (bass etc) I am getting a terrible sound almost like an engine "backfiring". It sounds like the LFM-1 can't handle these passages at all and is "bottoming out" ! The problem obviously goes away when I turn down the volume but I thought -20 was reasonable for a movie.

I am disappointed to say the least as even my old Paradigm sub did not experience this.

Am I doing something wrong-in my settings? Or is LOTR too much for any sub at this volume?

I played some music after the movie and the sub seemed to be fine. Hopefully I did not damage it.

Your comments and/or advice would be appreciated.

Thanks in advance.

What is the trim setting for the sub in the 950?

definitely sounds like a level setting

different sources/sound mixes

i come across the same type problem(different sub) changing sources.

i'd say get use to using the sub trim on the 950 remote.i programmed a macro in my remote to take me right to sub trim for my 1050(aftermarket remote)

Keta and Paintload

My trim level is set at 8 dB

Hope that helps

I had the same thing happen with an HSU Research VTF2 MK2. It really sounded like the thing was bottoming out. Or like it was working too hard to keep up with the rest of my system. So I exchanged it for a VTF3 MK2. (Larger driver and more powerful amp.) Now I am able to keep the volume on the sub turned down (trim on my 950 at 0) and it appears to be working seamlesly with the rest of my system. Since the exchange, it has not "botomed out" once.

My dealer hooked up th VTF2 to one of their systems and it seemed to work just fine on the same passages that bottomed it out on in my setup. So the only conclusion that we could come up with is that it was not properly sized for my setup / and theater environment.


Later,
Simp

One other thought comes to mind. Is your sub in an ideal location? Or did you put it in a less than ideal location and you turned up the trim/volume to compensate? Volume at "half" and trim up at 8 sounds pretty cranked up to me. But I ges that all depends on your setup and theater environment.


Later,
Simp

sraber brings up a good point.
you could be overcompensating for less than ideal sub placement.
i think, back it down,see if the sound quality clears up,should be able to play deeper also(with headroom)although not as loud
then start experimenting with different placement of the sub
then start pondering on a second sub
i just think you are overdriving,most likely there is nothing wrong

how big is your room?are you like me, a major bass head, and like to push the limits?

dannic:

"I have my speakers all set to small with crossovers all at 40. The LFM-1 crossover is cranked all the way to 160 to bypass and the sub volume is just over half way."

you can also try setting the subs x-over to the same as the 950's,before i smoked my monitor subs amp i preferred the subs sound this way vs. the "get the subs x-over out of the way/bypass"

which may work for some but not for me!

now i have a 100wpc receiver pushing the sub drivers coming off the 1050's lfe using only the 1050 bass management,it's real easy to overdrive the sub trying to get that extra oooomph!!

Paintload and Sraber

Great points-my sub is probably not in the ideal location. Placement was based on WAF and not for best bass response.

It is obvious now I should play with my settings. It looks like I had it too hot so I will definetely be experimenting.

Its also reaasuring to know that others have had similar experiences and its most likely not a fault of the LFM-1.

I will certainly be trying your suggestions. Many thanks for your time and input.

There are a few things going on here.

First, your crossover settings are WAY off, and that could certainly be causing some standing wave issues. I know your mains are full range speakers, but try the crossovers across the board closer to 80hz. I think you'll find it smooths out the sound quite a bit. Your surrounds, for example, are rated to 60Hz. Your crossover freq. should be a min. of 10hz above that point--and possibly higher. Even the fronts are rated to around 35hz, which means your crossover needs to be the 60hz setting. However, even at 60hz you're likely to get some odd issues between the bass produced by the front mains and the sub. You'll have to experiment a bit, but 80hz is likely your best bet for all speakers.

Second, I've had similar problems with my Definitive Technology sub, specifically with the first LOTR movie. What was happening is that I was experiencing a huge null at around 40hz, so I was pumping up my sub to compensate. However, that created a huge peak (15 or more db) at 50 or 60 hz. So when movies were loud (they can reach 100db when calibrated properly), certain frequencies were way above that point--clearly greater than almost any sub can handle.

The solution was twofold--evening out the crossover frequencies, and moving the sub. The combination of the two eventually eliminated most of my standing waves (I still have some nulls, but they're not nearly as bad), and I made sure I calibrated for the loudest frequencies, not the quietest. Then, I tested with a number of movies, and made the final adjustment by ear, making sure that movies with the loudest bass (LOTR, Star Wars AOTC first scene) didn't overload the sub. So now, for example, the tank-tapping scene in Finding Nemo is impactful, but not as earthshaking as it could be, but the spaceship in AOTC doesn't distort, either. You have to find a balance in an imperfect system.

I used to get the bottoming out from the THX logo, as well, and in some of the heavy bass scenes in Eternal Sunshine of the Spotless Mind. Now, properly placed and calibrated, the sub sounds great, and I never bottom out. I hope this helps.

Quote:

I have my speakers all set to small with crossovers all at 40. The LFM-1 crossover is cranked all the way to 160 to bypass and the sub volume is just over half way. My 950 volume is between -15 and -20.

I thought that as long as you have Bypass selected on the LFM that it did not matter what you have the crossover selected to (on the LFM). Am I incorrect?

I think he is saying 40hZ is set on the 950 and the sub is set at 160hZ to bypass it's crossover.

You are correct, wingnut - in order to disable the LFM-1's internal crossover, you should set the "X-OVER" switch to "BYPASS" rather than "ACTIVE". At that point, the position of the crossover control is no longer relevent since the circuit is being completely ignored.