Question on PA upgrade

joehindley103

Hi all.

We are a 4 piece cover band. Usual set up. 3 vocals in the mix and kick.

We use a pair of cheap alto 12" powered speakers over an excellent single 12" rcf sub. The sub is great considering it's a 12".

I'm considering upgrading the altos, they hiss a little and are slightly under powered. But they've served us very well.

I have a Yamaha dxr10 in my collection of gear. Should I buy another and use 2 x dxr10s as tops? Or sell the dxr10 and buy two new tops?? Maybe some more 12s. I'm unsure what to go for..

Advice appreciated 

John_P

If you like the spin of the dxr10 then  adding a second one would the easy way to upgrade - I would expect it to sound a lot better than the altos.  If it’s just vocals then a pair of 10s is ok for small venues with the sub to help out.    Adding a second sub would be more useful than changing to 12s when you already have one Yamaha imo.  

joehindley103

Good shout. I guess I'm just so used to using 12s as tops that using 10s is new territory for me. But yeh at the end of the day all the tops see is the freq above my crossover

Musicwolf

If it's for vocals then there are many live engineers, with more experience than myself, who prefer 10" to 12" for vocals.  10" + sub(s) is a good set up.  I'm also a fan of the DXR range.

joehindley103

@Musicwolf tks pal, sounds like good advice. 

Anybody had any issues running 2 subs, one mounted under each top and phase issues? I've heard that if you run 2 subs it is always best to put them together and in the centre..?

John_P

joehindley103 said:

@Musicwolf tks pal, sounds like good advice. 

Anybody had any issues running 2 subs, one mounted under each top and phase issues? I've heard that if you run 2 subs it is always best to put them together and in the centre..?

There is a bit of extra gain from putting subs together but it’s rarely practical in small venues and pubs.    One each side under the 10s will be fine.  If they have a phase switch then try it to check which setting gives the best sound but shouldn’t be an issue.    

joehindley103

@John_P cheers pal. Sounds like a plan. I'll keep my eye out for another dxr10

bob21

In principle, it's best to centre cluster subs to achieve a single source - but this is impractical in most small venues! 
When you're inside, this matters less - room reflections will help to fill in a lot of the 'gaps' where the two sources don't sum.

I wouldn't flip the polarity (phase, but not really) on one sub vs the other - it is more likely that you will cause cancellations if you start with the two sources out of phase.. Assuming they're in the same plane (like in line with the front of the stage), the likelihood is dead centre, they will sum as the distances are the same. If you reversed polarity on one box - this summation would be cancellation.. and suddenly no sub on the dance floor!

Danny1969

What desk do you have, people often think the best PA upgrade is the speakers but often your better off spending the money on a better featured desk with more control on dynamics and EQ  ..... a cheap digital desk offers a lot more control over what's actually going into your speakers. You might be surprised how good the alto's can be once things are sculptured a bit. If you already have a decent desk with enough tools to sculpture a bit already then ignore this. 

Hissing is often caused by gaining up the Altos without driving sufficient level from the desk ..... some models have enough gain to directly attach a dynamic mic but you generally want to run the speakers at 0dB and get the level driving from the desk. Which should be 0dB or +4 and the desk should be connected to the speakers with balanced XRL's ... not 2 long guitar leads or similar. Again, you probably know this anyway so ignore me if that's the case

Although I understand the principle of single point grouping subs what most of us are using in pubs and clubs aren't really subs in the sense they tend to have a lot of poke down to around 65 - 70Hz or so but are 10 or more dB down at 40hz or lower so you don't get the cancellation because you were never producing those frequencies to any great extent to begin with. Even using 4  X HK 18" subs a side outdoors the effect isn't that noticeable on our hire PA so it easier to stack the sides 

joehindley103

@Danny1969 totally agree. I run an X18 (Xair digital mixer) and can get the Altos sounding very good for budget speakers. The hiss is just audible during quiet times at rehearsals tbh. I have good gain staging, so I think it's just the nature of budget speakers. These are mark 1 altos too and run about 300w continuous so pretty low power and low spl.

Would like to upgrade at some point and have been very impressed with my single dxr10 when dialled in right

joehindley103

2 x dxr10s would be super portable too!

maltingsaudio

As Danny says about subs unless your using a big phat keyboard the average band produces bass not sub, ie frequencies below about 60 hz . The thump of a bass drum is about 70 - 85 Hz this is why the 12 “ sub is working for the  O.P, an  18” just sounds that much fuller. 

Phase issues occur basically when one speaker producing the same frequency  is moving forward when it’s pair on the other side is moving backwards. In practical terms for the pub musician this means the bass disappears and the tops sound odd when the system is out of phase. Without the need to buy expensive phase checkers etc the simple way to ensure your PA system should be in phase is just to check your cables are wired properly ie pin 1 is connected to pin 1, pin 2 to pin 2 etc

As to stacking 2 subs on each other or putting them either side of the stage it’s up to you however do bare in mind that when stacked the bass speakers will couple and radiate bass both forwards towards the audience and backwards onto the stage, how much of this depends on how efficient your subs are. This is also the reason you see at big gigs with big sub arrays, that some of them are facing away from the audience in order to phase cancel this effect. Google cardioid sub arrays for more information 

bob21

Danny1969 said:

the sense they tend to have a lot of poke down to around 65 - 70Hz or so but are 10 or more dB down at 40hz or lower so you don't get the cancellation because you were never producing those frequencies to any great extent to begin with. 

To be fair - the higher the frequency, the more noticeable the cancellations will be, as they will cover smaller areas, so people would be more likely to naturally move between a summation lobe and a cancellation lobe. In a world of 40Hz where the lobes are many metres, you tend to experience a gig in or out of it, so don't notice. Whereas getting towards the 100Hz end, you might move a few metres dancing or whatever - and that could be in and out of a cancellation.
It gets even messier at the point you're into the crossover with your main boxes (>100Hz) because then there are both phase interactions and interferences, especially if things aren't time and phase aligned perfectly!

To be fair - the vast majority of my work with subs is with large quantities of double 18s or triple 21" boxes, doing complicated spaced, cardioid, gradient or other arrays!

But in small venues you can get a significantly better result by putting both subs on one side, instead of one and one. You can use a speaker pole in that side, and a speaker stand on the other..

Against that, on a non-technical level - one sub per side makes a great pole base for a top - which saves having tripod stands; much safer for the punters..

ICBM

bob21 said:

But in small venues you can get a significantly better result by putting both subs on one side, instead of one and one. You can use a speaker pole in that side, and a speaker stand on the other..

Against that, on a non-technical level - one sub per side makes a great pole base for a top - which saves having tripod stands; much safer for the punters..

Counterintuitively, it can actually be better to use two subs as pole stands, but only run one of them. This also gives you a spare in the event of the used one going down, which isn’t that uncommon with cheaper powered subs...

ESBlonde

With subs you get an efficiency gain from something called half loading. So putting them on a solid floor, putting them together so their faces are touching and on the same plane, putting them against a wall (alongside), putting them in a corner. Very low frequencies are not directional so placement is not a worry in terms of stereo. But if they are not on a plane with the tops a timing issue can arise, this is why a phase switch can help if your crossover/DSP doesnt have a delay capability.
It is possible to create lobes and steer bass with arrays of subs when placed properly and applying delay to the outer cabinets but that's for big concerts and is largely wasted in the dog n duck. Use your ears and try different placements in different venues to get optimum results.

joehindley103

Tks for the tips all