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[Luke Geis]

Subs on an aux will free up some headroom within the sub, but if you're already running it that way and you are where you are at then there isn't much more to be gained.

A trick I employ to get a little bit more is to use a HP and LP filter set around the operating points. If the subs are only good from frequencies between 40hz and 100hz, then there is no point in letting frequencies beyond those points into the sub. I would use the HP filter set to around 40hz or higher to get rid of subsonic gack the sub won't do anything for. I would set the LP filter to around 100hz or lower in order to free up headroom and rid that part of the system of any signal that it will not be reproducing. This can free up a little bit of headroom and maintain the same impact, but it will only get you a few db or so. The last bit of EQ I would apply is to get rid of the peak frequency ( usually centered around 80hz in subs ) to try and get rid of some distortion and woof from the sub, but this will reduce potential output as you are reducing the peak frequency. It evens out the sound and does allow you to turn up a little more, but the sub won't be any louder than it was before.

Now the brass tacks are about realizing where the stop gap is and what your system is actually capable of. The Bose F1 system isn't exactly a powerhouse and will not rattle your teeth and pant legs. It does good for what it is, but being realistic to its performance capabilities lends it with much to be desired. You simply are out of gas when you can hear audible distortion and parts rattling. There just isn't much more to go beyond that point.

[Patrick Cognitore]

Subs on an aux will free up some headroom within the sub, but if you're already running it that way and you are where you are at then there isn't much more to be gained.

A trick I employ to get a little bit more is to use a HP and LP filter set around the operating points. If the subs are only good from frequencies between 40hz and 100hz, then there is no point in letting frequencies beyond those points into the sub. I would use the HP filter set to around 40hz or higher to get rid of subsonic gack the sub won't do anything for. I would set the LP filter to around 100hz or lower in order to free up headroom and rid that part of the system of any signal that it will not be reproducing. This can free up a little bit of headroom and maintain the same impact, but it will only get you a few db or so. The last bit of EQ I would apply is to get rid of the peak frequency ( usually centered around 80hz in subs ) to try and get rid of some distortion and woof from the sub, but this will reduce potential output as you are reducing the peak frequency. It evens out the sound and does allow you to turn up a little more, but the sub won't be any louder than it was before.

Now the brass tacks are about realizing where the stop gap is and what your system is actually capable of...being realistic to its performance capabilities lends it with much to be desired. You simply are out of gas when you can hear audible distortion and parts rattling. There just isn't much more to go beyond that point.

Just want to note that your advice of utilizing out of band filters is opposite of that of several other posters. I'd be inclined to agree with you.

However, it's also possible those filters are robbing some useful energy from the signal and/or causing some phase issues that are affecting the output.

But then again, the problem seems to be too much energy, as evidenced by the strained woofer sounds and grills rattling.

So I find myself agreeing with two completely opposite pieces of advice. Neither of which I don't think is the major issue, because in this instance we really just did not have enough gig for the rig.

And did I mention that while this straining and rumbling is happening that the internal processing seems to be doing jack squat? My hope would be that the limit and/or clip LEDs on the subs would be serving as a dummy indicator (as in: 'turn it down, dummy') but they're not.

The Bose F1 system isn't exactly a powerhouse and will not rattle your teeth and pant legs. It does good for what it is...

It sounds OK with playback. It's got that 'loudness button on', smiley face output that most folks seem to like. But TBH, at the price point of this Bose I would've expected and lot more output and much better quality audio. But I'm sure there were business reasons (that I'm not privy to) that this particular system was purchased.

Isn’t the Bose F1 a turnkey system where you just feed it a full range signal and the the internal crossover and processing does the work?
I would forget about aux fed subs. I doubt that you can improve on what the Bose engineers built into the system, especially with the eq in a xr18.

Agreed. The bus outputs do not have steep slope filters available, only a 12db per octave 'low cut'. And my preference in running this system would be straight from L/R with no aux fed subs, but that is not how the system has been run in the years before I joined the group.

We did take 5 minutes before the last gig to rewire the system to run as you spec'd above, without aux subs. It seemed to have a bit more full-range clarity to my ear, but was not a revelation in any way. In fact, I would've needed to redo the mix completely as the balance between channels ended up out of whack. That fact in itself tells me that our gain staging and balance between tops and aux-fed subs is not right.
--------------------

My role in this band is as the bass player. I've been with the band almost three months and they've be gracious enough to allow me to take on some audio duties. I'm now seeing and hearing less than optimal things in the system and want to help improve them. But it also puts me in the delicate situation of seeming to criticize the previous operation choice of my employer, so I want to have a full understanding of what the issue(s) may be and offer a recommended solution framed in the proper way.

[Paul G. OBrien]

It sounds OK with playback. It's got that 'loudness button on', smiley face output that most folks seem to like. But TBH, at the price point of this Bose I would've expected and lot more output and much better quality audio. But I'm sure there were business reasons (that I'm not privy to) that this particular system was purchased.

Bose has always claimed a level of superiority in their advertising that attracts a certain consumer who simply takes their word for it, they do generate very stylish and compact products that perform well for their size but one thing they have never accomplished is LOUD. And I don't mean loud for the sake of it I mean loud with control, I am yet to hear any Bose product that sounds any good beyond about 3/4 of full output, yet I have standard PA speakers that are regularly pushed to limiting with very little audible degradation. For what you get their products are over priced IMO, it definitely seems that you don't have enough rig for the gig and adding more subs would be a solution but if there is a decision to spend more money you have to ask yourself if a wholesale change to something that really is better would be money better spent.

[lindsay Dean]

The Bose system you have is okay for medium low-level use
I E music playback, speech, acoustic acts.
but it will never carry a full band as said before to a decent volume.

[Patrick Cognitore]

The Bose system you have is okay for medium low-level use
I E music playback, speech, acoustic acts.
but it will never carry a full band as said before to a decent volume.

I hear you. But even now with the 15% off sale Bose is running this system is over $4000. The standard street price with carry bags had been over $5000.

And there would be no need for $2000+ worth of subs for speech or acoustic use.

[Jay Marr]

I hear you. But even now with the 15% off sale Bose is running this system is over $4000. The standard street price with carry bags had been over $5000.

And there would be no need for $2000+ worth of subs for speech or acoustic use.

I have a friend with this same system and they often have the same issue with the subs not keeping up with the tops.
Standard bar band.

It's simply not enough rig for the gig.

He often swaps out the subs for QSC KW118s or QSC HPR118s and has much more punch and headroom on the low end.

[Luke Geis]

You should note that I said, " to get a little more ". This implies that phase and system tuning is now irrelevant to the task at hand which is to:

A. Keep the system from blowing up

B. Get a little more potential SPL while adhering to A.

The phase issues are not an issue as much if you do your system tuning with those filters in place ( ala Smaart or other measurement software ). The HP filter will not be so problematic as much as the LP filter will be. With the type of slope utilized in most HP/LP filters, the resultant phase shift will be negligible or at least minimally invasive. Especially in subs on aux systems where only a few key instruments are introduced into both halves of the system.

Now ideally you shouldn't need to do any kind of out of band EQing, but when you think about its concept, it makes total sense. Mostly it depends on your system type and setup. In the case where you are using a crossover that has three inputs ( one for the subs ) the three inputs will see the total of the signal you send it. In the case of the subs, a lot of that info is not going to be amplified and is simply eating headroom into the input. Secondly, the crossover will do what it does, but the information that is out of band still exists and still utilizes headroom. Reducing most of the information just outside of the crossovers bands allows all of the relevant signals through at the cost of some slight phase issues, but free's up that much more headroom and rids that part of the system of that much more information that would cause phase issues anyways.

We all like to think that when we align the subs and the mains that they are both in perfect phase harmony. This could not be further from the truth. It will only ever be correct in one specific superposition and it will only be correct over a small segment of the frequency response. When we align the subs to the mains we align for the best phase at a frequency range of interest ( decided by magnitude response and resultant crossover points ). The rest is still out of phase, we just see it as phase wraps that appear to line up. Perhaps I need to do a video on it? In either case, the phase shift introduced by the HP/LP filters is not really a huge issue in the grand scheme of things. If you need more mileage out of your system, the small sacrifice is probably going to be outweighed by the benefits.

[Patrick Cognitore]

You should note that I said, " to get a little more ".

I agree with your approach and the reasoning.

It's likely that in these instances we need more than a little more. I'm not sure what that is  - 3db, 6db, 15db? My guess is at least 6db, which we would get from doubling the subs. Not sure that makes sense. Well, I am sure...it doesn't. But I don't make the financial decisions.

[Luke Geis]

My experience shows that with subs on an aux you can acquire roughly 9db of headroom in conjunction with out of band EQ. The vocals really eat up a lot of media in the low end despite the HP filter.

This does not negate not having enough rig for the gig of course. While I think 6db is probably the minimum needed to get from not enough to just enough, another 3db isn't going to take you from just enough to more than enough. For me, it is more about getting a safety margin back from a known point of performance. I have the level I need, but the limit light is flickering on, how can I eliminate that? I have not specifically tested this technique in the real world to see just how much it truly saves, but in one experiment I did with Reaper I showed a 4db improvement with just the out of band EQ alone. With the EQ and simulated subs on aux I saw a 7db improvement overall.

[Tim McCulloch]

My experience shows that with subs on an aux you can acquire roughly 9db of headroom in conjunction with out of band EQ. The vocals really eat up a lot of media in the low end despite the HP filter.

This does not negate not having enough rig for the gig of course. While I think 6db is probably the minimum needed to get from not enough to just enough, another 3db isn't going to take you from just enough to more than enough. For me, it is more about getting a safety margin back from a known point of performance. I have the level I need, but the limit light is flickering on, how can I eliminate that? I have not specifically tested this technique in the real world to see just how much it truly saves, but in one experiment I did with Reaper I showed a 4db improvement with just the out of band EQ alone. With the EQ and simulated subs on aux I saw a 7db improvement overall.

I'm skeptical.  Out of band EQ is good for a couple of things but making a +7dB batch of Magically Delicious Headroom ain't one of them.  My measured experience was about +3dB, you pick where the compromise occurs.

The more I think about Patrick's situation the more it seems likely that they ventured into the Land of Unrealistic Expectations (due south of the Land of Misfit Toys).

[ProSoundWeb Community]