Subwoofers with internal passive crossovers

[rumblefish]

Does anyone have a success story regarding the use of the passive internal crossovers contained in some subs like Carvin and Peavey?
We have mains that consist of a 15 and a horn (Yamaha S115V) and we have ample QSC power to power this type of sub/main setup.
Who is using this setup instead of using an electronic crossover? Am I foolish to think this setup would actually sound good?

 

[baba]

I'm confused.

Unless you mean there are Carvin and Peavey subs that take the powered signal from the amp, internally xover and send the lows to their speakers, but also send a powered high/mid signal on to a daisy chained S115V. If that's the case, you have no control over how much juice you send the subs vs the mains. Bad setup.

 

[rumblefish]

Yes, I'm talking about a signal chain that goes from mixer to a two channel RMX2450 amp to the subs, then up to the mains.
Those type of subs have an input labelled full range and an output labelled hi-pass to mains.

 

[baba]

Yes, I'm talking about a signal chain that goes from mixer to a two channel RMX2450 amp to the subs, then up to the mains.
Those type of subs have an input labelled full range and an output labelled hi-pass to mains.

So the question is, is the output labeled hi-pass sending a powered signal or not. I'm guessing not, which would mean you would need another amp between the sub and your Yamaha main. If it IS powered, that's a bad setup because you have no control over how much power goes to each.

 

[rumblefish]

It is a powered signal passed thru the sub and up to the main.
The engineers at Yamaha, Peavey, Behringer, and many others designed this setup to be a "poor mans" PA insofar that one can avoid the use and setup of an active crossover.
I know this system robs some power but I have power to spare. It is also true that you can't control the sub output level, but for some reason I'm not worried about the bass output being excessive.
I was hoping that somebody was utilizing their PA equipment this way so I could get a real world review on what to expect.
My band has been using a sound guy with a monster system but the $200 per night we're paying him is getting old.
We have enough PA gear among us to play out, except for any subs. I figured by slapping a pair of unpowered subs under our mains I'd have a system that sounds halfway decent.

 

[toobalicious]

i have done this before out of necessity. it worked. it was loud. it sounded pretty good. pretty good enough, in fact, that this tpye of setup was used until a true bi-amped (more than two amps, but only two-way) could be afforded. and ive got to tell you, that it was a night and day difference, even considering that the speakers were the exact same (and trying *not* to consider that there was more available power). you just have *so* much more control over your system, which is especially useful in boomy rooms, for example.

 

[walterw]

when a dirt DOD or behringer crossover can be scored for under $100 and would be a vast improvement, why bother?

 

[rumblefish]

when a dirt DOD or behringer crossover can be scored for under $100 and would be a vast improvement, why bother?

you're right of course.

 

[hellfleet]

It works fine for a simple PA, many are supplied like that and do the job required.
We had a simple PA in my last band that we really just used for vocals and a bit of kick, I can't remember the model but it was a Peavey set. We had a powered mixer that sent an output to the subs which then sent a powered highs signal to the tops. Obviously not as good as a big setup but very convenient, quick to setup and sounded decent.

 

[JTE]

It's for using a single power amp. You have a speaker cable from the amp to the sub, and the high-pass of the crossover goes via another cable to regular full-range cabinets. It probably works OK, but my limited experience shows that it gives all the disadvantages of dedicated subs without any of the advantages. More woof out front, but your amp is still trying to power those lows, which robs power from the critical mids that define your sound.

John

 

[Rugaar]

The BFM sub I built last fall has a passive x-over and we think it sounds great. No problem getting a thump you can hear and feel in small to medium size bars. We played an outdoor gig a few weeks ago and even then it gave us a noticeably full sound.

It really depends on the type of music you're playing, the size of the venues and your volume level. We're moderately loud but not overbearing and we mostly play small to mid size bars so it fits 99% of our needs--we'll just rent something if we need the occasional larger system. We have experimented with running the sub off one channel and the mains off the other and using our backup PM to run our monitors. It works well but it's a PITA carrying both PM's around.

Sub placement is a big part of getting a good sound. Corner loading can give up to a 6 db increase and wall loading can give up to 3 db. Having 2 subs, one under each speaker on a stick spread at opposite sides of the stage, is probably the worst possible setup you could use. (phase cancellation) You'd get much better results with a single or a stacked pair utilizing boundary loading.

my 2¢

 

[Jazzdogg]

I'm confused.

Unless you mean there are Carvin and Peavey subs that take the powered signal from the amp, internally xover and send the lows to their speakers, but also send a powered high/mid signal on to a daisy chained S115V. If that's the case, you have no control over how much juice you send the subs vs the mains. Bad setup.

I agree that this kind of setup isn't ideal, but you can add a modicum of control by placing an EQ between the mixer and the power amp.

 

[baba]

I agree that this kind of setup isn't ideal, but you can add a modicum of control by placing an EQ between the mixer and the power amp.

Agreed, that would be key with this setup.

 

[Rugaar]

Hmm...well, I just control mine with the EQ on my PM and it seems to work fine. My internal x-over is @ 150 Hz so depending on the room I just adjust my EQ sliders that are at or below that level for the sub (I typically boost them about 3-6 db for a bit more oomph) and EQ points above 150 Hz will only affect my tops. (PV PR15's) Maybe I don't have as much control as you guys are requiring but we've been using it this way for about 9 months now and have no complaints. It's been a great system for us so far and I'd recommend it for anyone looking for better sound in similar situations. (smaller bar gigs, <200 ppl, mid-power PM with a couple speakers on sticks and a couple monitors)

FYI--Here's a couple of threads from other forums, started by the guy that first built one of these. (BFM Omni 12 210 sub) He explains it much better than I can.

BFM forum

Link Removed

 

[rumblefish]

I'm the OP.
I was debating just what sub(s) and mains to order for my band.
I finally ordered 2 LM153's and a 1801NA Powered Sub from Carvin.
The LM153 is the hardshell version of the LS1503 3-way box that so many of you have adapted for bass usage.
Oh, and by the way, I bought a crossover too! A nice dbx 223.
The 223 has a mono-sum sub output that will send low frequencies to my one (for now) powered sub and the LM153's will now be powered by my QSC RMX1850HD.
Briefly, my signal chain will be as follows:


Yamaha Mixer with effects to
Behringer Compressor ( Lead Vocals channel one and Kick drum channel two.)
to a BBE Sonic Maximizer to the dbx Crossover to the power amp.

Monitors will be powered separately.
I can't wait to hear this rig.
A full review will be forthcoming in a few weeks.

 

[baba]

Much better choice! Nice work.

 

[rumblefish]

I just ordered the Carvin rig yesterday and today I got an email saying the sub was back-ordered.
So I called Carvin and was amazed by the following:

1. A real person answered, he spoke English
2.He called down to the production foreman who said
3.The sub will be built tomorrow and shipped then

I'm happy to support this company, employing American workers and providing outstanding customer support.
I think it is cool that they have people who actually know whats going on and can pinpoint a production date.

 

[walterw]

Briefly, my signal chain will be as follows:


Yamaha Mixer with effects to
Behringer Compressor ( Lead Vocals channel one and Kick drum channel two.)
to a BBE Sonic Maximizer to the dbx Crossover to the power amp.

this makes no sense.

you're going to run vocals out of one main out on the board and kick drum out of the other main out, through the compressor's left and right channels, then through the sonic maximizer (yuck!) into the crossover?

or are you going to (properly) insert that compressor on vocals and (not so properly) kick drum, then go out of the main out, through the BBE into the crossover?

what you want to do, if possible, is to pan all vocals into a subgroup (or all to one side of the main outs, with all the instruments panned to the other side, and using the mono out to go to the crossover), and insert that compressor on the group.

the compressor is nice for smoothing out vocal levels and letting you push up vocals without them peaking too much, but you don't want to compress monitors, or you'll get feedback and blow out the singers' voices.

if you insert the compressor right onto a vocal channel, that channel's monitor outs will get compressed, too.

i would lose the gimmicky BBE in favor of an actually useful graphic EQ. board goes to EQ, EQ goes to crossover.

don't bother compressing a kick drum until you get into much bigger PA systems.