Confused about how an ICBM works (1 Viewer)

[Kevin_W]

In trying to understand exactly what the ICBM does and if I can use it in my setup, I have a couple long winded questions that I will explain the best I can. First, in the most simplistic of terms, I understand the ICBM to allow its owner to filter unwanted bass frequencies from any of inputs you use on it. Thus eliminating a potential 20hz signal from hitting, for example, your center channel. I also understand that using the ICBM and your 6 channel inputs on the receiver is all an analog process and the receiver will just pass whatever it receives on to its amp section thus bypassing any bass management on the receiver. That is what I understand and please correct me if I'm wrong.

Now here is what I don't understand. For someone like me who does not have any full range speakers but rather a dedicated subwoofer hooked to the receiver's LFE output, will this ICBM be a benefit to me if I get DVD-a? The reason I ask, is that I have yet to understand how the analog subwoofer *in* of the 6 channel inputs gets routed to the LFE output. Is this what's happening? Is it just the natural design of the 6 channel inputs that the receiver actually routes the subwoofer in to the digital domain of the LFE output? Is that how I'll get bass from my DVD-a disc's?

Sorry for what is probably a stupid question, but I really have been fighting with this scenario since I keep thinking that there is no digital processing of any input of the 6 channel inputs and thus no bass signals will get to my subwoofer via the LFE output (and no bass for me as result).

Thanks in advance!

Kevin

 

[Butch C]

Well an InterContinental Ballistic Missle is a multi stage rocket propelled out of the earths atmosphere tipped with one or multiple warheads and guided to drop directly down on a predetermined target. On the ther hand a cruise missle is...oh...I must be talking about something else.

 

[Chris Zell]

I'm a little confused about your question - I read it a few times, and I'm not sure I understood exactly what you were asking. Anyhow ...

Here is what the ICBM does: You set the cuttoff freq. of all the 6 possible channels. The low pass of all channels is summed WITH the LFE input signal (which is wired from your pre/pro or DVD-A player sub output) and routed to the sub outputs (can be stereo or mono). This is done in the analog domain. Since you have small speakers, this is great for you. They don't get any low bass that can cause distortion, and overdrive them. The sub(s), which can much better handle it, and are hopefully mpre optimally placed for bass, play most of the lowest stuff.

This is essentially what most receivers and pre/pros do, only in the digital domain. The ICBM gives you the ability to do bass management for DVD-A discs, which is not possible in any of the pre/pros I'm aware of. If you put it before your preamp, the ICBM sends all the bass to the .1 input of the preamp, and straight to the sub output.

Or you can use the the ICBM like I do - as an additional crossover after the preamp. I have the mains set to large on the preamp (so all the bass goes to the main preamp outputs), and the ICBM is my crossover for these main outputs. The highpass section goes to my mains (which are bookshelf speaks on stands), and the lowpass section goes to a digital parametric EQ to tame the bass resonant peaks. Didn't want the have the digital unit in the signal path of the mains - not another AtoD and DtoA path, so I neede the ICBM to allow that. Works fine for the bass - can't tell the extra conversions are there.

Did that help at all?

Cheers,

CZ

 

[Kevin_W]

Thanks for the reply Chris. Sorry for the lousy post... I always seem to have a hard time conveying into words what I am thinking and tend to use about 1000 words to ask a simple question.
Based on what you wrote, I think you've answered my question. What I wasn't sure about was how the bass passed from all 6 channels and arrived at the receiver's LFE output. I kept getting hung up on since its an analog input the bass doesn't get routed to the LFE output like it does from a digital input. Thanks for the help!
Kevin

 

[Philip Hamm]

I use my ICBM the same way. It's between my Pre/Pro and my amplifier in my separates set-up, handling all bass management chores. Speakers are set to large on all channels from all inputs. It allows me to run different crossover frequencies for different speakers, which I find really convenient.

By the way, the ICBM is a really sweet piece of gear IMHO. I love it.

 

[RobG]

I was curious about this unit as well. So you can set different levels for all speakers? Like if you have large mains that can handle more bass than say your surrounds and center? Does the adj. level on the ICBM for the sub conflict with the adj. built in to the sub?

 

[RobG]

After looking at it on the Outlaw site, it states its used for DVD-A or SACD, neither of which I use, so disregard my questions, thanks.

 

[Philip Hamm]

Rob,

DVD-A or SACD is not required for the ICBM. As I said in my post, I use it for all my speakers all the time between my preamp and power amp. It works great this way. I have my main L/R speakers crossed over at 60Hz (surprising, they sound much better than 80 which is what I expected to use - I think I have a bass hump from my mains at around 70), my center crossed over at 100Hz and my rears crossed over at 80. It really works best for my room.

It does not interfere with the crossover in the sub as long as the sub's crossover is set to a level above the highest setting selected for any speakers in the ICBM. For

 

[RobG]

Philip, thanks for the info. Maybe I will look into it after all. How is the new pre/pro/amp sounding with some break-in time? I only got in a few hours of time on my amp before taking my rec. in for warranty repair

 

[Kevin_W]

I have another question - but I will be more clear this time
When it comes to DVD-A soundtracks, how much do they write to the .1 LFE channel? If I understand everything I've read in this thread correctly, without full range speakers all around or an ICBM, the only *good* bass I'll get is whatever is written to the LFE track.

 

[Philip Hamm]

Rob,

Sounding better than I expected and still getting better every day.

Kevin,

In my very limited DVD-A experience, full range signals including bass drum and bass instruments are being routed to the five main speakers and the LFE is used very sparingly. This agrees with the extensive DTS audio experience I have. Without the ICBM I was missing a great deal of DVD-A and DTS CD soundtracks with my bookshelf mains. And naturally the high resolution stereo tracks are two channel full range. Without an ICBM or large mains, lots of bass is missing.

 

[SkiingNinja]

* Get DVD-A
* Get Blue Man Group - Audio
* Play loud
* Blow woofer in main speaker
* Buy ICBM
* -->

 

[Steve Morgan]

Phillip, you say it sounds great with the ICBM so there is no problem with out being able to set speaker distances? Are your speakers equal distance from your listening position? Just curious,I am thinking about the ICBM. I have a Ref 30 which has adjustable crossover but it is global and I would like to be able to set the crossover on each speaker but with out time alignment I wonder how it would muddy up my sound.My speakers are not equal distnace from listening position. Any thought?

Cheers,

Steve

 

[Philip Hamm]

I don't worry about time alignment. My speakers are not equadistant. That is a legit concern. The ICBM gets confused by time aligned signals.

 

[Scott Merryfield]

It works great this way. I have my main L/R speakers crossed over at 60Hz (surprising, they sound much better than 80 which is what I expected to use - I think I have a bass hump from my mains at around 70), my center crossed over at 100Hz and my rears crossed over at 80.

Philip,

Is my memory failing me? I thought you had B&W 602 S2 speakers across the three front channels? If so, do the 602's seem to handle bass down to 60Hz well?

I'm curious, since I am trying to decide on a new receiver. Since the Denon 4802 requires that all channels be set at the same crossover, I figured I would have to settle for 80Hz for my setup -- 604S2 mains, LCR6S2 center and 602S2 surrounds. If the 602's can handle 60Hz frequencies okay, I may have to rethink my choices.

 

[Michael R Price]

So the ICBM is just a 6 channel active crossover with a mono-summing capability for the sub? Or, is there some sort of additional capability?

And what is meant by 'confused' by time-aligned signals? I would assume that if you have a time-aligned system the ICBM would mess up the time alignment... but how could such a signal confuse it?

 

[ling_w]

The ICBM allows crossing from center to main, surround to main, and then main to sub, all at different freq. This way, you don't have to have cross over your main at the same freq as your other speaker that has the least amount bass. You can also have the sub duplicate the bass in the speakers producing the bass.

 

[Philip Hamm]

Is my memory failing me? I thought you had B&W 602 S2 speakers across the three front channels? If so, do the 602's seem to handle bass down to 60Hz well?

It's my room. When I crossover the 602s at 60 the whole system sounds much more balanced than 80. However, I have no such hump on the location of the center and rears. Having them crossed over at 80-100 sounds great. (with 70's quad mixes with plenty of those freq's in the rears)

 

[Chuck Kent]

Ling: I'm confused. The bass management you outline does not matchup with my experience.
I'm running an ICBM in my system and the normal crossover setup is center to sub, surrounds to sub and mains to sub (and of course, the sub also gets it's own signal from the .1 signal.) The alternate setting is to have the mains receive the same bass as the sub's bass.
Just curious...

 

[BruceD]

Michael,

Time alignment (typically called delay) is used to synchronize the arrival of sound at the listening position when all speakers are not exactly equidistant from the listening position.

So for instance, if the center is in a straight line with the mains (instead of back a foot or so) or the surrounds are closer than the mains, time alignment is used to adjust the arrival of sound to match that of equidistant speakers.

If you re-direct bass to the sub that has been adjusted with time alignment, the ICBM won't pass this correctly. It may cause frequency peaks and valleys or other anomolies that you may or may not notice.

Recommendations when using the ICBM for DD/DTS bass management is to have all speakers exactly the same distance from the listening position and all delay turned off in the DD/DTS processor.