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Author Topic: Bose F1 Sub, having issues. Any users have feedback?  (Read 3087 times)

Caleb Dueck

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #20 on: December 19, 2018, 11:13:27 pm »

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).

As soon as I saw the thread title, my first thought was "Not enough rig for the gig". 

I've also used out of band  and creative EQ and HP/LP filters to "help" low grade equipment get through a show without dying.  Agreed that some "creative crap coercion" can give less-bad sound, but it can't give much if any extra headroom.  Mainly raising the HPF on subs by 5Hz or so. 
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Chris Grimshaw

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #21 on: December 20, 2018, 03:45:46 am »

With the EQ and simulated subs on aux I saw a 7db improvement overall.

I'm also skeptical.
Did you make sure you'd be within cone excursion limits?
What about port air velocity getting too high?


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.

<snip>

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.

With regards to the first chunk of text...

- Using headroom on the input of a crossover isn't as evil as you seem to imply.
- The signals you're attenuating with out-of-band EQ are already being attenuated by the crossover. Why not just use a steeper crossover slope and maintain phase alignment?

For the second chunk of text...
- When the main speakers and subwoofers are vertically aligned, the right crossover will mean they're working in "perfect phase harmony" over the entire dancefloor, stage, and load-in area. Both cabinets will be omnidirectional at 100Hz, so we've got rotational symmetry.
- If the phase wraps line up, the speakers are still in phase.
- The phase shifts from crossover filters are an issue. The phase shifts determine if the crossover is gonna work correctly (ie, get the drivers working together) or not (drivers cancelling each other out).


Ignoring the proper summation between cabinets is a sure-fire way of losing some SPL, which directly contradicts what you're trying to achieve.

Chris
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Patrick Cognitore

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #22 on: December 20, 2018, 12:18:44 pm »

I believe it. Although I've found that with many systems more subs are needed. I really prefer 2 subs for every one top with my PRX700 system.

I will say that we've actually had an issue with the tops clipping (on snare hits) if main output get pushed too much. The subs however are not clipping or limiting, but yet the balance is still way off with not enough low end and the aforementioned 'bad sounds' coming from the cabs.

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.
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Luke Geis

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #23 on: December 20, 2018, 08:33:58 pm »

Ok, I made a video showing two different scenarios in which both showed at least a +6db increase in headroom in more real-world use. What it is: Shows that roughly +6db ( possibly more depending on how you apply the EQ and all ) is easily attainable if needed without significant detriment to the sound. What it isn't: It is not a cure-all and it does have downsides, those downsides are probably not of worry if you need to employ the trick anyway.

https://www.youtube.com/watch?v=2x6Ag3tefi0
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Patrick Cognitore

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #24 on: December 21, 2018, 11:05:53 am »

"There is a phase shift, but you're not gonna die". ;D

Looks good, thanks for doing the video.

Forgive my ignorance, I'm assuming the source material is pink noise? And I'd guess that the reduction that the out of band filters have at the sub input could be even greater (or less) depending on the real world program material.

Ok, I made a video showing two different scenarios in which both showed at least a +6db increase in headroom in more real-world use. What it is: Shows that roughly +6db ( possibly more depending on how you apply the EQ and all ) is easily attainable if needed without significant detriment to the sound. What it isn't: It is not a cure-all and it does have downsides, those downsides are probably not of worry if you need to employ the trick anyway.

https://www.youtube.com/watch?v=2x6Ag3tefi0
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Luke Geis

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #25 on: December 21, 2018, 05:25:50 pm »

^^^^^^^ Correct on pink noise. Many may not have noticed, but the subs were on and producing noise the whole time. You couldn't really tell when I switched the EQ in and out.

The crossover in this case was set at 120hz, and the HI-cut filter was set at 140hz. You could reduce even more energy by running the HI-cut filter lower to 120hz or wherever your crossover was set if you wanted. Also the Low-pass filter was set at 30hz in this case, most subs don't reproduce that low ( especially single 18" units ) and you could run it up as far as the -10db rating of the sub ( around 35hz for most ).

The pink noise vs. typical media won't really change the outcome much. Perhaps another db or two, but nothing significant. This trick is truly only worth 6-9db in headroom increase which as mentioned before isn't going to be enough in most cases to get from zero to hero.

Going back to the purpose of this trick, the phase shift is probably the least of one's worries. If they didn't even time align things to begin with, your shooting in the dark anyway. The one reason I don't really worry about major phase issues with subs on an aux is because so little media is in the subs anyway and the problems associated with phase shift are really SPL and co-location dependent. If the subs are somewhat well aligned and the crossover is set for a good acoustic setting ( as in electrically they are not the same ), most of the media that would be problematic with phase will be out of the equation anyway even if you don't take the time to re-align after employing this trick.

Humans cannot detect phase when the two sources are independent of one another. Heck we can barely locate the source of where an 80hz signal is coming from. This is another reason I am a fan of utilizing low crossover settings for subs. I typically run no higher than 80hz if I can and will go as low as 60hz if the mains will allow for it. I also try and set the crossover of the mains to get the most even transition from the subs. This usually means a higher crossover setting between 80hz to 100hz or higher depending on the sub. Keeping in mind that at typical crossover points around 80-100hz, the mains and subs can be out of alignment by as much as 2.5' to as much as 3.5' and still couple well enough. So if you align the subs and mains at all, the introduction of the out of band EQ will still have the subs within 90* of phase. You won't die.......
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brian maddox

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #26 on: December 21, 2018, 08:34:07 pm »

^^^^^^^ Correct on pink noise. Many may not have noticed, but the subs were on and producing noise the whole time. You couldn't really tell when I switched the EQ in and out.

The crossover in this case was set at 120hz, and the HI-cut filter was set at 140hz. You could reduce even more energy by running the HI-cut filter lower to 120hz or wherever your crossover was set if you wanted. Also the Low-pass filter was set at 30hz in this case, most subs don't reproduce that low ( especially single 18" units ) and you could run it up as far as the -10db rating of the sub ( around 35hz for most ).

The pink noise vs. typical media won't really change the outcome much. Perhaps another db or two, but nothing significant. This trick is truly only worth 6-9db in headroom increase which as mentioned before isn't going to be enough in most cases to get from zero to hero.

Going back to the purpose of this trick, the phase shift is probably the least of one's worries. If they didn't even time align things to begin with, your shooting in the dark anyway. The one reason I don't really worry about major phase issues with subs on an aux is because so little media is in the subs anyway and the problems associated with phase shift are really SPL and co-location dependent. If the subs are somewhat well aligned and the crossover is set for a good acoustic setting ( as in electrically they are not the same ), most of the media that would be problematic with phase will be out of the equation anyway even if you don't take the time to re-align after employing this trick.

Humans cannot detect phase when the two sources are independent of one another. Heck we can barely locate the source of where an 80hz signal is coming from. This is another reason I am a fan of utilizing low crossover settings for subs. I typically run no higher than 80hz if I can and will go as low as 60hz if the mains will allow for it. I also try and set the crossover of the mains to get the most even transition from the subs. This usually means a higher crossover setting between 80hz to 100hz or higher depending on the sub. Keeping in mind that at typical crossover points around 80-100hz, the mains and subs can be out of alignment by as much as 2.5' to as much as 3.5' and still couple well enough. So if you align the subs and mains at all, the introduction of the out of band EQ will still have the subs within 90* of phase. You won't die.......

^^^^ My name is Brian Maddox and i approve this message....
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Patrick Cognitore

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #27 on: January 02, 2019, 01:28:54 pm »

Minor Update:

Played the same venue as the OP on Saturday, 12/29.

I should note I didn't mix this time around, but just added some tweaks during soundcheck. Also, I used a different bass on this gig than the last one. And the one I used on this gig has much less fundamental presence on Low B and E strings than my other bass, according to the mixer EQ RTA.

I raised the Bass HPF to 40hz. The aux fed sub routing stayed the same, but I lowered the out of band 'low pass' (really just a 'high cut EQ') to around 120hz.

System volume was kept lower overall and that kept the system from sounding strained. Even at that lower level my bass was causing the tops to go into limit (yes, the tops not the subs). Lowering the compression threshold to -40db on that channel kept them out of limit.

The mix overall ended up sounding OK, but really just not enough oomph for this size room. This pic is of the dance floor, banquet tables are placed just outside the pillars. This pic shows a small fraction of the room, it extends another 30' behind the camera position and another 50 to 70' on each side.


« Last Edit: January 02, 2019, 01:31:10 pm by Patrick Cognitore »
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Luke Geis

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #28 on: January 02, 2019, 02:41:40 pm »

That is a pretty big room.

I have said it before ( not in this thread ), but I feel that a PA capable of 135db peak is loud enough to do just about any gig that you can appropriately throw at it. Obviously, a pair of 12" speakers won't fill a football stadium. When you start running speakers in larger spaces where you NEED significant SPL beyond 50', lower output units just can't hang.

The theory is simple. After you account for crest factor and safety ( keeping the speaker out of limiting ) you are subtracting a minimum of 16db from the peak capability of a speaker. This places a 135db peak ( not a realistic number anyway, but a factor for performance ) speaker around the 119db area for real-world output capability. This is the output at 1 meter or roughly 3', so you then need to account for losses in the air. The inverse square law says for every doubling of distance you will lose -6db. So at 2 meters ( 6' roughly ), you would then have 113db, 4 meters ( 12' ish ) 107db, etc. etc.... 12' away is usually enough for smaller gigs to have the core of the people and needed coverage to be within. This allows you to hit rock show volume over an area roughly 50'-75 wide and about 24' deep ( just over 100db at 24' deep ). 24' is the practical limit in distance away from the PA where you can't concern yourself with " Rock show levels " anymore with typical point source PA's. You can have reasonable output to 50', but it won't be over 100db over a considerable bandwidth.

There is another mathematical calculation which the name and calculation escapes my brain at the moment, but it prescribes a slightly different outcome than the inverse square law. It states that the attenuation over distance is dependent upon the wavelength. This is why low frequencies tend to carry over a further distance. Higher frequencies are quickly eaten up by the atmosphere and dissipated. Not really to the point, but just to explain why it seems that lower frequencies do carry out better.

Getting back on topic, you can see how a PA almost needs to be at least capable of about 133db at a minimum in order to just be able to get realistic SPL's that move air. Once you start getting below about a 133db peak speaker though, the truth in advertising starts to show; or not... We are banking on whether the peak SPL number a speaker says it can do is real. We assume that the number can be touched briefly over a series of frequencies that are said to be within +/- 3db. We know that is BS, but it is an indicator of performance. The reduction I do of 16db accounts for 6db of that output being just for safety. Or simply put, if I powered the speaker only up to its continuous rating. The other 10db is really more a pipe dream and assumes you can get the media to within a -10db crest factor.

Most live bands sit around a -15db crest factor withlight to moderate compression. I can get to a -10db crest factor with a live band, but it starts to sound sort of processed at that point. You can just tell that there is something going on because the dynamics are essentially gone and everything sounds like it's at 11 all the time. Really in your face and locked in kind of sound. I like this because it makes the job of mixing easier ( like being in the box ), but musicians don't tend to like it if they notice it, or even hear that you have compression on their channel. I have only met a handful of musicians in my day who are truly masters at modulating their dynamics, and if they were all that good, we wouldn't need compression at all. The need for getting the crest factor down to -10db isn't even always a matter of needing to glue the mix together, but literally a need to keep from blowing the PA up. You can't have spurious snare hits, bass slaps or horn blasts that sail uncontrolled through the PA when you are near the PA's limits. As you have noted you had to limit the Bass channel a bit to keep the PA out of limiting. You already know at this point that you need more rig for the gig, but as seen there are tricks to get a little more. You went from subs that were obviously distorting to not even going into limiting and found that limiting certain instruments helps keep the PA intact.
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Robert Lunceford

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Re: Bose F1 Sub, having issues. Any users have feedback?
« Reply #29 on: January 02, 2019, 11:30:32 pm »

Minor Update:

Played the same venue as the OP on Saturday, 12/29.

I should note I didn't mix this time around, but just added some tweaks during soundcheck. Also, I used a different bass on this gig than the last one. And the one I used on this gig has much less fundamental presence on Low B and E strings than my other bass, according to the mixer EQ RTA.

I raised the Bass HPF to 40hz. The aux fed sub routing stayed the same, but I lowered the out of band 'low pass' (really just a 'high cut EQ') to around 120hz.

System volume was kept lower overall and that kept the system from sounding strained. Even at that lower level my bass was causing the tops to go into limit (yes, the tops not the subs). Lowering the compression threshold to -40db on that channel kept them out of limit.

The mix overall ended up sounding OK, but really just not enough oomph for this size room. This pic is of the dance floor, banquet tables are placed just outside the pillars. This pic shows a small fraction of the room, it extends another 30' behind the camera position and another 50 to 70' on each side.

After seeing the photo of the room, I believe it is possible that the problem is not with the Bose system but with the room. I am taking an educated guess that the room is very reverberant and that even with no music, the sound level from the crowd alone is very high. I doubt that using a louder system would sound any better in that room. I think you are fighting a losing battle trying to compete with the crowd noise. I would also guess that even with no crowd, and just the band playing, that the sound is bouncing around so much that it is hard to hear anything clearly. A natural reaction is to turn it up louder since it is hard to hear any detail. This is wrong and you should actually turn down the volume to try and get some clarity by reducing the level of the sound bouncing around.
I looked on youtube for some F1 videos and Bose seems to have sold quite a few of these units and they sound surprisingly good in many of the videos. I was surprised how good they sounded and the level that they were playing in some fairly large rooms and outdoors.
Here is an official Bose video where they placed a F1 system in a 1,000 seat concert venue and had several top level engineers try the system out.   https://www.youtube.com/watch?v=keUtck_F7es

 
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