Help with PA and subs

[M@23]

Hi,
My band runs a set of Peavey Impulse tops through a Peavey XR684 powered mixer, this is all the guitarist's gear. I do want to buy my own PA eventually, but short term we'd like to add a sub. I'm a bit lost as to whether I need active or passive though? Active seems like the way to go but would that pair alright with the passive tops and PA? I've no idea! Just looking at cheaper units like Alto and Behringer 12 or 15 inchers.

[Guest bassman7755]

That peavey mixer is fairly low powered so you can rule out being able to drive passive sub/top pairs with it. Yes you could add active sub(s) but you would still have a full range signal going to the tops which isn't a show stopper but not the most efficient use of the peavey amp.

If you have the 12 or 15 inch impulse tops then they are massively over specced for the mixer output power I'd be very temped to bypass the built in amp and drive those tops with a decently powerful external amp, you might find that you dont need subs.

[JTUK]

Hmmm.... subs are a tough call and need research.
Also, what comes into the equation in weight and size and this further skews the process.

Things like the Mackie thumps aren't good but it depends how discerning you can afford the be.

For me, I'd start with RCF but they aren't cheap (705's upwards) but if you only use one...~(which is 'enough' for a pub)
you start the compromise.

Active just for convenience and the light issue also means space and weight become factors.

Yam DXS12/15 are decent ... but be reasonable with your expectation...Kick and depth is fine.

If you want serious oomph and performance you will need to look further up the tree.

For a pubs, small club function, the 12' subs are ok... but not much further even with 2, IMO.

[M@23]

[quote name='bassman7755' timestamp='1467540466' post='3084328']
That peavey mixer is fairly low powered so you can rule out being able to drive passive sub/top pairs with it. Yes you could add active sub(s) but you would still have a full range signal going to the tops which isn't a show stopper but not the most efficient use of the peavey amp.

If you have the 12 or 15 inch impulse tops then they are massively over specced for the mixer output power I'd be very temped to bypass the built in amp and drive those tops with a decently powerful external amp, you might find that you dont need subs.
[/quote]

Ah, ok. That's very interesting. Thank you. The tops are the 12" ones.

[M@23]

[quote name='JTUK' timestamp='1467544566' post='3084381']
Hmmm.... subs are a tough call and need research.
Also, what comes into the equation in weight and size and this further skews the process.

Things like the Mackie thumps aren't good but it depends how discerning you can afford the be.

For me, I'd start with RCF but they aren't cheap (705's upwards) but if you only use one...~(which is 'enough' for a pub)
you start the compromise.

Active just for convenience and the light issue also means space and weight become factors.

Yam DXS12/15 are decent ... but be reasonable with your expectation...Kick and depth is fine.

If you want serious oomph and performance you will need to look further up the tree.

For a pubs, small club function, the 12' subs are ok... but not much further even with 2, IMO.
[/quote]

Food for thought, thanks. In my old band we had a nice Soundcraft mixer and decent power amp, which is now unused. Maybe I'd be better buying the others and of that and getting a sub to go with that setup.
Not too fussed on the size and weight of the sub, without getting ridiculous.

[leftybassman392]

Another way you could do it:

Any decent active sub should have a built-in X-over. Bypass the mixer power section & run a (stereo) line-level signal to the sub. Use the highpass O/Ps from the sub to an external (stereo) power amp that can then feed the tops. PA systems normally run in mono so even though you're using a stereo signal path it should be fine. Or you could just run it in mono anyway and feed the tops as normal with the power amp set up for mono operation. I would routinely go stereo but that's just me I suspect.

[EBS_freak]

If you don't run a monitor on the existing setup, I would look to go powered for your PA and with the PA you mention above, use the Aux (monitor) feed into a powered sub.

[M@23]

[quote name='EBS_freak' timestamp='1467639832' post='3085043']
If you don't run a monitor on the existing setup, I would look to go powered for your PA and with the PA you mention above, use the Aux (monitor) feed into a powered sub.
[/quote]

Nice one mate. I wondered if I could plumb it in that way. Cheers.

[leftybassman392]

Just a thought:

It's your system and your money, but the whole point of subs is to take the extreme bottom end away from the tops. If you just plumb your sub into the Aux out then you're not doing that (and hence are losing the whole reason for having it at all); and unless you set the system up very carefully you could get phase cancellation as well (which will have the net result of actually losing deep bass output instead of enhancing it).

Do you want the sub to do the job it's there to do, or do you just want to be able to tell people you have a sub in your system?

Edited July 5, 2016 by leftybassman392

[mrtcat]

[quote name='leftybassman392' timestamp='1467699165' post='3085379']
Just a thought:

It's your system and your money, but the whole point of subs is to take the extreme bottom end away from the tops. If you just plumb your sub into the Aux out then you're not doing that (and hence are losing the whole reason for having it at all); and unless you set the system up very carefully you could get phase cancellation as well (which will have the net result of actually losing deep bass output instead of enhancing it).

Do you want the sub to do the job it's there to do, or do you just want to be able to tell people you have a sub in your system?
[/quote]

I would say that taking the bottom end out of the tops is one of the advantages but not the main reason for having a sub. A sub can reproduce low end far better than a full range speaker so that is its main benefit. If there's an eq on main output just roll of anything below 80 hz in the main mix and that shouldn't affect the aux send to the sub. Any decent sub will have a phase switch.

Edited July 5, 2016 by mrtcat

[leftybassman392]

Actually there's several benefits to using a x-over with a sub (and while I'm at it - and with my pedant's hat on - a phase switch doesn't eliminate phase issues, it justs shifts them to a different frequency so they - hopefully - don't get in the way so much), but as I say it's your system bud. If it works for you then it's job done.

Edited July 5, 2016 by leftybassman392

[Phil Starr]

[quote name='leftybassman392' timestamp='1467699165' post='3085379']
Just a thought:

It's your system and your money, but the whole point of subs is to take the extreme bottom end away from the tops. If you just plumb your sub into the Aux out then you're not doing that (and hence are losing the whole reason for having it at all); and unless you set the system up very carefully you could get phase cancellation as well (which will have the net result of actually losing deep bass output instead of enhancing it).

Do you want the sub to do the job it's there to do, or do you just want to be able to tell people you have a sub in your system?
[/quote]

This is right.

Essentially there is little point in sending the full range signal to the tops and the bins other than to get a 'disco bass' effect. With all the bass going to the tops they are still going to overload at modest levels and at that point turning the subs up will only end up giving you an artificial sounding response curve.

you can't use the 80Hz filters either as you would need an unfiltered signal to the bins which you cannot do with your mixer.



You need a crossover somewhere in the system. Either buy a crossover, look for a mixer with a crossover to a sub built in, look for an active sub with a stereo crossover built in or buy an amp with a crossover built in.

[JapanAxe]

I'd go back a bit further and ask why do you want subs? If you are putting bass guitar, bass drum or keyboards through the PA, fine, but if not I would question their usefulness.

[M@23]

[quote name='JapanAxe' timestamp='1467706922' post='3085443']
I'd go back a bit further and ask why do you want subs? If you are putting bass guitar, bass drum or keyboards through the PA, fine, but if not I would question their usefulness.
[/quote]

Yep, that's it. We want to put kick and keys through and perhaps a touch of bass as and when.

[M@23]

[quote name='Phil Starr' timestamp='1467706656' post='3085438']


This is right.

Essentially there is little point in sending the full range signal to the tops and the bins other than to get a 'disco bass' effect. With all the bass going to the tops they are still going to overload at modest levels and at that point turning the subs up will only end up giving you an artificial sounding response curve.

you can't use the 80Hz filters either as you would need an unfiltered signal to the bins which you cannot do with your mixer.



You need a crossover somewhere in the system. Either buy a crossover, look for a mixer with a crossover to a sub built in, look for an active sub with a stereo crossover built in or buy an amp with a crossover built in.
[/quote]

Thanks for that. To be honest, I'm probably going to knock the idea on the head and put that money towards buying my own PA. I thought it may be a quick fix and am easy addition, but maybe not as simple as initially thought.

[JTUK]

[quote name='M@23' timestamp='1467722911' post='3085624']
Yep, that's it. We want to put kick and keys through and perhaps a touch of bass as and when.
[/quote]

Depending how good the tops are...

Good tops will just about take a kick and still give good vox at a decent level and maybe a keys bleed too...ie, he still runs backline. No bass, IMO.
Something like KW112 will do this qwell as they are wooden boxes and are more bass capable.

Composite will have a slight sound trade-off.. as any demo in large shops like Andertons with a P.A demo room will show you.
You might decide you can live with that trade-off, but we talking about modern designs like RCF 712, Yam DX12 and QSC's..

To be frank, I doubt PV are in that league...and depending how hard a life they've had.
IMO..PV score well for abuse..not sound, typically.

If you are 'happy with your P.A as is sound-wise..then get a active sub that is a bit future proof, and run from an Aux/mon send.

The Yam 12" subs are smallish and light...and cheap. You'll add another one soon and upgrade the tops to active 10/12's.

If always planning to run subs, then good quality 10's are the the way to go, IMO... the only reason I'd go 12's would be for the extra low end
and you have subs for that anyway.

Something like the above allows you to upgrade/upscale piece by piece as the funds allow...#

Or bite the bullet, buy a quality rig with subs for £2k or so and sub it out to the band.

You are basically going to replace everything you have atm anyway..

[M@23]

[quote name='JTUK' timestamp='1467723789' post='3085629'].

Something like the above allows you to upgrade/upscale piece by piece as the funds allow...#

Or bite the bullet, buy a quality rig with subs for £2k or so and sub it out to the band.
[/quote]

Thanks JT. Very helpful post. The above is the decision to be made I think. I might actually change track and just start acquiring my own PA piece by piece. The guitarist's PA has had a hard life. If I'd have invested years ago I'd have had my money's worth out of it easily, so maybe now it's time to focus on that. I'm doing more gigs and functions where I put the band together for whatever specific event so I should really have my own setup instead of borrowing.

[EBS_freak]

Just to clarify, the HPF on the first six channels on the XR684 is set at 80Hz - so that will take a whole world of hurt of your tops.

The monitor send is full range and if you have a powered sub, chances are it will have a crossover on it anyway. This means your sub will take care of typically everything sub 100hz.

Running the sub off the monitor is only like running a sub off an aux and is far from unusual in the pro world. Just because it's not usual in a pub band doesn't mean it's not a viable solution - in fact, in pro PA it's the preferable solution. By having control of the monitor send you explicitly keep vocals out of the subs which is infinitely more useful at keeping low end rumble out of the subs than running crossovers. (Better that nothing unwanted be present feeding into the subs that doesn't have to be right?)

Edited July 5, 2016 by EBS_freak

[JTUK]

[quote name='M@23' timestamp='1467745489' post='3085887']
Thanks JT. Very helpful post. The above is the decision to be made I think. I might actually change track and just start acquiring my own PA piece by piece. The guitarist's PA has had a hard life. If I'd have invested years ago I'd have had my money's worth out of it easily, so maybe now it's time to focus on that. I'm doing more gigs and functions where I put the band together for whatever specific event so I should really have my own setup instead of borrowing.
[/quote]

Don't forget the hire-out then..
You'll be carrying it, setting it up and breaking it down etc etc..

Any gig over £250 gets a hire fee, they chip in on set-up/break-down and you'll be running a kitty..

[Phil Starr]

[quote name='EBS_freak' timestamp='1467745763' post='3085896']
Just to clarify, the HPF on the first six channels on the XR684 is set at 80Hz - so that will take a whole world of hurt of your tops.[/quote]

Spot on. Keeps all the subsonic crap picked up by the stage mics out of the mains and really protects them from over excursion and you won't need or hear the sub 80Hz stuff anyway.

[quote name='EBS_freak' timestamp='1467745763' post='3085896']The monitor send is full range and if you have a powered sub, chances are it will have a crossover on it anyway. This means your sub will take care of typically everything sub 100hz.[/quote]

My apologies, that's right about the HPF filter, I took a brief look at the manual and hadn't spotted that it works on the bus (all the first six channels at once) rather than on each input channel. It's an unusual arrangement but I should have spotted it.

[quote name='EBS_freak' timestamp='1467745763' post='3085896']Running the sub off the monitor is only like running a sub off an aux and is far from unusual in the pro world. Just because it's not usual in a pub band doesn't mean it's not a viable solution - in fact, in pro PA it's the preferable solution. By having control of the monitor send you explicitly keep vocals out of the subs which is infinitely more useful at keeping low end rumble out of the subs than running crossovers. (Better that nothing unwanted be present feeding into the subs that doesn't have to be right?)
[/quote]

Yeah I had thought of inputting something about Aux Fed Subs but given the nature of the question decided it was possibly overkill. For those who don't know it is a well tried and tested method of running a PA. To get the best out of it as a system you kind of need to understand a bit about sound and (for me) a separate mix for the subs and mains.

For anyone interested in Aux Fed Subs this is an interesting article [url="http://www.prosoundweb.com/article/a_detailed_explanation_of_the_aux_fed_subwoofer_technique/"]http://www.prosoundw...ofer_technique/[/url]

I think the OP is moving towards building up a decent PA (those Peavey mains aren't great) so that's a good decision but he could try what you've been suggesting all along.

Edited July 6, 2016 by Phil Starr

[EBS_freak]

That's a great article that really puts forward the concept concisely and clearly.

For the OP - it may be worth going for some Subs in the short term - but if you are looking to invest in a decent PA, I would forget this setup altogether, save your money and start with some killer tops.

Something like some RCF 735/745 will serve you well - and you may find they actually develop enough bass for you to reconsider the need for if you even need to even start carrying around subs. I know some guys who are using these speakers with great results and the sound is certainly not lacking in bass. Obviously, the larger the venue you go, the more bottom end you are going to need - and thats when you need to start adding more speakers, and/or ideally subs.

An affordable digital desk - something like a XR18, DL804, Ui... will help you get the most out of those speakers too. Gating and compressing (especially on the kick for example), will give you a lot more headroom for starters and help you get even more out of your cabs.

Skimping on PA - especially cabs - is a false economy.

Good luck!

Edited July 6, 2016 by EBS_freak

[M@23]

Cheers gents. All very helpful and insightful info. Need to start doing a bit of reading I think before jumping in.

[ivansc]

My 2c

I play in a rather loud 60s band.
We routinely run with a pair of 12" RCF tops and a powered mixer, piano and guitars through the PA, plus a kick mic and an overhead for the drummer.
I run a Little Mark III and an efficient 600watt 4ohm 2x10.
Very easy to get buried if I dont have my bass through a sub.
On the other hand I own two powered subs, one is a 15" 500 watt studiospares jobbie that weighs a ton and the other is a Voce Systems 12" 600 watter.
I have only ever used both subs when we played a 1800 seater Xmas ball at an indoor bowls venue & that was with my own 1000 watt Dynachord powered mixer and speakers in tandem with the existing 1000 watter!
Sometimes you really dont need that much in the sub area, really. P.S. Anyone in the Huntingdon/Cambridge UK area looking for a sub, I am thinking about maybe selling one or both of mine cheaply.

[M@23]

After all that, the guitarist just text to say he has picked a Mackie PPM1008 - which came through his shop. It has a 'Main Sub' out apparently, so I'm back to the original plan of buying one or two 12 inch subs to try! Hopefully if that all goes to plan then new tops will follow.

Edited to ask...
Is it worth picking up a couple of Behringer BD1200 secondhand for 350 or so, or spending that on one better sub?

Edited July 8, 2016 by M@23

[JTUK]

You'd have to hear it..but I'd be thinking it would be quite wolly and undefined, which exactly what the Mackie was.
Not a fan of Mackie these days anyway but respect the price point.

Subject to hearing, I think you need to hear a crap sub... and then you'll not waste your money.