L1 Model II

Let's talk about the L1® Portable Line Array Systems

Using proprietary Bose® technology, L1 systems combine  PA and monitors into a single, highly portable unit. The  loudspeaker can be positioned behind or to the side —and you hear what the audience hears.

Highly portable PA and monitor combined for solo performers, DJs and general-purpose use. Fixed vertical control with 180° horizontal coverage Reduced vulnerability to feedback.

Three systems to choose from (Compact, Model 1S, Model II)
Two passive bass module options (B1 or B2)
Consistent coverage and tonal balance, portability and easy setup.

First,  I want to say I love my L1s and have been using them since 2010, and don't plan on getting rid of them until BOSE releases the next version, but I can't help but notice that the bass is not as strong at high volume levels.

Luckily for me I get to play at a lot of the same venues (I DJ) for crowds up to 250 people and I get to do proper sound checks before gigs.

This might not be published or discussed often, but it is quite evident that the bass is weaker when pushing the L1 at high volume levels.  At lower to mid levels, the bass sounds terrific, and in fact, sometimes too much

As soon as the party gets going, it feels a little thin.  Not necessarily right away, but the louder I go, the worse it gets. I had a chance to put this theory through a test this past weekend when we did our sound check, and when I lower the volume, the bass becomes much fuller.  I really only notice the bass lessen when running the system close to its max (right before flickering on the input) on modern compressed playback music.  Keep in mind, I don't do live sound.

What I am wondering, and it's very possible BOSE has not disclosed this, but does the internal system limit the bass when driving very hard?  Is there some type of roll off at it gets louder for protection or am I just hearing power compression

https://www.sweetwater.com/insync/power-compression/

This occurs with B1 or B2, just more noticeable with the B1.

When walking over to the L1, it seems as if it is still pumping out a lot of content, just not as much in the lower octave-- Almost like it looses -6db from 50-40 hertz.

 

Original Post

Hi jaswrx,

Here's an explanation that was offered by Chris-at-Bose (in 2006).

— ST

Chris-at-Bose posted:
Hi folks,
quote:
L1 drop-off was hardly noticable
B1 volume however dropped off halfway the distance of the L1.

As many of you know first-hand, nearby direct sound from the L1 falls off with distance more slowly than most other speakers, including all bass speakers, and including B1s. We rarely notice this difference indoors, because room modes in the bass impose large changes from place to place that dominate over the different rates of fall-off of the direct sound waves from the L1 and B1.

But outdoors, there is nothing to prevent us from noticing that the bass falls off more rapidly with distance than the L1's sound does. This will happen no matter how many B1s we have, no matter what EQ or presets we use, and it will also happen if we use other subs, no matter how big they are. The only ways to fully prevent it would be to either give up the slow fall-off of the L1 Frown or make a line array of bass speakers at least 15 feet tall (wow!), but, aside from the expense, such a thing would be extremely dangerous. Eek So we have to find a way to optimize the effect because we can't make it go away.

Before I explain how to do that, I want to describe the effect in a different way that makes the solution more clear. Since the bass and mid-highs are falling at different rates with distance, there can be only one distance where the balance between bass and mid-highs is "perfect". To my ears, the L1 and B1 achieve this balance point outdoors somewhere in the 10-20 foot range, call it 15 feet. But how much closer or farther must I go to hear a small change in the balance? Human hearing is not very sensitive to small changes in bass level, so 3dB counts as a small change in this frequency region. If I go to either half the distance (7.5 feet) or double the distance (30 feet) I hear a small change of 3dB in the bass balance compared to the ideal. That's because the L1 changes by 3 dB per doubling or halving of distance, while the B1 changes 6 dB, so the difference between them changes 3 dB either way. So there is a large region of distance where the bass is very close to the ideal level and that region covers about a 4 to 1 distance range, in this case about 7.5 to 30 feet.

Now what if I boost the level of the bass by 3dB with a tone control? (A tone control isn't perfect compensation for this effect at all frequencies, but it's not bad.) Now the point of "perfect balance" moves out from about 15 feet to about 30 feet, and the range over which the balance is close to ideal becomes about 15-60 feet, still about a 4 to 1 range. If I boost the bass control even more, the range moves out further, but keeps the 4 to 1 ratio. So now you see how to optimize this effect. Simply apply modest bass boost until the tonal balance is not quite thin at the largest distance you want to cover. Then the balance will be very close to correct from that distance to about 1/4 of that distance. Inside that range, the bass will be modestly stronger than normal, but we all tolerate a little extra bass better than we tolerate too little. Smile

There is one thing to keep in mind when applying this outdoor optimization. You are asking for more bass from your B1s and they may not have more to give at the level you want to deliver. If you try to eliminate the thinness with a bass control and it doesn't increase the bass you hear, then your B1s are already giving all they've got and you will need more B1s (for this job) to get the bass control to have any effect. (Remember that more B1s will not replace the need to use the bass tone control here, because the PS1 keeps the tonal balance the same as you add more B1s.)

But before you invest in more B1s, make sure you are getting all the bass you are entitled to from the ones you have. For stereo music playback, you can get a little more bass by stacking your left and right B1s tight together. Outdoors, if there is a hard wall nearby, you can get a good deal more bass by placing all the B1s right at the wall. If you can't get right to the wall, then keep the B1s at least 7 feet away from the wall. If you place B1s outdoors anywhere from 2 to 7 feet from a hard wall, you will get a big hole in the bass response--bass notes will be very weak at some pitches while other pitches will be okay. The reduction in bass in that case will be significant. Try to avoid such placement if you can.

Overall, outdoor settings demand more from your sound system in the bass than indoor settings, because outdoors there is no bass reinforcement from a room. Also, people are often farther away outdoors. Both factors lead to your often needing more B1s outdoors than indoors. So John L is probably right in his first post--he may need more B1s, but please try these other ideas before getting out your wallet.
Hope this is helpful.
Chris

I respect Chris a lot, and would even agree with all the above, but I want to clarify this has nothing to do with the B1 or B2 keeping up with the radiator arrays in large or outdoor areas.

BUT, this can happen in a small space that only holds an estimated 25 people.  I am noticing the effect when within 10 feet of standing by the L1 setup, regardless of location. 

The only thing that I did pick up on from Chris was the note regarding B1s not going any louder with more tone control, which IMO means they must be limited by some type of processing, probably to prevent damage from excess EQ or input signal bring driven to hard??

Here is what he said:

"There is one thing to keep in mind when applying this outdoor optimization. You are asking for more bass from your B1s and they may not have more to give at the level you want to deliver. If you try to eliminate the thinness with a bass control and it doesn't increase the bass you hear, then your B1s are already giving all they've got and you will need more B1s (for this job) to get the bass control to have any effect" 

I suppose I could take out the radiators to listen closer on the B1s, and perhaps measure if there is a sonic difference at high volumes ( low to med volume vs right before flickering the input signal).

One thing that makes it hard to tell what's happening is that the L1 only shows the input signal, and not the output signal, so we can't see if the systems is limiting on output (if that is what is really happening).

 

 

Hi jaswrx,

The L1 systems have limiters, and when you hit the limit, the systems will not get any louder. If the issue is not the Cylindrical Radiator® outperforming the bass modules, then it's possible that you're hitting the limiter for the bass system.

ST

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