Powered PA Speaker As Bass Amp

[stewblack]

I know this is a thing, I get why folk opt for it, understand the implications and applications. 

However.... 

How do you know that a powered monitor / pa speaker is suitable for bass guitar? 

Obviously without buying it first. Do you just read the spec? And if it can handle below a certain number of hz then it's good to go? 

Or is there something else sets the suitable ones apart?

I notice one BCer uses a QSC k12 whereas another uses 2 of them. This may not mean much, after all I use rigs way bigger than they need to be. 

So, what do you look for when sizing these things up? 

[Silvia Bluejay]

Is it not so much the specs, but the way the drivers deal with them? I seem to remember noticing that on PA speakers highs and mids are usually somehow 'favoured' over lows, even if the specs say that the delivered range starts at, for instance, 45 or 50 Hz. So if you use one for just bass, it doesn't sound as good as a 'proper' bass speaker, even when the cone is the same size.

That's why it makes a difference when a (sub)woofer is added to the PA system, in those cases where the bass doesn't have its own rig.

Looking forward to hearing the experts, of course.

[Bill Fitzmaurice]

You can't go by the specs, as they're far too incomplete to be of any real use. I can say that the vast majority of powered PA, even those loaded with 15s, are made to work best in the vocal range, with the lows handled by subs. They also don't have pre-amps voiced for bass. That makes them very much a try before you buy proposition.

[Baloney Balderdash]

I am about to make my bass rig mobile, and I have pondered on at some point buying an active PA speaker, just to have something in place of an amp.

The one I have in sight is the ralatively cheap The Box PA 502 A.

Judging from the specs at least it ought to be be able to handle bass fairly well.

15" 300W woofer and 100W tweeter, with a frequency response that claims to be 35Hz to 20kHz (-10dB)/40Hz to 18kHz (-3dB), which should mean that as long as you will not need to go lower than the low E of a standard tuned 4 string bass, it should reproduce it quite well.

That's in theory though.

But if these numbers are legit some dedicated bass cabs in existence got worse low end response.

 

Here's a link to it from Thomann:

https://www.thomann.de/gb/the_box_pa502a_aktives_fullrangesystem.htm?ref=intl&shp=eyJjb3VudHJ5IjoiZ2IiLCJjdXJyZW5jeSI6IjQiLCJsYW5ndWFnZSI6ImVuIn0%3D 

 

And here's a link to the manual:

https://images.static-thomann.de/pics/atg/atgdata/document/manual/160815_c_160815_r2_en_online.pdf

 

 

Edited August 4, 2020 by Baloney Balderdash

[Phil Starr]

It's no different than choosing a 'proper' bass speaker really. If you buy something cheap it's going to have cheap drivers in it and they won't work very well. Spend more and there is no reason why a bass driver in a PA speaker won't handle bass as well as a bass guitar speaker. After all it's only got to produce the bass at a level to balance with the rest of the band which is what you should be doing anyway.

Equally a 1x10 bass driver isn't enough for most of us and a 10" PA speaker isn't going to be magically louder. If you normally go out with a 2x12 then 2 12"PA speakers are going to be what you need. Again a 12" Barefaced is more likely to be enough compared with a lesser speaker and a 12" QSC is likely to blow a lot of cheaper speakers away. On top of this it's a good idea to look at what others have done loads of us have gone for the QSC or the RCF PA speakers and so you can be confident that they'll do the job.

[Bill Fitzmaurice]

Those specs are way shy of being useful. For instance, while it may be -10dB at 35Hz, what is the 1w/1m SPL? 98dB? 88dB? That's critical information which is lacking. I can say just by looking at it that it won't have a big low end, because  the trapezoid shape causes the box volume to be too small to have a big low end.

[Dan Dare]

I think Bill's absolutely right. If you get a large enough PA cab to give you the low end you need, it will probably be as large as or even larger than your bass rig, so nothing gained.

I also find that putting my bass through a PA results in a clean, but rather characterless sound, no doubt because I'm used to the baked in tone of bass rigs (they all have that, even when set supposedly 'flat').

[stewblack]

1 hour ago, Dan Dare said:

I think Bill's absolutely right. If you get a large enough PA cab to give you the low end you need, it will probably be as large as or even larger than your bass rig, so nothing gained.

I also find that putting my bass through a PA results in a clean, but rather characterless sound, no doubt because I'm used to the baked in tone of bass rigs (they all have that, even when set supposedly 'flat').

So, am I asking the wrong question? Is the FRFR cabs people speak of a whole different thing? I thought they were just powered monitors (but good ones). 

[Moos3h]

I've just ordered a Yamaha DBR12 for sort of this purpose. We are now 'ampless' as a band so I'll use the Yamaha as a monitor/amp when I can't be arsed with the IEM setup. Main signal will still go via the FOH but should mean I hear more of what the tone sounds like to the audience - that's the plan, anyway...

[Bill Fitzmaurice]

FRFR means full range flat response. Ideally that's what PA is, but you can't get flat response to low frequencies at stage volumes without either the cab being large or there being a separate sub.

[stewblack]

40 minutes ago, Moos3h said:

I've just ordered a Yamaha DBR12 for sort of this purpose. We are now 'ampless' as a band so I'll use the Yamaha as a monitor/amp when I can't be arsed with the IEM setup. Main signal will still go via the FOH but should mean I hear more of what the tone sounds like to the audience - that's the plan, anyway...

Good luck 🤞 

[Moos3h]

12 minutes ago, stewblack said:

Good luck 🤞 

Cheers! I figure it will almost certainly be loud enough, it's just whether it will be deep enough to give the feel of the bass...I suspect that is where it will struggle, but it's better than what I do now (one IEM, one out so I can hear 'the room').

 

What I was HUGELY fed up of was huge bass speakers that you could hear from Grimsby, but stood right next to it, I may as well have unplugged...having a monitor firing back at me just for the bass tone should cure that at least.

[stewblack]

15 minutes ago, Moos3h said:

Cheers! I figure it will almost certainly be loud enough, it's just whether it will be deep enough to give the feel of the bass...I suspect that is where it will struggle, but it's better than what I do now (one IEM, one out so I can hear 'the room').

 

What I was HUGELY fed up of was huge bass speakers that you could hear from Grimsby, but stood right next to it, I may as well have unplugged...having a monitor firing back at me just for the bass tone should cure that at least.

Makes perfect sense to me. Only time I've played with no amp (long story short; multi band event, told not to bring one, band before us had supplied bass rig up till that point, but, understandably had never planned to leave it all night) I was mixed into a floor wedge along with much else. 

It wasn't great but I could make out what I was playing. Difference with your plan is you have control over the level, tone, mix etc. I had 10 seconds with a harried sound guy! 

[Bill Fitzmaurice]

2 hours ago, Moos3h said:

What I was HUGELY fed up of was huge bass speakers that you could hear from Grimsby, but stood right next to it, I may as well have unplugged..

That's the fault of the room, not the speaker. Reflections off nearby walls and the ceiling create low frequency null zones. If you're standing in one of those null zones the bass will disappear.  When you move away from the null zone the true output of the cab will be heard.

[Silvia Bluejay]

And longer wavelengths such as bass frequencies are best appreciated at a distance anyway.

[Tubster]

My experience differs slightly. Plugged borrowed bass directly into a Yamaha DXR 12 . Sounded like absolute a..e,! So bailed and used a keyboard setup instead. I was hugely surprised.

scenario 2 - plugged Yammie 434 directly into desk and out via power amp to 4 modern passive ev12s. Equally  wimpy and hideous. Both above situations were done in huge rush.

Scenario 3 - used Markbass mini 801 super tiny one with single 8 inch speaker and then DI out to desk into same PA as scenario 2. Absolute night and day - fabulous full fat sound.

So indicates some kind of preamp or front end is needed before it reaches the PA speaker. Maybe an active bass might have had better luck? 

All of the above was done in incredible haste and with operatives with zero to nil experience of dialling in a decent bass sound. 

[jassbass]

A decent powered pa speaker can do a good job but i woukd definitely use a preamp 1st

I use an Ebs microbass preamp pedal then to a rcf 712 or even 310 and sounds better than alot of backline ive had.I must say only tried in the house but seemed good

[Nobatron]

It depends on the PA speaker really.

You see a lot of PA speakers, usually 15", aimed at DJs which boast a decent low end extension but really when you hear them they have a couple of notes that resonate low down so they'll push out a kick drum to punch you in the chest but don't do much in terms of intelligible low end that you'd need for a bass guitar.

Brands like QSC, EV and on the upper end d&b, L-Acoustics, Nexo, etc make speakers that would do a better job but if you look at the specs of their 12" speakers they tend to publish more realistic ratings which don't rate them down as low as the cheaper ones. Really you'd expect to use these with a sub for the low end.

Most gigs I do these days I have PA support for bass. Typically if the system has subwoofers I'll go through the PA and if not I won't. I'd apply the same thinking to a bass amp. I'd rather use a system which I know will replicate the frequencies I need and a bass amp is designed for this so I know it will.

[skidder652003]

I've found that even my RCF 315 wedge monitor not really capable of giving me the volume and clarity I'd like onstage, I'm seriously reconsidering going back to in ears, or even turning my bass rig around and facing me!

[stewblack]

This is fascinating stuff, thank you to everyone who has contributed to the discussion. 

My knowledge has deepened, however I am a little confused. A strong body of opinion suggests PA cabs/ powered monitors may not be great for bass, while others go out gigging with them quite happily. 

Or is it those who gig with them only use them for monitoring and not as backline? 

[Nobatron]

I'm sure you could absolutely put together a useable rig with PA components but I think it comes down to what you're going for.

A QSC K12.2 is currently £795 from Thomann. Within the same budget you could get a really nice combo or head / cab setup from Markbass, EBS, GK, etc. K12s are great but they're not going to give you as good a bass response as the dedicated rig which is specifically voiced for bass guitar.

Also you wouldn't be able to plug a bass direct into a K12 so you'd need to buy a preamp of some kind to put in front of it so that's another expense unless you have one already.

However if what you actually want is a stage monitor for you to monitor the band as well as yourself then the K12 is going to be the better option. That way you would DI into your sound desk which would handle the preamp duties and output that to the monitor. But for me a wedge instead of an amp is a compromise, on the gigs I've done with wedges and no amp I've been left wanting. In ears is a different kettle of fish though.

Another use case for the monitor would be if you wanted something you could use for keys or other instruments as well.

[jrixn1]

I suppose it depends which Markbass combo; a CMD121H is £700 but a K1 is £1300.  I replaced my Shuttle 9.2 + Big Baby 2 rig (cost £1500 new) with an RCF 732-A (cost £650 new), and I don't find the RCF's bass response lacking in any way; in fact, with a five-string bass, I high-pass it at 60Hz.

[jrixn1]

1 hour ago, stewblack said:

My knowledge has deepened, however I am a little confused. A strong body of opinion suggests PA cabs/ powered monitors may not be great for bass, while others go out gigging with them quite happily. 

Or is it those who gig with them only use them for monitoring and not as backline? 

I think the question shouldn't be phrased as traditional rig vs powered speaker; it's more about low-quality gear vs high-quality gear.  A £350 powered PA speaker won't be good as a £1000 bass combo.

I use a powered speaker for either monitoring or backline, depending on the gig situation.

[Phil Starr]

1 hour ago, stewblack said:

This is fascinating stuff, thank you to everyone who has contributed to the discussion. 

My knowledge has deepened, however I am a little confused. A strong body of opinion suggests PA cabs/ powered monitors may not be great for bass, while others go out gigging with them quite happily. 

Or is it those who gig with them only use them for monitoring and not as backline? 

I think it is just about two equally good ways of doing the same thing. You can either regard your bass amplification as part of your sound and go for something that sounds really good to your ears because the built in shaping of the amp adds something. Alternatively you can go for something with a neutral sound but shape it up with a bit of EQ to get the sound you want. I've a couple of RCF10's that I use sometimes and I tend to use them with my Zoom B1 to give a sound I'm happy with. More frequently I use a 2x10 bass cab which is absolutely not flat but which I also like. 

[Happy Jack]

We are, aren't we? We're actually going to re-do the entire FRFR topic less than a year after it ran to 97 pages (or whatever).