Outlaw Audio ICBM-1 Integrated Controlled Bass Manager 
Home Theater Accessories Accessories
Written by Richard Elen   
Thursday, 01 August 2002

Introduction
A look at Outlaw Audio's website makes it appear that the company's avowed specialty is audiophile quality at mass-market prices. If the ICBM-1 bass management system is anything to go by, they’re good at it. The unit costs a mere $249 and does a very important job very well for those who need bass management, as many readers are.

But before we get a look at the unit itself, let’s consider bass management and why you probably don’t have something like this unit already. Modern digital audio distribution systems like DVD-Audio and Super Audio CD offer six channels of audio, all of which are full range – they can go from DC to somewhere like half the sample rate. Even a regular DVD-Video disc can handle full range audio on five out of the six channels: the “.1” in a 5.1 system is the so-called “Low Frequency Effects” or LFE channel. In the case of Dolby Digital (and some DTS systems) the highest frequency the LFE can carry is limited to around 120 Hz.

You may be lucky enough to have a room full of full-range speakers, but most people aren’t, and as a result, we have to put up with at least a couple and quite often five smaller speakers, which can’t handle all the bass that might come along. Indeed, the other speakers might even be damaged by it, and you certainly would not hear the bass very well. The answer to this dilemma is to add a subwoofer – a special loudspeaker deliberately designed to handle bass frequencies alone.

So what do you do with the subwoofer? Hook it up to the LFE? No, you do not. That way leads to disaster, because the LFE is NOT the sub-woofer channel. What you do is hook your equipment up to a bass management system. In a nutshell, what a bass management system does is to insure that whatever channel bass information comes in on, the bass is fed to speakers that can handle it. This of course includes bass present on the LFE.

As an aside, it should be pointed out that the LFE is a holdover from the days of analog cinema surround systems, and it’s designed, as the name says, to handle extra-low bass effects, such as you might find in disaster and action movies. These really don’t exist in music, and even if they did, with a modern DVD-A or SACD capable of handling any bass signals that might exist on any channel, the LFE is a bit redundant. This is why record companies like Telarc and Chesky use it for something more fun, namely height channels, which are actually mastered for speakers positioned above your left and right main speakers.

Now, every Dolby or DTS decoder – whether it’s in your player or your receiver or preamp – includes bass management, It is mandatory. But if you have a six- or seven-channel analog input on your receiver or preamp for high-resolution players, these will bypass any bass management in your receiver or preamp. And if you have a six-channel analog output on your DVD-A or SACD player, this may bypass any bass management in the player, too – even if the player also handles DVD-V discs and has a bass management menu associated with any built-in surround decoder! This means that when you sit down to listen to an SACD or DVD-A, all your bass management might as well not be there.

Installation and Setup
This is where Outlaw’s ICBM-1 comes in. This long, thin (1.76 x 17.6 x seven-inch) unit goes between your DVD-Audio or SACD player’s analog outs and the special analog ins on your receiver or preamp – or, more usefully, between your preamp and power amp. It pulls the bass off channels that will be fed to speakers that can’t handle it and feeds it to channels with large speakers, or a subwoofer, or both – with more control than you could have dreamed of. This is a pretty vital function, basically consisting of a bunch of high-pass filters feeding your regular speakers, paired with an equivalent set of low-pass filters to drive the sub and/or other bass-capable drivers.

My existing setup has a Sony CE-775 SACD player and a Kenwood DV-5700 DVD-Audio player feeding their six respective analog outs into a homemade switch box and, from there, into the receiver. I inserted the ICBM between the switch box and the receiver ins with another six interconnects, and plugged its little 15v wall-wart into a socket switched by my receiver. This unit can also handle a seventh (center rear surround) channel. If you are using such a system and have a separate pre and power amp, you’d place the ICBM between the two; in my case, current hi-res audio players only output six channels.

The next thing you need to do is to insure that you aren’t doing bass management twice. The Kenwood doesn’t have bass management on DVD-A playback but it does when I play back DVD-V, and I am only using its analog outs (so I can’t ignore the bass management that’s involved when playing a DVD-V). The Sony SACD player, on the other hand, has quite a good bass management system.

What you do now is disable any bass management that might be present, so that the ICBM gets to do all the work. The CE-775 has a “direct multi-channel out” mode, disabling any bass management, which is exactly what’s required here. The Kenwood, however, does not offer such an option. If you have a Kenwood or other equipment lacking the multi-channel out, go into the speaker setup menu for the player and tell it that all the speakers are large (i.e., they can all handle bass). It doesn’t really matter whether this setting allows you to say that there is a subwoofer on the system or not, because the ICBM is going to pull low-end information from wherever it exists. So if your player doesn’t let you turn on the sub when the front speakers are large (some do, some don’t), don’t worry.

The ICBM is what would have been called in an earlier time a “multi-channel crossover,” meaning that it is able to redirect incoming signals below a certain frequency and send them somewhere else. Looking at the front panel of the ICBM, we see a set of four identical knobs, which determine the frequency at which this happens for each left/right front, center front, left/right surround and center surround (if you have one). There is a slight difference here: the left/right front control determines below what frequency sound is fed to the sub; for the others, the knob sets the frequency below which sound is sent to the sub or the left and right front speakers (more on this in a moment). There are two further controls: “LFE Mix,” which sets the level of the LFE (not the sub) relative to the other signals, and “Subwoofer Level,” which sets the level of subwoofer output feed (not the LFE).

On the rear panel, among the forest of gold-plated RCA connectors, are three switches. One determines whether you have mono or stereo subs. The common wisdom is that bass is not directional, but it sure behaves like it is sometimes. As a result, it is often helpful to use a pair of subs mounted left and right. If that’s to your taste, you switch this switch to stereo and plug the two subs into the L and R outputs. An adjacent switch determines the slope of the low-pass aspect of the crossover (the part that drives the sub), either normal (12dB per octave) or “special,” which is a sharp 36dB/octave low pass for some subwoofers that prefer a steeper crossover, notably THX-certified subs. Unless you have one of these subs, “normal” is fine.

The final switch, up at the other end, is confusing, but as the manual points out, the fact that it needs to be thought about a bit is completely outweighed by its usefulness. It’s called “left/right recombine” and, when it’s on, it redirects bass to the front left and right speakers. So if you don’t have a sub, you would set this switch to “on” and set the left/right front crossover frequency to “bypass”. If you do have a sub (I do), you try out listening to the system with the switch both on and off and see what works best. With this switch on, the front left/right crossover frequency determines what goes to the sub (set the frequency to “bypass” and this means nothing at all: it all goes to the front left and right instead).

As far as setting the crossover points is concerned, the optimum frequency will depend on the bass handling capability of your speakers. If you know the 3dB-down point of your speakers, the manual suggests that you add 10 Hz and set the crossover to the next value up from there, which is a pretty good rule of thumb. If, for example, you know your speaker’s response is –3dB at 55Hz, say, you add 10 (65Hz) and set the crossover frequency to the next setting up, namely 80Hz. If you don’t have access to that information, or if it’s not terribly meaningful, there is a handy chart that correlates speaker size to the optimum setting. Basically, the larger the speakers (i.e., the lower the bass they can handle), the lower the best crossover frequency setting, from 120Hz for little satellite speakers to bypass or 40Hz for tower speakers with massive drivers. In the final analysis, you listen and tweak. The main thing you’re listening for is a smooth transition from high to low frequencies, and the best possible bass definition – and, of course, no distortion.

Listening Tests
All of the above also applies to the LFE Mix control. Remembering that the ICBM controls the level of the LFE coming in from your player, you can turn this down if the extreme bass effects are too much (but the rest of the bass sounds good). It does not mess with the tonal balance of your system, so you can simply set it as you like. Just make sure that you are adjusting to something that’s actually on the LFE – T.Rex footfalls in “Jurassic Park” do this job admirably. Bass synth on your favorite rock surround album quite likely isn’t (or at least shouldn’t be) present on the LFE, so be warned.

The tricky one is the Subwoofer Level control. I would say do your adjustments playing back a test disc and adjusting the subwoofer level knob accordingly. I assume that your sub level is already set up about right for Dolby Digital or DTS, so you may want to avoid messing with the levels in the receiver or on the back of the sub itself, and just tweak this knob on the Outlaw until bass elements sound nicely in balance. In my experience, test tones are not much use for this, so play back something that you know. If you have a DVD-A player with a DTS decoder in it as I do, and you regard your regular system as being set up correctly, you could do this: play your fave surround bass experience (you know mine: it’s “Cloudbreak” from Alan Parsons’ DTS remix of On Air), while listening to the digital output from the player hooked into the DTS decoder in your receiver, thereby bypassing the Outlaw. Remembering how that sounds, compare it to listening to the six-channel analog outs from the player (using the player’s on-board decoder) going through the Outlaw. In my case, that’s just a matter of switching the seven-channel input on (overriding the previous selection) and then turning it off again. Adjust the sub level knob on the Outlaw until the output sounds similar to the other version. Just bear in mind that the Outlaw is likely to be a lot better at bass management than your receiver and allow for that.

By all means, try sweep tones and even sound pressure level meters, but be warned that there are enough factors around at the bass end to mess up measurements of this type. For example, I tried the sweep tone that is on the Chesky Ultimate DVD Surround Set-Up Disc, which is actually designed to locate rattles in your speakers and other parts of your room. I set up a sound pressure level meter and ran the test, and while I could adjust the settings on the Outlaw until I got a reasonably stable level all the way up, you could still see all manner of wavering as the tone went past room resonance. When adjusted for the flattest average SPL, it didn’t sound particularly flat at all.

I had much more reliable results adjusting the settings while listening to music. The “Real Bass” (guitar) test on the Chesky disc was helpful here, and I then went on to try a number of other DVD and SACD sources. The cannons on Telarc’s 1812 sounded very similar on both the DVD-A and SACD versions, which they had not done previously, because my SACD player has its own bass management but the DVD-A player doesn’t. With the Outlaw, both were handled the same way, and both sounded great. The Outlaw has sophisticated crossovers for each part of your system, providing much better control than the somewhat basic approach on the Sony CE-775 (though the fact that it has bass management at all is a good selling point for this budget player). It is, of course, a great deal better than the nothing that my DVD-A player offers.

I played Linn Records’ new SACD multichannel release of Poulenc’s Concerto for Organ. As I expected, the organ pedal notes in several sections of this interesting work (I’ll be reviewing it shortly) came across very smoothly, without distortion and with nice definition. I am currently playing with the tiny little Sunfire Super Junior sub, which is quite an astonishing beast with a remarkable low bass extension, and the Outlaw handled it beautifully.

On to something more contemporary, I played some tracks from the DTS soundtrack on the Eagles’ Hell Freezes Over DVD-Video, which I acquired recently. My friends at JBL have used this as a trade show 5.1 demo disc for years, and it was great to hear what I’ve been missing: it’s a great performance, beautifully recorded and mixed by Elliot Scheiner. The bass parts, and the entire bass end of the audio, came across perfectly, with excellent definition and a smooth crossover from the mains to the sub.

I actually tried a number of different combinations of the L/R Recombine and Front L/R crossover settings. My JBL 4311 front mains have woofers with 10-inch voice coils, which according to the manual can be crossed over as low as 40Hz. This indeed works fine with Recombine Off: bass frequencies below 40Hz go to the sub, and the Sunfire especially had a great time with that. However, with Recombine On, the bass below the crossover frequency goes to the sub, but the front mains still get a full range signal unless the crossover for them is set to Bypass. Here I had the smoothest results with the front mains crossed over at 80 Hz – again, as suggested in the book, the bass was now being split between the mains and the sub.

Next, some movies. Although the main use of this unit will be for listening to hi-res music from DVD-A and/or SACD, if you decide to use your player’s analog outputs for everything, then you’ll be playing movies through the box, too. I checked my usual favorite, "The Fifth Element" (Columbia/TriStar Home Entertainment), and got what I expected: great bass handling in the rumbly bits. But I also went on to check out "Stargate," especially Chapter 8 with its powering up of, and transition through, the Stargate for the first time. The sound was impressive and, moreover, the bass was not out of balance. The Outlaw ICBM is likely to be a lot more sophisticated than any existing bass management in either your receiver or your player. It’s easy to get loud, rumbly, boomy bass and think that’s really cool: cars go by sounding like that all the time. But what you actually want is a nice smooth response across the usable frequency range of your system, especially at those pesky crossover points. The ICBM will help you get it… if you are prepared to take a little time and effort.

The Downside
Time and effort are really the only things I can think of as downsides to this cool product. If you’re going to get the best out of it, you will want to do a bit of tweaking. You need to know the response of your speakers – all of them – or at least use the handy guide in the manual. You need to carefully read the section on the recombine switch – and the rest of the manual, while you’re at it. You need to disable any existing bass management on the sources you’re feeding into the box (if they have bass management in some modes and not in others). Then you need to mess with it in real life and be prepared to spend some time to get it exactly right.

Conclusion
I am afraid that Outlaw can beg for this component -- it ain’t going back. If you, like me, have one or more hi-res audio players, and if they have either no or only vestigial bass management when playing back DVD-A or SACD material, then you need this box. It will also serve you well if you have a separate preamp and multi-channel power amp, as it can go between the two and sort out your bass management worries. The unit does not audibly degrade the input signal as far as I could hear – the specs are very good on the signal-to-noise and distortion front, though I did not measure them. The unit adds sophisticated bass management that perfectly matches your highest-quality audio sources – the ones that most need it. And the price is right. What more can I say?
Manufacturer Outlaw Audio
Model ICBM-1 Integrated Controlled Bass Manager
Reviewer Richard Elen





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