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The problem of Subs in Pubs.


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OK given the way these threads sometimes go I think I need to start with a disclaimer: I'm not anti the use of subs in pubs or anywhere else. In fact I'm intending making more use of my subs where appropriate and want to share experiences and any practical tips that people may have to offer.

 

So I play in three 'bands' two typical four piece pub bands (singer, guitar, bass, drums) and a duo (two vox, guitar, bass, programmed drums) on an average night we play to 50 people. 100+ would be a very good night or a festival. PA is either 15's or 10's and we use in-ears for the bands and floor monitors for the duo. Recently I've tried the 10's with a single sub for one of the band gigs and have started to use this as a set up for rehearsals. In the past I have used my subs paired with 12" tops.

 

My first observation is that there isn't a perfect set up or a 'right' answer to the problems. As Erwin Rommel once said; "no plan survives the first contact with the enemy" and that is true of setting up PA in a strange venue. Those who insist in placing subs centrally clearly haven't been asked to set up in a typical british pub with no raised platform or indeed any defined stage area. Fully 30% of our venues have the only access to the toilets to the side of or directly behind our 'stage' :) Immediately any speakers on poles are a hazard as drunk customers push past the band on their way to relieve themselves and the floor monitors become a trip hazard. In my experience speaker placement is a compromise between pubilc safety, avoiding claims for damages and acoustic perfection with the former being the most important consideration.

 

Subs are great, the 15" drivers in mine are specialist, long throw low frequency speakers that our perfom the mid/bass 15's in my best 15" tops and bass is fuller more defined. Kick drums in particular sound great with subs. Outdoors sus are pretty much essential as you lose the reflective surfaces that rinforce the bass indoors. By taking a huge chunk of power from the tops they can be pushed harder, run cooler and the sound is less distorted. I can get away with 10" tops with subs but run out of steam without them. 15's block the view of the stage and at nearly 20kg are a significant lift. A 10" lightweight top mounted on a sub is much more stable than a 20kg 15" top on a stand and far less likely to cause anyone harm

 

Subs are a pita, they are necessarily massive making transport difficult, in many venues they set off room resonances so you end up filtering out the extra frequencies. Because they are omnidirectiona and you have more of the really low frequencies all the bass spills back onto the stage. That can cause havoc with bass feedback on drum mics and acoustic guitars and drowns anyone without well fitted in-ears in a thick soup of overwhelming low bass. Often there is nowhere else to put them other than under the tops and then you have to live with comb filtering problems.

 

So let's hear your experiences, ever tried subs? Had any problems? Positive experiences? Practical tips to offer?

Edited by Phil Starr
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IME when a room is so small that sub placement is an issue you don't need subs. Good quality ten or twelve inch mains shouldn't have any problems, as they should always be high passed no lower than 80Hz. As for central placement of subs, that should very seldom be employed anyway. The beauty of omnidirectionality is that subs can be placed out of the way.

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  • Phil Starr changed the title to The problem of Subs in Pubs.

Following this thread... I have very little technical knowledge but need to build some up, quick!

 

We have a large active sub which failed on us last night. Because we were using the sub I only had my SWR Working Pro 10 (100 watts, supposed to be to tilt back at me for my monitoring only) rather than my full Ashdown Rig. We lost the kick drum sound through the sub and had to put a small amount of bass into the tops which for some reason the rest of the band hate doing... But we play iPhone playlists through these which also have bass frequencies so in an emergency I think it's acceptable!

 

We are looking at possibly having to replace the sub now if this one is completely fried. 

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We use 2 RCF 705 (MK1) subs with 2 RCF 712 tops in my 4 piece rock covers band for pubs and all other gigs, unless the venue is too large for our PA to comfortably handle.  Everything is miked (bass, guitar, drums, keys, vocals) and goes through these but obviously volume is adjusted according to the venue.  We use poles to mount the tops above the subs.  

 

We use a high pass filter set appropriately for each individual channel on the desk to avoid problems with excessive low frequencies.  This also helps to avoid pushing the PA too hard so that it's running with plenty of  headroom to spare.  Sub placement hasn't been an issue so we've never considered using only one sub or mounting the tops on tripods.  I would be nervous doing the latter in smaller venues as I think this would significantly increase the likelihood of a drunk punter tripping and knocking them over.  

 

The biggest PITA (as @Phil Starr mentioned) is carrying the subs.  I would like to upgrade to the RCF 905's which are lighter than our 705's and have more headroom, but that's unlikely to happen as we've probably only got a couple of years left as a band (due to age/health issues) so I can't see the others being keen to do this. 

Edited by gazhowe
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@Silvia Bluejay and I only bring the subs along to carefully-selected gigs; most of the time we just run a pair of decent 1x12 passive tops with the whole band going through them at sensible volumes. 

 

We use a pair of MarkAudio 2x10 subs at really large venues (including outdoor gigs, natch) and at the very few gigs we play where they actually demand high volumes.

 

When using the subs we put the passive tops above and drive them from the subs' on-board power amps so although we now have to carry the subs we save on carrying separate power amps.

 

Location is driven by practicality rather than audio perfection and these days we invariably lay the 2x10 subs flat on the ground (for stability) rather than upright as we used to (avoiding combing etc).

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We have active 15" tops and the drummer owns and transports a sub. We use it at almost every pub gig, some of which are fairly small. With a pole it supports a top, so good for space. I place my monitor on it, so again a win for floor space. It is used to reinforce the bass drum as the tops don't diver that punch you need. I am usually through the PA too so the sub helps with the bottom end. In smaller pubs I take myself out of the tops and just put a bit through the sub for some low end reinforcement. Works fine for us, a 4 piece with vocals, guitar, bass and drums.

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Some basic sub placement notes: While it’s customary with PA to have speakers to either side of the stage that’s usually not the best way to place subs. Subs work best when they’re placed either close together for mutual coupling, or spread very wide to cover large areas. The basic rule is to have them either less than a quarter-wavelength apart or more than two wavelengths apart for their pass band, which for 40 to 100 Hz means less than 1 metre or more than 20 metres.

Boundary loading should be used whenever it’s practical to do so. Having subs next to a wall gets you 6dB of additional sensitivity, putting them in a corner an extra 12dB. In most cases you’ll have best results aiming the subs towards the wall or corner from about 30cm away from the boundary. The long wavelengths from subs are omnidirectional and cannot be directionally located, so there's no need to have them near the mains or even near the stage.

 

Yes, subs to the left and right with mains on poles above them is convenient. But more often than not that gives the worst possible result. https://www.fulcrum-acoustic.com/wp-content/uploads/2019/10/3_The-Subwoofer-Power-Alley-1.pdf

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Just to quickly add to what @Happy Jack said:

 

- I find that in small rooms the subs are actually detrimental, compared to the use of 10 or 12" tops only, because of the crossover frequencies. To my ears, unless tops + subs are set to be pretty damn loud (yeah, right, in your average pub or club), the separation between the two sets of frequencies is too clear and really irritating.

 

- Since the 10/12" tops aren't very good at reproducing real bass frequencies, I HPF them; however, Jack often also uses his on-stage bass rig to provide some proper bass for the audience. Not too loud, but loud enough to make the bass sound more rounded and enjoyable. No need for high volumes anyway, as bass frequencies sound better from afar than close to the stage.

 

When all is said and done, there is no sure-fire way to get a perfect sound in a pub or small club, and ultimately, there is no need for it: concentrating on having a good, tight, entertaining band is by far the most important thing in this type of gigs.

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2 hours ago, uk_lefty said:

Following this thread... I have very little technical knowledge but need to build some up, quick!

 

We have a large active sub which failed on us last night. Because we were using the sub I only had my SWR Working Pro 10 (100 watts, supposed to be to tilt back at me for my monitoring only) rather than my full Ashdown Rig. We lost the kick drum sound through the sub and had to put a small amount of bass into the tops which for some reason the rest of the band hate doing... But we play iPhone playlists through these which also have bass frequencies so in an emergency I think it's acceptable!

 

We are looking at possibly having to replace the sub now if this one is completely fried. 

Bad luck, if you are at all handy it's worth trying to find out whether the fault is in the amp (ouch if it is) or the speaker which is replaceable if you are at all handy. It could of course be a lead or even a fuse.

 

The sound from a playlist will probably be heavily compressed meaning that although it will sound louder and probably bass heavy it isn't demanding the peaks that your live set will be demanding, depending of course on how you set it up. Most active tops will take a little bass or even quite a lot. If they are active there may also be quite a lot of protection built in to protect your speakers from excessive distortion or harm. It's quite hard to really damage modern DSP controlled speakers though I have had my RCF 310's turn themselves off once when someone who should have known better re-booted a mixer that was playing up without turning the volumes down and muting averything.

 

Good luck with the fault finding.

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I've never worried too much about subs under tops. Whilst completely accepting the phasing issues and the creation of power alleys I've found in small venues with multiple path lengths sound is reflected off nearby hard surfaces  andit isn't as much of a problem as it will be in more open spaces. On the other hand stable supports for your speakers when people are dancing only a few cm away for me is the crucial issue. It's worth mentioning also that the issue of power alleys applies equally to the bass coming from your tops. The cancellation depends only on the distance between the speakers and the frequency/wavelength so outdoors where you have more space to group your subs together there is an extra reason to opt for using subs.

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3 hours ago, uk_lefty said:

We have a large active sub which failed on us last night.

 

Define "failed".

 

The last time one of our subs failed, it completely failed to power up when switched on. We later discovered that the venue had a defective 13A socket built into the stage and there was nowt wrong with the sub. 🙄

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22 minutes ago, Phil Starr said:

 It's worth mentioning also that the issue of power alleys applies equally to the bass coming from your tops.

True, but it's all about the wavelengths. The shorter the wavelengths the less the power alley effect. Having the mains at least two wavelengths apart at 100Hz is only some 7 metres, while at 200Hz it's only some 3.5 metres. Since the bulk of the content from mains lies above 200Hz to the extent that power alley exists it doesn't matter all that much. It's a different story with subs, where all of the content lies below 100Hz.

Quote

Whilst completely accepting the phasing issues and the creation of power alleys I've found in small venues with multiple path lengths sound is reflected off nearby hard surfaces  andit isn't as much of a problem as it will be in more open spaces.

Also true, but when the space is that small chances are you either don't need subs or you only need one.

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Bill's advice is, as usual, excellent, in particular, his recommendation to high pass subs no lower than 80Hz. Most people try to push far too much low frequency energy into a room, with horrible results - one note, booming bass, no definition and masking of higher frequencies. They generally crank the system up in an attempt to overcome this, resulting in more of a sonic mess. Two subs is overkill in most pub venues. I only ever need to use one and frequently roll that off in volume by 3db or more.

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49 minutes ago, Happy Jack said:

 

Define "failed".

 

The last time one of our subs failed, it completely failed to power up when switched on. We later discovered that the venue had a defective 13A socket built into the stage and there was nowt wrong with the sub. 🙄

Won't power on. We changed the fuse in the sun unit itself, changed kettle leads and sockets. I've brought it home and tried again, another new kettle lead and the power on led doesn't light. 

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59 minutes ago, Dan Dare said:

Bill's advice is, as usual, excellent, in particular, his recommendation to high pass subs no lower than 80Hz. 

The advice is to high pass tops at no lower than 80hz. High passing subs at 80hz would really defeat the object of having them in the first place.

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It's OK, we knew what he meant. ☺️

The best FOH mixers in pro-touring sound high pass the bass channel between 60 and 80Hz, so the bass sounds like a bass and not a 30 ton dump truck dropping a load. There's still bass content in the subs, but not so much that it drowns out everything else.

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1 hour ago, mrtcat said:

The advice is to high pass tops at no lower than 80hz. High passing subs at 80hz would really defeat the object of having them in the first place.

 

1 minute ago, Bill Fitzmaurice said:

It's OK, we knew what he meant. ☺️

The best FOH mixers in pro-touring sound high pass the bass channel between 60 and 80Hz, so the bass sounds like a bass and not a 30 ton dump truck dropping a load. There's still bass content in the subs, but not so much that it drowns out everything else.

 

Thanks Bill. My bad. Should have read more carefully. I'd still high pass subs. I do mine (there will be some LF content below that in them due to the filter slope) to avoid the other issues (I like the dump truck analogy) I mentioned. And I only use one in the vast majority of cases.

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1 hour ago, uk_lefty said:

Won't power on. We changed the fuse in the sun unit itself, changed kettle leads and sockets. I've brought it home and tried again, another new kettle lead and the power on led doesn't light. 

 

Bloody consumer electronics ... almost certainly cheaper to replace than to investigate / repair / fail again.

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2 hours ago, uk_lefty said:

Won't power on. We changed the fuse in the sun unit itself, changed kettle leads and sockets. I've brought it home and tried again, another new kettle lead and the power on led doesn't light. 

 

Might just be the switch.

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3 hours ago, Bill Fitzmaurice said:

You should high pass subs, at their lower corner frequency. That's typically between 30 and 40Hz. 

 

Makes a lot of sense. Human hearing doesn't typically go below 20Hz so anything below that is just subsonic high-energy crud! High passing / low cutting those sub sonic frequencies will leave the subs free to focus on the 30Hz+ range which is as low as a 5 string bass goes anyway. 

It seems to me that would always make sense in a pub venue which is what this thread is about.

Just wondering whether it would also hold true in a larger dance club situation where the punters are enjoying "feeling" the bass?

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I nearly always use my subs in the pub band format of one either side directly under the pole mounted tops. Yes, it might lead to problems for a pro sound engineer, but honestly, down the Dog n Duck on a Friday or Saturday night, 99% of punters wont notice. The advantage of the subs is they are big, heavy, substantial and have prevented the tops being knocked onto an unsuspecting guitarist (or heavens preserve, bass player i.e. me) by a drunk punter on more than one occasion. 

From the sound point of view it may be less than perfect but as one of your PA stacks is probably pointing at the end of the bar, it really doesnt make that much difference. On that rare occasion we play a social club, the subs go side-by-side in the centre in front of the stage with the tops on stands either side of the stage. The increased performance of the subs in this configuration is noticeable but this config would be totally impractical in all of our other gigs, which like Phil says, lack any sort of raised stage area. 

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3 hours ago, Al Krow said:

 

Makes a lot of sense. Human hearing doesn't typically go below 20Hz so anything below that is just subsonic high-energy crud! High passing / low cutting those sub sonic frequencies will leave the subs free to focus on the 30Hz+ range which is as low as a 5 string bass goes anyway. 

It seems to me that would always make sense in a pub venue which is what this thread is about.

Just wondering whether it would also hold true in a larger dance club situation where the punters are enjoying "feeling" the bass?

Right idea, but shift it all up an octave. The punter chest cavity resonates around 80hz. That's the centre of "thump".

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15 hours ago, Happy Jack said:

 

Bloody consumer electronics ... almost certainly cheaper to replace than to investigate / repair / fail again.

Exactly 364 days after purchase. Built in obsolescence is really evolving.

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