Subs

[AxelF]

I'm after some advice re subs please - we're a 5 piece pub covers band playing indie/rock and we run a silent stage (bar acoustic drums) with everything straight into a Behringer XR18 and then two RCF935s for the front of house.

 

It might be just GAS but I'd love to add a sub or two, just for a bit of extra oomph on the kick and maybe bass too, and have seen lots of sometimes conflicting advice on the subject in lots of different places.

 

I've read that having two subs separated and underneath the tops can lead to comb filtering and stacking them centrally isn't an option given the size of places we're playing. Would having just one sub under one of the tops be an option or is that a stupid idea? One problem I can see straight away is one of the tops would be getting a low passed signal while the other would be getting a full range signal. Does anyone do this, or are two subs under the tops the way forward at this level? Thanks!

[Jakester]

Like you, I've seen a lot of comments suggesting that subs under tops is less than optimal, but whenever I've played venues with that setup, it's never been a noticeable issue. 

 

I have a single sub which comes out at bigger gigs - generally for ease it's stacked under one of the tops. Provided you've got your crossover set properly (usually via the sub itself if its powered) locating a single sub at the side of the stage under a top shouldn't cause too many issues. The "ideal" location is right at the front though.

 

57 minutes ago, AxelF said:

One problem I can see straight away is one of the tops would be getting a low passed signal while the other would be getting a full range signal.

 

I just run both tops off the sub (i.e. using the crossover in the sub). That way you don't get up with the problem above. 

[Downunderwonder]

Had a gig in a cocktail bar that liked to get rowdy with a DJ later. My PA cab and amp went on top of their massive overkill 2x18 sub and my little sub went on the other side in the other corner. No wukin' furries.

 

Point being subs like being up against walls and particularly in corners. Then they run really low power as the boundary reinforcement gets free dB.

 

Just put your subs to one side or the other and be far enough from the rear wall that you don't have a gnarly 1/4 wavelength cancellation. At 14ft out you get another reinforcement at 80hz which is the breadbasket of your kickdrum.

 

One side of the room will be more bassy than than the other but not enough that anyone consciously notices. 

[Al Krow]

Two RCF 935s sounds awesome for pub venues! We're getting by very comfortably with 912As / 732As, which I'm sure will be outdone by your two tops. 

 

My personal take, is the main beneficiary to the band sound from the sub itself will be to kick drum albeit also giving more headroom to the tops above the crossover frequency (typically 80Hz / 110Hz).

 

Are you lacking in volume for any of the instruments or vocals ie do you need the additional headroom for the tops, or feeling that you need more low end kick? Just playing devil's advocate and wondering if your sound is going to benefit much from adding subs for most of your pub gigs?

Edited September 13, 2023 by Al Krow

[Woodinblack]

3 hours ago, AxelF said:

I'm after some advice re subs please - we're a 5 piece pub covers band playing indie/rock and we run a silent stage (bar acoustic drums) with everything straight into a Behringer XR18 and then two RCF935s for the front of house.

 

Can't see why you would need any subs with that, its way more than we have.

I have a sub, a small one that I bring out for outdoor gigs only, that allows the speakers to have some of the bass taken out of it.

[AxelF]

Thanks all, I think you're right Al - I/the punters probably wouldn't notice much difference, it's likely just GAS, I'd love to try one though and see!

[Downunderwonder]

13 minutes ago, AxelF said:

Thanks all, I think you're right Al - I/the punters probably wouldn't notice much difference, it's likely just GAS, I'd love to try one though and see!

A nicely pumped up kick will sound much better coming from a well placed sub or two. Just don't get carried away. You could easily catch lead kick syndrome.

[Phil Starr]

Hi Axel. I've got RCF745's so in terms of bass output I'm pretty confident you don't need subs for pub covers.

 

The question though is would it improve your sound and is it worth the investment.  I have subs it does improve the sound and gives you the possibility of being self sufficient outdoors where you lose the bass because half of it is lost when the speakers are radiating 360deg. The improvement comes because you gain a little extra in the low end and the levels of distortion reduce when you HPF your tops, though no-one would sensibly use 15" tops if they had subs at every gig. I have subs but haven't used them in a pub for over 10years. I bought 15" tops so i wouldn't need them.

 

You get problems with subs though, any bass room resonances can be exacerbated by increasing the low end. If I'm having problems I frequently HPF the whole PA at 50hz to cut the mud. If you have sound crew, hours to set up and soundcheck, all of this can be sorted given time and expertise but that isn't how most pub gigs go is it? Subs will also tend to swamp the stage with low frequencies so you'll have to re-eq your bass sound on stage and the rest of the band might struggle over all the extra warmth. that will vary depending upon the venue and it can be anything from barely noticeable to disastrous.

 

Technically having the subs separated causes comb filtering issues. out in the open that causes areas where there is too much bass and areas where you can't hear the bass even though it is balanced at the mixing desk. If you see a PA set up at a festival with huge bass bins at the bass of left and right then you can be certain the sound engineers have no idea what they are doing  If you do go ahead it makes more sense to go for one big sub than two little ones and a single sub is probably a more sensible option than a pair for most pub gigs. they are better central  but it's usually not critical and you can be flexible. Using an active system almost all subs will have crossovers built in so you pass your mixers output to that and then feed the mains from the crossover in the sub to left and right, the sub takes care of that.

 

this is well worth a watch

 

 

 

 

Edited September 13, 2023 by Phil Starr

[Al Krow]

"If you have sound crew, hours to set up and soundcheck, all of this can be sorted"

 

You'd really hope so wouldn't you, haha?! Just been to a festival and the support band to the headliners had some of the worst rumbling bass which almost killed their set. Could see the bass player grimacing, fiddling about with his on board EQ and finally stopping playing altogether. The sound guy deserved to be shot...or at least be sent on an HPF 101 course! 

 

1 hour ago, Downunderwonder said:

A nicely pumped up kick will sound much better coming from a well placed sub or two. Just don't get carried away. You could easily catch lead kick syndrome.

 

Ah that's where the track got its name from...only taken me a decade for the penny to drop 😁

[Woodinblack]

19 minutes ago, Al Krow said:

You'd really hope so wouldn't you, haha?! Just been to a festival and the support band to the headliners had some of the worst rumbling bass which almost killed their set. Could see the bass player grimacing, fiddling about with his on board EQ and finally stopping playing altogether. The sound guy deserved to be shot...or at least be sent on an HPF 101 course!

 

I had some of the worst rumbling bass on saturday, it was so loud, but turned out in the crowd it sounded perfect and the guitarist couldn't even hear any bass

[Al Krow]

Believe me, the bass sounded a very long way from perfect on that particular set at the All Points East festival 😅

 

[Woodinblack]

I remember being at a placebo gig in newport, and the support comes on and the bass player has a US standard Jaguar, I thought that looks nice, wonder what it sounds like. I will never know, as I imagine the much would have sounded the same if they took the jack out of the bass and just put their finger on the end of it - the same mushy drone.

[Phil Starr]

@AxelF you may have started something here. We probably need somewhere to talk about subs generally

 

Just to be clear, the comb filtering problem from widely spaced subs is about the bass frequencies and the distance between the speakers and not whether they are subs or just PA speakers on poles. You'll get the same problem from your 935's if you use them outdoors. I noticed this the first time at an open air gig a few weeks back with my RCF745's. The band usually use in-ears but we had a dep drummer with an acoustic kit who doesn't use in ears. It was the first time we'd played with him so I brought the kitchen sink and he ended up with a 10" floor monitor. At his request I turned the sound right down on my bass rig and up in the monitors so the audience were getting bass almost entirely from the PA. Walking around at sound check the beaming was really obvious. More so than I'd ever noticed before. Unsurprising really.

 

Normally indoors the bass has many pathways to your ears, it bounces off walls and ceilings which fills in the gaps caused by the comb filtering, but also smearing/distorting the sound, one reason why bass often sounds muffled and distorted at pub gigs. At previous outdoor gigs we'd usually had a provided PA, or my bass amp had been providing most of the sound, or at least enough to fill in the gaps. It's something I'm going to have to look at with the band having moved towards 'silent stage' including electronic drums. I'm certainly going to be trying swapping out my 15's for a pair of RCF 310's with a single sub to see how that works at a technical rehearsal soon.

 

From your point of view you might want to look long term at some more portable tops if you do go for subs.

[Pirellithecat]

Just back from a gig.  Small area for the band .... pub.   Loud.    Thought I'd take all the gear just to practice set up etc.  But did we really need the Sub?  
Absolutely!

Of all the improvements to the PA, the most noticeable, even in small pubs, is its effect on the kick drum.  Tried it on and off and there's no question that it really solidifies the sound of the band.

Not only that, but it's much better (under a PA top) at stabilising the PA when inebriated yobs fall into the band, baptising us in beer!   Again.

 

But the point I really wanted to make is that I suspect it's a much better option to buy one high quality sub that 2 lesser quality units.    It avoids the positioning/interference debate, makes life easier in terms of transport and is likely to do the job well.   

I can fit my bass rig (2 cabs) Sub (RCF 705) 2 tops (932's) 2 bags of wires, stands, monitor, mixer me and me bass and pedal board into an ID3 (think golf with less carbon).  Just.   And drive over Wrynose Pass to last night's gig.

[Phil Starr]

18 hours ago, Pirellithecat said:

 And drive over Wrynose Pass to last night's gig.

Good Grief! Was this an open air at the top of Scafell? Whereabouts are you based in Cumbria? 

 

Completely agree btw about subs being better than tripods in a boisterous pub and about just having one decent one instead of two lesser ones.

[Pirellithecat]

Based in The Duddon Valley  - a few miles from the bottom of Wrynose - so shortest route to Keswick (tourists allowing) is over the top!

[Phil Starr]

Lovely, I know the North Lakes better as my sister in law lives in Ivegill just north of the Lakes, though we've had a couple of stays in and around Windermere so we are getting to know the south area a bit better. What's the name of your band?

[Bill Fitzmaurice]

On 12/09/2023 at 04:45, Jakester said:

Like you, I've seen a lot of comments suggesting that subs under tops is less than optimal, but whenever I've played venues with that setup, it's never been a noticeable issue.

Lots of things aren't particularly noticeable if you're not able to make side by side comparisons. When you put subs under tops you not only lose boundary loading, by not have them close to a wall, you also can have cancellation notches when they're 1/4 wavelength out from a wall. If they're split by less than two wavelengths you will have power alley comb filtering. That's the science, and the science is never wrong.

There are three reasons why people put subs under mains.

#1: "That's how everybody does it".

#2: "It's the only way we know to do it".

#3: "We don't know any better way to do it/we don't know why it's the wrong way to do it".

 

Now you know.

[Al Krow]

32 minutes ago, Bill Fitzmaurice said:

Lots of things aren't particularly noticeable if you're not able to make side by side comparisons. When you put subs under tops you not only lose boundary loading, by not have them close to a wall, you also can have cancellation notches when they're 1/4 wavelength out from a wall. If they're split by less than two wavelengths you will have power alley comb filtering. That's the science, and the science is never wrong.

There are three reasons why people put subs under mains.

#1: "That's how everybody does it".

#2: "It's the only way we know to do it".

#3: "We don't know any better way to do it/we don't know why it's the wrong way to do it".

 

Now you know.

 

But if you're putting subs behind the mics in order to have them close to a wall you can get awful low end feedback. 

[Woodinblack]

2 minutes ago, Al Krow said:

 

But if you're putting subs behind the mics in order to have them close to a wall you can get awful low end feedback. 

 

Your mics pick up your subs? Apart from the bass drum I don't have any mics that can go down that low

[Al Krow]

10 minutes ago, Woodinblack said:

 

Your mics pick up your subs? Apart from the bass drum I don't have any mics that can go down that low

 

Crossover of 110 Hz?

 

Your point is probably, however, fair even if your vocal mic is responsive only down to 80 Hz. 

 

But as you say it is the kick, which is benefiting most from the sub, and kick drum mic position viz the sub would have been a likely culprit. The low-end stage bleed is going to be more range dispersed as well, agreed? 

[Woodinblack]

30 minutes ago, Al Krow said:

Crossover of 110 Hz?

 

My sub doesn't go up that high, but there is no reason for a vocal mic for our group needs to go much below 80.

 

30 minutes ago, Al Krow said:

But as you say it is the kick, which is benefiting most from the sub, and kick drum mic position viz the sub would have been a likely culprit. The low-end stage bleed is going to be more range dispersed as well, agreed? 

 

We only use the sub open air anyway, so it is never much of an issue for us.

[Al Krow]

6 minutes ago, Woodinblack said:

We only use the sub open air anyway, so it is never much of an issue for us.

 

In which case putting it against a wall ain't ever really going to be a thing then? 😁

[Bill Fitzmaurice]

1 hour ago, Al Krow said:

 

But if you're putting subs behind the mics in order to have them close to a wall you can get awful low end feedback. 

It's not likely, with the exception of drum mics. But two points. First, sub output is omni-directional. Be they in front or in back of you the mics will still pick up the same content in the sub frequencies. Second, there's no need to put them in back of the band to wall load them. They can go off to either side, as not only are the subwoofer frequencies radiated omni-directionally, they're also not directionally locatable with our hearing. No matter where they are the directional cues for their content won't come from them, they'll come from the harmonics of the low frequency content which  comes from the tops.

 

If you're at all serious about PA the comments made here by Downunderwonder, Phil and myself are Gospel. Where low frequencies are concerned getting it right with PA is far more complicated than with bass amps, as nothing about how sound below 100Hz works is instinctive. You have to be taught. The guys who automatically put subs under mains split to either side have not been.

[vsmith1]

On 17/09/2023 at 11:35, Pirellithecat said:

Just back from a gig.  Small area for the band .... pub.   Loud.    Thought I'd take all the gear just to practice set up etc.  But did we really need the Sub?  
Absolutely!

Of all the improvements to the PA, the most noticeable, even in small pubs, is its effect on the kick drum.  Tried it on and off and there's no question that it really solidifies the sound of the band.

Not only that, but it's much better (under a PA top) at stabilising the PA when inebriated yobs fall into the band, baptising us in beer!   Again.

 

But the point I really wanted to make is that I suspect it's a much better option to buy one high quality sub that 2 lesser quality units.    It avoids the positioning/interference debate, makes life easier in terms of transport and is likely to do the job well.   

I can fit my bass rig (2 cabs) Sub (RCF 705) 2 tops (932's) 2 bags of wires, stands, monitor, mixer me and me bass and pedal board into an ID3 (think golf with less carbon).  Just.   And drive over Wrynose Pass to last night's gig.

I agree. Just to add that in one of my bands, the drummer uses a e-kit so the kick drum needs that support from a sub. In the other band, the drummer sometimes uses an ekit and the sub again is essential. I also DI my bass out into the PA and again is supported by the sub. It makes the stage area quieter. 

 

In terms of kit: both bands have 2xtops and 1xsub. One top sits on a pole in the sub.