PA Subs - questions and recommendations

[redbandit599]

Hi all

After a truly horrible on stage sound at a recent party we played (huge barn of a village hall, massive ceiling height, hard walls everywhere!) we've been thinking about having a re-shuffle of pa and monitoring.

All keen to get quieter backline and put more through the PA - maybe look at in ears (guitarists/drummer especially keen on these.)

We'll dip our toe on iem with some cheapies first.

Thinking about adding sub/subs to our pa for the first time - we run two RCF 325s at present, which are great and can handle a bit of guitar, kick and vox no problem. Plenty loud enough for what we do.

However, we also run the backline fairly high (one 212, one 112 guitar rigs and my two berg 112s) - I don't go into the PA currently - obviously this might change and I'll need to run a feed for the iems.

This band plays rock - so a solid low mid bottom end required, but not reggae/dub fat

So, sub questions ?

-Without getting into top end prices any views on decent boxes for the typical pub band/occasional hall type venues we do? Behringer b1220D caught my eye, or maybe second hand Yamaha DXS 12, Alto's any good?
- Like the look and size of 12" subs - are they any good? Do you need two?
- Is one 15" enough?
- How can you tell if your chosen sub can support your tops? ( I haven't seen this rated and am conscious our RCFs are quite big.)
- I use a Gramma Pad to isolate my cabs on wooden floors etc - is this something that is an issue (added cost) for subs too?

Thanks all!

Jason

[Phil Starr]

Hi Jason, my initial thoughts are that with your two RCF's both with 15's you want something even more capable of bass in the bottom octave than they are or there is no point, and the RCF's are pretty capable. You've also got two 12" Bergs and your subs would have to produce those levels without distorting. Again something pretty capable is needed. Single 12's aren't going to do it and probably Behringer and Alto aren't either. You've got high end kit and you'll add nothing by going this way.

Going for a couple of 15's would equal what you already have but dedicated subs would handle the deep bass better than the 15's in your RCF's. They'd also reduce the power going to the RCF's and help with thermal compression and intermodulation distortion.

If you want to keep costs down I'd go for a single sub to start with and maybe add another if you need it later. Personally I'd go for the matching RCF and maybe start looking for used rather than going for a cheap brand.

However.... Try it without any subs first. Make sure you use the bass filters on all your channels on the mixer except bass and drums, unless you have a 50Hz filter which you could use on those too. Keep the volume sensible and maybe roll off the bass a little if you are playing a really big venue. Remember the thing you are trying to achieve is better sound not more sound. Reducing volumes on stage just cleans all the muck from the backline out of the vocal mics and the better control of the PA means all your audience (more or less) get a better balanced sound. You may not need subs for anything but the once a year gig. Mine sit in the cupboard most of the year, the only run out they usually get is when we play a rowdy pub where the extra weight stops people knocking the tops over

Edited July 20, 2017 by Phil Starr

[EBS_freak]

RCF 705s are probably the best for your system. They are good capable subs and a good match for your tops. They won't pin you to the wall but they will fill out the sound nicely. What you have to remember is that they are only really there for your kick and a bit of sub bass - you don't actually want loads of deep down bass in most gig situations as thats when things get swampy. The biggest improvement you'll notice is that it takes all the energy sapping lows out of your tops and enable you tops to work more freely with the frequencies that they excel at. I would always recommend a pair with a couple of tops, better to work your subs not as hard to keep things tight in the lows without running out of puff. It all depends how loud your band is - but with a rock band, two tops, two subs sounds great and aesthetically looks better than having tripod stands.

I have experience of a band with the 12 inch RCF subs - they aren't actually too bad for what they are... they will fill out the bottom end but they won't pump out the lows at any considerable volumes. What I will say though, is that you will need some sort of compressor/limiter and at least a gate on kick drum, without, the sub will struggle to put out anything particularly useful. The big advantage is the weight and size. Dead easy to lift and transport. When you go above a 15, the weight and physical size tends to become an issue.

What I will say though, is that your cabs are fairly entry level and instead of investing in subs, you may want to consider chopping them in for some more cable front of house. I've talked about a couple of cabs across the forum and those are the RCF 735 and 745 cabs. As single 15inch cabs, they will keep up with a lot of smaller tops and sub setups of other manufacturers... check out this link - [url="http://basschat.co.uk/topic/293804-gigging-without-a-pa/page__view__findpost__p__3161870"]#164[/url] - gives you an idea about what those cabs are about. They 3 and 4 inch voice coils make a BIG difference over the competition.

Edited July 20, 2017 by EBS_freak

[redbandit599]

Cheers all -usefull stuff there.

Do you isolate your subs , or maybe just not use them on boomy floors?

[EBS_freak]

[quote name='redbandit599' timestamp='1500593074' post='3339039']
Cheers all -usefull stuff there.

Do you isolate your subs , or maybe just not use them on boomy floors?
[/quote]
No - they should couple to the floors. If the room is "boomy", you need to tune your PA to the room using a 31 band eq on the outputs.

[redbandit599]

Cool - we run a Soundcraft Ui16 mixer which is great for gates, filters and eq and the like - so that sounds doable.

Edited July 21, 2017 by redbandit599