Confused about how an ICBM works (1 Viewer)

[ling_w]

Chuck,

This is what I was told, especially with respect to the ICBM magnepan edition (the only difference is the higher crossover freq for the center.) Basically the center would cross over to the mains. This is important to the magnepan world in which the sound characteristics of planars are preserved as long as possible until it is not feasable anymore, then it is crossoved over to the sub.

If that is not the case, there is no point in Magnepan pushing the product as the greatest accessory since sliced bread.

 

[Chuck Kent]

Ling: I looked around a bit and really can't find anything on the Magnelanar version of the ICBM. I remember seeing something about the x-over frequencies being different, but I can't recall anything about the redirected bass going through the mains before it goes to the sub. Anyway, I'm reasonably sure that the standard unit is not that way. I know in my system, I wouldn't want it to do that...

 

[ling_w]

Chuck,

The magnepan's version was mentioned on the Outlaw newsletter, and the only thing differnet is the crossover freq. If they redisgned the whole thing for magnepan, the price differential would be quite substantial.

Also on ICBM's manual, page 12:

B Center Front Channel Crossover Frequency Control – sets frequency at which bass will be filtered out of center front channels and redirected into subwoofer or front left/right channels.

 

[BruceD]

ling and chuck,

Just like most receivers and prepros if you don't have a sub connected, center and surrounds are re-directed to mains.

 

[ling_w]

BruceD & Chuck,

As in outlaw ICBM's documentation specifies:

I L/R Recombine On/Off Switch – redirects bass out of all channels not set to bypass, and into front left/right channels. Does not deactivate subwoofer.

...

Setting the Left/Right Recombine switch

The Left/Right Recombine switch redirects the bass into the front left and right speakers. You should definitely set this switch to “on” if you do not use a subwoofer.

However, we have designed the ICBM’s circuits so that you can still use a subwoofer with the Left/Right Recombine switch activated. The reason we did this is that even if you have fairly large front left and right speakers, you may want to route some of the front left/right signal to the subwoofer to reinforce the bass output from those channels.

So from the above, setting the Left/Right Recombine switch, you can reroute bass from any of the speakers with higher crossover freq than the mains into your main speaker. Then at main crossover freq to the sub, it will redirect all those same speakers' signal to the sub.

This is done so that you preserve the sound characteristics of your speakers until none of them could handle it anymore, in which you let the sub take over. It is also prefereable for the center to be crossed over this way, since it will symmetrically spread its bass load to speakers on its left and right, instead of to a subwoofer sitting somewhere (usually asymetrically) else.

 

[Chuck Kent]

Ling: I see what you're saying. I agree that the ICBM can perform somewhat similarly to what you wrote. But not exactly...

In your original post on the ICBM's rerouting setup, you noted that all "small" speakers have their bass filtered out and sent to the mains. Then, with the mains also bass filtered (quite likely at a different frequency), all of the filtered bass signals then continue on to the sub.

The ICBM allows crossing from center to main, surround to main, and then main to sub, all at different freq.

But this is not the case.

The Recombine Switch allows the ICBM to be used in a system that has no sub (IOW, with the bass redirection being similar to the scenario you've outlined with the key difference that there is NO sub), or in a system that the user wants to use the sub to supplement the bass that remains in the mains. But the important thing to keep in mind is that if the Recombine Switch is on, the mains ALWAYS play as full range. No matter what the mains frequency crossover selector is set at. (If the Recombine Switch is on, the mains freq. crossover selector controls what the lowpass crossover point is for the sub. But the mains remain fullrange.)

IMO, I don't think most users would want to use the Recombine setting. One of the key reasons I bought the ICBM was to highpass my mains at 40 or 60Hz. If a user switches on the Recombine Switch, the mains highpassing goes away...

 

[Michael R Price]

Ah, thanks Bruce, I was thinking of time-aligned as in a time-aligned speaker that tries to synchronize each of its drivers phase responses for better transient response.

 

[BruceD]

ling,

As I said, just like most receivers and prepros if you don't have a sub connected, center and surrounds are re-directed to mains.

And, just like some receivers and prepros, you can send out extra bass by enabling mains+sub for bass reproduction.

I agree with Chuck, this is quite different than the way you tried to describe it.