Sub woofers - sublime or ridiculous?

[Phil Starr]

22 hours ago, Al Krow said:

alto tx212s subwoofer  On sale at PMT for < £350.  20kg weight is very appealing, but is a single sub delivering 450W RMS going to cut the mustard?

 

Maybe worth paying the extra and getting something like this (1,200W RMS): Alto Trusonic TS12S Active Powered Subwoofer and figuring out how best to manage handle the additional weight?

It's so difficult to compare PA speakers on specs nowadays. I'm seeing over-quoting of specs by 4x regularly and similar over-quoting of db levels for sound output. The sums in their advertising literally don't add up. The idea that a single 12" speaker can handle 2,600W of sub bass frequencies is just absurd as is the idea that it can ouput 130db sound levels.

 

However i do know from direct experience that the TX series and the TS series are chalk and cheese and I personally wouldn't look at the TX. I don't think the 26kg for a sub is that bad, you'll struggle to find anything much lighter and it isn't something you have to lift onto a pole, Lidl and Aldi have both sold little trolleys you could wheel them on in the last fortnight and our local stores still have them in stock.

[Al Krow]

Cheers Phil. I'll be dropping the TX from my shortlist then! The TS looks more capable on a number of fronts including a frequency range of up to 140hz which is nicely into the low mids.

 

Couldn't immediately find anything about the X-over f though?

 

What are these really useful trolleys you mention? Do they pack away nicely to take up minimal boot space?

[Bill Fitzmaurice]

You don't want to go to 140Hz, that gets into the directionally locatable frequencies, which limits placement options. 80 to 100Hz is the preferred range.

[Al Krow]

9 minutes ago, Bill Fitzmaurice said:

You don't want to go to 140Hz, that gets into the directionally locatable frequencies, which limits placement options. 80 to 100Hz is the preferred range.

 

Sure, but wouldn't it also helpfully take a bit more of the bass load off the tops?

 

I guess it's a bit irrelevant if the X-over is fixed at a lower f? 

[Phil Starr]

18 hours ago, Al Krow said:

 

What are these really useful trolleys you mention? Do they pack away nicely to take up minimal boot space?

 

https://www.aldi.co.uk/dolly-trolley/p/829523790959200

Lidl were doing them too around a fortnight ago but they are widely available. I bought a Lidl one; max load is 250kg so you can stack all eight subs

Edited August 9 by Phil Starr

[Phil Starr]

The frequency response is probably just the highest frequency they would recommend for the crossover and it would depend upon your tops. Even with eights you'd normally crossover below that. Yes the subs will reduce the bass load but that is a two part help. The crossover is the bit doing the job here. You are effectively adding  an HPF for your PA. All ported cabs have a point just above the tuning frequency where there is an excursion peak and there is also increasing excursion as the freqency drops it's extreme excursion that will lead to failure of the speakers most of the time. Obviously the crossover will also remove some of the electrical power from the tops too so that will mean less heat in the coil but in practice the power going through the subs isn't much so the coil temperatures in your tops won't drop much either.

 

That leads me to ask why you want to do this? Your active speakers are protected from almost all overload issues as i found out when an idiot sound engineer overloaded one of my ART310's accidentally when he had problems with the router on his Behringer mixer. It simply switched itself off and it reset when I unplugged it and works perfectly since. You can probably clean up bass in your PA by using an HPF  without affecting the sound much. A designated HPF will probably fiter at 24db/octave and the one in the sub probably at 12db/octave, depending upon how it is done in your model/make. Are your speakers showing any signs of stress at the moment? Are you loud enough at most gigs? Do you want more bass in the mix and more of that deep booming disco bass? There are threads on BassChat about sound engineers ruining gigs with over enthusiastic use of sub-bass.

 

Adding subs isn't all joy, there's an upside and a downside. The downside is obviously more to carry and a bloody big box at that. You then add in a box which radiates sub bass out at 360deg including backwards exciting room resonances in most British venues with their tiny misshaped rooms. The backwards sound floods the stage with sub bass which is a total pita It's more complexity and there will be a longer set up time and a bit of a learning curve until you get it all working well. I've got subs but they go out once a year probably and almost always to open air gigs.

 

Obviously they can also be great, you don't have to have them too loud and you can filter out the unwanted frequencies or trim them down with eq. The will reduce the excursion of the mid/bass drivers in your tops and they will allow you to use smaller mid/bass drivers and smaller tops. I'm using mine now a bit more and taking 10's not 15's and I'm toying with the idea of using a small sub with 8" tops for some gigs with my duo. RCF do a rather nice 2x6 top which I'm wondering about but that is probably just GAS. Are you considering new tops? I fear I might not be the only one suffering from GAS

 

 

 

 

 

 

[Al Krow]

The point about venues is spot on Phil.

 

Subs in British pubs is often going to be overkill / unnecessary - but can be a nice to have if you get it right.

For larger venues and definitely for outdoors, particularly where there is no wall/floor reinforcement for the bass, it seems they start to become a "must have".  We've very much noticed at the couple of outdoor gigs we've done that the bass has to be set quite loud but then falls at immediate FoH but seems to tail off pretty rapidly - I'm guessing that's to be expected?

 

In terms of thinking about new tops nope, haha, we're not currently thinking of getting anything else. We're pretty content with the band's RCF 732As and my RCF 912As, which we alternate and is a real treat not for me to have lug the PA to every gig. I may be tempted to upgrade mine to an RCF 932A at some point, but that is well down the pecking order below (i) a better digital desk (maybe the A&H CQ18) and (ii) a sub.

[Bill Fitzmaurice]

The bad news is to keep up with your RCF tops you'd need at the minimum a pair of 15" subs, especially outdoors. The laws of acoustics will not be denied.

[Jack]

3 hours ago, Bill Fitzmaurice said:

The bad news is to keep up with your RCF tops you'd need at the minimum a pair of 15" subs, especially outdoors. The laws of acoustics will not be denied.

Outdoors maybe but my indie band has a pair of 732s and a pair of 705iis. Indoors we just use one sub, it easily outpaces both tops. Excuse the fan photo nicked from Facebook, normally I purposefully try to not photograph the pa and cables. The guitarists both have amps on stage, but I just have a (usually highpassed) wedge, the one sub is doing it all. 

 

Edited August 9 by Jack

[Bill Fitzmaurice]

That means the tops aren't near their limit. At some point they'd be able to go significantly louder than one sub, unless it was loaded with an eighteen.

[Phil Starr]

11 hours ago, Jack said:

Outdoors maybe but my indie band has a pair of 732s and a pair of 705iis. Indoors we just use one sub, it easily outpaces both tops. Excuse the fan photo nicked from Facebook, normally I purposefully try to not photograph the pa and cables. The guitarists both have amps on stage, but I just have a (usually highpassed) wedge, the one sub is doing it all. 

This is my experience too.

 

Indoors with the sub on the floor and probably close to a side or rear wall you will get anything from 6-18db of reinforcement of the lowest frequencies so one sub in this situation is equal to two or more. In addition music generally contains very little sound below 100Hz. Specifically Indie music, but most of the pop rock covers pub bands tend to play. You only have to look at a meter to see that the spectrum will have the bass down an average 12db or so depending upon the song. Try playing any well recorded music through the PA and switch the tops off and you'll find there is almost nothing coming out of the subs even when playing the PA at quite loud volumes. RCF rate both the 732's and 705's as 131db peak. Those figures are inflated but by presumably by the same amount. You can add 6db for the second top and 6db for room reinforcement to the single sub in an enclosed space but you'll probably need the second one outdoors.

 

In any case there is no way you'd push out full volume from the 732's into the vast majority of UK venues with fewer than 200 people present at which point you are usually looking at a touring rig or a hire company providing PA.

 

the original question was "Sub Woofers - sublime or ridiculous" and the answer of course is neither, just a useful tool that you might need or might not.

 

 

[Al Krow]

"Try playing any well recorded music through the PA and switch the tops off and you'll find there is almost nothing coming out of the subs even when playing the PA at quite loud volumes."

 

That is such an interesting observation! What is it about studio engineered music that, in practical terms, it does away with the need for subs and obviously sounds great?

 

Edited August 10 by Al Krow

[Stub Mandrel]

This is a very interesting thread.

 

Reality is, so many gigs are not on nice stages facing out into spacious auditoriums...

 

We have a situation where pa is the BL's dad's hobby. So we get lots of PA in tiny venues. We don't get told to turn down and generally the feedback on sound quality is good. I don't know settings used.

 

The PA is @Bill Fitzmaurice' pet nightmare - mackie with tops on sticks out of the subs. (High end mackie not 'thump').

 

Personally, I think we would be better without subs in pub gigs, actually I wouldn't di my bass as I have to keep my volume right down so the PA has some function... similarly the guitarist has a power soak on his 50W Marshall and effectively runs it at a handful of watts. He has tried going ampless, but wasn't happy with it. For his style overdriven vales are the way.

 

In the pic below I could barely move around and with my cab up on a bench seat behind me and a cab by my head I had some very odd intermodulation effects that had me convinced I was in the wrong key a couple of times.

 

I would bring a tiny hybrid 50W head to gigs like this but it has no di out. The alternative is to go ampless and just use a di box, but I would still need a monitor which is all my rig is functioning as in this situation.

 

Larger gigs, my rig basically provides missing top end as I usually get a bass heavy pa sound that doesn't suit a three piece...

 

If I'd have been setting up the PA, it would gave been two tops with vocals (there would have been space for me to gave a mic) and also snare and kick. It's almost always worth miking these even for small gigs if you want people to dance.

 

 

Contrast with my other band. Similar size venue but more space for the band. Four vocals through the tops, nothing else. Everyone happy with the soundalthough I felt drums and vocals were a touch loud.

 

[Jack]

On 09/08/2024 at 22:39, Bill Fitzmaurice said:

That means the tops aren't near their limit. At some point they'd be able to go significantly louder than one sub, unless it was loaded with an eighteen.

Bill I'm sorry but that just isn't the case. The tops are pushed and the sub is idling.

 

Different for a reggae band maybe. 

[Phil Starr]

18 hours ago, Al Krow said:

What is it about studio engineered music that, in practical terms, it does away with the need for subs and obviously sounds great?

I'm going to duck that one Al. Beyond my pay grade, I'm not a studio engineer.

 

This was a practical observation sparked off because I've just bought a new sub. (I know, there's me telling everyone else not to bother). We were trying to see where to set the levels relative to the tops and initially I couldn't be certain that they were actually working at all, so I turned off the tops to check. Sure enough there was a faint rumble. I turned the sub up a bit and reconnected the tops and now it was way too loud. To be fair I've noticed this many times before when using subs, a little goes a long way.

 

I suppose the thing I'm trying to say more generally is to ignore the idea that there is one solution for every band. Very few of us actually 'need' to take a huge sub with us to every gig in the UK and that's probably true in most of Europe. Gigs in the USA may be different. For many of us too music is a hobby, it's OK to want a sub you don't need or to choose not to go that route. We all play in a unique variety of venues and the Venn diagram of our set lists probably shows a remarkably small area of overlap even for the cheesiest covers bands (guilty as charged there). Some music has more bass content than others but most has very little content below 80Hz. We are also talking about portable PA often set up in small spaces so our decisions are based upon a balance where practicality and sound quality has to be balanced. Some of us have to transport the PA in a family car, others struggle to lift 20kg tops above their heads or to move a 30kg sub at all. Sometimes you have to play gigs where the PA needs to be discreet and other gigs are in a barn (literally down here in the West Country). I try not to jump to conclusions about what sort of band people play in. Cost is a factor too, you might be better off investing in better tops than spending £500 on a cheap sub or saving your money altogether.

 

If you are playing some sort of pop/rock music indoors to audiences of 20-100 people then you aren't going to need subs and if your tops are good quality active 12's then you can put all your instruments through them quite safely in the sense that they won't break. Towards the top end of that audience size and in bigger rooms subs might add something and also clean up the sound in your tops. If that is what you are trying to do a small sub might be appropriate. The driver in a sub is made differently from the driver in your tops so even a 12" sub will add something. If you are struggling to lift your tops then using small speakers as tops and adding in subs you can wheel in makes a lot of sense. If you just want to be really loud, play huge venues or a style of music that is unusually rich in lower frequencies then you are going to need a bigger PA and at some point the argument for carrying subs becomes pretty strong. There isn't some rule that says you need huge subs for every occasion or every band.

[Downunderwonder]

20 hours ago, Al Krow said:

"Try playing any well recorded music through the PA and switch the tops off and you'll find there is almost nothing coming out of the subs even when playing the PA at quite loud volumes."

 

That is such an interesting observation! What is it about studio engineered music that, in practical terms, it does away with the need for subs and obviously sounds great?

 

It is music intended for the AM radio of old, and old playback systems that sub frequencies only gave problems. Modern stuff on FM seems to get my sub going.

[Al Krow]

47 minutes ago, Phil Starr said:

I'm going to duck that one Al. Beyond my pay grade, I'm not a studio engineer.

 

This was a practical observation sparked off because I've just bought a new sub. (I know, there's me telling everyone else not to bother). We were trying to see where to set the levels relative to the tops and initially I couldn't be certain that they were actually working at all, so I turned off the tops to check. Sure enough there was a faint rumble. I turned the sub up a bit and reconnected the tops and now it was way too loud. To be fair I've noticed this many times before when using subs, a little goes a long way.

 

I suppose the thing I'm trying to say more generally is to ignore the idea that there is one solution for every band. Very few of us actually 'need' to take a huge sub with us to every gig in the UK and that's probably true in most of Europe. Gigs in the USA may be different. For many of us too music is a hobby, it's OK to want a sub you don't need or to choose not to go that route. We all play in a unique variety of venues and the Venn diagram of our set lists probably shows a remarkably small area of overlap even for the cheesiest covers bands (guilty as charged there). Some music has more bass content than others but most has very little content below 80Hz. We are also talking about portable PA often set up in small spaces so our decisions are based upon a balance where practicality and sound quality has to be balanced. Some of us have to transport the PA in a family car, others struggle to lift 20kg tops above their heads or to move a 30kg sub at all. Sometimes you have to play gigs where the PA needs to be discreet and other gigs are in a barn (literally down here in the West Country). I try not to jump to conclusions about what sort of band people play in. Cost is a factor too, you might be better off investing in better tops than spending £500 on a cheap sub or saving your money altogether.

 

If you are playing some sort of pop/rock music indoors to audiences of 20-100 people then you aren't going to need subs and if your tops are good quality active 12's then you can put all your instruments through them quite safely in the sense that they won't break. Towards the top end of that audience size and in bigger rooms subs might add something and also clean up the sound in your tops. If that is what you are trying to do a small sub might be appropriate. The driver in a sub is made differently from the driver in your tops so even a 12" sub will add something. If you are struggling to lift your tops then using small speakers as tops and adding in subs you can wheel in makes a lot of sense. If you just want to be really loud, play huge venues or a style of music that is unusually rich in lower frequencies then you are going to need a bigger PA and at some point the argument for carrying subs becomes pretty strong. There isn't some rule that says you need huge subs for every occasion or every band.

 

That all makes good sense Phil.

 

When playing function gigs, our band have been advised that pretty much most function bands augment their tops with a sub. And there's no doubt that the kick drum can really benefit from a sub.

[Bill Fitzmaurice]

4 hours ago, Phil Starr said:

This was a practical observation sparked off because I've just bought a new sub. (I know, there's me telling everyone else not to bother). We were trying to see where to set the levels relative to the tops and initially I couldn't be certain that they were actually working at all, so I turned off the tops to check. Sure enough there was a faint rumble. I turned the sub up a bit and reconnected the tops and now it was way too loud. To be fair I've noticed this many times before when using subs, a little goes a long way.

It's probably not as little as it seems to be. A look at an equal loudness chart reveals why. If the system is at 100dB at 500Hz, where our hearing is most sensitive, it has to be at 110dB at 50Hz to sound flat. That's a 10x power difference between the subs and the mains. Even when flat the mains should always sound louder than the subs, because our perception of loudness lies in the mids, not the lows. If you turn off the mains the subs shouldn't sound as loud as the mains. If they do they're too loud. The presence of subs shouldn't be obvious. What should be obvious is what happens when you turn the subs off. 

Quote

Try playing any well recorded music through the PA and switch the tops off and you'll find there is almost nothing coming out of the subs even when playing the PA at quite loud volumes.

In that case the subs aren't loud enough. Pretty much all recordings since 1990 were mixed using subs in the studio, so if switching off the subs makes no difference you're not hearing what's on the recording. To that end the better FOH guys will take two RTAs when setting up the system. One will be that of their preferred reference recording, taken at the channel strip, to see the frequency content of the recording. The other will be that of the system. They'll adjust the system EQ to approximate as closely as possible the source frequency content while compensating for the room response.

 

 

[Owen]

I teach on a Music Tech course. One of the activities is letting our DJs loose on the lunchtime crowd in the canteen. We leave the PA system up there (QSC KW122 and  KW181 Sub) and part of the activity is for them to rig it, run it and de-rig it. Sometimes I wander past the canteen when they are doing a set. It is fair to say that they have not yet grasped the concept of sub not overpowering the tops

[Dan Dare]

On 11/08/2024 at 13:20, Bill Fitzmaurice said:

It's probably not as little as it seems to be. A look at an equal loudness chart reveals why. If the system is at 100dB at 500Hz, where our hearing is most sensitive, it has to be at 110dB at 50Hz to sound flat. That's a 10x power difference between the subs and the mains. Even when flat the mains should always sound louder than the subs, because our perception of loudness lies in the mids, not the lows. If you turn off the mains the subs shouldn't sound as loud as the mains. If they do they're too loud. The presence of subs shouldn't be obvious. What should be obvious is what happens when you turn the subs off. 

 

This is great advice from Bill. The contribution of a sub should be such that you don't notice it of itself, but you would miss it if it wasn't there. I'd suggest that, in average sized venues - pubs/bars, clubs, etc - quality 10 plus horn top boxes, augmented by a suitable sub (singular in most cases), are all you need.

 

I learned this some years ago, when my band was playing a wedding. The venue was a large hotel banqueting room, holding several hundred guests. The DJ showed up with a little Nexo system - two 10+horn tops and a compact sub in a bandpass type enclosure. He was driving it with some fairly serious amplification and a Nexo DSP. It blew our much larger (and cheaper) system out of the water, not just in terms of power, but also clarity and dispersion. It sounded like a giant h-fi in comparison to our gear and it all fitted in the back of a small hatchback.

 

Smaller tops have less visual impact and are smaller, lighter and easier to carry/lift onto poles and if the worst comes to the worst and one gets knocked one over (I've seen it happen), it's less likely to kill whoever it lands on, which is a bonus.