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Sub woofers - sublime or ridiculous?


Al Krow

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I don't fully understand the situation you're imagining. I use a 120W bass combo which has a 15" speaker in it; and it does a good job of 1) clearly reproducing the lowest notes and 2) "colouring" the tone, in a nice way, to make it sound more pleasant to my ears than (for example - which I have done on a number of occasions) going straight into a PA or a FRFR amplifier of some kind.

If you had an amp of some kind, and then needed another amp (or cabinet) to "help out" with the sound, then amp #1 isn't really doing the job....and you'd be lugging around 2 amps, or you'd be regularly using a bi-amped rig, or something like that. For me, I'll stick with the 0 or 1 things to carry around in addition to the bass.

Also, AIUI PA systems are rather good at reproducing what goes in. If you had some kind of pre-amp or effects unit or equaliser pedal board or whatever, which produced that "nice, bass-sounding" signal but from then on you went straight into a PA, I dare say it would sound good - or a simple tweak on the EQ could make it sound good. Subs, in the sound reinforcement world, are there to "take the stress" off the main speakers, because bass needs disproportionately more power to realise the actual acoustic volume, as the volume is turned up and up. You'd typically have a PA system with subs if it were north of (say) 500W, while below that its a non-issue. Or if it is an issue, its for whoever looks after the PA to worry about.

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So sub woofer common with PA set ups if the PA speakers are smaller than 15"?

Just also wondering whether for more subby material e.g. reggae they are standard?

Or for folk using 'low end' pedals like the DOD Meatbox?

Edited by Al Krow
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The #1 reggae cab is the 'Fridge, and it's by no means a sub. A real sub on the back line is a bad idea, since you won't know what it's doing out in the room. Even real subs on PA can be problematic when the FOH engineer doesn't know what the electric bass is supposed to sound like. Those who do will high pass the bass channel between 60 and 80Hz, to end up with response in the PA similar to the back line amp. That means if the PA is well engineered most of the electric bass content coming out of the subs  is between 60 and 100Hz. The worst bass mix I ever heard was Greg Lake. His stage tone might have been good, he was using an SVT. But out front a moron sound man had him so loud below 80Hz that when Greg played anything below a D note it drowned out the rest of the band, while anything he played above that literally disappeared and wasn't heard at all. If Greg had heard what that sound man was doing he'd have pummeled him.

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Most bass backline equipment is pretty poor at reproducing the lowest frequencies, certainly at higher sound levels, so I think it's perfectly reasonable to wonder, as Al is doing,  whether incorporating a subwoofer into your backline might be a good idea.

The way I've always viewed it, though, is that if you're in a situation where you feel the bass guitar needs some subwoofer support, then it's almost certainly true that the kick drum does too.
At this point it becomes a PA issue rather than a backline issue - ie your PA system needs a subwoofer, and if it's got one, then there's no benefit in also adding one to your backline.

Also, as Bill points out, excess sub-bass frequencies are frequently a huge problem in contemporary live sound mixes. WWWWWWOOOOOOOOOOOOOOOOOOOOOOMMMMM! 😡

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Yes absolutely! The other obvious bit I've missed is mic'ing up the kick drum. This seems to be a key area for sound engineers wanting to make use of their sub woofers. 

I kinda think of that dance beat low end as being "felt" (= separate sub woofer?) whereas what I want primarily to achieve for my bass lines is to be articulately heard (= rest of PA or bass amp/cab depending on venue). 

Would a sub woofer allow you to get the best of both worlds or the worst? 

In other words: sublime or ridiculous?! 

@paulbuzz I think where you're going is that a subwoofer could well add something, but most likely as an addition to the PA. 

Edited by Al Krow
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I think that in most cases the kick drum is the primary factor in determining whether your PA needs a sub or not.

 - Is the band attempting to perform at a volume at which the kick drum, unmiked, would be too quiet?
     YES: The PA needs a sub, and both the kick drum and the bass guitar should be in the PA's FOH mix. Hence no point in a bass backline sub.
     NO: The PA doesn't need a sub (and neither does the bass backline).

I'm not up-to-date enough with currently available PA gear to have any meaningful opinion on which are the best value subs at various price/performance points.

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I'm not sure how much output my bass has below around 80Hz, so depending on the FOH system I'm probably not in the subs that much anyway. I can see why reggae players or whatever might feel differently.

 

Either way I really don't want that stuff on stage. Something that loud and low will likely do nothing useful apart from rattle mic stands and woof into every open channel.

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36 minutes ago, paulbuzz said:

I think that in most cases the kick drum is the primary factor in determining whether your PA needs a sub or not.

That depends on the PA. The current preferred topology is mains that work from between 80 and 100Hz and up, with subs handling below that. This is in stark contrast to PA up to about 20 years ago that usually ran the full bandwidth in a single cab. Those systems didn't go particularly low and loud, in fact they had low frequency response not all that different from electric bass cabs. Modern subs do have low frequency response significantly different from electric bass cabs, which in tasteful hands can be a good thing, in tasteless hands a very bad thing. If you have mains that only go to 80-100Hz and you want to put low frequency sources in the PA you need subs, but you need someone at the helm who knows what he's doing, not just the proverbial friend of the band.

Edited by Bill Fitzmaurice
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25 minutes ago, Bill Fitzmaurice said:

Modern subs do have low frequency response significantly different from electric bass cabs, which in tasteful hands can be a good thing, in tasteless hands a very bad thing. 

Agree absolutely. Your anecdote about Greg Lake's bass sound is distressingly familiar.

I don't know what's wrong with the people responsible for these mixes. It's as if they've somehow become persuaded that the spectral balance of electronic dance music is appropriate for all other forms of music too.
Or is it just complying with what they think people expect from the sound at live gigs these days?

Either way, it seems to have become a very common aesthetic for live sound mixes, with hugely detrimental effects on the entire mix, and the bass guitar in particular.

Apologies to Al if I'm getting a bit off-topic here.

Edited by paulbuzz
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1 hour ago, paulbuzz said:

Agree absolutely. Your anecdote about Greg Lake's bass sound is distressingly familiar.

I don't know what's wrong with the people responsible for these mixes. It's as if they've somehow become persuaded that the spectral balance of electronic dance music is appropriate for all other forms of music too.
Or is it just complying with what they think people expect from the sound at live gigs these days?

Either way, it seems to have become a very common aesthetic for live sound mixes, with hugely detrimental effects on the entire mix, and the bass guitar in particular.

Apologies to Al if I'm getting a bit off-topic here.

No need to apologise at all. It's all good stuff! 

On a related point, I find myself asking the sound engineers to dial down the subs otherwise our sound can become dominated by the low end.

In contrast I'm wondering whether a quality sub woofer, used judiciously, might add something to our PA particularly as we just have 10" RCFs and we're thinking about mic'ing up the kick drum / putting the bass through also. Our RCFs are active, so I guess we'd be looking at a powered sub woofer or maybe scrapping our set up and starting from scratch, but that's going to be a major ££spend.

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If you're doing gigs with a PA that just has active 10" speakers and feel that the kick drum and bass guitar could do with a bit of a lift, I'd say that was an ideal set up to which to add one or two active subs.
(I wouldn't even consider putting kick drum or bass into a PA that's just a pair of 10"s.)

Were you intending to mic up any of the rest of the kit? If you think it's just the kick that's getting a bit lost, in my opinion it would be fine to add a bit of reinforcement to the kick drum only, but others would argue that if you're going to mic the kick, you really ought to add overhead and snare mics too as a minimum. At this point though, you're starting to add quite a bit of extra gear and complexity to your setup and soundcheck.

There are loads of models of subs that are intended for exactly your kind of setup, at widely varying price points. I'll leave the recommendation of specific models to those that are more familiar with the currently available models...

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Bill's right (as usual). I always find the amount of low end my PA subs produce out in the room can be surprising and I find myself cutting them, sometimes considerably. You need a high quality sub for clean bass, too. A budget boom box just won't cut it. I did experiment recently with using one of my Fohhn PA subs with one of my Phil Jones bass cabs and it sounded good once I'd got the relative levels right, but it took a bit of fiddling about (and of course, you ideally need an active sub or separate power amp/crossover if using a passive sub so you can balance things properly). I decided the improvement wasn't worth the aggravation of carrying the extra stuff around.

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we have 2 x 15 active RCF's and 1 x Mackie sub, everything is mic'd to FOH,  but only the Kick, Toms and Bass through the Sub with high pass filter. The bass is turned way down through the sub, with the emphasis on the kick for that thud in the chest without mud. So IMO deffo no sub for backline, strictly FOH, but possibly not necessary for quality 15" PA Tops and a good quality Bass Backline, especially if we're talking Dog n Duck territory.

PS Mackie subs are terrible, should have gone for another RCF :(

Edited by skidder652003
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39 minutes ago, skidder652003 said:

we have 2 x 15 active RCF's and 1 x Mackie sub,

No offense, but that's exactly what you don't want. Fifteens are for subs, or very high power three-way mains. Tens or twelves are best for mains, they have better midrange response and dispersion, and they're easier to lug. You don't want to use one sub with two mains. The demands on driver power handling, cone displacement and cabinet size go up as frequency goes down. That means the cab size and power ratio of subs should be about 4:1 compared to the mains.

Edited by Bill Fitzmaurice
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6 minutes ago, Bill Fitzmaurice said:

No offense, but that's exactly what you don't want. Fifteens are for subs, or very high power three-way mains. Tens or twelves are best for mains, they have better midrange response and dispersion, and they're easier to lug. You don't want to use one sub with two mains. The demands on driver power handling, cone displacement and cabinet size go up as frequency goes down. That means the cab size and power ratio of subs should be about 4:1 compared to the mains.

Thats interesting, thanks, so 2 x 12's would be more suitable?

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23 minutes ago, Bill Fitzmaurice said:

Tens or twelves are best for mains, they have better midrange response and dispersion, and they're easier to lug. 

I've been thinking this for years and hoping someone with deeper knowledge of speaker cone size would be able to confirm, but I've had a load of baloney about it doesn't matter these days whether speaker cones are 5" or 18". 

Sense at last. Thank you!

[Apologies that's a complete aside to this thread, but a "yeah finally!" point... :) ]

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1 hour ago, skidder652003 said:

Thats interesting, thanks, so 2 x 12's would be more suitable?

A pair of 1x12 mains and a pair of 1x15 or 1x18 subs is adequate for the average room. Also, the subs should not be under the mains. The mains should be on poles in front of the mics to prevent feedback, the subs should be placed together close to a wall for boundary reinforcement and to prevent boundary reflection sourced response nulls.

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50 minutes ago, Al Krow said:

. . . .  but I've had a load of baloney about it doesn't matter these days whether speaker cones are 5" or 18".

It doesn't. . . . and it isn't "baloney".

The comments about "size" have been made in relation to bass rigs. This comment is being made in relation to PA systems. These represent different requirements, criteria and solutions.

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12 minutes ago, chris_b said:

It doesn't. . . . and it isn't "baloney".

The comments about "size" have been made in relation to bass rigs. This comment is being made in relation to PA systems. These represent different requirements, criteria and solutions.

I'm sure @Bill Fitzmaurice will no doubt be along to confirm that you are correct (assuming that you are) but I'd be very interested to know why his general point about mid-range response and dispersion being overall better with 10" or 12" cones should not apply to all speaker cones irrespective of whether they happen to be inserted into a bass cab or PA cab? At the end of the day we're talking about speaker cones. 

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